Cancer Research Infection and Cancer: Biology, Therapeutics, and Prevention Susan G. Komen for the Cure-AACR Outstanding Investigator Award for Breast Cancer Research
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[Cancer Research 62, 7203-7206, December 15, 2002]
© 2002 American Association for Cancer Research

Advances in Brief

Vascular Endothelial Growth Factor Promotes Breast Carcinoma Invasion in an Autocrine Manner by Regulating the Chemokine Receptor CXCR41

Robin E. Bachelder2, Melissa A. Wendt and Arthur M. Mercurio

Division of Cancer Biology and Angiogenesis, Department of Pathology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts 02215


   ABSTRACT
Top
 ABSTRACT
Introduction
 Materials and Methods
 Results and Discussion
 REFERENCES
 
We report that vascular endothelial growth factor (VEGF), a major angiogenic factor, is also arequisite autocrine factor for breast carcinoma invasion in vitro and that the VEGF receptor Neuropilin-1 but not Flt-1 is essential for this function. VEGF regulates expression of the chemokine receptor CXCR4, and this VEGF target is needed for invasion but not for cell survival. CXCR4 mediates migration of breast carcinoma cells toward stromal-derived factor-1, and this migration is dependent on autocrine VEGF. Of interest, a CXCR4-inhibitory peptide that is currently in HIV clinical trials suppressed invasion. Our findings indicate that a VEGF autocrine pathway induces chemokine receptor expression in breast carcinoma cells, thus promoting their directed migration toward specific chemokines.


   Introduction
Top
 ABSTRACT
 Introduction
Materials and Methods
 Results and Discussion
 REFERENCES
 
Tumor cells often acquire the ability to support autocrine signaling pathways by expressing growth factors and their cognate surface receptors. In this direction, we reported recently that VEGF,3 a major angiogenic factor, is also an essential autocrine factor for the survival of metastatic breast carcinoma cells in vitro (1 , 2) . Key issues, however, are establishing the extent to which such autocrine pathways facilitate tumor invasion and defining the mechanisms involved. Although previous studies have indicated the ability of exogenous VEGF to promote tumor cell migration, they did not establish an autocrine function for this factor (3, 4, 5) . We report here that VEGF produced by breast carcinoma cells is critical for their invasion, and that the chemokine receptor CXCR4, which mediates the migration of these cells toward SDF-1, is an important target of this autocrine pathway.


   Materials and Methods
Top
 ABSTRACT
 Introduction
 Materials and Methods
Results and Discussion
 REFERENCES
 
Reagents.
The MDA-MB-231 breast carcinoma cell line was obtained from the Lombardi Breast Cancer Depository (Georgetown University). The generation of MDA-MB-435 breast carcinoma cells that stably express the {alpha}6ß4 integrin has been described previously (6) . Human dermal fibroblasts were provided by Dr. Donald Senger (Beth Israel Deaconess Medical Center). Reagents used in this study, and their respective sources, are as follows: ZVAD-FMK (Promega), Annexin V-FITC (Biosource), pertussis toxin (Calbiochem), cholera toxin (Calbiochem), recombinant VEGF165 (Biological Resources Branch, National Cancer Institute), recombinant human SDF-1 (Calbiochem), and ALX40–4C (N-{alpha}-acetyl-nona-D-arginine amide; American Peptide Company). The Abs used in this study were obtained from the following sources: rabbit IgG, mouse IgG1, mouse IgG, mouse IgG2b and rabbit anti-actin (Sigma); Flt-1 polyclonal Ab (Santa Cruz); SDF-1-neutralizing Ab (R&D Systems); and horseradish peroxidase-conjugated goat antimouse and goat antirabbit IgG (Jackson Immunoresearch). A polyclonal Ab directed against rat NP-1 amino acids 813–827 and a NP-1-specific mAb were purchased from Oncogene Sciences and Santa Cruz, respectively. CXCR4-specific Abs (mAb 12G5, IgG2a, 44717.111, IgG2b and 44716.111, IgG2b) were provided by the NIH AIDS Research and Reference Reagent Program. A rabbit polyclonal Ab directed against human VEGF was provided by Dr. Donald Senger.

