Am J Physiol Cell Physiol Information on EB 2010
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
 QUICK SEARCH:   [advanced]


     


Am J Physiol Cell Physiol 292: C987-C995, 2007. First published August 30, 2006; doi:10.1152/ajpcell.00406.2006
0363-6143/07 $8.00
This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow All Versions of this Article:
292/3/C987    most recent
00406.2006v1
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in Web of Science
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Web of Science (8)
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Kryczek, I.
Right arrow Articles by Zou, W.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Kryczek, I.
Right arrow Articles by Zou, W.

INVITED REVIEW

Stroma-derived factor (SDF-1/CXCL12) and human tumor pathogenesis

Ilona Kryczek,1 Shuang Wei,1 Evan Keller,2 Rebecca Liu,3 and Weiping Zou1

Departments of 1Surgery, 2Urology, and 3Obstetrics and Genecology, University of Michigan, Ann Arbor, Michigan


    ABSTRACT
 TOP
 ABSTRACT
 EXPRESSION OF CXCL12 IN...
 REGULATION OF CXCL12 EXPRESSION...
 CXCL12, TUMOR PROLIFERATION, AND...
 CXCL12 AND TUMOR VASCULARIZATION
 CXCL12 AND TUMOR METASTASIS
 CXCL12 AND CANCER STEM...
 CXCL12 AND TUMOR...
 CXCL12 AND THERAPEUTIC...
 REFERENCES
 
The chemokine stroma-derived factor (SDF-1/CXCL12) plays multiple roles in tumor pathogenesis. It has been demonstrated that CXCL12 promotes tumor growth and malignancy, enhances tumor angiogenesis, participates in tumor metastasis, and contributes to immunosuppressive networks within the tumor microenvironment. Therefore, it stands to reason that the CXCL12/CXCR4 pathway is an important target for the development of novel anti-cancer therapies. In this review, we consider the pathological nature and characteristics of the CXCL12/CXCR4 pathway in the tumor microenvironment. Strategies for therapeutically targeting the CXCL12/CXCR4 axis also are discussed.

migration; immune suppression; tumor angiogenesis; tumor metastasis; stem cells


STROMA-DERIVED FACTOR 1 (SDF-1, or CXCL12) was initially cloned by Tashiro et al. (135) and later identified as a growth factor for B cell progenitor cells, a chemotactic factor for T cells and monocytes, and in B cell lymphopoiesis and bone marrow myelopoiesis. CXCL12 is a 68-amino acid small (8 kDa) cytokine that belongs to the CXC chemokine family. CXCL12 is expressed in two isoforms, SDF-1{alpha} and SDF-1beta, from a single gene that encodes two splice variants. The two encoded proteins are almost identical, except for the last four amino acids of SDF-1beta, which are absent in SDF-1{alpha}. Biological and functional differences between the CXCL12 isoforms have not been described. The CXCL12 gene is mapped in chromosome 10, whereas most of the other genes encoding CXC chemokines reside on chromosome 4 (126).

It was long thought that CXCL12 bound exclusively to CXCR4 and that CXCR4 was its sole receptor. However, CXCR7 was identified as another receptor for CXCL12 at the end of 2005 (4). The immunological activities of CXCL12/CXCR4 have been largely studied in the context of immune cell trafficking. Interestingly, both CXCL12 and CXCR4 knockout mice are embryonic lethal, with any surviving pups dying within an hour of birth, suggesting that the CXCL12/CXCR4 pathway mediates multiple biological activities (93, 132). The lethal effect of CXCL12 and CXCR4 knockout is related to the pleiotropic activity of CXCL12 and CXCR4, which are critical for hematopoietic, neural, vascular, and craniofacial organogenesis (80, 93, 132).

In this review, we focus on the pathological nature and characteristics of CXCL12 in the tumor microenvironment. We discuss therapeutic strategies of targeting the CXCL12/CXCR4 pathway in the treatment of human cancer.


    EXPRESSION OF CXCL12 IN HUMAN TUMOR ENVIRONMENT
 TOP
 ABSTRACT
 EXPRESSION OF CXCL12 IN...
 REGULATION OF CXCL12 EXPRESSION...
 CXCL12, TUMOR PROLIFERATION, AND...
 CXCL12 AND TUMOR VASCULARIZATION
 CXCL12 AND TUMOR METASTASIS
 CXCL12 AND CANCER STEM...
 CXCL12 AND TUMOR...
 CXCL12 AND THERAPEUTIC...
 REFERENCES
 
CXCL12 was initially cloned from bone marrow stromal cells (135). Strikingly, CXCL12 is widely expressed in various organs including heart, liver, brain, kidney, skeletal muscle, and lymphoid organs. Vascular endothelial cells, stromal fibroblasts, and osteoblasts are the major cellular source for CXCL12 in these organs (36, 59, 99, 102, 157). Interestingly, high levels of functional CXCL12 were first reported in human ovarian cancer in 2001 (65, 119, 156). Subsequent studies documented a strong correlation between CXCL12 expression and bone marrow and lymph node metastasis of breast (90) and prostate cancer (133). Interest in the role of CXCL12/CXCR4 in tumor pathology was provoked by these studies. In addition to ovarian cancer, CXCL12 expression is reported in breast cancer (3, 57), glioblastoma (6, 106), pancreatic cancer (64, 81), prostate cancer (23, 131), thyroid cancer (51), and many other human tumors (Table 1). This list continues to grow, following the current interest of studying chemokines and chemokine receptors in human tumor pathogenesis.


View this table:
[in this window]
[in a new window]

 
Table 1. CXCL12 expression in human nonhematological tumors

 
Tumor stroma is an active element of tumor microenvironment. Recently, it was shown that in breast cancer, activated stroma fibroblasts produce CXCL12 (1, 96) and contribute to tumor vascularization by endothelial stem cell attraction (96). It also has been suggested that CXCL12 is involved in prostate epithelial cell transformation induced by aging fibroblasts (8). Although CXCL12 does not directly induce transformation, CXCL12 may provide conditions supportive of a transforming event. Therefore, stroma and cancer cells, two main components of tumor microenvironment, can produce CXCL12.


    REGULATION OF CXCL12 EXPRESSION IN HUMAN TUMOR
 TOP
 ABSTRACT
 EXPRESSION OF CXCL12 IN...
 REGULATION OF CXCL12 EXPRESSION...
 CXCL12, TUMOR PROLIFERATION, AND...
 CXCL12 AND TUMOR VASCULARIZATION
 CXCL12 AND TUMOR METASTASIS
 CXCL12 AND CANCER STEM...
 CXCL12 AND TUMOR...
 CXCL12 AND THERAPEUTIC...
 REFERENCES
 
Strikingly, regulation of CXCL12 expression in the tumor microenvironment has been poorly studied. It has been reported that estradiol activates estrogen receptor and induces the production of CXCL12 by tumor cells (39). We have observed that hypoxia triggers CXCL12 expression by primary human ovarian tumor cells (66) and prostate tumor cell lines (unpublished data). Hypoxia-inducible factor (HIF)-1 is the central mediator of the cellular response to hypoxia (123). In the promoter region of CXCL12 gene, there are two potential HIF-1-binding sites, termed HBS1 and HBS2. It is thought that the HBS1 region is responsible for HIF-1-dependent induction of CXCL12 synthesis in endothelial cells (16). Hypoxia also induces CXCL12 expression in synovial fibroblasts (48) and hematopoietic stem cells (HSC) (16). These data suggest that hypoxia may be a common condition to induce CXCL12 expression. Altogether, CXCL12 is widely expressed in various human tumors. CXCL12 expression would be regulated by hypoxia-and hormone-triggered signal pathway.


    CXCL12, TUMOR PROLIFERATION, AND SURVIVAL
 TOP
 ABSTRACT
 EXPRESSION OF CXCL12 IN...
 REGULATION OF CXCL12 EXPRESSION...
 CXCL12, TUMOR PROLIFERATION, AND...
 CXCL12 AND TUMOR VASCULARIZATION
 CXCL12 AND TUMOR METASTASIS
 CXCL12 AND CANCER STEM...
 CXCL12 AND TUMOR...
 CXCL12 AND THERAPEUTIC...
 REFERENCES
 
There is evidence to demonstrate that CXCL12 can modulate tumor cell proliferation and survival. Sehgal et al. (121) provided the first evidence for mitotic CXCL12 activity in human tumors, where transfection of an antisense RNA that blocks CXCR4 translation inhibited glioma cell proliferation. Later, Barbero et al. (6) confirmed that glioma cell proliferation can be induced by exogenous CXCL12. CXCL12-dependent proliferation correlated with the activation of ERK1/2 and AKT pathways. Both these pathways are known to be involved with the transduction of proliferative signals in normal and tumor glial cells (128).

In addition to glioma cells, CXCL12 can induce proliferation of several tumor cell lines, including ovarian carcinoma (120), small cell lung cancer (100), prostate cancer(23), neck squamous cell carcinoma (58), and pancreatic cancer (81). Mechanistically, CXCL12-dependent cell proliferation is linked to ERK activation (23, 60, 81, 100, 120).

CXCL12/CXCR4-mediated tumor cell proliferation may be regulated through estrogen signaling (39). About 60% of human ovarian and breast cancers are hormone dependent and overexpress the progesterone and/or estrogen receptors (55, 77). Hall et al. (39) demonstrated that CXCL12 was required for estrogen-induced proliferation of both breast and ovarian cancers.

CXCL12 also can regulate tumor cell apoptosis. CXCL12 activates NF-{kappa}B (45), which in turn inhibits radiation-induced tumor necrosis factor-{alpha} (TNF-{alpha}) production and tumor apoptosis (140). Moreover, activation of NF-{kappa}B can sensitize cancer cells to CXCL12 stimulation through upregulation of CXCR4 expression (45, 70).

Many chemotherapeutic drugs exert their effects by inducing apoptosis in the targeted cell population. CXCL12 can protect tumor cells from drug-induced apoptosis directly through the activation of antiapoptotic pathways but also indirectly by modulating the adherence of cancer cells. For example, CXCL12 mediates adhesion of small-cell lung cancer cells (SCLC) to marrow stroma cells and protects SCLC against etoposide-induced apoptosis. The protective effect could be antagonized by CXCR4-specific inhibitors as well as by blocking integrin {alpha}4 (41, 124). Similar observations are found in myeloma (44), glioma cells (138), and head and neck cancer (91). In support of this observation, CXCL12 activates integrin {alpha}4 on vascular endothelial cells and protects plasmacytoid dendritic cell from apoptosis in patients with ovarian cancer (156). Thus CXCL12 signals may be implicated in tumor cell proliferation and survival.

