BACKGROUND: Glioblastoma (GBM) is an aggressive cancer with limited therapeutic options. Investigating the mechanisms underlying temozolomide (TMZ) resistance and enhancing its sensitivity remain critical for improving GBM treatment outcomes. Ubiquitin-conjugating enzyme E2S (UBE2S) has been implicated in various cancers; however, its role in TMZ resistance in GBM remains unclear.
METHODS: After UBE2S knockdown, cell viability, apoptosis, and DNA damage were measured in TMZ-treated GBM cells. Immunoprecipitation coupled with mass spectrometry was employed to identify a protein complex involving UBE2S and phosphoglycerate mutase 1 (PGAM1). Co-immunoprecipitation and ubiquitination assays were conducted to examine the interactions among UBE2S, PGAM1, and Otubain-2 (OTUB2). In vivo, a GBM mouse model was used to evaluate the impact of UBE2S knockdown on TMZ efficacy.
RESULTS: UBE2S was found to be overexpressed in GBM cells, where it interacts with PGAM1 and OTUB2 to inhibit PGAM1 degradation via K48-linked deubiquitylation. This interaction increased PGAM1 protein levels, promoting DNA repair and reducing apoptosis, thereby decreasing the sensitivity of GBM cells to TMZ.
CONCLUSION: UBE2S plays a critical role in TMZ resistance by stabilizing PGAM1 protein levels through its interaction with OTUB2. Targeting UBE2S represents a promising therapeutic strategy to enhance TMZ efficacy and overcome chemotherapy resistance in GBM.
