Interplay between KLF4 and ZEB2/SIP1 in the regulation of E-cadherin expression.

E-cadherin expression is repressed by ZEB2/SIP1 while it is induced by KLF4. Independent data from the literature indicate that these two transcription factors could bind close to each other in the proximal region of the E-cadherin gene promoter. We have here explored a potential competition between ZEB2 and KLF4 for the binding to the E-cadherin promoter. We show an inverse correlation between ZEB2 expression levels and KLF4 recruitment on the E-cadherin promoter in three breast cancer cell lines and in A431/HA.ZEB2 cells in which ZEB2 expression is induced by doxycycline (DOX). We identified a region of the E-cadherin promoter bound by KLF4 which is necessary for the activation of the E-cadherin promoter activity after KLF4 overexpression. This region is localized between positions -28 and -10 and thus overlaps with one of the ZEB2 binding sites. Deleting the bipartite ZEB2 binding site results in increased KLF4 induced E-cadherin promoter activity. Taken together, our results suggest that E-cadherin expression in cancer cells is controlled by a balance between ZEB2 and KLF4 expression levels.