Determination of Protein Expression.
Proteins were extracted from cells directly in their wells with radioimmunoprecipitation assay (RIPA) buffer [150 mM NaCl, 1% NP40, 0.5% sodium deoxycholate, 0.1% SDS, 50 mM Tris (pH 8.0)]. VEGF expression was assessed by immunoblotting, as described previously (2) . Similarly, CXCR4 was detected by immunoblotting extracted proteins with a CXCR4-specific mAb (12G5). To control for protein loading, these blots were also probed with an actin-specific Ab.

To assess Flt-1 and NP-1 cell surface expression, cells were incubated with the following Abs at 2 µg/ml: mouse IgG, rabbit IgG, NP-1-specific mAb, and Flt-1 polyclonal Ab, followed by the appropriate phycoerythrin-conjugated secondary Ab; the cells were then analyzed by flow cytometry. To determine cell surface CXCR4 expression, cells were fixed with 4% paraformaldehyde and were incubated on ice for 20 min with the CXCR4-specific mAb 12G5 (5 µg/ml) or a mouse IgG2A (5 µg/ml). These cells were then washed with PBS, incubated on ice for 20 min with a phycoerythrin-conjugated goat antimouse IgG, and analyzed by flow cytometry.

Invasion and Migration Assays.
Matrigel invasion assays, using NIH3T3-conditioned medium as a chemoattractant, were performed as described previously (6) . Migration toward SDF-1 (100 nM in 0.1% BSA/DMEM) was assessed using collagen (Cohesion; 15 µg/ml)-coated Transwell chambers. The effects of inhibitory Abs, drugs, or peptides on invasion were determined by preincubating cells with the indicated inhibitory reagent for 30 min on ice. The ability of these cells to invade Matrigel was then assessed, as described above, in the presence of the indicated reagent.

RT-PCR.
RNA was isolated using the Qiagen RNeasy kit. This RNA was added to one-step RT-PCR reactions (Qiagen), using either human Flt-1 specific primers (7) or NP-1-specific primers (8) . RT was performed at 50°C for 30 min, followed by a 95°C 15-min heat inactivation step. This cDNA was then subjected to 30 cycles of amplification using the following parameters: 94°C for 1 min, 55°C for 1 min, and 72°C for 1 min. A final extension step was then performed for 10 min at 72°C.


   Results and Discussion
Top
 ABSTRACT
 Introduction
 Materials and Methods
 Results and Discussion
REFERENCES
 
Autocrine VEGF Is Required for the Invasion of Breast Carcinoma Cells.
We assessed the impact of reducing VEGF expression in invasive breast carcinoma cells on their ability to invade Matrigel using antisense phosphorothioate oligodeoxynucleotides (oligos). These antisense (AS) oligos reduced VEGF expression in each of two breast carcinoma cell lines by ~70% compared with a control sense oligo, as determined by immunoblotting (Fig. 1, A and B)Citation . To prevent the apoptosis that occurs in these cells after a reduction in VEGF expression (1 , 2) , the cells were maintained in the continual presence of the caspase inhibitor, ZVAD-FMK. As shown in Fig. 1ACitation , this reagent inhibited the apoptosis that we had previously observed in VEGF AS-transfected MDA-MB-231 cells (96% effective). Expression of AS VEGF oligos resulted in a significant reduction (65%) in Matrigel invasion of MDA-MB-231 cells (Fig. 1B)Citation . This effect was a specific consequence of reduced VEGF expression because the addition of recombinant VEGF restored their ability to invade Matrigel (Fig. 1B)Citation . In addition, AS VEGF oligos inhibited the Matrigel invasion of MDA-MB-435/ß4 cells, a highly invasive breast carcinoma cell line that stably expresses the {alpha}6ß4 integrin (Fig. 1BCitation ; Ref. 6 ). We conclude from these data that VEGF produced by breast carcinoma cells is necessary for their invasion in vitro.