The role of CXCL12 in controlling tumor growth and survival has been demonstrated in in vitro models. However, in some cases, the in vitro observations are not fully supported by in vivo experimental data. For example, glioma cells proliferate in vitro in response to CXCL12 (6); however, they proliferate in vivo independently of CXCL12 (106). Furthermore, tumor cells exhibit low proliferation in glioblastoma tissues, where high levels of CXCL12 expression are observed. Analysis of CXCR4/CXCL12 localization revealed an association of both CXCL12 and CXCR4 with regions of necrosis and angiogenesis (106), suggesting a role of CXCL12 in angiogenesis in vivo.


    CXCL12 AND TUMOR VASCULARIZATION
 TOP
 ABSTRACT
 EXPRESSION OF CXCL12 IN...
 REGULATION OF CXCL12 EXPRESSION...
 CXCL12, TUMOR PROLIFERATION, AND...
 CXCL12 AND TUMOR VASCULARIZATION
 CXCL12 AND TUMOR METASTASIS
 CXCL12 AND CANCER STEM...
 CXCL12 AND TUMOR...
 CXCL12 AND THERAPEUTIC...
 REFERENCES
 
The CXC chemokine family can be divided into two subfamilies, depending on the presence or absence of the highly conserved three-amino acid motif Glu-Leu-Arg (ELR) situated at the NH2 terminus. Members of the CXC chemokine family containing the ELR motif are potent inducers of angiogenic activity, whereas chemokines that lack the ELR motif are rather angiostatic.

CXCL12 is an ELR CXC chemokine; however, it exhibits angiogenic activity. Initially, the angiogenic role of CXCL12 was observed in mice lacking CXCL12 or CXCR4 (80, 132). These mice had defective formation of large vessels supplying the gastrointestinal tract. Subsequent in vitro studies suggested a potential effect of CXCL12 on blood vessel formation. For example, CXCL12 stimulates the formation of capillary-like structures with human vascular endothelial cells (83, 86, 109). Interestingly, although high concentrations of CXCL12 are able to induce angiogenesis in vivo (83), our studies have shown that pathological levels of CXCL12 alone failed to induce meaningful vascularization in vivo. However, pathological concentrations of CXCL12 induced potent neoangiogenesis in vivo in the presence of low concentrations of vascular endothelial growth factor (VEGF) (66), revealing profound synergistic effects between CXCL12 and VEGF. Furthermore, CXCL12 attracts plasmacytoid dendritic cells (DCs) into the tumor environment, and in turn tumor plasmacytoid DCs induce neoangiogenesis through production of IL-8 and TNF-{alpha} (21). Therefore, a multifactor model is proposed to explain the mechanism whereby CXCL12 induces vascularization (109, 147). In this model, CXCL12 synergizes with soluble factors, including fibroblast growth factor (FGF) family members and VEGF (66, 92), and coordinates with immune cells, including plasmacytoid DCs (21), to induce potent vascularization in vivo.

Migration, expansion, and survival of vascular endothelial cells form the essential functional network of angiogenesis. Vascular endothelial cell migration is strongly dependent on CXCL12 (37, 109). In support of this, neutralizing antibodies against CXCL12 inhibit endothelial cell invasion into subcutaneously injected Matrigel (111). Hypoxia simultaneously stimulates CXCR4 expression (16, 129) and CXCL12 (66) production. Therefore, it is reasoned that hypoxia would promote vascular endothelial cell migration toward CXCL12 and induce tumor vascularization in a CXCL12-dependent manner.


    CXCL12 AND TUMOR METASTASIS
 TOP
 ABSTRACT
 EXPRESSION OF CXCL12 IN...
 REGULATION OF CXCL12 EXPRESSION...
 CXCL12, TUMOR PROLIFERATION, AND...
 CXCL12 AND TUMOR VASCULARIZATION
 CXCL12 AND TUMOR METASTASIS
 CXCL12 AND CANCER STEM...
 CXCL12 AND TUMOR...
 CXCL12 AND THERAPEUTIC...
 REFERENCES
 
Tumor metastasis was once viewed as a passive consequence of a single tumor cell simply "escaping" from a primary tumor and traveling great distances through draining lymph nodes and blood, lodging in small blood vessels and thereby forming micrometastases (152). Recent data, however, have demonstrated that tumor metastasis is an active process employing multiple molecular and cellular mechanisms (17, 19). The interaction between tumor cells and stroma is crucial for tumor metastasis (19).

CXCL12 and Tumor Cell Adhesion Cancer dissemination can be viewed as a tissue remodeling process that involves proteolytic degradation of extracellular matrix. Metalloproteases (MMPs) are a family of enzymes involved in the degradation of extracellular matrix in the surrounding normal tissue and known to mediate cancer invasion and metastases (28). Activation of MMPs breaks down the physical barriers of metastasis, thus promoting invasion by cancer cells (49). Several studies have documented that CXCL12 induces MMP synthesis in different cell types (62, 75, 81, 127, 148) and facilitates tumor cell adhesion and colonization.

CXCL12 also modulates the expression and function of cell surface integrin molecules and, in turn, promotes tumor cell adhesion. Integrins are a large family of heterodimeric transmembrane glycoproteins that attach cells to extracellular matrix proteins of the basement membrane or to ligands on other cells. CXCL12 induces adhesion of SCLCs to VCAM-1, fibronectin, and collagen (13, 41).

CXCL12 and Tumor Cell Migration The CXCL12/CXCR4 pathway is involved in the "homing" of lymphocytes. It was hypothesized that chemokines and chemokine receptors including CXCL12/CXCR4 might mediate cancer cells to "home" to specific secondary sites, thereby promoting organ-specific metastasis. In 2001, Muller et al. (90) provided the first evidence that the CXCL12/CXCR4 pathway mediates human breast cancer metastasis. In vivo blocking of CXCR4 with the use of a specific antibody (90) or selective synthetic polypeptide (73) or siRNA (74) resulted in significant inhibition of breast cancer metastasis to regional lymph nodes as well as in the lung. In the presence of neutralizing CXCL12 antibodies, NSCLC tumor metastases also were significantly reduced (100). Blocking of CXCR4 expression on the cell surface greatly reduced the ability of colon cancer cells to metastasize to the liver and lungs (150). Furthermore, antibody-mediated neutralization of CXCR4 was found to limit skeletal metastasis in prostate cancer (130). Induction of CXCR4 expression resulted in a dramatic increase in pulmonary metastases of melanoma cells, a situation that could be blocked using potent CXCR4 inhibitors. Subcutaneously injected prostate cancer cells transfected with CXCR4 grew larger tumors with increased muscle invasion compared with parental cells (23). In further support of the role of CXCL12 in tumor metastasis, high levels of CXCL12 are often found in lymph nodes, lung, liver, and bone marrow, where tumors frequently metastasize (90, 100, 101, 130). Nonetheless, although the molecular mechanism of action has yet to be established, these studies demonstrate the pivotal role of CXCL12/CXCR4 in tumor metastasis.

Hypoxia induces CXCR4 expression on tumor cells (54, 117), which would sensitize tumor cells to CXCL12 signals and promote tumor metastasis. However, hypoxia simultaneously stimulates both CXCR4 and CXCL12 expression (66). Human cancer cells including neuroblastoma (32), glioblastoma (6, 106), ovarian (66, 120, 156), breast (3, 57), colon (54), pancreas (64), and prostate (131) express CXCL12 (Table 1). It is reasoned that endogenous CXCL12, together with CXCR4 on tumor cells, should keep cancer cells within the primary tumor environment, rather than facilitate metastasis over a long distance. Nonetheless, the effects of CXCL12/CXCR4 on tumor metastasis may be explained by multiple factors in the tumor environment.

Heterogeneous CXCL12 expression in different tumors. Ovarian cancers constitutively express high levels of CXCL12 (65, 66, 156). CXCL12 expression may be restricted to either the metastatic lesion or limited fragments of primary tumor.

CXCL12 sensitivity. The uncoupling of CXCR4 following receptor internalization by endocytosis may persist even after the receptor is recycled to the cell surface (125). Tumor cells by themselves also can modulate their sensitivity to the CXCL12 by regulating CD26 expression. CD26 (known as dipeptidyl peptidase IV, DPPIV) is a ubiquitously expressed 110-kDa membrane-bound extracellular peptidase and has a variety of roles in the development of human malignancies as well as in normal T cell biology. Absence of CD26 peptidase activity enhances HSC cell migration toward a CXCL12 gradient in vitro. Moreover, removal of endogenous CD26 on donor HSCs has been demonstrated to increase homing and engraftment of HSCs in vivo (18). Mizokami et al. (85) demonstrated that expression of CD26/DPPIV in endometrial carcinoma can directly modulate CXCL12 functions. CD26 is expressed on the surface of normal epithelial cells, but it is often lost in various cancers (143, 144). Hypoxia can upregulate CD26 expression on tumor cells (114) and, in turn, could decrease the sensitivity of tumor cells to local CXCL12.

Tumor cells moving away from high local levels of CXCL12. Although the mechanism remains to be defined, antigen-induced T-cell recruitment into the peritoneal cavity can be reversed by high but not low concentrations of CXCL12 (104). Analogously, one may speculate that high levels of CXCL12 in the tumor environment would trigger tumor cells migrating away from primary tumor and foster tumor metastasis.

CXCL12 is not the exclusive chemokine that regulates tumor cell trafficking. In summary, although other factors need to be considered, it is evident that the CXCL12/CXCR4 pathway is implicated in the mechanistic process of tumor metastasis, including tumor cell adhesion and migration.


    CXCL12 AND CANCER STEM CELLS
 TOP
 ABSTRACT
 EXPRESSION OF CXCL12 IN...
 REGULATION OF CXCL12 EXPRESSION...
 CXCL12, TUMOR PROLIFERATION, AND...
 CXCL12 AND TUMOR VASCULARIZATION
 CXCL12 AND TUMOR METASTASIS
 CXCL12 AND CANCER STEM...
 CXCL12 AND TUMOR...
 CXCL12 AND THERAPEUTIC...
 REFERENCES
 
CXCL12 plays a pivotal role in the regulation of trafficking of normal HSCs and their homing in bone marrow (2, 63, 98). Moreover, CXCR4 is also expressed on nonhematopoietic stem cells (12, 35, 52). Stem cells may be the origin of vascular endothelial cells for tumor neovascularization (42, 79, 134). In support of this, stromal fibroblasts in invasive human breast carcinomas promote tumor growth and angiogenesis through CXCL12 secretion (96). It is postulated that CXCL12 in the tumor microenvironment may be critical for recruiting endothelial stem cells to initiate tumor vascularization (96). On the other hand, cancer stem cells also express CXCR4 (69). Therefore, CXCL12 may mediate cancer stem cell trafficking and metastasis to organs that highly express CXCL12, such as bone marrow, lymph nodes, liver, and lung.


