SUMO-specific peptidase 3 mediates the SUMO3 modification of BECN1 to repress cell autophagy in gliomas.

Abstract

SUMO Specific Peptidase 3 (SENP3) is involved in the occurrence and development of various cancers. However, its effects on gliomas have been barely reported. Herein, this research was designed to probe the potential mechanisms of SENP3 mediating beclin-1(BECN1) SUMO3 modification in autophagy in gliomas. SENP3 expression in gliomas was analyzed through bioinformatic information. Clinical samples of glioma tissues were collected and frozen. SENP3 expression was evaluated with western blot. In glioma cells, autophagy- and apoptosis-related proteins, viability, and apoptosis were assessed with western blot and immunofluorescence, the cell counting kit-8, and flow cytometry, respectively. The SUMO modification of BECN1 and interactions between BECN1 and PIK3C3 were identified with Ni-NTA pull-down and co-immunoprecipitation assays, respectively. The tumor formation assay was carried out in nude mice for in vivo validation. Bioinformatics analysis predicted the overexpression of SENP3 in gliomas, which was confirmed in clinical samples and glioma cells. SENP3 silencing promoted autophagy and apoptosis and inhibited viability in glioma cells, which was counteracted by further autophagy inhibition. Mechanistically, SENP3 facilitated BECN1 deSUMOylation to mediate the SUMO3 modification of BECN1, thus impeding the formation of BECN1-PIK3C3 complexes. The loss of the SUMO part in BECN1 lowered the protein expression of LC3 and the value of LC3BII/LC3BI in glioma cells. Additionally, SENP3 silencing boosted autophagy and repressed tumor growth in mice, which was neutralized by further autophagy repression. SENP3 fosters the deSUMOylation of BECN1 to block the formation of BECN1-PIK3C3 complexes, thus restraining glioma cell autophagy.