Centromere protein U mediates the ubiquitination and degradation of RPS3 to facilitate temozolomide resistance in glioblastoma

Aims

Temozolomide (TMZ) is the first-line chemotherapeutic agent for glioblastoma (GBM) therapy; however, resistance to TMZ remains a major obstacle in GBM treatment. The aim of this study is to elucidate the mechanisms underlying TMZ resistance and explore how to enhance the sensitivity of GBM to TMZ.

Methods

GBM organoids were generated from patient samples, and organoid-based TMZ sensitivity testing was performed. Transcriptome sequencing was conducted on GBM organoids, which identified Centromere protein U (CENPU) as a novel key gene mediating TMZ resistance. Histopathological assessments were carried out using immunohistochemistry (IHC) and Hematoxylin and Eosin (HE) staining. Single-cell sequencing data were utilized to determine the functional states of CENPU in GBM cells. Intracranial and subcutaneous glioma mouse models were constructed to evaluate the effect of CENPU on TMZ sensitivity. The underlying mechanisms were further investigated using immunofluorescence, lentivirus transduction, co-immunoprecipitation, mass spectrometry, alkaline comet assay et al.

Results

CENPU was found to be highly expressed in TMZ-resistant GBM organoids and enhanced the TMZ resistance of GBM cells by promoting DNA damage repair. Its abnormal expression correlates with poor clinical outcomes in glioma patients. In vivo studies demonstrated that downregulation of CENPU enhances the sensitivity of GBM to TMZ. Correspondingly, rescue of CENPU expression reversed this effect on TMZ sensitivity in GBM cells. Mechanistically, CENPU cooperates with TRIM5α to promote the ubiquitination and degradation of RPS3 by inducing its polyubiquitination at the K214 residue. This process subsequently activates the ERK1/2 pathway and promotes the expression of E2F1 and RAD51. Consequently, the degradation of RPS3 and upregulation of RAD51 in GBM cells enhance DNA damage repair, thereby contributing to TMZ resistance.

Conclusion

Our study identified CENPU as a novel key gene mediating TMZ resistance and elucidated its molecular mechanisms, providing a new target to overcome TMZ resistance in GBM.