Purpose: Aberrant activation of the Wingless-type (Wnt) pathway plays a significant role in the pathogenesis of several human cancers. Wnt inhibitory factor-1 (Wif-1) was identified as one of the secreted antagonists that can bind Wnt protein.We hypothesize that Wif-1plays an important role in bladder cancer pathogenesis. Experimental Design: To test this hypothesis, epigenetic and genetic pathways involved in the Wif-1gene modulation and expression ofWnt/h-catenin-related genes were analyzed in 4 bladder tumor cell lines and 54 bladder tumor and matched normal bladder mucosa. Results: Wif-1 mRNA expression was significantly enhanced after 5-aza-2V -deoxycytidine treatment in bladder tumor cell lines. Wif-1 promoter methylation level was significantly higher and Wif-1 mRNA expression was significantly lower in bladder tumor samples than in bladder mucosa samples. In the total bladder tumor and bladder mucosa samples, an inverse correlation was found between promoter methylation and Wif-1 mRNA transcript levels. However, lossof-heterozygosity at chromosome 12q14.3 close to the Wif-1 gene loci was a rare event (3.7%). Nuclear accumulation of h-catenin was significantly more frequent in bladder tumor than in bladder mucosa and inversely correlated with Wif-1 expression. In addition, known targets of the canonical Wnt/h-catenin signaling pathway, such as c-myc and cyclin D1, were up-regulated in bladder tumor compared with bladder mucosa, and this up-regulation was associated with reduced Wif-1 expression at both mRNA and protein levels. Furthermore, transfection of Wif-1 small interfering RNA into bladder tumor cells expressing Wif-1 mRNA transcripts had increased levels of c-myc and cyclin D1and accelerated cell growth. Conclusion: This is the first report showing that CpG hypermethylation of the Wif-1promoter is a frequent event in bladder tumor and may contribute to pathogenesis of bladder cancer through aberrant canonical Wnt/h-catenin signaling pathway. The present study elucidates novel pathways that are involved in the pathogenesis of bladder cancer.

Dexamethasone inhibited the growth of GR-positive cancers, possibly through the disruption of the NF-kappaB-IL-6 pathway.

Purpose: Cytochrome P450 1B1 (CYP1B1), a dioxin inducible member of the CYP supergene family, is overexpressed in various human malignancies including prostate cancer. We hypothesized that promoter/enhancer CpG methylation contributes to the regulation of CYP1B1 expression in human prostate tissue. Experimental Design: Expression and induction of the CYP1B1 gene in clinical prostate tissues and prostate cancer cell lines were investigated. The methylation status of the CYP1B1 gene was analyzed in 175 prostate cancer and 96 benign prostatic hyperplasia samples using methylationspecific PCR (MSP) and bisulfite-modified DNA sequencing. MSP primers covered dioxin response elements (DRE) and Sp1sites that are important for the expression of CYP1B1. Results: Expressions of CYP1B1mRNA and protein were increased in prostate cancer. The aryl hydrocarbon receptor (AhR)/AhR nuclear translocator (ARNT) heterodimer complex activates gene transcription by binding to the DREs of CYP1B1. In prostate cancer cells, CYP1B1 mRNA was induced by 2,3,7,8-tetrachlorodigenzo-p-dioxin (TCDD) and/or demethylation agent (5-aza-2-deoxycytidine). There was no change in the expressions of AhR and ARNT. Methylation of promoter/enhancer regions was significantly higher in benign prostatic hyperplasia compared with prostate cancer. MSP-positive patients had significantly lower risk for prostate cancer as compared with MSP-negative patients. There was no correlation between CYP1B1 methylation status and clinicopathologic features. Conclusions: CYP1B1is overexpressed in prostate cancer and regulated by hypomethylation of its promoter/enhancer region. This is the first report about CYP1B1 regulation in human clinical prostate samples showing that hypomethylation of the CYP1B1 gene may play an important role in prostate cancer.

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