    CXCL12 AND TUMOR IMMUNOSUPPRESSION
 TOP
 ABSTRACT
 EXPRESSION OF CXCL12 IN...
 REGULATION OF CXCL12 EXPRESSION...
 CXCL12, TUMOR PROLIFERATION, AND...
 CXCL12 AND TUMOR VASCULARIZATION
 CXCL12 AND TUMOR METASTASIS
 CXCL12 AND CANCER STEM...
 CXCL12 AND TUMOR...
 CXCL12 AND THERAPEUTIC...
 REFERENCES
 
Appropriate trafficking and retention of immune cells is indispensable to mediate efficient immune responses in vivo (78). Multiple immune suppressive modes of action are involved in tumor immune evasion (22, 67, 68, 156). These mechanisms are extensively reviewed in the literature (154, 155). CXCL12 contributes to tumor immunosuppression through recruiting of specific immune cell populations. We focus our discussion on CXCL12 in the tumor environment and its role in tumor immunosuppression.

CXCL12 and CD4+CD25+ regulatory T cells. Bone marrow is a common site for human tumor metastasis, suggesting that bone marrow may provide an immunosuppressive environment for tumor retention and growth. Interestingly, a number of reports have demonstrated that functional memory T cells exist in bone marrow (7, 82). Bone marrow can serve as a site for naive tumor-associated antigen (TAA)-specific T cell priming (7, 31, 82, 136). Indeed, TAA-specific T cells isolated from the bone marrow of tumor-bearing mice and cancer patients are functional in vitro and are able to prevent tumor growth when transferred to another host. These data suggest that these TAA-specific T cells are functionally suppressed in the bone marrow (30, 31, 82, 136). This notion was supported by our recent observation that large numbers of functional CD4+ regulatory T (Treg) cells accumulate in the bone marrow of healthy volunteers and mice (153). This observation was confirmed in a FOXP3 bicistronic reporter knock-in mouse model (139). In this model, a bicistronic reporter expressing a red fluorescent protein was knocked into the endogenous FOXP3 locus. High levels of FOXP3-expressing T cells (with red fluorescence) were found in the bone marrow (139).

Strikingly, bone marrow CD4+ Treg cells express functional CXCR4, and CD4+ Treg cell release from bone marrow is achieved through granulocyte-colony-stimulating factor reducing marrow expression of CXCL12 (153). Activation of Treg cells upregulates CXCR4 expression and enables them to migrate to the bone marrow in a CXCL12-dependent manner (153), suggesting that bone marrow could serve as a functional reservoir for activated Treg cells. Thus CXCR4/CXCL12 signals are crucial for bone marrow trafficking of activated CD4+ Treg cells. High levels of Treg cells in the bone marrow may provide an immune shield to facilitate bone marrow metastasis. Therefore, CXCL12 may contribute to tumor bone marrow metastasis by recruiting Treg cells.

CXCL12 and plasmacytoid DCs. Functional plasmacytoid DCs are found in the tumor environment of patients with ovarian cancer (156), melanoma (110), and head and neck squamous cell carcinoma (HNSCC) (40). Tumor cells produce CXCL12 and plasmacytoid DCs express VLA-5 and CXCR4, the key molecules that mediate plasmacytoid DC tumor trafficking (156). CXCL12 further protects tumor plasmacytoid DCs from apoptosis (156). Strikingly, tumor-associated plasmacytoid DCs induce significant IL-10 production by T cells that suppresses myeloid DC-induced TAA-specific T cell effector functions (156). Tumor plasmacytoid DCs induced IL-10+CCR7+CD8+ T cells to home to the draining lymph nodes and suppress TAA-specific central priming (142). The fact that allogeneic plasmacytoid DCs are able to induce CD4+ (89) and CD8+ (34) suppressive regulatory T cells supports these data. A large amount of plasmacytoid DCs, but not functional mature myeloid DCs, accumulate in the tumor environment (156).

Notably, it has been shown in mouse models that locally accumulated CXCL12 can lead to the inhibition of tumor growth by facilitating the chemoattraction of leukocytes into the tumor area. In this respect, mouse leukemia and melanoma cells transfected with CXCL12 were rejected following injection into syngeneic mice (26). CXCL12 produced by melanoma cells attracts cytotoxic T cells through their binding to CXCR4. Blockade of CXCL12/CXCR4 signal inhibits CTL migration toward tumor cells (151). Likewise, depending on circumstances, it is possible that CXCL12 stimulates T cell immunity against a tumor. However, CXCL12 elicits potent effects on the tumor growth, angiogenesis, and immunity. The net effects of CXCL12 in human tumor appear not to be beneficial.


    CXCL12 AND THERAPEUTIC APPLICATIONS
 TOP
 ABSTRACT
 EXPRESSION OF CXCL12 IN...
 REGULATION OF CXCL12 EXPRESSION...
 CXCL12, TUMOR PROLIFERATION, AND...
 CXCL12 AND TUMOR VASCULARIZATION
 CXCL12 AND TUMOR METASTASIS
 CXCL12 AND CANCER STEM...
 CXCL12 AND TUMOR...
 CXCL12 AND THERAPEUTIC...
 REFERENCES
 
Compelling evidence demonstrates that CXCL12/CXCR4 signal is implicated in tumor proliferation, survival, vascularization, metastasis, and immunosuppression (Fig. 1). The in vivo blockade of this pathway reduces tumor growth and metastasis in mouse models (10, 90, 108, 150). Statistical studies suggest a possible negative association between high levels of CXCR4 expression and patient outcome in certain human tumors (57, 61, 64, 115). Targeting CXCL12/CXCR4 pathway is a logic strategy in treating cancer patients.


Figure 1
View larger version (25K):
[in this window]
[in a new window]

 
Fig. 1. Multiple modes of actions are implicated in CXCL12-mediated tumor biology. 1) CXCL12 promotes tumor growth and malignancy. 2) CXCL12 enhances tumor neovascularization. 3) CXCL12 fosters an immunosuppressive environment. 4) CXCL12 mediates tumor cell migration, adhesion, and invasion. mDC, myeloid dendritic cells; pDC, plasmacytoid dendritic cells.

 
CXCR4 is one of the coreceptors for human immunodeficiency virus (HIV). AMD3100 is a CXCR4 antagonist and has been used in human clinical trials for treatment of HIV infection (24, 46). Phase I pharmacokinetic studies demonstrated the feasibility of intravenous dosing and showed that AMD3100 was well tolerated by the healthy volunteers (47). AMD3100 also mobilized CD34+ cells from the bone marrow into the peripheral blood of healthy volunteers as well as cancer patients (25, 76). Although these studies did not test AMD3100 as an anti-cancer intervention, the observations suggest that CXCL12/CXCR4 inhibitors would be potentially used in clinical trials in treating cancer patients.

On the other hand, thousands of patients worldwide have received treatment with angiogenesis inhibitors or antagonists. Bevacizumab, a monoclonal antibody against VEGF, is one of them (53). Although administration of bevacizumab results in increased patient survival with certain cancers (20, 50, 56, 145), the clinical efficacy needs significant improvement. CXCL12 and VEGF synergistically induce tumor vascularization (66). It is thus expected that combination of anti-VEGF and anti-CXCL12 may be more effective.

Notably, CXCR4 and CXCL12 are expressed on multiple immune cells, vascular endothelial cells as well as stem cells. It is possible that targeting CXCR4/CXCL12 pathway may yield unexpected clinical effects. Nonetheless, it is evident that CXCR4/CXCL12 pathway is actively implicated in tumor pathogenesis and plays a significant role in tumor immunopathogenesis. Therefore, manipulation of this pathway represents new strategy for cancer treatment (154). Of course, we need to bear in mind that although targeting CXCR4/CXCL12 is an attractive option in treating human tumors, it is highly likely that to attain effective, reliable, and consistent clinical efficacy, a complicated combinatorial therapeutic regimen may be warranted.


    FOOTNOTES
 

Address for reprint requests and other correspondence: W. Zou, Univ. of Michigan School of Medicine, C560B MSRB II, 1150 W. Medical Center Dr., Ann Arbor, MI 48109-0669 (e-mail: wzou{at}umich.edu)


    REFERENCES
 TOP
 ABSTRACT
 EXPRESSION OF CXCL12 IN...
 REGULATION OF CXCL12 EXPRESSION...
 CXCL12, TUMOR PROLIFERATION, AND...
 CXCL12 AND TUMOR VASCULARIZATION
 CXCL12 AND TUMOR METASTASIS
 CXCL12 AND CANCER STEM...
 CXCL12 AND TUMOR...
 CXCL12 AND THERAPEUTIC...
 REFERENCES
 
1. Allinen M, Beroukhim R, Cai L, Brennan C, Lahti-Domenici J, Huang H, Porter D, Hu M, Chin L, Richardson A, Schnitt S, Sellers WR, Polyak K. Molecular characterization of the tumor microenvironment in breast cancer. Cancer Cell 6: 17–32, 2004.[CrossRef][Web of Science][Medline]

2. Ara T, Tokoyoda K, Sugiyama T, Egawa T, Kawabata K, Nagasawa T. Long-term hematopoietic stem cells require stromal cell-derived factor-1 for colonizing bone marrow during ontogeny. Immunity 19: 257–267, 2003.[CrossRef][Web of Science][Medline]

3. Bachelder RE, Wendt MA, Mercurio AM. Vascular endothelial growth factor promotes breast carcinoma invasion in an autocrine manner by regulating the chemokine receptor CXCR4. Cancer Res 62: 7203–7206, 2002.[Abstract/Free Full Text]

4. Balabanian K, Lagane B, Infantino S, Chow KY, Harriague J, Moepps B, Arenzana-Seisdedos F, Thelen M, Bachelerie F. The chemokine SDF-1/CXCL12 binds to and signals through the orphan receptor RDC1 in T lymphocytes. J Biol Chem 280: 35760–35766, 2005.[Abstract/Free Full Text]

