LncRNA LITATS1 suppresses TGF-beta-induced EMT and cancer cell plasticity by potentiating TbetaRI degradation

Epithelial cells acquire mesenchymal phenotypes through epithelial-mesenchymal transition (EMT) during cancer progression. However, how epithelial cells retain their epithelial traits and prevent malignant transformation is not well understood. Here, we report that the long noncoding RNA LITATS1 (LINC01137, ZC3H12A-DT) is an epithelial gatekeeper in normal epithelial cells and inhibits EMT in breast and non-small cell lung cancer cells. Transcriptome analysis identified LITATS1 as a TGF- target gene. LITATS1 expression is reduced in lung adenocarcinoma tissues compared to adjacent normal tissues, and correlates with a favorable prognosis in breast and non-small cell lung cancer patients. LITATS1 depletion promotes TGF--induced EMT, migration and extravasation in cancer cells. Unbiased pathway analysis demonstrated that LITATS1 knockdown potently and selectively potentiates TGF-/SMAD signaling. Mechanistically, LITATS1 enhances the polyubiquitination and proteasomal degradation of TGF- type I receptor (TRI). LITATS1 interacts with TRI and the E3 ligase SMURF2, promotingthe cytoplasmic retention of SMURF2. Our findings highlight a protective function of LITATS1 in epithelial integrity maintenance through attenuation of TGF-/SMAD signaling and EMT.