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.

Astrocyte-elevated gene-1 (AEG-1) has been reported to be upregulated in several malignancies and play a critical role in Ha-ras-mediated oncogenesis through the phosphatidylinositol 3-kinase/AKT signaling pathway. However, the role of AEG-1 in prostate cancer (PC) has never been reported. We now show that AEG-1 is overexpressed in clinical PC tissue samples and cultured PC cells compared to benign prostatic hyperplasia tissue samples and normal prostate epithelial cells. Interestingly, AEG-1 knockdown induced cell apoptosis through upregulation of forkhead box (FOXO) 3a activity. This alteration of FOXO3a activity was dependent on reduction of AKT activity in LNCaP and PC-3 cells with high constitutive AKT activity, but not in DU145 cells with low constitutive AKT activity, although AEG-1 knockdown had no impact on phosphatase and tensin homolog expression in these cells. AEG-1 knockdown also attenuated the constitutive activity of the nuclear factor jB (NF-jB) and the activator protein 1 (AP-1) with a corresponding depletion in the expression of NF-jB and AP-1-regulated genes (interleukin (IL)-6, IL-8 and matrix metalloproteinase-9) and significantly decreased cell invasion properties of PC-3 and DU145 cells. Overall, our findings suggest that aberrant AEG-1 expression plays a dominant role as a positive auto-feedback activator of AKT and as a suppressor of FOXO3a in PC cells. AEG-1 may therefore represent a novel genetic biomarker to serve as an attractive molecular target for new anticancer agents to prevent PC cell progression and metastasis.

Genistein is a phytoestrogen that has been reported to suppress the AKT signaling pathway in several malignancies. However, the molecular mechanism of genistein action is not known. We tested the hypothesis that genistein activates expression of several aberrantly silenced tumor suppressor genes (TSGs) that have unmethylated promoters such as PTEN, CYLD, p53 and FOXO3a. We report here that genistein activates TSGs through remodeling of the heterochromatic domains at promoters in prostate cancer cells by modulating histone H3-Lysine 9 (H3-K9) methylation and deacetylation. Genistein activation involved demethylation and acetylation of H3-K9 at the PTEN and the CYLD promoter, while acetylation of H3-K9 at the p53 and the FOXO3a promoter occurred through reduction of endogenous SIRT1 activity. There was a decrease of SIRT1 expression and accumulation of SIRT1 in the cytoplasm from the nucleus. Increased expression of these TSGs was also reciprocally related to attenuation of phosphorylated-AKT and NF-jB binding activity in prostate cancer cells. This is the first report describing a novel epigenetic pathway that activates TSGs by modulating either histone H3-Lysine 9 (H3-K9) methylation or deacetylation at gene promoters leading to inhibition of the AKT signaling pathway. These findings strengthen the understanding of how genistein may be chemoprotective in prostate cancer. ' 2008 Wiley-Liss, Inc.Key words: genistein; prostate cancer; tumor suppressor gene Genistein (4 0 ,5,7-trihydroxyflavone), a naturally occurring isoflavenoid abundant in soy products, has been identified as an inhibitor of protein tyrosine kinases, which play key roles in cell growth and apoptosis. 1,2 Genistein has been reported to have estrogenic properties and antineoplastic activity in multiple tumor types. 3 One mode by which hormonal agents work is by regulating gene activity by modulating epigenetic events such as histone acetylation and DNA methylation. 4,5 Genistein was also found to have epigenetic effects in the mouse prostate. 6 Taken together, these findings suggest that genistein's antitumor activity may be mediated by epigenetic-based pathways. On the other hand, genistein induces apoptosis and inhibits the activation of nuclear factor kappaB (NF-jB) pathway, which could be mediated via AKT (AKT8 virus oncogene cellular homolog) signaling, the most important survival pathway in cellular signaling. 7 However, the precise molecular mechanism has yet to be characterized.AKT is a serine/threonine protein kinase functioning downstream of phosphatidylinositol 3-kinase (PI3K) in response to mitogen or growth factor stimulation. High-levels of AKT activation have been associated with the development and metastasis of several cancers. 8 AKT activation not only directly inhibits apoptosis by multiple mechanisms involved in inhibiting the conformational change of Bax, BAD and caspase-9 but also modulates apoptosis indirectly by influencing the activities of several transcription factors, including fork head transcription factors (FOXO) and...