CIIA induces the epithelial-mesenchymal transition and cell invasion

LncRNA MIR22HG inhibits growth, migration and invasion through regulating the miR-10a-5p/NCOR2 axis in hepatocellular carcinoma cells

Despite the rapidly identified numbers of lncRNA in humans, exploration of the molecular mechanisms of lncRNA is lagging, because the molecular mechanisms of lncRNA can be various and complex in different conditions. In this study, we found a new molecular mechanism for a versatile molecule, MIR22HG. MIR22HG is an lncRNA that contributes to the initiation and progression of many human cancers, including hepatocellular carcinoma (HCC). We report that MIR22HG was downregulated in 120 HCC samples compared with adjacent nontumor liver tissues. More interestingly, decreased expression of MIR22HG in HCC could predict poor prognosis of HCC patients. Knockdown of MIR22HG promoted the growth, migration and invasion of HCC cells. In exploring the molecular mechanism of MIR22HG, we found that MIR22HG functioned as a tumor suppressor in hepatocellular carcinomas, in part through serving as a competing endogenous RNA to modulate the miRNA‐10a‐5p level. Moreover, NCOR2 was verified to act as the downstream target gene of MIR22HG/miR‐10a‐5p. In addition, the MIR22HG/miRNA‐10a‐5p/NCOR2 axis inhibited the activation of the Wnt/β‐catenin pathway. Together, our results demonstrated that MIR22HG inhibited HCC progression in part through the miR‐10a‐5p/NCOR2 signaling axis and might act as a new prognostic biomarker for HCC patients.

CIIA functions as a molecular switch for the Rac1-specific GEF activity of SOS1

CIIA mediates the TGF-β–induced activation of SOS1–Rac1 signaling and cell migration.

Son of sevenless 1 (SOS1) is a dual guanine nucleotide exchange factor (GEF) that activates the guanosine triphosphatases Rac1 and Ras, which mediate signaling initiated by peptide growth factors. In this paper, we show that CIIA is a new binding partner of SOS1. CIIA promoted the SOS1–Rac1 interaction and inhibited the SOS1–Ras interaction. Furthermore, CIIA promoted the formation of an SOS1–EPS8 complex and SOS1-mediated Rac1 activation, whereas it inhibited SOS1-mediated activation of Ras. Transforming growth factor β (TGF-β) up-regulated the expression of CIIA and thereby promoted the association between CIIA and SOS1 in A549 human lung adenocarcinoma cells. Depletion of CIIA in these cells by ribonucleic acid interference inhibited the TGF-β–induced interaction between SOS1 and EPS8, activation of Rac1, and cell migration. Together, these results suggest that CIIA mediates the TGF-β–induced activation of SOS1–Rac1 signaling and cell migration in A549 cells. They further show that CIIA functions as a molecular switch for the GEF activity of SOS1, directing this activity toward Rac1.