5. Banisadr G, Dicou E, Berbar T, Rostene W, Lombet A, Haour F. Characterization and visualization of [125I] stromal cell-derived factor-1{alpha} binding to CXCR4 receptors in rat brain and human neuroblastoma cells. J Neuroimmunol 110: 151–160, 2000.[CrossRef][Web of Science][Medline]

6. Barbero S, Bonavia R, Bajetto A, Porcile C, Pirani P, Ravetti JL, Zona GL, Spaziante R, Florio T, Schettini G. Stromal cell-derived factor 1{alpha} stimulates human glioblastoma cell growth through the activation of both extracellular signal-regulated kinases 1/2 and Akt. Cancer Res 63: 1969–1974, 2003.[Abstract/Free Full Text]

7. Becker TC, Coley SM, Wherry EJ, Ahmed R. Bone marrow is a preferred site for homeostatic proliferation of memory CD8 T cells. J Immunol 174: 1269–1273, 2005.[Abstract/Free Full Text]

8. Begley L, Monteleon C, Shah RB, Macdonald JW, Macoska JA. CXCL12 overexpression and secretion by aging fibroblasts enhance human prostate epithelial proliferation in vitro. Aging Cell 4: 291–298, 2005.[CrossRef][Web of Science][Medline]

9. Begum NA, Shibuta K, Mori M, Barnard GF. Reduced expression of the CXCR4 receptor mRNA in hepatocellular carcinoma and lack of inducibility of its ligand {alpha}-chemokine hIRH/SDF1{alpha}/PBSF in vitro. Int J Oncol 14: 927–934, 1999.[Web of Science][Medline]

10. Bertolini F, Dell'Agnola C, Mancuso P, Rabascio C, Burlini A, Monestiroli S, Gobbi A, Pruneri G, Martinelli G. CXCR4 neutralization, a novel therapeutic approach for non-Hodgkin's lymphoma. Cancer Res 62: 3106–3112, 2002.[Abstract/Free Full Text]

11. Brand S, Dambacher J, Beigel F, Olszak T, Diebold J, Otte JM, Goke B, Eichhorst ST. CXCR4 and CXCL12 are inversely expressed in colorectal cancer cells and modulate cancer cell migration, invasion and MMP-9 activation. Exp Cell Res 310: 117–130, 2005.[CrossRef][Web of Science][Medline]

12. Broxmeyer HE, Orschell CM, Clapp DW, Hangoc G, Cooper S, Plett PA, Liles WC, Li X, Graham-Evans B, Campbell TB, Calandra G, Bridger G, Dale DC, Srour EF. Rapid mobilization of murine and human hematopoietic stem and progenitor cells with AMD3100, a CXCR4 antagonist. J Exp Med 201: 1307–1318, 2005.[Abstract/Free Full Text]

13. Burger M, Glodek A, Hartmann T, Schmitt-Graff A, Silberstein LE, Fujii N, Kipps TJ, Burger JA. Functional expression of CXCR4 (CD184) on small-cell lung cancer cells mediates migration, integrin activation, and adhesion to stromal cells. Oncogene 22: 8093–8101, 2003.[CrossRef][Web of Science][Medline]

14. Castellone MD, Guarino V, De Falco V, Carlomagno F, Basolo F, Faviana P, Kruhoffer M, Orntoft T, Russell JP, Rothstein JL, Fusco A, Santoro M, Melillo RM. Functional expression of the CXCR4 chemokine receptor is induced by RET/PTC oncogenes and is a common event in human papillary thyroid carcinomas. Oncogene 23: 5958–5967, 2004.[CrossRef][Web of Science][Medline]

15. Catani MV, Corasaniti MT, Navarra M, Nistico G, Finazzi-Agro A, Melino G. gp120 induces cell death in human neuroblastoma cells through the CXCR4 and CCR5 chemokine receptors. J Neurochem 74: 2373–2379, 2000.[CrossRef][Web of Science][Medline]

16. Ceradini DJ, Kulkarni AR, Callaghan MJ, Tepper OM, Bastidas N, Kleinman ME, Capla JM, Galiano RD, Levine JP, Gurtner GC. Progenitor cell trafficking is regulated by hypoxic gradients through HIF-1 induction of SDF-1. Nat Med 10: 858–864, 2004.[CrossRef][Web of Science][Medline]

17. Chambers AF, Groom AC, MacDonald IC. Dissemination and growth of cancer cells in metastatic sites. Nat Rev Cancer 2: 563–572, 2002.[CrossRef][Web of Science][Medline]

18. Christopherson KW, 2nd Hangoc G, Mantel CR, Broxmeyer HE. Modulation of hematopoietic stem cell homing and engraftment by CD26. Science 305: 1000–1003, 2004.[Abstract/Free Full Text]

19. Chung LW. Prostate carcinoma bone-stroma interaction and its biologic and therapeutic implications. Cancer 97: 772–778, 2003.[CrossRef][Web of Science][Medline]

20. Cobleigh MA, Langmuir VK, Sledge GW, Miller KD, Haney L, Novotny WF, Reimann JD, Vassel A. A phase I/II dose-escalation trial of bevacizumab in previously treated metastatic breast cancer. Semin Oncol 30: 117–124, 2003.[CrossRef][Web of Science][Medline]

21. Curiel TJ, Cheng P, Mottram P, Alvarez X, Moons L, Evdemon-Hogan M, Wei S, Zou L, Kryczek I, Hoyle G, Lackner A, Carmeliet P, Zou W. Dendritic cell subsets differentially regulate angiogenesis in human ovarian cancer. Cancer Res 64: 5535–5538, 2004.[Abstract/Free Full Text]

22. Curiel TJ, Coukos G, Zou L, Alvarez X, Cheng P, Mottram P, Evdemon-Hogan M, Conejo-Garcia JR, Zhang L, Burow M, Zhu Y, Wei S, Kryczek I, Daniel B, Gordon A, Myers L, Lackner A, Disis ML, Knutson KL, Chen L, Zou W. Specific recruitment of regulatory T cells in ovarian carcinoma fosters immune privilege and predicts reduced survival. Nat Med 10: 942–949, 2004.[CrossRef][Web of Science][Medline]

23. Darash-Yahana M, Pikarsky E, Abramovitch R, Zeira E, Pal B, Karplus R, Beider K, Avniel S, Kasem S, Galun E, Peled A. Role of high expression levels of CXCR4 in tumor growth, vascularization, and metastasis. FASEB J 18: 1240–1242, 2004.[Abstract/Free Full Text]

24. De Clercq E. The bicyclam AMD3100 story. Nat Rev Drug Discov 2: 581–587, 2003.[CrossRef][Web of Science][Medline]

25. Devine SM, Flomenberg N, Vesole DH, Liesveld J, Weisdorf D, Badel K, Calandra G, DiPersio JF. Rapid mobilization of CD34+ cells following administration of the CXCR4 antagonist AMD3100 to patients with multiple myeloma and non-Hodgkin's lymphoma. J Clin Oncol 22: 1095–1102, 2004.[Abstract/Free Full Text]

26. Dunussi-Joannopoulos K, Zuberek K, Runyon K, Hawley RG, Wong A, Erickson J, Herrmann S, Leonard JP. Efficacious immunomodulatory activity of the chemokine stromal cell-derived factor 1 (SDF-1): local secretion of SDF-1 at the tumor site serves as T-cell chemoattractant and mediates T-cell-dependent antitumor responses. Blood 100: 1551–1558, 2002.[Abstract/Free Full Text]

27. Dwinell MB, Eckmann L, Leopard JD, Varki NM, Kagnoff MF. Chemokine receptor expression by human intestinal epithelial cells. Gastroenterology 117: 359–367, 1999.[CrossRef][Web of Science][Medline]

28. Egeblad M, Werb Z. New functions for the matrix metalloproteinases in cancer progression. Nat Rev Cancer 2: 161–174, 2002.[Web of Science][Medline]

29. Eisenhardt A, Frey U, Tack M, Rosskopf D, Lummen G, Rubben H, Siffert W. Expression analysis and potential functional role of the CXCR4 chemokine receptor in bladder cancer. Eur Urol 47: 111–117, 2005.[CrossRef][Web of Science][Medline]

30. Feuerer M, Beckhove P, Bai L, Solomayer EF, Bastert G, Diel IJ, Pedain C, Oberniedermayr M, Schirrmacher V, Umansky V. Therapy of human tumors in NOD/SCID mice with patient-derived reactivated memory T cells from bone marrow. Nat Med 7: 452–458, 2001.[CrossRef][Web of Science][Medline]

31. Feuerer M, Beckhove P, Garbi N, Mahnke Y, Limmer A, Hommel M, Hammerling GJ, Kyewski B, Hamann A, Umansky V, Schirrmacher V. Bone marrow as a priming site for T-cell responses to blood-borne antigen. Nat Med 9: 1151–1157, 2003.[CrossRef][Web of Science][Medline]

32. Geminder H, Sagi-Assif O, Goldberg L, Meshel T, Rechavi G, Witz IP, Ben-Baruch A. A possible role for CXCR4 and its ligand, the CXC chemokine stromal cell-derived factor-1, in the development of bone marrow metastases in neuroblastoma. J Immunol 167: 4747–4757, 2001.[Abstract/Free Full Text]

33. Gerritsen ME, Peale FV Jr, Wu T. Gene expression profiling in silico: relative expression of candidate angiogenesis associated genes in renal cell carcinomas. Exp Nephrol 10: 114–119, 2002.[CrossRef][Web of Science][Medline]

34. Gilliet M, Liu YJ. Generation of human CD8 T regulatory cells by CD40 ligand-activated plasmacytoid dendritic cells. J Exp Med 195: 695–704, 2002.[Abstract/Free Full Text]

35. Gomperts BN, Belperio JA, Rao PN, Randell SH, Fishbein MC, Burdick MD, Strieter RM. Circulating progenitor epithelial cells traffic via CXCR4/CXCL12 in response to airway injury. J Immunol 176: 1916–1927, 2006.[Abstract/Free Full Text]

36. Grunewald M, Avraham I, Dor Y, Bachar-Lustig E, Itin A, Yung S, Chimenti S, Landsman L, Abramovitch R, Keshet E. VEGF-induced adult neovascularization: recruitment, retention, and role of accessory cells. Cell 124: 175–189, 2006.[CrossRef][Web of Science][Medline]

