Genistein reverses hypermethylation and induces active histone modifications in tumor suppressor gene B‐Cell translocation gene 3 in prostate cancer

Abstract

Background BTG3/ANA/APRO4 is a candidate tumor suppressor gene in some malignancies. We report here that BTG3 is transcriptionally down-regulated in prostate cancer and the mechanism of inactivation is through promoter hypermethylation. Methods Prostate cancer and normal cell lines were treated with different doses of genistein and 5-aza-2’-deoxycytidine (5Aza-C). BTG3 mRNA expression was determined by quantitative real-time PCR in tissues and cell lines. BS-PCR, cloning and sequencing were used to examine promoter methylation in tumor samples and cell lines. Enzyme activity/inhibition assays were done to check the effect of genistein and 5Aza-C on DNA methyltransferases. ChIP assay was performed to analyze chromatin modifications caused by genistein treatment. Results BTG3 mRNA expression was down-regulated in cancer tissues and cells. Genistein and 5Aza-C induced BTG3 mRNA expression in all PC cell lines. Complete methylation of BTG3 promoter in tumor samples and cancer cell lines was observed. Genistein and 5Aza-C treatment significantly decreased promoter methylation, reactivating BTG3 expression. Genistein and 5Aza-C increased levels of acetylated histones 3, 4, 2H3K4, 3H3K4 and Pol II, decreased DNMTase, MBD2 activity and increased HAT activity. Conclusion This is the first report to show that BTG3 is silenced in prostate cancer and can be reactivated by genistein induced promoter demethylation and active histone modification. Genistein showed similar effects to that of 5Aza-C, which is currently undergoing phase II clinical trials as a treatment for prostate cancer. Since genistein is a natural, non-toxic, dietary isoflavone, these results indicate that genistein is a novel, advantageous therapeutic agent for treating prostate cancer.

Epigenetic deregulation of miR-29a and miR-1256 by isoflavone contributes to the inhibition of prostate cancer cell growth and invasion

“…20 TRIM68 could functionally interact to reverse the methylation status of several genes including BTG3, GSTP1, RASSF1A, EPH2, BRCA1, p16, RARβ and MGMT. [32][33][34][35] Studies have also shown the regulatory effects of isoflavone genistein on the methylation of miR-221/222 and miR-145 in PCa cells. 36,37 These findings suggest the demethylating function of isoflavone.…”

Plant Phytochemicals as Epigenetic Modulators: Role in Cancer Chemoprevention

“…A tumor suppressor gene, BTG3, which is downregulated in renal cancer due to promoter hypermethylation was demethylated in renal cell carcinoma A498, ACHN and HEK-293 cells by inhibition of DNMT activity and MBD2 after treatment with genistein. Genistein treatment significantly decreased promoter methylation, reactivated BTG3 expression, increased levels of acetylated histone H3 and H4, H3K4me2, H3K4me3, and RNA polymerase II, decreased DNA methyl transferase and methyl-binding domain protein 2 activity, and increased HAT activity in prostate cancer cells (70). Results on effect of genistein treatment on DNA methylation are inconsistent; while in vitro studies in cancer cells have shown inhibition of DNMT activity and DNA methylation, in vivo studies have suggested otherwise.…”

Nutraceuticals as Chemopreventive and Therapeutic agents in Gut Associated Pathogenesis

“…Out of various polyphenols, curcumin is one of the most widely studied DPs for its therapeutic use as an epigenetic drug for the treatment and prevention of different types of cancer including colorectal [102]. DPs like 2-epigallocatechin-3-gallate (EGCG) isolated from green tea and genistein isolted from soybean have been found to inhibit DNMT activity against cancer cell lines [103,104]. DNMT inhibitory activity is associated with reactivation of epigenetically silenced genes such as p16, RARb, MGMT, MLH1, BTG3 and GSTP1 in human cancer cells, suggesting a possible alternate phytotherapeutic modality by targeting epigenetically silenced tumor suppressor genes through dietary polyphenols [104,105].…”

“…DPs like 2-epigallocatechin-3-gallate (EGCG) isolated from green tea and genistein isolted from soybean have been found to inhibit DNMT activity against cancer cell lines [103,104]. DNMT inhibitory activity is associated with reactivation of epigenetically silenced genes such as p16, RARb, MGMT, MLH1, BTG3 and GSTP1 in human cancer cells, suggesting a possible alternate phytotherapeutic modality by targeting epigenetically silenced tumor suppressor genes through dietary polyphenols [104,105]. Curcumin has also been reported to exhibit epigenetic modulation in cancer cells by histone acetyltransferase (HAT) and DNMT1 inhibition activities [106][107][108][109].…”