Aberrant PLAC8 expression characterizes glioblastoma with temozolomide resistance and an immunosuppressive microenvironment.

Glioblastoma (GBM), Isocitrate Dehydrogenase-wildtype (IDH-WT) represents the most prevalent and clinically aggressive subtype of adult diffuse gliomas, typically associated with poor prognosis. Temozolomide (TMZ) remains the first-line chemotherapeutic agent for GBM; however, the emergence of TMZ resistance represents a major therapeutic obstacle in clinical practice. This study identifies placenta-specific 8 (PLAC8) as a novel mediator of TMZ resistance in IDH-WT GBM. Elevated PLAC8 expression was strongly correlated with poorer survival rates, higher tumor grades in glioma, establishing it as an independent prognostic factor. Notably, consistent upregulation of PLAC8 was observed in both TMZ-resistant GBM cells and TMZ-treated patients, suggesting its potential as a biomarker for TMZ resistance. Mechanistic studies revealed that PLAC8 regulates TMZ sensitivity in GBM cells through the AKT-mTOR signaling pathway. Additionally, integrated bioinformatics and clinical analyses demonstrated that PLAC8 expression positively correlates with immune cell infiltration while promoting an immunosuppressive tumor microenvironment and modulating immunotherapy-related biomarkers, suggesting its potential as a predictive biomarker for immunotherapy response. In conclusion, PLAC8 represents a promising biomarker and therapeutic target for overcoming TMZ resistance and guiding immunotherapy in GBM. This study provides valuable insights for the development of personalized treatment strategies aimed at improving patient outcomes.