This study aims to determine the contribution of polymorphisms in the genes of the β-catenin destruction complex to develop CRC, specifically adenomatous polyposis coli (APC) (rs11954856 G>T and rs459552 A>T), axis inhibition protein 1 (AXIN1) (rs9921222 C>T and rs1805105 C>T), AXIN2 (rs7224837 A>G), and dishevelled 2 (DVL2) (2074222 G>A and rs222836 C>T).
In this case report we describe a family with c.1972delA, p.Ser658Alafs*31 nonsense variant in AXIN2 where the three confirmed carriers presented with both oligodontia and colorectal adenomatous polyposis; mean number of teeth missing in carriers was 16.5 (range 11-22) and mean number of polyps in carriers was 49 (range 5->100, polyps were predominantly adenomatous).
Furthermore, GEN-27 decreased binding of p65 to the silencer region of CDX2 and increased binding of CDX2 to the promoter regions of APC and AXIN2, thus inhibiting the activation of β-catenin induced by TNF-α.
Wnt signalling is prevented by the proteosomal degradation of β-catenin, which occurs in a destruction complex containing adenomatous polyposis coli (APC), APC-like (APCL), Axin and Axin2.
This report expands the phenotype known to be related to AXIN2 alterations and raises the question of whether to screen AXIN2 in FAP cases negative for alterations in APC and MUTYH.
Furthermore, TNF-α-mediated downregulation of CDX2 was found to significantly decrease the mRNA levels of adenomatous polyposis coli (APC), axis inhibition protein 2 (AXIN2) and glycogen synthase kinase-3 beta (GSK3β), whereas the mRNA levels of Wnt targets were significantly elevated in TNF-α-treated Caco-2 cells.
Whereas in CIN CRCs APC (Adenomatous Polyposis Coli) is affected in most cases, high grade MSI (MSI-H) CRCs frequently display mutations in various genes, like the APC-, AXIN2- or CTNNBI (beta-CATENIN) gene itself.
Thus, we investigated potential differences in the expressions of APC and its Wnt partners conductin, beta-catenin, cyclin D1, and c-myc in normal colorectal mucosa and matched adenoma tissue of 14 FAP patients using real-time quantitative PCR.
Several other proteins, including adenomatous polyposis coli (APC), GSK3 beta, and Axin/Conductin, are instrumental in the regulation of beta-catenin/Armadillo.
Mammalian APC2, which closely resembles APC in overall domain structure, was functionally analyzed and shown to contain two SAMP domains, both of which are required for binding to conductin.