Synthetic Biology and Genetic Engineering

Several lines of evidences indicate that CXCR4 overexpression has been correlated with distant site metastasis and poor overall survival rate in patient with breast cancer. The tumor metastasis promoting molecule CXCR4 is considered as a potential therapeutic target for inhibiting breast cancer metastasis. Thus, novel agents that can downregulate CXCR4 expression have potential against breast cancer metastasis. In the present report, we have investigated the effect of thymoquinone (TQ), derived from the seeds of medicinal plant Nigella sativa, on the expression and regulation of CXCR4 in breast cancer cells. In addition, we have evaluated the effect of TQ in a metastasis mouse model established by intracardiac injection of luciferase-tagged MDAMB-231 breast cancer cells that metastasize to the bones. We observed that TQ could inhibit the expression of CXCR4 in MCF-7 and MDA-MB-231 cells in a dose and time dependent manner. TQ (2 mg/kg or 4 mg/kg) treatment for four weeks significantly inhibited tumor growth and significantly reduced metastases to multiple vital organs, including lungs, brain and bone. Immuno-histochemical analysis of the lung and brain tissue showed significant reduction in the expression of CXCR4, Ki67, MMP9, VEGFR2 and COX2 compared to tissues from control mice. TQ treatment also reduced the overall bone tumor burden. Overall, our results show that TQ exerts its antitumor and anti-metastatic effects by down-regulation of CXCR4 expression both in vitro and in vivo thus may have possible potential for the treatment of breast cancer.