E-cadherin is regulated by the transcriptional repressor SLUG during Ras-mediated transformation of intestinal epithelial cells

Background. Loss of the cell membrane protein E-cadherin is a critical event during Ras-mediated transformation of intestinal epithelial cells. The purpose of our study is to determine if activation of the transcriptional repressor SLUG is an important component of the mechanism of Ras-induced loss of E-cadherin. Methods. Rat intestinal epithelial (RIE) cells were engineered to express mutated human Ha-Ras(Val12) complementary DNA (H-Ras cells). Cell morphology was examined by light microscopy. RNA and protein expression were measured by semiquantitative polymerase chain reaction and Western blot analyses, respectively. Short interfering RNA with 2 different oligos was used to knock down the expression of SLUG. Results. Oncogenic ras induces upregulation of the transcriptional repressor SLUG and subsequent downregutation of the junctional protein E-cadherin. Gene silencing of SLUG by short interfering RNA allows E-cadherin to be reexpressed. E-cadherin protein reexpression allows partial rescue of the transformed phenotype. Conclusion. These data suggest a mechanism whereby Ras signaling causes an upregulation of transcriptional repressors and subsequent downregulation of E-cadherin as a malignant phenotype is propagated.