BTG3/ANA/APRO4 has been reported to be a tumor suppressor gene in some malignancies. It constitutes important negative regulatory mechanism for Src-mediated signaling, a negative regulator of the cell cycle and inhibits transcription factor E2F1. We report that BTG3 is downregulated in renal cancer and that the mechanism of inactivation is through promoter hypermethylation. Quantitative real-time polymerase chain reaction (PCR) showed that BTG3 was downregulated in cancer tissues and cells. Genistein and 5-aza-2'-deoxycytidine (5Aza-C) induced BTG3 messenger RNA (mRNA) expression in A498, ACHN and HEK-293 renal cell carcinoma (RCC) cell lines. Bisulfite-modified PCR and DNA sequencing results showed complete methylation of BTG3 promoter in tumor samples and cancer cell lines. Genistein and 5Aza-C treatment significantly decreased promoter methylation, reactivating BTG3 expression. Chromatin immunoprecipitation assay revealed that genistein and 5Aza-C increased levels of acetylated histones 3, 4, 2H3K4, 3H3K4 and RNA polymerase II at the BTG3 promoter indicative of active histone modifications. Enzymatic assays showed genistein and 5Aza-C decreased DNA Methyltransferase, methyl-CpG-binding domain 2 activity and increased HAT activity. Cell cycle and 3-(4,5-dimethylthiazole-2-yl)-2,5-biphenyl tetrazolium bromide cell proliferation assays showed that genistein has antiproliferative effect on cancer cell growth through induction of cell cycle arrest. This is the first report to show that BTG3 is epigenetically silenced in RCC and can be reactivated by genistein-induced promoter demethylation and active histone modification. Genistein had similar effects to that of 5Aza-C, which is a potent demethylating agent with high toxicity and instability. Genistein being a natural, non-toxic, dietary isoflavone is effective in retarding the growth of RCC cells, making it a promising candidate for epigenetic therapy in renal carcinoma.

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.

Purpose: The chemokine CXCL12 and its receptor CXCR4 have been found to be associated with cancer metastasis. A single nucleotide polymorphism of CXCL12 G801A has been described and is regarded as a target for cis-acting factor that has the ability to up-regulate CXCL12 expression. Currently, there are no reports investigating the role of CXCL12 G801A polymorphism in prostate cancer (PC). Experimental Design: We genotyped CXCL12 G801A and p53Arg72Pro in 167 PC patients and 167 age-matched healthy subjects. Genotyping was done with PCR-RFLP and confirmed by direct DNA sequencing. To investigate the effect of the CXCL12 G801A polymorphism on CXCL12 and CXCR4 expression, immunohistochemistry was done in genotyped PC tissues. Results: A significant increase in the GA + AA genotype of the CXCL12 G801A polymorphism was observed in PC patients compared with healthy controls. The frequency of CXCL12 AA genotype was significantly higher in a group of patients with lymph node metastasis (23%) compared with those without metastasis (7 %). The frequency of CXCL12 expression in AA + GA genotype carriers was significantly higher than that in GG genotype carriers. Among the carriers with CXCL12 GA + AA genotypes, CXCR4 expression was also significantly higher compared with those with the GG genotype. Moreover, among the groups with both CXCL12-and CXCR4-positive staining, the frequency of the CXCL12 GA + AA genotype was high. Although we did not find a significant relationship between the frequency of the Arg/Pro + Pro/Pro genotype of p53 Arg72Pro and susceptibility in PC, there was a combined effect of CXCL12 GA + AA genotype and the p53 72Arg/Pro + Pro/Pro genotype on the frequency of PC. These results indicate that the p53 codon 72 polymorphism may interact with CXCL12 G801A. Conclusions: This is the first report showing that CXCL12 G801A polymorphism may be a risk factor for PC. Moreover, this study suggests that this polymorphism can be an important marker for detecting microinvasion and PC metastasis.