PO-169 Rethinking the EGF-mediated tensin switch in colorectal cancer

Abstract

IntroductionTNS4 (tensin 4 or Cten) is a putative novel oncogene in colorectal, breast and pancreatic cancer, but a tumour suppressor in prostate cancer. A tensin switch has been described in breast cancer where EGF (epidermal growth factor) activates TNS4 and down-regulates TNS3 which results in capping the tail of ITGB1 (integrin B1). However in colorectal cancer, the same tensin switch has not been verified. We have explored effects of TNS4 upregulation by EGF stimulation in colorectal cancer cell lines and how the interaction between ITGB1 and TNS4 might drive the epithelial to mesenchymal transition (EMT).Material and methodsUpon EGF stimulation (20 ng/mL) of several colorectal cancer cell lines of known KRAS mutant status, TNS4 and ITGB1 levels were detected by western blot, together with other EMT markers. Co-Immunoprecipitation was performed to detect possible interactions between TNS4 and ITGB1 upon stimulation and confocal imaging of immunofluorescence stainings were carried out to confirm co-localization.Results and discussionsAfter 20 ng/ml EGF stimulation for 24 hour, TNS4 and ITGB1 upregulation occurs in cell lines with wild-type KRAS allele, but not in mutant KRAS cell lines. This is not accompanied by an upregulation in TNS3, as described before. IGTB1 co-immunoprecipitates with TNS4 after EGF stimulation, but not in untreated controls. This is accompanied by alteration of EMT markers expression, and is mediated by TNS4, in accordance with recent reports.ConclusionWe may have identified a mechanism of interaction between ITGB1 and TNS4 that is implicated in the epithelial to mesenchymal transition by driving phenotypical changes at early metastatic stages. These results still warrant confirmation and further investigation to understand how tensins and integrins regulate cell motility during metastasis.