Epigenetic regulation of human WIF1 and DNA methylation situation of WIF1 and GSTM5 in urothelial carcinoma.

WNT inhibitory factor 1 (WIF1) is known to function as a tumor suppressor gene; it inhibits oncogene activation by preventing WNT signaling. This study investigated the epigenetic regulation of WIF1 gene in bladder cancer. We observed a positive relationship between WIF1 mRNA expression and survival probability of bladder cancer patients. The WIF1 gene expression could be enhanced by DNA demethylation drug 5-aza-2'-deoxycytidine (5-aza-dC) and histone deacetylase inhibitor trichostatin A (TSA), suggesting that epigenetic modifications could regulate WIF1 gene expression. Overexpression of WIF1 inhibited cell proliferation and migration in 5637 cells, confirming the tumor suppressor role of WIF1. 5-Aza-dC dose dependently increased WIF1 gene expression while reducing DNA methylation level, suggesting that reversing WIF1 DNA methylation could activate its gene expression. We collected the cancer tissues and urine pellets of bladder cancer patients and only urine pellets from non-bladder cancer volunteers for DNA methylation analysis, but the methylation level of WIF1 gene -184 to +29 did not differ between patients and controls. We also analyzed glutathione S-transferase Mu 5 (GSTM5) gene methylation level because GSTM5 DNA hypermethylation was suggested to be a tumor biomarker in our previous study. It confirmed a higher GSTM5 DNA methylation in bladder cancer patients than in controls. In summary, this study suggests that the 5-aza-dC activated WIF1 gene which showed an anti-cancer effect, while WIF1 promoter -184 to +29 did not provide a suitable methylation assay region in clinical samples. In contrast, GSTM5 promoter -258 to -89 is a useful region for DNA methylation assay because it shows a higher methylation level in bladder cancer patients.

The suppressive role of phytochemical-induced glutathione S-transferase Mu 2 in human urothelial carcinoma cells.

Glutathione S-transferases (GSTs) belong to one class of phase 2 detoxification enzymes which are important in metabolism and/or detoxification of various electrophilic endogenous metabolites and xenobiotics. From the available database, we found that GSTM2 gene expression is lower in high stages of bladder urothelial carcinoma than in stage 1 and normal bladder tissue. GSTM2 overexpression retards invasion, migration and tumor sphere formation of bladder cancer cells. Analysis of GSTM2 promoter activity shows that one SP1 site located at - 48 to - 40 bp is important for GSTM2 gene expression in BFTC 905 cells. An SP1 inhibitor, mithramycin A, inhibits GSTM2 promoter activity and protein expression. SP1 overexpression also increases GSTM2 expression in BFTC 905 and 5637 cells. Eight potential phytochemicals were analyzed for GSTM2 promoter activation, and results indicated that baicalein, berberrubine, chalcone, curcumin, resveratrol, and wogonin can increase promoter activity. In endogenous GSTM2 expression, berberrubine and resveratrol activated GSTM2 mRNA and protein expression the most. A DNA methylation inhibitor, 5-aza-deoxycytidine, can decrease GSTM2 gene methylation level and then increase its gene expression; 50 µM berberrubine decreased the GSTM2 gene methylation level, providing a mechanism for activating GSTM2 gene expression. Berberrubine and resveratrol also increased SP1 protein expression as one of the mechanisms for GSTM2 gene expression. In summary, berberrubine and resveratrol activates GSTM2 expression which inhibits cell proliferation, migration, and invasion of bladder cancer cells. The GSTM2 expression mechanism is partially via SP1 activation, and the effect of berberrubine is also partly via DNA CpG demethylation.

CCAAT/enhancer-binding protein delta mediates tumor necrosis factor alpha-induced Aurora kinase C transcription and promotes genomic instability.

Epidemiologic and clinical research indicates that chronic inflammation increases the risk of certain cancers, possibly through chromosomal instability. However, the mechanism of inflammation-dependent chromosomal instability associated with tumorigenesis is not well characterized. The transcription factor CCAAT/enhancer-binding protein δ (C/EBPδ, CEBPD) is induced by tumor necrosis factor α (TNFα) and expressed in chronically inflamed tissue. In this study, we show that TNFα promotes aneuploidy. Loss of CEBPD attenuated TNFα-induced aneuploidy, and CEBPD caused centromere abnormality. Additionally, TNFα-induced CEBPD expression augmented anchorage-independent growth. We found that TNFα induced expression of aurora kinase C (AURKC) through CEBPD, and that AURKC also causes aneuploidy. Furthermore, high CEBPD expression correlated with AURKC expression in inflamed cervical tissue specimens. These data provide insight into a novel function for CEBPD in inducing genomic instability through the activation of AURKC expression in response to inflammatory signals.