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  		Fig. 1. Breast carcinoma invasion is dependent on endogenously expressed VEGF and NP-1. MDA-MB-231 and MDA-MB-435/ß4 cells were transfected transiently with either a VEGF sense or AS phosphorothioate oligodeoxynucleotide, as described previously (1) . These cells were allowed to recover in heparin (10 µg/ml) + ZVAD-FMK (20 µM)-containing medium in the absence or presence of recombinant VEGF165 (100 ng/ml). In A, the level of apoptosis was determined by annexin V-FITC + propidium iodide (PI) staining, as described previously (1) . In parallel, equivalent amounts of protein extracted from these cells were subjected to VEGF or actin immunoblotting. Similar results were observed in three independent experiments. In B, the indicated cells were placed in the upper well of a Matrigel-coated Transwell chamber and allowed to migrate for 4 h toward conditioned NIH3T3 medium in the presence of ZVAD-FMK. The results represent the mean number of invasive cells (±SD) from two wells (four fields/well). Similar results were obtained in four separate experiments. Protein expression was assessed as described in A. In C, MDA-MB-435/ß4 and MDA-MB-231 mRNA was subjected to RT-PCR for NP-1 and Flt-1. In parallel, cell surface expression of NP-1 and Flt-1 was assessed on MDA-MB-231 cells by flow cytometry. In D, MDA-MB-231 cells were preincubated on ice with the following Abs at 10 µg/ml: rabbit IgG, mouse IgG1, NP-1-specific, or Flt-1-specific Ab. The ability of these cells to invade Matrigel toward conditioned NIH3T3 medium in a 4-h assay (+ ZVAD-FMK) was then determined. The results represent the mean number of invasive cells (±SD) from two wells (four fields/well), and are representative of 4 separate trials. kDa, Mr in thousands.

 
The VEGF Receptor NP-1 Supports VEGF Autocrine Invasive Function in Breast Carcinoma Cells.
If VEGF autocrine signaling is an important component of invasion, then invasive cells must express specific receptors that mediate this signaling. The results from previous studies indicated that MDA-MB-231 cells lack the classical VEGF receptor tyrosine kinases Flt-1 and KDR (9) but express NP-1 (1 , 10) . On the basis of these results, it has been assumed that NP-1, a receptor that lacks classical consensus signaling sites, must cooperate with a signaling-competent coreceptor to deliver VEGF signals in MDA-MB-231 cells. Interestingly, we detected both NP-1 and Flt-1 in both MDA-MB-435/ß4 and MDA-MB-231 cells by RT-PCR (Fig. 1C)Citation . To confirm these findings at the protein level, we also detected NP-1 and Flt-1 expression on the surface of MDA-MB-231 (Fig. 1C)Citation and MDA-435/ß4 (data not shown) cells by flow cytometry. To examine the involvement of Flt-1 in invasion, MDA-MB-231 cells were incubated with either a rabbit immunoglobulin or Flt-1 polyclonal Ab that inhibits monocyte migration by blocking VEGF binding to Flt-1 (11) . Surprisingly, invasion was not decreased by this Flt-1 Ab (Fig. 1D)Citation , even at 100 µg/ml (data not shown). In contrast, a NP-1-specific Ab inhibited invasion significantly, compared with a control IgG in the presence of ZVAD-FMK (Fig. 1D)Citation , but it did not influence survival under these conditions (data not shown). This NP-1-specific Ab also inhibited the invasion of MDA-MB-435/ß4-expressing cells (data not shown). These data establish that endogenously expressed NP-1, but not Flt-1, contributes to breast carcinoma invasion.

