Smad3 regulates the miR-200 family in gastric cancer

To find potential microRNA links between Smad3 and E-cadherin, we characterized the microRNA profiles of two gastric cancer cell lines: SNU484-LPCX, which does not express Smad3, and SNU484-Smad3, in which Smad3 is overexpressed. We found that miR-200 families, among other differentially expressed miRNAs, are overexpressed in SNU484-Smad3. Through subsequent studies, including silencing of Smad3 in SNU484-Smad3 and expression profiling of epithelial-mesenchymal markers and ZEB1/2, known repressors of E-cadherin, we found that Smad3 regulates miR-200 families at the transcriptional level, which regulate ZEB 1/2, known transcriptional repressors of E-cadherin, at the post-transcriptional level. This represents an important link between the TGF-beta signaling pathway and post-transcriptional regulation by miRNAs. Examination of small RNA expression in 2 different cell lines (SNU484-LPCX, SNU484-Smad3).