However, in the colon carcinoma cell line SW480, which has negligible E-cadherin expression, CAS did not associate with beta-catenin, plakoglobin, or alpha-catenin, suggesting that E-cadherin is the protein which bridges CAS to the rest of the complex.
Together with the other alterations, beta-catenin accumulation may contribute to the development and progression of colon carcinoma both by dedifferentiation and through proteolytic activity.
In two recently described human oesophageal adenocarcinoma cell lines JROECL 47 and JROECL 50, derived from one tumour, we detected identical E-cadherin and beta-catenin gene mutations as in colon carcinoma cell line HCT 116.
Our findings suggest APC mutations alter regulation of both beta- and gamma-catenin, perhaps explaining why the frequency of APC mutations in colon cancer far exceeds that of beta-catenin mutations.
Lowering of cellular p300 levels by using a ribozyme directed against p300 reduced TCF transcriptional activity and inhibited the neoplastic growth properties of a beta-catenin-transformed rat epithelial cell line and a human colon carcinoma line with a beta-catenin mutation.
If certain polymorphisms in Wnt signaling through beta-catenin predispose to colon cancer, this might manifest as decreased binding affinity of proteins such as axin or the adenomatous polyposis coli protein to beta-catenin.
In this study, we used HCT-15 colon carcinoma and NIH 3T3 fibroblasts as models to investigate the effects of a phosphotyrosine phosphatase (PTPase) inhibitor on the localization of beta-catenin, the binding affinity to LEF-1 (Lymphoid Enhancer Factor), and on LEF-1-dependent transactivation function.
These studies formally demonstrate the critical role of beta-catenin signaling in the neoplastic growth of APC-mutant colon cancer cells and suggest that strategies targeting beta-catenin may be of use in the therapy of colon cancer.
This study concluded that rectal cancer may involve more nuclear beta-catenin in the APC/beta-catenin pathway than colon cancer and/or nuclear beta-catenin may have another role in rectal cancer independently of APC.
To more precisely delineate the role of beta-catenin signaling in colon cancer growth, we treated mice bearing APC-mutant SW480 colon cancer xenografts with antisense oligonucleotides (ODNs) directed against beta-catenin mRNA and examined effects on beta-catenin expression and tumor growth.
In 30 human cell lines derived from different origins, axin2 and hnkd were expressed only in human colon cancer cell lines that are known to have activating mutations in the Wnt/beta-catenin pathway.
Furthermore, these colon carcinoma cell lines differ in their mechanism of Wnt pathway activation, with adenomatous polyposis coli (APC) mutant SW620 cells having high levels of BCT complexes and APC wild-type HCT-116 cells having mutant beta-catenin, low levels of BCT complexes and correspondingly higher levels of free Tcf.
We conducted a large-scale analysis of beta-catenin and MMP-7 expression in human colon cancer to determine the potential clinical importance of these molecules.
Mutation of the adenomatous polyposis coli and beta-catenin genes in colon cancer leads to constitutive activation of transcription from promoters containing binding sites for Tcf/LEF transcription factors.
Our findings identify LEF-1 as key regulator of beta-catenin nuclear localization and stability and suggest that overexpression of LEF-1 in colon cancer and melanoma cells may contribute to the accumulation of oncogenic beta-catenin in the nucleus.
Although activating mutations in the genes for adenomatous polyposis coli (APC) and beta-catenin are clearly associated with colon cancer, less is understood about the role of the upstream secreted ligands (Wnts) and their receptors (frizzled, Fz) in this process.
The results indicate that induction of Nr-CAM transcription by beta-catenin or plakoglobin plays a role in melanoma and colon cancer tumorigenesis, probably by promoting cell growth and motility.
Heterozygous loss of PPARgamma causes an increase in beta-catenin levels and a greater incidence of colon cancer when animals are treated with azoxymethane.
In summary, we demonstrated the selective targeting of colorectal cancers with activated beta-catenin by AdTOP-CMV-TK and GCV treatment in animal models, as well as its therapeutic potential for colon cancer metastasized to liver.