Heterotrimeric G Protein Activity Is Important for Breast Carcinoma Invasion but not Survival.
Given that our studies indicate the importance of autocrine VEGF in both breast carcinoma survival (1 , 2) and invasion, we postulated that different downstream targets of VEGF signaling mediate these distinct VEGF functions. The fact that GPCRs are important for cell migration and invasion (12, 13, 14) provided a logical focal point to examine this possibility. As shown in Fig. 2ACitation , pertussis toxin, a specific inhibitor of G{alpha}i proteins, inhibited invasion completely but cholera toxin, an inhibitor of G{alpha}s proteins, had no effect. Surprisingly, however, neither drug influenced the survival of these cells (Fig. 2A)Citation . These findings indicate a requirement for G{alpha}i signaling in invasion but not in survival.



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  		Fig. 2. VEGF regulates CXCR4 expression. In A, MDA-MB-231 cells were preincubated for 12 h with no drug, with cholera toxin (10 µg/ml), or with pertussis toxin (250 ng/ml), and their ability to invade Matrigel was assessed in a 4-h assay in the continual presence of drug. The data represent the mean number of invasive cells (±SD) from two wells (four fields/well). In parallel, the level of apoptosis was determined by annexin V-FITC + propidium iodide staining. Similar results were obtained in two experiments. In B, MDA-MB-231 and MDA-MB-435/ß4 cells were transfected transiently with either a VEGF sense (S) or AS oligo and allowed to recover in the presence or absence of recombinant VEGF165, as described for Fig. 1Citation . After 15 h, equivalent amounts of total cellular protein extracted from these cells were subjected to CXCR4 and actin blotting. The data are representative of those obtained in five independent experiments. In C, MDA-MB-231 cells were transfected as described in B. After 48 h, CXCR4 and uPAR cell surface expression were determined by flow cytometry. Similar results were obtained in two independent experiments.

 
The Chemokine Receptor CXCR4 Is a Target of VEGF Autocrine Signaling That Promotes Breast Carcinoma Invasion but not Survival.
The dependence of invasion on G{alpha}i proteins suggested that VEGF might promote invasion by regulating a GPCR. For this reason, we were intrigued by the observation that the G{alpha}i-coupled receptor CXCR4 is expressed in breast carcinoma cells and that it significantly impacts their metastasis (12) . On the basis of this report, we postulated that CXCR4 is a target of VEGF autocrine signaling and that CXCR4 links VEGF to invasion. To test this hypothesis, we examined the effect of inhibiting VEGF on the expression of CXCR4. Indeed, we detected significantly reduced levels of CXCR4 protein in VEGF AS- relative to VEGF sense-transfected MDA-MB-231 and MDA-MB-435/ß4 cells, and the addition of recombinant VEGF to AS-transfected cells restored CXCR4 expression (Fig. 2B)Citation . Also, a significant reduction in CXCR4 surface expression (36%) was observed in VEGF AS-transfected relative to sense-transfected MDA-MB-231 cells (Fig. 2C)Citation . In contrast, we detected similar surface expression of uPAR in VEGF sense-transfected and VEGF AS-transfected cells (Fig. 2C)Citation , demonstrating that the expression of all cell surface proteins is not influenced by VEGF. Together, these data establish that endogenous VEGF is an important determinant of CXCR4 expression in breast carcinoma cells.

VEGF Promotes the Migration and Invasion of MDA-MB-231 Breast Carcinoma Cells toward Exogenous Sources of SDF-1.
We next sought to identify the source of the CXCR4 ligand, SDF-1, that stimulates CXCR4 signaling in breast carcinoma cells. The invasion of MDA-MB-231 cells toward conditioned NIH3T3 medium was inhibited significantly (40%) by an SDF-1-neutralizing Ab (Fig. 3A)Citation . This finding supports the importance of SDF-1 in breast carcinoma invasion, but it does not exclude a potential contribution of SDF-1 produced by the tumor cells themselves. However, we were unable to detect either SDF-1{alpha} or -1ß mRNA in MDA-MB-231 cells (Fig. 3B)Citation . Furthermore, we did not detect SDF-1{alpha} or -1ß protein in the culture medium of these cells by ELISA (data not shown). These data indicate that the ability of MDA-MB-231 cells to invade Matrigel is dependent on an exogenous source of SDF-1.



