Delta-catenin promotes the proliferation and invasion of colorectal cancer cells by binding to E-cadherin in a competitive manner with p120 catenin

δ-Catenin is the only member of the p120 catenin (p120ctn) subfamily whose normal pattern of expression is restricted to the brain. Similar to p120ctn, δ-catenin can bind to the juxtamembrane domain of E-cadherin. We examined the expression of δ-catenin, p120ctn, and E-cadherin using immunohistochemistry in 95 cases of colorectal cancer (CRC) and 15 normal colon tissues. Co-immunoprecipitation was used to examine whether δ-catenin competed with p120ctn to bind E-cadherin in CRC cells. The effects of δ-catenin overexpression or siRNA-mediated knockdown on the proliferation and invasive ability of CRC cells were investigated using the MTT and Matrigel invasion assays. The results showed that positive δ-catenin expression was significantly more frequent in CRC compared to normal colon tissues and associated with poor differentiation, stage III–IV disease, and lymph node metastasis in CRC (all P < 0.05). In two CRC cell lines, δ-catenin bound to E-cadherin in competition with p120ctn. Overexpression of δ-catenin promoted the proliferation and invasion of CRC cells; knockdown of δ-catenin reduced CRC cell proliferation and invasion. In conclusion, we speculate that overexpression of δ-catenin reduces the expression of E-cadherin and alters the balance between E-cadherin and p120ctn, which in turn affects the formation of intercellular adhesions and promotes invasion and metastasis in CRC.