Genistein potentiates the effect of 17-beta estradiol on human hepatocellular carcinoma cell line

Abstract

BACKGROUND: Hepatocellular carcinoma (HCC) is one of the most common malignant tumors. This cancer may be due to a multistep process with an accumulation of epigenetic alterations in tumor suppressor genes (TSGs), leading to hypermethylation of the genes. Hypermethylation of TSGs is associated with silencing and inactivation of them. It is well-known that DNA hypomethylation is the initial epigenetic abnormality recognized in human tumors. Estrogen receptor alpha (ERalpha) is one of the TSGs which modulates gene transcription and its hypermethylation is because of overactivity of DNA methyltransferases. Fortunately, epigenetic changes especially hypermethylation can be reversed by pharmacological compounds such as genistein (GE) and 17-beta estradiol (E2) which involve in preventing the development of certain cancers by maintaining a protective DNA methylation. The aim of the present study was to analyze the effects of GE on ERalpha and DNMT1 genes expression and also apoptotic and antiproliferative effects of GE and E2 on HCC. MATERIALS AND METHODS: Cells were treated with various concentrations of GE and E2 and the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide assay was used. Furthermore, cells were treated with single dose of GE and E2 (25 muM) and flow cytometry assay was performed. The expression level of the genes was determined by quantitative real-time reverse transcription polymerase chain reaction. RESULTS: GE increased ERalpha and decreased DNMT1 genes expression, GE and E2 inhibited cell viability and induced apoptosis significantly. CONCLUSION: GE can epigenetically increase ERalpha expression by inhibition of DNMT1 expression which in turn increases apoptotic effect of E2. Furthermore, a combination of GE and E2 can induce apoptosis more significantly.