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  		Fig. 3. VEGF regulates MDA-MB-231 migration and invasion toward exogenous SDF-1. In A, the ability of MDA-MB-231 cells to invade Matrigel toward conditioned NIH3T3 medium containing either a control mouse IgG1(10 µg/ml) or an SDF-neutralizing mAb (10 µg/ml) was determined in a 4-h assay. In B, the concentration of SDF RNA in total RNA isolated from MDA-MB-231 cells and human dermal fibroblasts was assessed using an SDF ELISA kit (R&D) according to the manufacturer’s recommended protocol. Similar results were obtained in three experiments. In C, MDA-MB-231 cells were allowed to migrate for 4 h toward either serum-free medium or serum-free medium supplemented with SDF-1 (100 nM). In D, MDA-MB-231 cells were transfected with either VEGF sense or AS oligos, allowed to recover in ZVAD-containing medium, and tested for their ability to migrate toward SDF-1, as described in C. The data for A, C, and D represent the mean number of migratory or invasive cells from two wells (four fields/well). Similar data were obtained in three independent experiments.

 
The above data imply that CXCR4-dependent migration and invasion require VEGF. A definitive test of this hypothesis would be to demonstrate that a reduction in VEGF expression abrogates migration toward SDF-1, a ligand for CXCR4 and not for other GPCRs (15 , 16) . As expected from previous studies (12) , MDA-MB-231 cells migrate robustly toward SDF-1 (Fig. 3C)Citation . This migration, however, was reduced substantially by expression of the VEGF AS oligonucleotide (Fig. 3D)Citation . Although these data do not exclude a role for VEGF in chemokinesis, they indicate that endogenous VEGF regulates breast carcinoma invasion by inducing CXCR4 expression, which drives their directed migration toward SDF-1.

Finally, to establish a definitive role for CXCR4 in invasion, the effect of a CXCR4-neutralizing peptide (ALX40–4C) was tested. This peptide blocks the binding of SDF-1 to CXCR4 without influencing the binding of other chemokines to their respective GPCRs (17 , 18) . As shown in Fig. 4ACitation , ALX40–4C inhibited Matrigel invasion by ~75%, but it did not decrease cell viability (data not shown). The invasion but not the survival of MDA-MB-231 cells was also inhibited by a CXCR4-specific Ab (Fig. 4B)Citation , substantiating the peptide results. These data demonstrate a distinct contribution of CXCR4 to the invasion but not to the survival of breast carcinoma cells. On the basis of these data, we suggest that ALX40–4C may be an effective therapeutic in preventing breast cancer spread. Of note, Phase I/II clinical trials in HIV-infected individuals have demonstrated that the i.v. administration of this peptide, which inhibits HIV (15, 16, 17, 18) is safe and results in serum concentrations capable of inhibiting CXCR4 function (19) .



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  		Fig. 4. Inhibitors of CXCR4 suppress MDA-MB-231 invasion but not survival. In A, MDA-MB-231 cells were preincubated on ice in the presence or absence of the CXCR4-neutralizing peptide ALX40–4C (50 µM), and their ability to invade Matrigel in a 4-h assay was determined. The effect of these drugs on cell survival was also assessed by annexin V-FITC + propidium iodide staining. These data are representative of those obtained in three separate experiments. In B, MDA-MB-231 cells were preincubated with either a CXCR4-specific (44716.111) or isotype-matched control mAb (20 µg/ml), and their ability to invade Matrigel, as well as the level of apoptosis in these cells, was assessed. The data from A and B represent the mean number of invasive cells (±SD) from two wells (four fields/well), and are representative of the results obtained in three separate experiments.