37. Gupta SK, Lysko PG, Pillarisetti K, Ohlstein E, Stadel JM. Chemokine receptors in human endothelial cells. Functional expression of CXCR4 and its transcriptional regulation by inflammatory cytokines. J Biol Chem 273: 4282–4287, 1998.[Abstract/Free Full Text]

38. Hagerstrand D, Hesselager G, Achterberg S, Wickenberg Bolin U, Kowanetz M, Kastemar M, Heldin CH, Isaksson A, Nister M, Ostman A. Characterization of an imatinib-sensitive subset of high-grade human glioma cultures. Oncogene 25: 4913–4922, 2006.[CrossRef][Web of Science][Medline]

39. Hall JM, Korach KS. Stromal cell-derived factor 1, a novel target of estrogen receptor action, mediates the mitogenic effects of estradiol in ovarian and breast cancer cells. Mol Endocrinol 17: 792–803, 2003.[Abstract/Free Full Text]

40. Hartmann E, Wollenberg B, Rothenfusser S, Wagner M, Wellisch D, Mack B, Giese T, Gires O, Endres S, Hartmann G. Identification and functional analysis of tumor-infiltrating plasmacytoid dendritic cells in head and neck cancer. Cancer Res 63: 6478–6487, 2003.[Abstract/Free Full Text]

41. Hartmann TN, Burger JA, Glodek A, Fujii N, Burger M. CXCR4 chemokine receptor and integrin signaling co-operate in mediating adhesion and chemoresistance in small cell lung cancer (SCLC) cells. Oncogene 24: 4462–4471, 2005.[CrossRef][Web of Science][Medline]

42. Hattori K, Dias S, Heissig B, Hackett NR, Lyden D, Tateno M, Hicklin DJ, Zhu Z, Witte L, Crystal RG, Moore MA, Rafii S. Vascular endothelial growth factor and angiopoietin-1 stimulate postnatal hematopoiesis by recruitment of vasculogenic and hematopoietic stem cells. J Exp Med 193: 1005–1014, 2001.[Abstract/Free Full Text]

43. Haviv YS, van Houdt WJ, Lu B, Curiel DT, Zhu ZB. Transcriptional targeting in renal cancer cell lines via the human CXCR4 promoter. Mol Cancer Ther 3: 687–691, 2004.[Abstract/Free Full Text]

44. Hazlehurst LA, Damiano JS, Buyuksal I, Pledger WJ, Dalton WS. Adhesion to fibronectin via beta1 integrins regulates p27kip1 levels and contributes to cell adhesion mediated drug resistance (CAM-DR). Oncogene 19: 4319–4327, 2000.[CrossRef][Web of Science][Medline]

45. Helbig G, Christopherson KW 2nd, Bhat-Nakshatri P, Kumar S, Kishimoto H, Miller KD, Broxmeyer HE, Nakshatri H. NF-{kappa}B promotes breast cancer cell migration and metastasis by inducing the expression of the chemokine receptor CXCR4. J Biol Chem 278: 21631–21638, 2003.[Abstract/Free Full Text]

46. Hendrix CW, Collier AC, Lederman MM, Schols D, Pollard RB, Brown S, Jackson JB, Coombs RW, Glesby MJ, Flexner CW, Bridger GJ, Badel K, MacFarland RT, Henson GW, Calandra G. Safety, pharmacokinetics, and antiviral activity of AMD3100, a selective CXCR4 receptor inhibitor, in HIV-1 infection. J Acquir Immune Defic Syndr 37: 1253–1262, 2004.[CrossRef][Web of Science][Medline]

47. Hendrix CW, Flexner C, MacFarland RT, Giandomenico C, Fuchs EJ, Redpath E, Bridger G, Henson GW. Pharmacokinetics and safety of AMD-3100, a novel antagonist of the CXCR-4 chemokine receptor, in human volunteers. Antimicrob Agents Chemother 44: 1667–1673, 2000.[Abstract/Free Full Text]

48. Hitchon C, Wong K, Ma G, Reed J, Lyttle D, El-Gabalawy H. Hypoxia-induced production of stromal cell-derived factor 1 (CXCL12) and vascular endothelial growth factor by synovial fibroblasts. Arthritis Rheum 46: 2587–2597, 2002.[CrossRef][Web of Science][Medline]

49. Hojilla CV, Mohammed FF, Khokha R. Matrix metalloproteinases and their tissue inhibitors direct cell fate during cancer development. Br J Cancer 89: 1817–1821, 2003.[CrossRef][Web of Science][Medline]

50. Hurwitz H, Fehrenbacher L, Novotny W, Cartwright T, Hainsworth J, Heim W, Berlin J, Baron A, Griffing S, Holmgren E, Ferrara N, Fyfe G, Rogers B, Ross R, Kabbinavar F. Bevacizumab plus irinotecan, fluorouracil, and leucovorin for metastatic colorectal cancer. N Engl J Med 350: 2335–2342, 2004.[Abstract/Free Full Text]

51. Hwang JH, Chung HK, Kim DW, Hwang ES, Suh JM, Kim H, You KH, Kwon OY, Ro HK, Jo DY, Shong M. CXC chemokine receptor 4 expression and function in human anaplastic thyroid cancer cells. J Clin Endocrinol Metab 88: 408–416, 2003.[Abstract/Free Full Text]

52. Imitola J, Raddassi K, Park KI, Mueller FJ, Nieto M, Teng YD, Frenkel D, Li J, Sidman RL, Walsh CA, Snyder EY, Khoury SJ. Directed migration of neural stem cells to sites of CNS injury by the stromal cell-derived factor 1{alpha}/CXC chemokine receptor 4 pathway. Proc Natl Acad Sci USA 101: 18117–18122, 2004.[Abstract/Free Full Text]

53. Jain RK. Normalization of tumor vasculature: an emerging concept in antiangiogenic therapy. Science 307: 58–62, 2005.[Abstract/Free Full Text]

54. Jordan NJ, Kolios G, Abbot SE, Sinai MA, Thompson DA, Petraki K, Westwick J. Expression of functional CXCR4 chemokine receptors on human colonic epithelial cells. J Clin Invest 104: 1061–1069, 1999.[Web of Science][Medline]

55. Jordan VC, Morrow M. Tamoxifen, raloxifene, and the prevention of breast cancer. Endocr Rev 20: 253–278, 1999.[Abstract/Free Full Text]

56. Kabbinavar F, Hurwitz HI, Fehrenbacher L, Meropol NJ, Novotny WF, Lieberman G, Griffing S, Bergsland E. Phase II, randomized trial comparing bevacizumab plus fluorouracil (FU)/leucovorin (LV) with FU/LV alone in patients with metastatic colorectal cancer. J Clin Oncol 21: 60–65, 2003.[Abstract/Free Full Text]

57. Kang H, Watkins G, Parr C, Douglas-Jones A, Mansel RE, Jiang WG. Stromal cell derived factor-1: its influence on invasiveness and migration of breast cancer cells in vitro, and its association with prognosis and survival in human breast cancer. Breast Cancer Res 7: R402–R410, 2005.[CrossRef][Web of Science][Medline]

58. Katayama A, Ogino T, Bandoh N, Nonaka S, Harabuchi Y. Expression of CXCR4 and its down-regulation by IFN-{gamma} in head and neck squamous cell carcinoma. Clin Cancer Res 11: 2937–2946, 2005.[Abstract/Free Full Text]

59. Katayama Y, Battista M, Kao WM, Hidalgo A, Peired AJ, Thomas SA, Frenette PS. Signals from the sympathetic nervous system regulate hematopoietic stem cell egress from bone marrow. Cell 124: 407–421, 2006.[CrossRef][Web of Science][Medline]

60. Kijima T, Maulik G, Ma PC, Tibaldi EV, Turner RE, Rollins B, Sattler M, Johnson BE, Salgia R. Regulation of cellular proliferation, cytoskeletal function, and signal transduction through CXCR4 and c-Kit in small cell lung cancer cells. Cancer Res 62: 6304–6311, 2002.[Abstract/Free Full Text]

61. Kim J, Takeuchi H, Lam ST, Turner RR, Wang HJ, Kuo C, Foshag L, Bilchik AJ, Hoon DS. Chemokine receptor CXCR4 expression in colorectal cancer patients increases the risk for recurrence and for poor survival. J Clin Oncol 23: 2744–2753, 2005.[Abstract/Free Full Text]

62. Klier CM, Nelson EL, Cohen CD, Horuk R, Schlondorff D, Nelson PJ. Chemokine-induced secretion of gelatinase B in primary human monocytes. Biol Chem 382: 1405–1410, 2001.[CrossRef][Web of Science][Medline]

63. Kollet O, Petit I, Kahn J, Samira S, Dar A, Peled A, Deutsch V, Gunetti M, Piacibello W, Nagler A, Lapidot T. Human CD34+CXCR4 sorted cells harbor intracellular CXCR4, which can be functionally expressed and provide NOD/SCID repopulation. Blood 100: 2778–2786, 2002.[Abstract/Free Full Text]

64. Koshiba T, Hosotani R, Miyamoto Y, Ida J, Tsuji S, Nakajima S, Kawaguchi M, Kobayashi H, Doi R, Hori T, Fujii N, Imamura M. Expression of stromal cell-derived factor 1 and CXCR4 ligand receptor system in pancreatic cancer: a possible role for tumor progression. Clin Cancer Res 6: 3530–3535, 2000.[Abstract/Free Full Text]

65. Kryczek I, Grybos M, Dlubek D, Klimczak A, Rabczynski J, Lange A. Accumulation of CD45RO+ cells in peritoneal carcinomatous fluid favours survival of ovarian carcinoma patients. Cancer Immunol Immunother 51: 513–519, 2002.[CrossRef][Web of Science][Medline]

66. Kryczek I, Lange A, Mottram P, Alvarez X, Cheng P, Hogan M, Moons L, Wei S, Zou L, Machelon V, Emilie D, Terrassa M, Lackner A, Curiel TJ, Carmeliet P, Zou W. CXCL12 and vascular endothelial growth factor synergistically induce neoangiogenesis in human ovarian cancers. Cancer Res 65: 465–472, 2005.[Abstract/Free Full Text]

67. Kryczek I, Wei S, Zou L, Zhu G, Mottram P, Xu H, Chen L, Zou W. Cutting edge: induction of B7–H4 on APCs through IL-10: novel suppressive mode for regulatory T cells. J Immunol 177: 40–44, 2006.[Abstract/Free Full Text]

