The chemokine CCL5 as a potential prognostic factor predicting disease progression in stage II breast cancer patients

PURPOSE

The aim of this study was to determine the prognostic value of the chemokine CCL5, considered as a promalignancy factor in breast cancer, in predicting breast cancer progression and to evaluate its ability to strengthen the prognostic significance of other biomarkers.

EXPERIMENTAL DESIGN

The expression of CCL5, alone and in conjunction with estrogen receptor (ER)-alpha, ER-beta, progesterone receptor (PR), and HER-2/neu (ErbB2), was determined in breast tumor cells by immunohistochemistry. The study included 142 breast cancer patients, including individuals in whom disease has progressed.

RESULTS

Using Cox proportional hazard models, univariate analysis suggested that, in stage I breast cancer patients, CCL5 was not a significant predictor of disease progression. In contrast, in stage II patients, the expression of CCL5 (CCL5(+)), the absence of ER-alpha (ER-alpha(-)), and the lack of PR expression (PR(-)) increased significantly the risk for disease progression (P = 0.0045, 0.0041, and 0.0107, respectively). The prognostic strength of CCL5, as well as of ER-alpha(-), improved by combining them together (CCL5(+)/ER-alpha(-): P = 0.0001), being highly evident in the stage IIA subgroup [CCL5(+)/ER-alpha(-) (P = 0.0003); ER-alpha(-) (P = 0.0315)]. In the stage II group as a whole, the combinations of CCL5(-)/ER-alpha(+) and CCL5(-)/PR(+) were highly correlated with an improved prognosis. Multivariate analysis indicated that, in stage II patients, ER-alpha and CCL5 were independent predictors of disease progression.

CONCLUSIONS

CCL5 could be considered as a biomarker for disease progression in stage II breast cancer patients, with the CCL5(+)/ER-alpha(-) combination providing improved prediction of disease progression, primarily in the stage IIA subgroup.

Concomitant expression of the chemokines RANTES and MCP-1 in human breast cancer: a basis for tumor-promoting interactions

The chemokines RANTES (CCL5) and MCP-1 (CCL2) were suggested to contribute, independently, to breast malignancy. In the present study, we asked if the two chemokines are jointly expressed in clinical samples of breast cancer patients, and do they interact in breast tumor cells. We found that RANTES and MCP-1 were expressed by breast tumor cells in primary tumors of Ductal Carcinoma In Situ and of Invasive Ductal Carcinoma, but minimally in normal breast epithelial duct cells. The chemokines were also detected in metastases and pleural effusions. Novel findings showed that co-expression of RANTES and MCP-1 in the same tumor was associated with more advanced stages of disease, suggesting that breast tumors "benefit" from interactions between the two chemokines. Accordingly, MCP-1 significantly promoted the release of RANTES from endogenous pre-made vesicles, in an active process that depended on calcium from intracellular and extracellular sources, and on intracellular transport of RANTES towards exocytosis. Our findings show a chemokine-triggered release of stored pro-malignancy chemokine from breast tumor cells. These observations support a major tumor-promoting role for co-expression of the chemokines in breast malignancy, and agree with the significant association of joint RANTES and MCP-1 expression with advanced stages of breast cancer.

The expression of the chemokine receptor CXCR3 and its ligand, CXCL10, in human breast adenocarcinoma cell lines

The acquisition of a metastatic phenotype in breast epithelial cells is a progressive process, influenced by a large variety of cellular and soluble factors. Of these, members of the chemokine superfamily, such as CCL2, CCL5, CXCL8 and CXCL12 have been recently suggested to promote breast cancer progression. A pre-requisite for elucidation of the role of other chemokines in breast cancer progression is the characterization of chemokine and chemokine receptor expression by breast tumor cells. The present study focuses on CXCL10, a CXC chemokine that was recently suggested to have anti-malignant properties, and its corresponding receptor CXCR3. CXCR3 expression was detected in three human breast adenocarcinoma cell lines, MDA-MB-231, MCF-7 and T47D. CXCR3 expression was potently up-regulated by growing the cells under stress conditions, imposed by serum starvation. Unlike many other chemokine receptors, CXCR3 expression was not down-regulated by exposure to high concentrations (500ng/ml) of its ligand, CXCL10, but rather was promoted. CXCL10-induced up-regulation of CXCR3 expression in the three cell lines was inhibited by cycloheximide, indicating that de novo protein synthesis is required for this process. In addition to CXCR3, the secretion of CXCL10 was noted in the MDA-MB-231, MCF-7 and T47D cells. CXCL10 secretion was found to be down-regulated by IL-6, a potentially pro-malignant cytokine in breast cancer. The concomitant expression of CXCR3 and CXCL10 in breast tumor cells suggests that a CXCR3-CXCL10 axis may function in these cells, and paves the way for an in depth analysis of CXCL10-CXCR3 interactions in breast tumor cells.

The angiogenic factors CXCL8 and VEGF in breast cancer: regulation by an array of pro-malignancy factors

The regulation of secretion of the angiogenic factors CXCL8 and Vascular Endothelial Growth Factors (VEGF) was determined in breast tumor cells and in monocytic cells (as host cells that contribute to breast cancer). CXCL8 secretion, and partly the secretion of VEGF, were up-regulated in monocytic cells, but not in breast tumor cells, by the CC chemokines CCL5 and CCL2. EGF potently up-regulated CXCL8 secretion by breast tumor cells, and its effect was promoted by a consecutive treatment of the cells by estrogen and progesterone. These findings provide evidence for a complex set of pro-malignancy factors that may control the expression of angiogenic mediators at breast tumor sites.

The CC chemokine RANTES in breast carcinoma progression: regulation of expression and potential mechanisms of promalignant activity

Breast cancer progression may be affected by various cellular components expressed by the tumor cells and/or by microenvironmental factors. Many studies report the correlation between breast cancer progression and monocyte infiltration into the tumor site. We have identified recently the CC chemokine regulated on activation, normal T cell expressed and secreted (RANTES), a major monocyte chemoattractant expressed by breast tumor cells, as a potential contributor to breast cancer progression. In the present study, analysis of the regulation of RANTES expression demonstrates that the expression of RANTES in breast tumor cells is elevated significantly and in a synergistic manner by IFN-gamma and tumor necrosis factor-alpha. Identification of the mechanisms by which RANTES may contribute to breast cancer progression included the analysis of the potential ability of RANTES to act in paracrine and indirect mechanisms, as well as directly on the tumor cells, to promote disease progression. Our results suggest that breast tumor cell-derived RANTES may promote breast cancer progression by its partial contribution to monocyte migration into breast tumor sites. Moreover, RANTES promotes the expression of matrix metalloproteinase (MMP) 9 by THP-1 monocytic cells and elevates vascularity in chick chorioallantoic membrane assays. Tumor necrosis factor-alpha, a major monocyte-derived cytokine, was found to promote the expression of MMP9 and MMP2 by MCF-7 and T47D breast adenocarcinoma cells, respectively, and to induce the de novo expression of an additional proteolytic enzyme by T47D cells, presumably MMP9. The possibility that RANTES may act directly on breast tumor cells was supported by detection of the expression of the CCR5 RANTES receptor in biopsy sections of breast cancer patients and by the ability of RANTES to promote the expression of MMP9 by MCF-7 cells. In all, our study suggests that the expression of RANTES by breast tumor cells results not only in monocyte migration to the tumor site but also in protumorigenic activities of RANTES and of proinflammatory cytokines that may facilitate metastasis formation and contribute to disease progression.