We observed that a synthetic inhibitor of β-catenin, JW74, significantly increased formation of BaP-induced DNA adducts in both colorectal adenoma and carcinoma-derived cell lines.
Human colorectal adenomas (N = 158) with aberrant (cytoplasmic and nuclear) β-catenin expression had a higher percentage of immunohistochemical DR4 and DR5 staining per tumour (mean: 73 and 88%, respectively) than those with membranous β-catenin staining only (mean: 50 and 70%, respectively, P < 0.01 for both).
The study shows for the first time that β-catenin knockdown upregulates 15-PGDH in colorectal adenoma and carcinoma cells without affecting COX-2 protein levels.
Furthermore, β-catenin knockdown in vitro increases PGT expression in both colorectal adenoma- and carcinoma-derived cell lines, as does dnTCF4 induction in LS174T cells.
Two hundred sixty-nine colorectal adenomas were examined for KRAS and BRAF mutation and immunohistochemical staining of β-catenin, O6-Methyl Guanine DNA Methyltransferase (MGMT), and p53.
We report here that Na(+)/H(+) exchanger 3 regulating factor 1 (NHERF1)/EBP50, an adaptor molecule that interacts with β-catenin, undergoes successive alterations during the colorectal adenoma-to-carcinoma transition, ranging from loss of normal apical membrane distribution to ectopic cytoplasmic overexpression.
Results showed that the expression profiles of LKB1, beta-catenin and IFITM1 in PJSs were similar to those in CRAs both at the mRNA and protein levels.
Here, we have investigated the expression of key components of beta-catenin-independent Wnt response pathways to determine whether their profiles change during the transition from normal mucosa to colorectal adenomas.
Here we show a correlated high expression of beta-catenin and securin (hPTTG1) in colorectal adenomas and carcinomas and further demonstrate that securin is a target of beta-catenin transcriptional activation.
Molecular changes (K-ras and beta-catenin mutations, chromosome 18q allele loss (LOH), APC LOH, microsatellite instability (MSI), and expression of beta-catenin and p53) were examined in four series of CRC patients with proven or probable hereditary disease: hereditary non-polyposis colon cancer (HNPCC); MYH associated polyposis (MAP); multiple (>5) colorectal adenomas without familial adenomatous polyposis (FAP); and other families/cases referred to family cancer clinics (FCC series).
Nuclear beta-catenin expression was assessed in pretreatment colorectal adenomas and in adenomas after treatment with sulindac from five patients with familial adenomatous polyposis (FAP).
We previously found that 31% of colorectal adenomas and 84% of carcinomas showed reduced membranous staining of beta-catenin, while 46% of adenomas and 79% of carcinomas displayed beta-catenin nuclear expression.
beta-Catenin is essential for the function of cadherins, a family of Ca2+-dependent cell-cell adhesion molecules, by linking them to (alpha)-catenin and the actin cytoskeleton. beta-Catenin also binds to adenomatous polyposis coli (APC) protein, a cytosolic protein that is the product of a tumor suppressor gene mutated in colorectal adenomas.