The Wnt signaling pathway is essential for development and organogenesis. Wnt signaling stabilizes beta-catenin, which accumulates in the cytoplasm, binds to 1-cell factor (TCF; also known as lymphocyte enhancer-binding factor, LEF) and then upregulates downstream genes. Mutations in CTNNB1 (encoding beta-catenin) or APC (adenomatous polyposis coli) have been reported in human neoplasms including colon cancers and hepatocellular carcinomas (HCCs). Because HCC5 tend to show accumulation of beta-catenin more often than mutations in CTNNB1, we looked for mutations in AXIN1, encoding a key factor for Wnt signaling, in 6 HCC cell lines and 100 primary HCC5. Among the 4 cell lines and 87 HCC5 in which we did not detect CTNNB1 mutations, we identified AXIN1 mutations in 3 cell lines and 6 mutations in 5 of the primary HCCs. In cell lines containing mutations in either gene, we observed increased DNA binding of TCF associated with beta-catenin in nuclei. Adenovirus mediated gene transfer of wild-type AXINI induced apoptosis in hepatocellular and colorectal cancer cells that had accumulated beta-catenin as a consequence of either APC, CTNNB1 or AXIN1 mutation, suggesting that axin may be an effective therapeutic molecule for suppressing growth of hepatocellular and colorectal cancers.

Purpose: MicroRNAs (miRNA) are small noncoding RNAs thought to be involved in physiologic and developmental processes by negatively regulating the expression of target genes. Little is known about the role of miRNAs in normal and cancer cells. It is possible that deregulation of miRNA may contribute to the oncogenesis of some cancers. We studied the expression level of the miRNA processing enzyme (DICER1, DGCR8, and RNASEN) in esophageal squamous cell carcinoma (ESCC). Experimental Design: The expression levels of DICER1, DGCR8, and RNASEN mRNA in 73 ESCC tissues were compared with that in corresponding normal esophageal epithelium by Taqman real-time reverse-transcription PCR.We also examined RNASEN protein expression in 27 cell lines. The role of RNASEN in cell proliferation in ESCC cells was assessed by small interfering RNA. Paraffin sections of ESCC patients were immunohistochemically investigated. Results: We found that RNASEN expression levels were enhanced in a fraction of esophageal cancers. Multivariate Cox regression analysis showed that the prognostic effect of RNASEN (P = 0.0036) seems to be independent of disease stage (P = 0.0060). Knockdown of RNASEN in esophageal cancer cell lines resulted in a 46% to 85% reduction in cell number. In an immunohistochemical study, the intensity of RNASEN expression was often increased in the tumor compared with that in normal epithelium. Conclusions: The relationship between the RNASEN expression and the prognosis of the ESCC patients warrants a further study on the role of miRNA and tumor progression.

Cell cycle progression is monitored by checkpoint mechanisms to ensure the integrity of the genome and the fidelity of sister chromatid separation. Failure of such checkpoint functions results in genomic instability, a condition that predisposes cells to neoplastic transformation and tumor progression. Recently, Scolnick and Halazonetis defined a new mitotic checkpoint that acts at prophase and delays chromosome condensation in response to mitotic stress, and identified a gene, named checkpoint with FHA and ring finger (Chfr), that seems to be required for delaying prophase in human cells. In the present study, we examined human Chfr mRNA expression in 15 human esophageal cancer cell lines and 43 primary esophageal cancers to investigate the potential involvement of Chfr in the pathogenesis of esophageal cancers. We report here that a significant proportion of human esophageal cancer has loss of expression of Chfr gene. Furthermore, we found aberrant hypermethylation of the promoter region of this checkpoint gene in four of 15 (26.7%) esophageal cancer cell lines and in seven of 43 (16.3%) primary cancers.

Scutellaria baicalensis (SB) and SB-derived polyphenols possess anti-proliferative activities in several cancers, including pancreatic cancer (PaCa). However, the precise molecular mechanisms have not been fully defined. SB extract and SB-derived polyphenols (wogonin, baicalin, and baicalein) were used to determine their anti-proliferative mechanisms. Baicalein significantly inhibited the proliferation of PaCa cell lines in a dose-dependent manner, whereas wogonin and baicalin exhibited a much less robust effect. Treatment with baicalein induced apoptosis with release of cytochrome c from mitochondria, and activation of caspase-3 and -7 and PARP. The general caspase inhibitor zVAD-fmk reversed baicalein-induced apoptosis, indicating a caspase-dependent mechanism. Baicalein decreased expression of Mcl-1, an anti-apoptotic member of the Bcl-2 protein family, presumably through a transcriptional mechanism. Genetic knockdown of Mcl-1 resulted in marked induction of apoptosis. The effect of baicalein on apoptosis was significantly attenuated by Mcl-1 over-expression, suggesting a critical role of Mcl-1 in this process. Our results provide evidence that baicalein induces apoptosis in pancreatic cancer cells through down-regulation of the anti-apoptotic Mcl-1 protein.