 
The data we report in this study establish a link between autocrine growth factors and chemokine receptors and add an important dimension to the biology of tumor invasion and metastasis. Specifically, our findings raise the possibility that the acquisition of an invasive phenotype is a multistep process involving the initiation of autocrine signaling loops involving specific growth factors such as VEGF, and the consequent expression of chemokine receptors such as CXCR4 that enable tumor cells to migrate toward chemoattractant gradients. Interestingly, although VEGF autocrine signaling also impacts breast carcinoma cell survival (1 , 2) , the ability of this pathway to stimulate CXCR4 expression influences invasion but not cell survival, which suggests that these two autocrine VEGF functions are dependent on distinct downstream targets. Our finding that VEGF regulates CXCR4 expression is relevant because SDF-1, the ligand for this receptor, is present in tumor stroma and in tissues such as lymph and lung (12) , which are the primary targets of invasive breast carcinoma cells. Of interest, our identification of a specific inhibitory peptide for CXCR4-dependent invasion suggests a rational approach for treating breast cancer patients, especially when used in combination with drugs that target VEGF signaling.


   ACKNOWLEDGMENTS
 
We thank Drs. Don Senger, Greg Robinson, and Masabumi Shibuya for providing valuable reagents and advice. Valuable discussions were had with Richard Bates, Aimee Crago, Jun Chung, and Elizabeth Lipscomb.


   FOOTNOTES
 
The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

1 Supported by NIH Grants CA89209 and CA80789. Back

2 To whom requests for reprints should be addressed, at Division of Cancer Biology and Angiogenesis, Department of Pathology, Beth Israel Deaconess Medical Center, Boston, Massachusetts 02215. E-mail: rbacheld{at}caregroup.harvard.edu Back

3 The abbreviations used are: VEGF, vascular endothelial growth factor; SDF, stromal-derived factor; Ab, antibody; mAb, monoclonal Ab; RT, reverse transcription; NP-1, neuropilin-1; GPCR, G protein-coupled receptor; uPAR, urokinase plasminogen activator receptor. Back

Received 8/21/02. Accepted 10/30/02.