68. Kryczek I, Zou L, Rodriguez P, Zhu G, Wei S, Mottram P, Brumlik M, Cheng P, Curiel T, Myers L, Lackner A, Alvarez X, Ochoa A, Chen L, Zou W. B7–H4 expression identifies a novel suppressive macrophage population in human ovarian carcinoma. J Exp Med 203: 871–881, 2006.[Abstract/Free Full Text]

69. Kucia M, Reca R, Miekus K, Wanzeck J, Wojakowski W, Janowska-Wieczorek A, Ratajczak J, Ratajczak MZ. Trafficking of normal stem cells and metastasis of cancer stem cells involve similar mechanisms: pivotal role of the SDF-1-CXCR4 axis. Stem Cells 23: 879–894, 2005.[CrossRef][Web of Science][Medline]

70. Kukreja P, Abdel-Mageed AB, Mondal D, Liu K, Agrawal KC. Up-regulation of CXCR4 expression in PC-3 cells by stromal-derived factor-1{alpha} (CXCL12) increases endothelial adhesion and transendothelial migration: role of MEK/ERK signaling pathway-dependent NF-{kappa}B activation. Cancer Res 65: 9891–9898, 2005.[Abstract/Free Full Text]

71. Kwak MK, Hur K, Park do J, Lee HJ, Lee HS, Kim WH, Lee KU, Choe KJ, Yang HK. Expression of chemokine receptors in human gastric cancer. Tumour Biol 26: 65–70, 2005.[CrossRef][Medline]

72. Li YM, Pan Y, Wei Y, Cheng X, Zhou BP, Tan M, Zhou X, Xia W, Hortobagyi GN, Yu D, Hung MC. Upregulation of CXCR4 is essential for HER2-mediated tumor metastasis. Cancer Cell 6: 459–469, 2004.[CrossRef][Web of Science][Medline]

73. Liang Z, Wu T, Lou H, Yu X, Taichman RS, Lau SK, Nie S, Umbreit J, Shim H. Inhibition of breast cancer metastasis by selective synthetic polypeptide against CXCR4. Cancer Res 64: 4302–4308, 2004.[Abstract/Free Full Text]

74. Liang Z, Yoon Y, Votaw J, Goodman MM, Williams L, Shim H. Silencing of CXCR4 blocks breast cancer metastasis. Cancer Res 65: 967–971, 2005.[Abstract/Free Full Text]

75. Libura J, Drukala J, Majka M, Tomescu O, Navenot JM, Kucia M, Marquez L, Peiper SC, Barr FG, Janowska-Wieczorek A, Ratajczak MZ. CXCR4-SDF-1 signaling is active in rhabdomyosarcoma cells and regulates locomotion, chemotaxis, and adhesion. Blood 100: 2597–2606, 2002.[Abstract/Free Full Text]

76. Liles WC, Broxmeyer HE, Rodger E, Wood B, Hubel K, Cooper S, Hangoc G, Bridger GJ, Henson GW, Calandra G, Dale DC. Mobilization of hematopoietic progenitor cells in healthy volunteers by AMD3100, a CXCR4 antagonist. Blood 102: 2728–2730, 2003.[Abstract/Free Full Text]

77. Lindgren P, Backstrom T, Mahlck CG, Ridderheim M, Cajander S. Steroid receptors and hormones in relation to cell proliferation and apoptosis in poorly differentiated epithelial ovarian tumors. Int J Oncol 19: 31–38, 2001.[Web of Science][Medline]

78. Luster AD. The role of chemokines in linking innate and adaptive immunity. Curr Opin Immunol 14: 129–135, 2002.[CrossRef][Web of Science][Medline]

79. Lyden D, Hattori K, Dias S, Costa C, Blaikie P, Butros L, Chadburn A, Heissig B, Marks W, Witte L, Wu Y, Hicklin D, Zhu Z, Hackett NR, Crystal RG, Moore MA, Hajjar KA, Manova K, Benezra R, Rafii S. Impaired recruitment of bone-marrow-derived endothelial and hematopoietic precursor cells blocks tumor angiogenesis and growth. Nat Med 7: 1194–1201, 2001.[CrossRef][Web of Science][Medline]

80. Ma Q, Jones D, Borghesani PR, Segal RA, Nagasawa T, Kishimoto T, Bronson RT, Springer TA. Impaired B-lymphopoiesis, myelopoiesis, and derailed cerebellar neuron migration in CXCR4- and SDF-1-deficient mice. Proc Natl Acad Sci USA 95: 9448–9453, 1998.[Abstract/Free Full Text]

81. Marchesi F, Monti P, Leone BE, Zerbi A, Vecchi A, Piemonti L, Mantovani A, Allavena P. Increased survival, proliferation, and migration in metastatic human pancreatic tumor cells expressing functional CXCR4. Cancer Res 64: 8420–8427, 2004.[Abstract/Free Full Text]

82. Mazo IB, Honczarenko M, Leung H, Cavanagh LL, Bonasio R, Weninger W, Engelke K, Xia L, McEver RP, Koni PA, Silberstein LE, von Andrian UH. Bone marrow is a major reservoir and site of recruitment for central memory CD8+ T cells. Immunity 22: 259–270, 2005.[CrossRef][Web of Science][Medline]

83. Mirshahi F, Pourtau J, Li H, Muraine M, Trochon V, Legrand E, Vannier J, Soria J, Vasse M, Soria C. SDF-1 activity on microvascular endothelial cells: consequences on angiogenesis in in vitro and in vivo models. Thromb Res 99: 587–594, 2000.[CrossRef][Web of Science][Medline]

84. Mitra P, De A, Ethier MF, Mimori K, Kodys K, Shibuta K, Mori M, Madison JM, Miller-Graziano C, Barnard GF. Loss of chemokine SDF-1{alpha}-mediated CXCR4 signalling and receptor internalization in human hepatoma cell line HepG2. Cell Signal 13: 311–319, 2001.[CrossRef][Web of Science][Medline]

85. Mizokami Y, Kajiyama H, Shibata K, Ino K, Kikkawa F, Mizutani S. Stromal cell-derived factor-1{alpha}-induced cell proliferation and its possible regulation by CD26/dipeptidyl peptidase IV in endometrial adenocarcinoma. Int J Cancer 110: 652–659, 2004.[CrossRef][Web of Science][Medline]

86. Molino M, Woolkalis MJ, Prevost N, Pratico D, Barnathan ES, Taraboletti G, Haggarty BS, Hesselgesser J, Horuk R, Hoxie JA, Brass LF. CXCR4 on human endothelial cells can serve as both a mediator of biological responses and as a receptor for HIV-2. Biochim Biophys Acta 1500: 227–240, 2000.[Medline]

87. Mori T, Doi R, Koizumi M, Toyoda E, Ito D, Kami K, Masui T, Fujimoto K, Tamamura H, Hiramatsu K, Fujii N, Imamura M. CXCR4 antagonist inhibits stromal cell-derived factor 1-induced migration and invasion of human pancreatic cancer. Mol Cancer Ther 3: 29–37, 2004.[Abstract/Free Full Text]

88. Mori T, Kim J, Yamano T, Takeuchi H, Huang S, Umetani N, Koyanagi K, Hoon DS. Epigenetic up-regulation of C-C chemokine receptor 7 and C-X-C chemokine receptor 4 expression in melanoma cells. Cancer Res 65: 1800–1807, 2005.[Abstract/Free Full Text]

89. Moseman EA, Liang X, Dawson AJ, Panoskaltsis-Mortari A, Krieg AM, Liu YJ, Blazar BR, Chen W. Human plasmacytoid dendritic cells activated by CpG oligodeoxynucleotides induce the generation of CD4+CD25+ regulatory T cells. J Immunol 173: 4433–4442, 2004.[Abstract/Free Full Text]

90. Muller A, Homey B, Soto H, Ge N, Catron D, Buchanan ME, McClanahan T, Murphy E, Yuan W, Wagner SN, Barrera JL, Mohar A, Verastegui E, Zlotnik A. Involvement of chemokine receptors in breast cancer metastasis. Nature 410: 50–56, 2001.[CrossRef][Medline]

91. Muller A, Sonkoly E, Eulert C, Gerber PA, Kubitza R, Schirlau K, Franken-Kunkel P, Poremba C, Snyderman C, Klotz LO, Ruzicka T, Bier H, Zlotnik A, Whiteside TL, Homey B, Hoffmann TK. Chemokine receptors in head and neck cancer: association with metastatic spread and regulation during chemotherapy. Int J Cancer 118: 2147–2157, 2006.[CrossRef][Web of Science][Medline]

92. Murdoch C. CXCR4: chemokine receptor extraordinaire. Immunol Rev 177: 175–184, 2000.[CrossRef][Web of Science][Medline]

93. Nagasawa T, Hirota S, Tachibana K, Takakura N, Nishikawa S, Kitamura Y, Yoshida N, Kikutani H, Kishimoto T. Defects of B-cell lymphopoiesis and bone-marrow myelopoiesis in mice lacking the CXC chemokine PBSF/SDF-1. Nature 382: 635–638, 1996.[CrossRef][Medline]

94. Oda Y, Yamamoto H, Tamiya S, Matsuda S, Tanaka K, Yokoyama R, Iwamoto Y, Tsuneyoshi M. CXCR4 and VEGF expression in the primary site and the metastatic site of human osteosarcoma: analysis within a group of patients, all of whom developed lung metastasis. Mod Pathol, 2006.

95. Oh JW, Drabik K, Kutsch O, Choi C, Tousson A, Benveniste EN. CXC chemokine receptor 4 expression and function in human astroglioma cells. J Immunol 166: 2695–2704, 2001.[Abstract/Free Full Text]

96. Orimo A, Gupta PB, Sgroi DC, Arenzana-Seisdedos F, Delaunay T, Naeem R, Carey VJ, Richardson AL, Weinberg RA. Stromal fibroblasts present in invasive human breast carcinomas promote tumor growth and angiogenesis through elevated SDF-1/CXCL12 secretion. Cell 121: 335–348, 2005.[CrossRef][Web of Science][Medline]

97. Ottaiano A, di Palma A, Napolitano M, Pisano C, Pignata S, Tatangelo F, Botti G, Acquaviva AM, Castello G, Ascierto PA, Iaffaioli RV, Scala S. Inhibitory effects of anti-CXCR4 antibodies on human colon cancer cells. Cancer Immunol Immunother 54: 781–791, 2004.

