Abstract:Introduction: Silibinin, a polyphenolic flavonoid isolated from the milk thistle plant (Silybummarianum), has various applications in cancer therapy. This investigation aimed to examine the effects of silibinin on proliferation and chemokine receptor expression on MDA-MB-231 cells, a highly metastatic human breast cancer cell line. Methods: The cytotoxic effect of silibinin on MDA-MB-231 cells was determined by micro-culture tetrazolium test (MTT) assay. In addition, the expression of chemokine receptors CXCR3, CCR5 and CCR7 genes in response to silibinin was evaluated by Real-Time PCR. Results: Data analysis from MTT assay showed that silibinin had dose-dependent and time-dependent inhibitory effects on MDA-MB-231 cell line. Moreover, Real-Time PCR analysis showed that silibinin not only had no inhibitory effects on CXCR3, CCR5 and CCR7 gene expressions, but also could increase significantly the expression of these genes in a dose and time-dependent manner. Conclusion: These results revealed for the first time the increased possibility of CXCR3, CCR5 and CCR7 genes expression in response to silibinin in human breast cancer cells.