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 ABSTRACT
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 Materials and Methods
 Results and Discussion
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E. Tsoli, P. K Tsantoulis, A. Papalambros, B. Perunovic, D. England, D. A Rawlands, G. M Reynolds, D. Vlachodimitropoulos, S. L Morgan, C. A Spiliopoulou, et al.
Simultaneous evaluation of maspin and CXCR4 in patients with breast cancer
J. Clin. Pathol., March 1, 2007; 60(3): 261 - 266.
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 Am. J. Physiol. Cell Physiol.Home page
I. Kryczek, S. Wei, E. Keller, R. Liu, and W. Zou
Stroma-derived factor (SDF-1/CXCL12) and human tumor pathogenesis
Am J Physiol Cell Physiol, March 1, 2007; 292(3): C987 - C995.
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 Molecular Cancer TherapeuticsHome page
A. P. Taylor and D. M. Goldenberg
Role of placenta growth factor in malignancy and evidence that an antagonistic PlGF/Flt-1 peptide inhibits the growth and metastasis of human breast cancer xenografts
Mol. Cancer Ther., February 1, 2007; 6(2): 524 - 531.
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 Mol. Cell. Biol.Home page
Z. Ma, S. L. Gibson, M. A. Byrne, J. Zhang, M. F. White, and L. M. Shaw
Suppression of Insulin Receptor Substrate 1 (IRS-1) Promotes Mammary Tumor Metastasis
Mol. Cell. Biol., December 15, 2006; 26(24): 9338 - 9351.
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 Cancer Res.Home page
J. L. Wilson, J. Burchell, and M. J. Grimshaw
Endothelins Induce CCR7 Expression by Breast Tumor Cells via Endothelin Receptor A and Hypoxia-Inducible Factor-1
Cancer Res., December 15, 2006; 66(24): 11802 - 11807.
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W.-U. Kim, S. S. Kang, S.-A. Yoo, K.-H. Hong, D.-G. Bae, M.-S. Lee, S. W. Hong, C.-B. Chae, and C.-S. Cho
Interaction of Vascular Endothelial Growth Factor 165 with Neuropilin-1 Protects Rheumatoid Synoviocytes from Apoptotic Death by Regulating Bcl-2 Expression and Bax Translocation
J. Immunol., October 15, 2006; 177(8): 5727 - 5735.
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 Cancer Res.Home page
T. C. Walser, S. Rifat, X. Ma, N. Kundu, C. Ward, O. Goloubeva, M. G. Johnson, J. C. Medina, T. L. Collins, and A. M. Fulton
Antagonism of CXCR3 Inhibits Lung Metastasis in a Murine Model of Metastatic Breast Cancer.
Cancer Res., August 1, 2006; 66(15): 7701 - 7707.
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 Molecular Cancer TherapeuticsHome page
L. M. Ellis
The role of neuropilins in cancer
Mol. Cancer Ther., May 1, 2006; 5(5): 1099 - 1107.
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 Clin. Cancer Res.Home page
A. Ottaiano, R. Franco, A. Aiello Talamanca, G. Liguori, F. Tatangelo, P. Delrio, G. Nasti, E. Barletta, G. Facchini, B. Daniele, et al.
Overexpression of Both CXC Chemokine Receptor 4 and Vascular Endothelial Growth Factor Proteins Predicts Early Distant Relapse in Stage II-III Colorectal Cancer Patients.
Clin. Cancer Res., May 1, 2006; 12(9): 2795 - 2803.
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 Arch SurgHome page
A. L. Mulkeen, T. Silva, P. S. Yoo, J. C. Schmitz, E. Uchio, E. Chu, and C. Cha
Short Interfering RNA-Mediated Gene Silencing of Vascular Endothelial Growth Factor: Effects on Cellular Proliferation in Colon Cancer Cells
Arch Surg, April 1, 2006; 141(4): 367 - 374.
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 aacredbookHome page
B. N. Gomperts and R. M. Strieter
CXC Chemokines in Angiogenesis and Metastases
Am. Assoc. Cancer Res. Educ. Book, April 1, 2006; 2006(1): 11 - 18.
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 Cancer Res.Home page
K. Yasumoto, K. Koizumi, A. Kawashima, Y. Saitoh, Y. Arita, K. Shinohara, T. Minami, T. Nakayama, H. Sakurai, Y. Takahashi, et al.
Role of the CXCL12/CXCR4 Axis in Peritoneal Carcinomatosis of Gastric Cancer
Cancer Res., February 15, 2006; 66(4): 2181 - 2187.
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 EndocrinologyHome page
D. M. E. Harvell, J. K. Richer, D. C. Allred, C. A. Sartorius, and K. B. Horwitz
Estradiol Regulates Different Genes in Human Breast Tumor Xenografts Compared with the Identical Cells in Culture