98. Peled A, Petit I, Kollet O, Magid M, Ponomaryov T, Byk T, Nagler A, Ben-Hur H, Many A, Shultz L, Lider O, Alon R, Zipori D, Lapidot T. Dependence of human stem cell engraftment and repopulation of NOD/SCID mice on CXCR4. Science 283: 845–848, 1999.[Abstract/Free Full Text]

99. Petit I, Szyper-Kravitz M, Nagler A, Lahav M, Peled A, Habler L, Ponomaryov T, Taichman RS, Arenzana-Seisdedos F, Fujii N, Sandbank J, Zipori D, Lapidot T. G-CSF induces stem cell mobilization by decreasing bone marrow SDF-1 and up-regulating CXCR4. Nat Immunol 3: 687–694, 2002.[CrossRef][Web of Science][Medline]

100. Phillips RJ, Burdick MD, Lutz M, Belperio JA, Keane MP, Strieter RM. The stromal derived factor-1/CXCL12-CXC chemokine receptor 4 biological axis in non-small cell lung cancer metastases. Am J Respir Crit Care Med 167: 1676–1686, 2003.[Abstract/Free Full Text]

101. Phillips RJ, Mestas J, Gharaee-Kermani M, Burdick MD, Sica A, Belperio JA, Keane MP, Strieter RM. Epidermal growth factor and hypoxia-induced expression of CXC chemokine receptor 4 on non-small cell lung cancer cells is regulated by the phosphatidylinositol 3-kinase/PTEN/AKT/mammalian target of rapamycin signaling pathway and activation of hypoxia inducible factor-1{alpha}. J Biol Chem 280: 22473–22481, 2005.[Abstract/Free Full Text]

102. Ponomaryov T, Peled A, Petit I, Taichman RS, Habler L, Sandbank J, Arenzana-Seisdedos F, Magerus A, Caruz A, Fujii N, Nagler A, Lahav M, Szyper-Kravitz M, Zipori D, Lapidot T. Induction of the chemokine stromal-derived factor-1 following DNA damage improves human stem cell function. J Clin Invest 106: 1331–1339, 2000.[Web of Science][Medline]

103. Porcile C, Bajetto A, Barbieri F, Barbero S, Bonavia R, Biglieri M, Pirani P, Florio T, Schettini G. Stromal cell-derived factor-1{alpha} (SDF-1{alpha}/CXCL12) stimulates ovarian cancer cell growth through the EGF receptor transactivation. Exp Cell Res 308: 241–253, 2005.[CrossRef][Web of Science][Medline]

104. Poznansky MC, Olszak IT, Foxall R, Evans RH, Luster AD, Scadden DT. Active movement of T cells away from a chemokine. Nat Med 6: 543–548, 2000.[CrossRef][Web of Science][Medline]

105. Rein DT, Breidenbach M, Nettelbeck DM, Kawakami Y, Siegal GP, Huh WK, Wang M, Hemminki A, Bauerschmitz GJ, Yamamoto M, Adachi Y, Takayama K, Dall P, Curiel DT. Evaluation of tissue-specific promoters in carcinomas of the cervix uteri. J Gene Med 6: 1281–1289, 2004.[CrossRef][Web of Science][Medline]

106. Rempel SA, Dudas S, Ge S, Gutierrez JA. Identification and localization of the cytokine SDF1 and its receptor, CXC chemokine receptor 4, to regions of necrosis and angiogenesis in human glioblastoma. Clin Cancer Res 6: 102–111, 2000.[Abstract/Free Full Text]

107. Robledo MM, Bartolome RA, Longo N, Rodriguez-Frade JM, Mellado M, Longo I, van Muijen GN, Sanchez-Mateos P, Teixido J. Expression of functional chemokine receptors CXCR3 and CXCR4 on human melanoma cells. J Biol Chem 276: 45098–45105, 2001.[Abstract/Free Full Text]

108. Rubin JB, Kung AL, Klein RS, Chan JA, Sun Y, Schmidt K, Kieran MW, Luster AD, Segal RA. A small-molecule antagonist of CXCR4 inhibits intracranial growth of primary brain tumors. Proc Natl Acad Sci USA 100: 13513–13518, 2003.[Abstract/Free Full Text]

109. Salcedo R, Wasserman K, Young HA, Grimm MC, Howard OM, Anver MR, Kleinman HK, Murphy WJ, Oppenheim JJ. Vascular endothelial growth factor and basic fibroblast growth factor induce expression of CXCR4 on human endothelial cells: In vivo neovascularization induced by stromal-derived factor-1{alpha}. Am J Pathol 154: 1125–1135, 1999.[Abstract/Free Full Text]

110. Salio M, Cella M, Vermi W, Facchetti F, Palmowski MJ, Smith CL, Shepherd D, Colonna M, Cerundolo V. Plasmacytoid dendritic cells prime IFN-{gamma}-secreting melanoma-specific CD8 lymphocytes and are found in primary melanoma lesions. Eur J Immunol 33: 1052–1062, 2003.[CrossRef][Web of Science][Medline]

111. Salvucci O, Yao L, Villalba S, Sajewicz A, Pittaluga S, Tosato G. Regulation of endothelial cell branching morphogenesis by endogenous chemokine stromal-derived factor-1. Blood 99: 2703–2711, 2002.[Abstract/Free Full Text]

112. Samara GJ, Lawrence DM, Chiarelli CJ, Valentino MD, Lyubsky S, Zucker S, Vaday GG. CXCR4-mediated adhesion and MMP-9 secretion in head and neck squamous cell carcinoma. Cancer Lett 214: 231–241, 2004.[CrossRef][Web of Science][Medline]

113. Sato N, Fukushima N, Maitra A, Iacobuzio-Donahue CA, van Heek NT, Cameron JL, Yeo CJ, Hruban RH, Goggins M. Gene expression profiling identifies genes associated with invasive intraductal papillary mucinous neoplasms of the pancreas. Am J Pathol 164: 903–914, 2004.[Abstract/Free Full Text]

114. Sato Y, Fujiwara H, Higuchi T, Yoshioka S, Tatsumi K, Maeda M, Fujii S. Involvement of dipeptidyl peptidase IV in extravillous trophoblast invasion and differentiation. J Clin Endocrinol Metab 87: 4287–4296, 2002.[Abstract/Free Full Text]

115. Scala S, Ottaiano A, Ascierto PA, Cavalli M, Simeone E, Giuliano P, Napolitano M, Franco R, Botti G, Castello G. Expression of CXCR4 predicts poor prognosis in patients with malignant melanoma. Clin Cancer Res 11: 1835–1841, 2005.[Abstract/Free Full Text]

116. Schimanski CC, Schwald S, Simiantonaki N, Jayasinghe C, Gonner U, Wilsberg V, Junginger T, Berger MR, Galle PR, Moehler M. Effect of chemokine receptors CXCR4 and CCR7 on the metastatic behavior of human colorectal cancer. Clin Cancer Res 11: 1743–1750, 2005.[Abstract/Free Full Text]

117. Schioppa T, Uranchimeg B, Saccani A, Biswas SK, Doni A, Rapisarda A, Bernasconi S, Saccani S, Nebuloni M, Vago L, Mantovani A, Melillo G, Sica A. Regulation of the chemokine receptor CXCR4 by hypoxia. J Exp Med 198: 1391–1402, 2003.[Abstract/Free Full Text]

118. Schrader AJ, Lechner O, Templin M, Dittmar KE, Machtens S, Mengel M, Probst-Kepper M, Franzke A, Wollensak T, Gatzlaff P, Atzpodien J, Buer J, Lauber J. CXCR4/CXCL12 expression and signalling in kidney cancer. Br J Cancer 86: 1250–1256, 2002.[CrossRef][Web of Science][Medline]

119. Scotton CJ, Wilson JL, Milliken D, Stamp G, Balkwill FR. Epithelial cancer cell migration: a role for chemokine receptors? Cancer Res 61: 4961–4965, 2001.[Abstract/Free Full Text]

120. Scotton CJ, Wilson JL, Scott K, Stamp G, Wilbanks GD, Fricker S, Bridger G, Balkwill FR. Multiple actions of the chemokine CXCL12 on epithelial tumor cells in human ovarian cancer. Cancer Res 62: 5930–5938, 2002.[Abstract/Free Full Text]

121. Sehgal A, Keener C, Boynton AL, Warrick J, Murphy GP. CXCR-4, a chemokine receptor, is overexpressed in and required for proliferation of glioblastoma tumor cells. J Surg Oncol 69: 99–104, 1998.[CrossRef][Web of Science][Medline]

122. Sehgal A, Ricks S, Boynton AL, Warrick J, Murphy GP. Molecular characterization of CXCR-4: a potential brain tumor-associated gene. J Surg Oncol 69: 239–248, 1998.[CrossRef][Web of Science][Medline]

123. Semenza GL. Targeting HIF-1 for cancer therapy. Nat Rev Cancer 3: 721–732, 2003.[CrossRef][Web of Science][Medline]

124. Sethi T, Rintoul RC, Moore SM, MacKinnon AC, Salter D, Choo C, Chilvers ER, Dransfield I, Donnelly SC, Strieter R, Haslett C. Extracellular matrix proteins protect small cell lung cancer cells against apoptosis: a mechanism for small cell lung cancer growth and drug resistance in vivo. Nat Med 5: 662–668, 1999.[CrossRef][Web of Science][Medline]

125. Shen H, Cheng T, Olszak I, Garcia-Zepeda E, Lu Z, Herrmann S, Fallon R, Luster AD, Scadden DT. CXCR-4 desensitization is associated with tissue localization of hemopoietic progenitor cells. J Immunol 166: 5027–5033, 2001.[Abstract/Free Full Text]

126. Shirozu M, Nakano T, Inazawa J, Tashiro K, Tada H, Shinohara T, Honjo T. Structure and chromosomal localization of the human stromal cell-derived factor 1 (SDF1) gene. Genomics 28: 495–500, 1995.[CrossRef][Web of Science][Medline]

127. Singh S, Singh UP, Grizzle WE, Lillard JW Jr. CXCL12-CXCR4 interactions modulate prostate cancer cell migration, metalloproteinase expression and invasion. Lab Invest 84: 1666–1676, 2004.[CrossRef][Web of Science][Medline]

128. Sonoda Y, Ozawa T, Aldape KD, Deen DF, Berger MS, Pieper RO. Akt pathway activation converts anaplastic astrocytoma to glioblastoma multiforme in a human astrocyte model of glioma. Cancer Res 61: 6674–6678, 2001.[Abstract/Free Full Text]

