Genistein Reinforces the Inhibitory Effect of Cisplatin on Liver Cancer Recurrence and Metastasis after Curative Hepatectomy

Background: The high recurrence rate after hepatic resection in hepatocellular carcinoma (HCC) is a major obstacle to improving prognosis. The objective of the present study was to explore the function of genistein, a soy-derived isoflavone, in enhancing the inhibitory effect of cisplatin on HCC cell proliferation and on tumor recurrence and metastasis in nude mice after curative hepatectomy. Methods: Proliferation of human HCC cells (HCCLM3) was detected by 3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide (MTT) assay. Synergistic effects of genistein and cisplatin were evaluated with the median-effect formula. Nude mice bearing human HCC xenografts underwent tumour resection (hepatectomy) 10 days post implantation, then received intraperitoneal administration of genistein or cisplatin alone or the combination of the two drugs. 33 days after surgery, recurrent tumours and pulmonary metastasis were evaluated individually. MMP-2 level in recurrent tumours was detected by immunohistochemistry and real-time PCR; MMP-2 expression in HCCLM3 was detected by immunocytochemistry. Results: Genistein and cisplatin both suppressed the growth and proliferation of HCCLM3 cells. The two drugs exhibited synergistic effects even at relatively low concentrations. In vivo, mice in the combined genistein and cisplatin group had a smaller volume of liver recurrent tumors and fewer pulmonary metastatic foci compared with single drug treated groups. Cisplatin upregulated the expression of MMP-2 in both recurrent tumours and HCCLM3, while genistein abolished cisplatin-induced MMP-2 expression. Conclusions: Genistein reinforced the inhibitory effect of cisplatin on HCC cell proliferation and tumour recurrence and metastasis after curative hepatectomy in nude mice, possibly through mitigation of cisplatin-induced MMP-2 upregulation.