Endocrinology, February 1, 2006; 147(2): 700 - 713.
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 Cancer Res.Home page
B. M. Woerner, N. M. Warrington, A. L. Kung, A. Perry, and J. B. Rubin
Widespread CXCR4 Activation in Astrocytomas Revealed by Phospho-CXCR4-Specific Antibodies
Cancer Res., December 15, 2005; 65(24): 11392 - 11399.
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 Circ. Res.Home page
D. H. Walter, J. Haendeler, J. Reinhold, U. Rochwalsky, F. Seeger, J. Honold, J. Hoffmann, C. Urbich, R. Lehmann, F. Arenzana-Seisdesdos, et al.
Impaired CXCR4 Signaling Contributes to the Reduced Neovascularization Capacity of Endothelial Progenitor Cells From Patients With Coronary Artery Disease
Circ. Res., November 25, 2005; 97(11): 1142 - 1151.
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 Cancer Res.Home page
H. Kulbe, T. Hagemann, P. W. Szlosarek, F. R. Balkwill, and J. L. Wilson
The Inflammatory Cytokine Tumor Necrosis Factor-{alpha} Regulates Chemokine Receptor Expression on Ovarian Cancer Cells
Cancer Res., November 15, 2005; 65(22): 10355 - 10362.
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 Endocr Relat CancerHome page
G A Clines and T A Guise
Hypercalcaemia of malignancy and basic research on mechanisms responsible for osteolytic and osteoblastic metastasis to bone
Endocr. Relat. Cancer, September 1, 2005; 12(3): 549 - 583.
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 Stem CellsHome page
M. Kucia, R. Reca, K. Miekus, J. Wanzeck, W. Wojakowski, A. Janowska-Wieczorek, J. Ratajczak, and M. Z. Ratajczak
Trafficking of Normal Stem Cells and Metastasis of Cancer Stem Cells Involve Similar Mechanisms: Pivotal Role of the SDF-1-CXCR4 Axis
Stem Cells, August 1, 2005; 23(7): 879 - 894.
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 Cancer Res.Home page
B. Guleng, K. Tateishi, M. Ohta, F. Kanai, A. Jazag, H. Ijichi, Y. Tanaka, M. Washida, K. Morikane, Y. Fukushima, et al.
Blockade of the Stromal Cell-Derived Factor-1/CXCR4 Axis Attenuates In vivo Tumor Growth by Inhibiting Angiogenesis in a Vascular Endothelial Growth Factor-Independent Manner
Cancer Res., July 1, 2005; 65(13): 5864 - 5871.
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 Clin. Cancer Res.Home page
C. Laverdiere, B. H. Hoang, R. Yang, R. Sowers, J. Qin, P. A. Meyers, A. G. Huvos, J. H. Healey, and R. Gorlick
Messenger RNA Expression Levels of CXCR4 Correlate with Metastatic Behavior and Outcome in Patients with Osteosarcoma
Clin. Cancer Res., April 1, 2005; 11(7): 2561 - 2567.
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S. Scala, A. Ottaiano, P. A. Ascierto, M. Cavalli, E. Simeone, P. Giuliano, M. Napolitano, R. Franco, G. Botti, and G. Castello
Expression of CXCR4 Predicts Poor Prognosis in Patients with Malignant Melanoma
Clin. Cancer Res., March 1, 2005; 11(5): 1835 - 1841.
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 J. Biol. Chem.Home page
K. Brusselmans, F. Bono, D. Collen, J.-M. Herbert, P. Carmeliet, and M. Dewerchin
A Novel Role for Vascular Endothelial Growth Factor as an Autocrine Survival Factor for Embryonic Stem Cells during Hypoxia
J. Biol. Chem., February 4, 2005; 280(5): 3493 - 3499.
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 Cancer Res.Home page
I. Kryczek, A. Lange, P. Mottram, X. Alvarez, P. Cheng, M. Hogan, L. Moons, S. Wei, L. Zou, V. Machelon, et al.
CXCL12 and Vascular Endothelial Growth Factor Synergistically Induce Neoangiogenesis in Human Ovarian Cancers
Cancer Res., January 15, 2005; 65(2): 465 - 472.
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 Ann. N. Y. Acad. Sci.Home page
R. M. STRIETER, J. A. BELPERIO, M. D. BURDICK, S. SHARMA, S. M. DUBINETT, and M. P. KEANE
CXC Chemokines: Angiogenesis, Immunoangiostasis, and Metastases in Lung Cancer
Ann. N.Y. Acad. Sci., December 1, 2004; 1028(1): 351 - 360.
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 Cancer Res.Home page
M. C. P. Smith, K. E. Luker, J. R. Garbow, J. L. Prior, E. Jackson, D. Piwnica-Worms, and G. D. Luker
CXCR4 Regulates Growth of Both Primary and Metastatic Breast Cancer
Cancer Res., December 1, 2004; 64(23): 8604 - 8612.
[Abstract] [Full Text] [PDF]