129. Staller P, Sulitkova J, Lisztwan J, Moch H, Oakeley EJ, Krek W. Chemokine receptor CXCR4 downregulated by von Hippel-Lindau tumour suppressor pVHL. Nature 425: 307–311, 2003.[CrossRef][Medline]

130. Sun YX, Schneider A, Jung Y, Wang J, Dai J, Cook K, Osman NI, Koh-Paige AJ, Shim H, Pienta KJ, Keller ET, McCauley LK, Taichman RS. Skeletal localization and neutralization of the SDF-1(CXCL12)/CXCR4 axis blocks prostate cancer metastasis and growth in osseous sites in vivo. J Bone Miner Res 20: 318–329, 2005.[CrossRef][Web of Science][Medline]

131. Sun YX, Wang J, Shelburne CE, Lopatin DE, Chinnaiyan AM, Rubin MA, Pienta KJ, Taichman RS. Expression of CXCR4 and CXCL12 (SDF-1) in human prostate cancers (PCa) in vivo. J Cell Biochem 89: 462–473, 2003.[CrossRef][Web of Science][Medline]

132. Tachibana K, Hirota S, Iizasa H, Yoshida H, Kawabata K, Kataoka Y, Kitamura Y, Matsushima K, Yoshida N, Nishikawa S, Kishimoto T, Nagasawa T. The chemokine receptor CXCR4 is essential for vascularization of the gastrointestinal tract. Nature 393: 591–594, 1998.[CrossRef][Medline]

133. Taichman RS, Cooper C, Keller ET, Pienta KJ, Taichman NS, McCauley LK. Use of the stromal cell-derived factor-1/CXCR4 pathway in prostate cancer metastasis to bone. Cancer Res 62: 1832–1837, 2002.[Abstract/Free Full Text]

134. Takakura N, Watanabe T, Suenobu S, Yamada Y, Noda T, Ito Y, Satake M, Suda T. A role for hematopoietic stem cells in promoting angiogenesis. Cell 102: 199–209, 2000.[CrossRef][Web of Science][Medline]

135. Tashiro K, Tada H, Heilker R, Shirozu M, Nakano T, Honjo T. Signal sequence trap: a cloning strategy for secreted proteins and type I membrane proteins. Science 261: 600–603, 1993.[Abstract/Free Full Text]

136. Tripp RA, Topham DJ, Watson SR, Doherty PC. Bone marrow can function as a lymphoid organ during a primary immune response under conditions of disrupted lymphocyte trafficking. J Immunol 158: 3716–3720, 1997.[Abstract]

137. Uchida D, Begum NM, Almofti A, Nakashiro K, Kawamata H, Tateishi Y, Hamakawa H, Yoshida H, Sato M. Possible role of stromal-cell-derived factor-1/CXCR4 signaling on lymph node metastasis of oral squamous cell carcinoma. Exp Cell Res 290: 289–302, 2003.[CrossRef][Web of Science][Medline]

138. Uhm JH, Dooley NP, Kyritsis AP, Rao JS, Gladson CL. Vitronectin, a glioma-derived extracellular matrix protein, protects tumor cells from apoptotic death. Clin Cancer Res 5: 1587–1594, 1999.[Abstract/Free Full Text]

139. Wan YY, Flavell RA. Identifying Foxp3-expressing suppressor T cells with a bicistronic reporter. Proc Natl Acad Sci USA 102: 5126–5131, 2005.[Abstract/Free Full Text]

140. Wang CY, Mayo MW, Baldwin AS Jr. TNF- and cancer therapy-induced apoptosis: potentiation by inhibition of NF-{kappa}B. Science 274: 784–787, 1996.[Abstract/Free Full Text]

141. Wang N, Wu QL, Fang Y, Mai HQ, Zeng MS, Shen GP, Hou JH, Zeng YX. Expression of chemokine receptor CXCR4 in nasopharyngeal carcinoma: pattern of expression and correlation with clinical outcome. J Transl Med 3: 26, 2005.[CrossRef][Medline]

142. Wei S, Kryczek I, Zou L, Daniel B, Cheng P, Mottram P, Curiel T, Lange A, Zou W. Plasmacytoid dendritic cells induce CD8+ regulatory T cells in human ovarian carcinoma. Cancer Res 65: 5020–5026, 2005.[Abstract/Free Full Text]

143. Wesley UV, McGroarty M, Homoyouni A. Dipeptidyl peptidase inhibits malignant phenotype of prostate cancer cells by blocking basic fibroblast growth factor signaling pathway. Cancer Res 65: 1325–1334, 2005.[Abstract/Free Full Text]

144. Wesley UV, Tiwari S, Houghton AN. Role for dipeptidyl peptidase IV in tumor suppression of human non small cell lung carcinoma cells. Int J Cancer 109: 855–866, 2004.[CrossRef][Web of Science][Medline]

145. Yang JC, Haworth L, Sherry RM, Hwu P, Schwartzentruber DJ, Topalian SL, Steinberg SM, Chen HX, Rosenberg SA. A randomized trial of bevacizumab, an anti-vascular endothelial growth factor antibody, for metastatic renal cancer. N Engl J Med 349: 427–434, 2003.[Abstract/Free Full Text]

146. Yasumoto K, Koizumi K, Kawashima A, Saitoh Y, Arita Y, Shinohara K, Minami T, Nakayama T, Sakurai H, Takahashi Y, Yoshie O, Saiki I. Role of the CXCL12/CXCR4 axis in peritoneal carcinomatosis of gastric cancer. Cancer Res 66: 2181–2187, 2006.[Abstract/Free Full Text]

147. Yoshida S, Ono M, Shono T, Izumi H, Ishibashi T, Suzuki H, Kuwano M. Involvement of interleukin-8, vascular endothelial growth factor, and basic fibroblast growth factor in tumor necrosis factor {alpha}-dependent angiogenesis. Mol Cell Biol 17: 4015–4023, 1997.[Abstract]

148. Yu X, Collin-Osdoby P, Osdoby P. SDF-1 increases recruitment of osteoclast precursors by upregulation of matrix metalloproteinase-9 activity. Connect Tissue Res 44 Suppl 1: 79–84, 2003.

149. Zagzag D, Krishnamachary B, Yee H, Okuyama H, Chiriboga L, Ali MA, Melamed J, Semenza GL. Stromal cell-derived factor-1{alpha} and CXCR4 expression in hemangioblastoma and clear cell-renal cell carcinoma: von Hippel-Lindau loss-of-function induces expression of a ligand and its receptor. Cancer Res 65: 6178–6188, 2005.[Abstract/Free Full Text]

150. Zeelenberg IS, Ruuls-Van Stalle L, Roos E. The chemokine receptor CXCR4 is required for outgrowth of colon carcinoma micrometastases. Cancer Res 63: 3833–3839, 2003.[Abstract/Free Full Text]

151. Zhang T, Somasundaram R, Berencsi K, Caputo L, Rani P, Guerry D, Furth E, Rollins BJ, Putt M, Gimotty P, Swoboda R, Herlyn M, Herlyn D. CXC chemokine ligand 12 (stromal cell-derived factor 1{alpha}) and CXCR4-dependent migration of CTLs toward melanoma cells in organotypic culture. J Immunol 174: 5856–5863, 2005.[Abstract/Free Full Text]

152. Zlotnik A. Chemokines in neoplastic progression. Semin Cancer Biol 14: 181–185, 2004.[CrossRef][Web of Science][Medline]

153. Zou L, Barnett B, Safah H, Larussa VF, Evdemon-Hogan M, Mottram P, Wei S, David O, Curiel TJ, Zou W. Bone marrow is a reservoir for CD4+CD25+ regulatory T cells that traffic through CXCL12/CXCR4 signals. Cancer Res 64: 8451–8455, 2004.[Abstract/Free Full Text]

154. Zou W. Immunosuppressive networks in the tumour environment and their therapeutic relevance. Nat Rev Cancer 5: 263–274, 2005.[CrossRef][Web of Science][Medline]

155. Zou W. Regulatory T cells, tumour immunity and immunotherapy. Nat Rev Immunol 6: 295–307, 2006.[CrossRef][Web of Science][Medline]

156. Zou W, Machelon V, Coulomb-L'Hermin A, Borvak J, Nome F, Isaeva T, Wei S, Krzysiek R, Durand-Gasselin I, Gordon A, Pustilnik T, Curiel DT, Galanaud P, Capron F, Emilie D, Curiel TJ. Stromal-derived factor-1 in human tumors recruits and alters the function of plasmacytoid precursor dendritic cells. Nat Med 7: 1339–1346, 2001.[CrossRef][Web of Science][Medline]

157. Zou YR, Kottmann AH, Kuroda M, Taniuchi I, Littman DR. Function of the chemokine receptor CXCR4 in haematopoiesis and in cerebellar development. Nature 393: 595–599, 1998.[CrossRef][Medline]




This article has been cited by other articles:


Home page
Am. J. Pathol.Home page
Correlation of CXCL12 Expression and FoxP3+ Cell Infiltration with Human Papillomavirus Infection and Clinicopathological Progression of Cervical Cancer
Am. J. Pathol., October 1, 2009; 175(4): 1525 - 1535.



Home page
Clin. Cancer Res.Home page
L. Fischer, A. Korfel, S. Pfeiffer, P. Kiewe, H.-D. Volk, H. Cakiroglu, T. Widmann, and E. Thiel
CXCL13 and CXCL12 in Central Nervous System Lymphoma Patients
Clin. Cancer Res., October 1, 2009; 15(19): 5968 - 5973.
[Abstract] [Full Text] [PDF]


Home page
Molecular Cancer TherapeuticsHome page
J. Kwong, H. Kulbe, D. Wong, P. Chakravarty, and F. Balkwill
An antagonist of the chemokine receptor CXCR4 induces mitotic catastrophe in ovarian cancer cells
Mol. Cancer Ther., July 1, 2009; 8(7): 1893 - 1905.
[Abstract] [Full Text] [PDF]


This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow All Versions of this Article:
292/3/C987    most recent
00406.2006v1
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in Web of Science
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Web of Science (8)
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Kryczek, I.
Right arrow Articles by Zou, W.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Kryczek, I.
Right arrow Articles by Zou, W.


HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Visit Other APS Journals Online
Copyright © 2007 by the American Physiological Society.