GRSF1-mediated MIR-G-1 promotes malignant behavior and nuclear autophagy by directly upregulating TMED5 and LMNB1 in cervical cancer cells.

Emerging evidence has revealed that miRNAs could upregulate the expression levels of target genes. However, the molecular mechanism underlying upregulation of targets mediated by miRNAs remains unclear. In this study, we found a novel miRNA named MIR-G-1 by GRSF1-RNA immunoprecipitation (RIP)-deep sequencing, which could directly target and upregulate LMNB1 and TMED5 in a GRSF1-dependent manner in cervical cancer cells. In addition, upregulated MIR-G-1 in cervical cancer promoted a malignant phenotype in vitro and in vivo. TMED5 could interact with WNT7B and thus activated the canonical WNT-CTNNB1/β-catenin signaling pathway. MIR-G-1 mediated the activation of this pathway. Furthermore, MIR-G-1 promoted serum starvation-induced nuclear macroautophagy/autophagy, and accelerated taxol (TAX)-induced DNA-damage repair in cervical cancer cells. Collectively, these findings may provide a new insight into the upregulation mechanism and nuclear autophagy mediated by miRNAs and provide a potential biomarker for cervical cancer. Abbreviations: 3'UTR: 3' untranslated region; EMSA: electrophoretic mobility shift assay; EMT: epithelial-mesenchymal transition; GRSF1: G-rich RNA sequence binding factor 1; IF: immunofluorescence; IP: immunoprecipitation; IHC: immunohistochemistry; lnc: long noncoding; miRNA:microRNA; TAX: taxol; TMED5: transmembrane p24 trafficking protein 5.