Temozolomide(TMZ)represents a standard-of-care chemotherapeutic agent in glioblastoma(GBM).However,the development of drug resistance constitutes a significant hurdle in the treatment of malignant glioma.Although specific innovative approaches,such as immunotherapy,have shown favorable clinical outcomes,the inherent invasiveness of most gliomas continues to make them challenging to treat.Consequently,there is an urgent need to identify effective therapeutic targets for gliomas to overcome chemoresistance and facilitate drug development.This investigation used mass spectrometry to examine the proteomic profiles of six pairs of GBM patients who underwent standard-of-care treatment and surgery for both primary and recurrent tumors.A total of 648 proteins exhibiting significant differential expression were identified.Gene Set Enrichment Analysis(GSEA)unveiled notable alterations in pathways related to METABOLISM_OF_LIPIDS and BIOLOGICAL_OXIDATIONS between the primary and recurrent groups.Validation through glioma tissue arrays and the Xiangya cohort confirmed substantial upregulation of inositol 1,4,5-triphosphate(IP3)kinase B(ITPKB)in the recurrence group,correlating with poor survival in glioma patients.In TMZ-resistant cells,the depletion of ITPKB led to an increase in reactive oxygen species(ROS)related to NADPH oxidase(NOX)activity and restored cell sensitivity to TMz.Mechanistically,the decreased phosphorylation of the E3 ligase Trim25 at the S100 position in recurrent GBM samples accounted for the weakened ITPKB ubiquitination.This,in turn,elevated ITPKB stability and impaired ROS production.Furthermore,ITPKB depletion or the ITPKB inhibitor GNF362 effectively overcome TMZ chemoresistance in a glioma xenograft mouse model.These findings reveal a novel mechanism underlying TMZ resistance and propose ITPKB as a promising therapeutic target forTMZ-resistant GBM.
Glioma is a common tumor originating in the brain that has a high mortality rate.Temozolomide(TMZ)is the first-line treatment for high-grade gliomas.However,a large pro-portion of gliomas are resistant to TMZ,posing a great challenge to their treatment.In the study,the specific functions and mechanism(s)by which cortistatin(CORT)regulates TMZ resis-tance and glioma progression were evaluated.The decreased expression of CoRT was detected in glioma tissues,and highly expressed CORT was associated with a better survival rate in pa-tients with glioma.CORT overexpression notably decreased the capacity of glioma cells to pro-liferate and migrate in vitro and to form tumors in vivo.CORT overexpression also markedly suppressed the viability and enhanced the apoptosis of TMZ-resistant U251 cells by regulating MGMT,p21,and Puma expression.Importantly,CORT overexpression reduced the resistance of gliomas to TMZ in vivo.CORT expression Was negatively correlated with MGMT expression in both glioma tissues and cells,and it was found that CORT inhibited NF-kB pathway activation in glioma cells,thereby inhibiting MGMT expression.In conclusion,CORT regulates glioma cell growth,migration,apoptosis,and TMZ resistance by weakening the activity of NF-kB/p65 and thereby regulating MGMT expression.The CORT/NF-kB/MGMT axis might be regarded as a molecular mechanism contributing to the resistance of glioma to TMZ.Our data also suggest that CORT regulates the viability and metastatic potential of glioma cells,independent of its effects on TMZ resistance,providing evidence of novel therapeutic targets for glioma that should be evaluated infurther studies.