Smad3 regulates E-cadherin via miRNA-200 pathway.
To identify potential microRNA (miRNA) links between Smad3, a mediator of TGF-β (transforming growth factor-β) signaling, and E-cadherin, we characterized the miRNA 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 among differentially expressed miRNAs, miR-200 family members are overexpressed in SNU484-Smad3 cells. Subsequent studies, including analysis of the effects of silencing Smad3 in SNU484-Smad3 cells and a luciferase reporter assay, revealed that Smad3 directly binds to a Smad-binding element located in the promoter region of miR-200b/a, where it functions as a transcriptional activator. TGF-β did not affect the regulatory role of Smad3 in transcription of miR-200 and expression of epithelial-mesenchymal transition markers. We conclude that Smad3 regulates, at the transcriptional level, miR-200 family members, which themselves regulate ZEB1 and ZEB2, known transcriptional repressors of E-cadherin, at the posttranscriptional level in a TGF-β-independent manner. This represents a novel link between Smad3 and posttranscriptional regulation by miRNAs in epithelial-mesenchymal transition in gastric cancer cells.
Department of Molecular Medicine, Laboratory of Cancer Cell Biology, Lee Gil Ya Cancer and Diabetes Institute, Gachon University of Medicine and Science, Incheon, Korea.
S-M
SM
Ahn
J-Y
JY
Cha
J
J
Kim
D
D
Kim
H T H
HT
Trang
Y-M
YM
Kim
Y-H
YH
Cho
D
D
Park
S
S
Hong
D015820:Cadherins / Q000378:metabolism*; D045744:Cell Line, Tumor; D058750:Epithelial-Mesenchymal Transition; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D035683:MicroRNAs / Q000378:metabolism; D015398:Signal Transduction; D051900:Smad3 Protein / Q000378:metabolism*; D013274:Stomach Neoplasms / Q000378:metabolism*; D016212:Transforming Growth Factor beta / Q000378:metabolism
D015820:Cadherins; C533896:MIRN200 microRNA, human; D035683:MicroRNAs; C497790:SMAD3 protein, human; D051900:Smad3 Protein; D016212:Transforming Growth Factor beta