The Epigenetically Regulated Effects of Wnt Antagonists on the Expression of Genes in the Apoptosis Pathway in Human Bladder Cancer Cell Line (T24)

The epigenetic suppression of Wnt antagonists (sFRPs, DKKs, and WIF-1) causes the activation of both beta-catenin and target genes, which play an important role in cell proliferation, metastasis, and angiogenesis. This study is aimed to investigate, on transcriptional and protein levels, the synergic effects of unaccompanied and/or combined use of 5-aza-2'-deoxycytidine (DAC, 5-aza-dC), trichostatin A (TSA), and gemcitabine + cisplatin chemotherapeutic agents on the apoptotic pathway of human bladder cancer cell line T24. The anti-tumor effects of gemcitabine (0-500 nM), cisplatin (0-10 mu M), DAC (10 mu M), and TSA (300 nM) alone and/or together on T24 cells were determined by WST-1. ELISA method was used to analyze the effects of unaccompanied and combined use of gemcitabine + cisplatin, DAC, and TSA on cell proliferation and determine the cytotoxic and apoptotic dosages at the level of H3 histone acetylation. Methylation-specific PCR was used to evaluate methylation profiles of Wnt antagonist gene (WIF-1). In the case of unaccompanied and/or combined use of specified drugs, the variations in the expression levels of CTNNB1, GSK3 beta, c-MYC, CCND1, CASP-3, CASP-8, CASP-9, BCL2L1, and WIF-1 genes were determined by quantitative real-time PCR. Our results indicate that through inhibition of DNA methylation, expression of beta-catenin and Wnt antagonist re-activation and expressions of canonical Wnt/beta-catenin pathway target genes, c-myc and cyclin D1 (CCND1), have decreased. In addition, DAC, TSA, and gemcitabine + cisplatin combination caused an increase in GSK3 beta mRNA levels, which in turn significantly decreased CCND1 mRNA levels. Moreover, BCL2L1, an anti-apoptotic gene, was downregulated significantly. Meanwhile, both CASP-3 mRNA and active caspase-3 protein levels increased with respect to control (p < 0.01). The results revealed that use of quadruplicate gemcitabine + cisplatin + DAC + TSA combination led to a reduced inhibition of canonical Wnt/beta-catenin pathway and reduced cell proliferation. Our findings may offer a new approach to consider in the treatment of bladder cancer.