Study On The Function Of Ring Finger Protein 213 In Glioma And The Underlying Molecular Mechanism

Glioma,which accounts for 40% to 50% of brain tumors,is the most common intracranial malignancy.Duo to the special location,rapid growth and high degree of heterogeneity in glioma,the therapy as well as the prognosis is still a big problem in neurosurgery.Ring finger protein 213(RNF213),519 kDa,contains two domains: an AAA+ ATPase domain and a E3 ligase domain.RNF213 is a large protein encoded by the RNF213 gene with an AAA+ ATPase and E3 ligase domain and a molecular weight of 519 kDa.RNF213 was reported to be associated with MMD and gene mutation was detected in several kinds of tumors such as liver,PDA,gastric cancer.Meanwhile,RNF213 was reported to be associated with glioma.However,the role of RNF213 in glioma and the underlying mechanism is still unknown to date.In this study,we found that RNF213 was expressed significantly lower in malignant glioma tissues compared to the adjacent normal control tissues.K-M method suggested that patients with low RNF213 expression displayed much worse 5-year survival rate.In addition,RNF213 was shown to be expressed weakly in glioma tumor tissues while it was strong in adjacent normal control tissues by immunohistochemistry analysis.These data suggest that RNF213 might play important role in tumorigenesis of glioma in clinic.To explore the function of RNF213 in glioma,we determined the expression of RNF213 in tumor cell lines including A172 and U87 MG cells and normal control cells HEB by RT-qPCR.RNF213 was shown to express at moderate level in tumor cell lines and lower than that in HEB cells.Then we chose U87 MG cell for the following experiments.We decreased the level of RNF213 by RNAi technology and confirmed it at both protein and RNA level.Then we found that knockdown of RNF213 in U87 MG cells promoted cell proliferation,colony formation,cell migration and invasiveness compared to the NC control.Moreover,knockdown of RNF213 promoted cell cycle transition but decreased cell apoptosis in U87 MG cells.In contrast,the proliferation,invasiveness and apoptosis displayed reverse effects when RNF213 was overexpressed in U87 MG cells by lentivirus carrying RNF213 gene.Furthermore,we demonstrated that RNF213 knockdown promoted tumor growth in vivo assay compared to the control.Therefore,we proved that RNF213 played a tumor suppressor role in glioma.To elucidate the mechanism of RNF213 in glioma,gene expression array was used to detect the responsive genes and signaling pathway by RNF213.As shown,RNF213 mainly regulated MAPK/JNK signaling pathway.And this was further confirmed in western blotting assay.The expression of c-Jun,JNK,MEKK1 was significantly higher in RNF213 knockdown cells than that in the control.Then we found that RNF213 could bind to SOCS1 protein by CoIP assay and bioinformatic analysis with String tool.Moreover,we proved that SOCS1 could regulate the expression of c-Jun,JNK,MEKK1 and the ability of U87 MG including cell proliferation,invasiveness and apoptosis regardless of RNF213.Therefore,we proved that RNF213 could regulate MAPK/JNK signaling pathway through SOCS1 in glioma.In summary,we prove for first time that RNF213 regulates MAPK/JNK signaling pathway through SOCS1 in glioma and plays a tumor suppressor role.This study will provide a new clue for glioma and a new candidate target for drug development.