C-terminal Tensin-like (CTEN) is an Oncogene Which Alters Cell Motility Possibly Through Repression of E-cadherin in Colorectal Cancer

The Tensin gene family encodes proteins thought to modulate integrin function. C-terminal Tensin-like (CTEN) is a member of the Tensin gene family which lacks the N-terminus actin-binding domain. Cten is reported to have both oncogenic and tumour-suppressor functions. We investigated the role that Cten may play in colorectal cancer (CRC). By quantitative RT-PCR CTEN is up-regulated (i.e. > two-fold increase) in 62% of cell lines and 69% of tumours compared with normal mucosa, consistent with CTEN being a possible oncogene. Stable transfection of HCT116 and SW480 (CRC cell lines with low endogenous Cten expression) with a Cten expression vector gave identical results in both cell lines. Forced Cten expression did not cause change in cell numbers, although it did confer resistance to staurosporine-induced apoptosis (p < 0.005). Cten also induced epithelial-mesenchymal transition (EMT) in tumour cells accompanied by a significant increase in both cell migration (transwell migration and cell wounding assays, p < 0.001 and p < 0.05, respectively) and cell invasion (invasion through Matrigel, p < 0.001). Given the observed EMT, we investigated the levels of E-cadherin. Cten induction was associated with a reduction in E-cadherin protein expression but not levels of E-cadherin mRNA. These data suggest that CTEN is an oncogene in CRC which stimulates EMT, cell migration and invasion and may therefore have a role in tumour invasion/spread. Furthermore, Cten induction is associated with post-transcriptional repression of E-cadherin.