Karyopherin Subunit Alpha 3 Drives Temozolomide Resistance in Glioblastoma by Upregulating MGMT and Activating STAT3 to Sustain Glioma Stem Cells

ABSTRACT Glioblastoma (GBM) invariably develops resistance to temozolomide (TMZ), the frontline chemotherapeutic agent, leading to treatment failure. The molecular mechanisms underlying this resistance remain incompletely understood. Here, we identify karyopherin subunit alpha 3 (KPNA3) as a potential contributor to TMZ resistance. Through integrated bioinformatics analysis of TMZ‐resistant glioma cells (SF126R) and patient databases, we found KPNA3 expression is elevated in TMZ‐resistant contexts and correlates with poor prognosis in TMZ‐treated patients. Functional studies demonstrated that KPNA3 knockdown in resistant cells impaired malignant behaviors, re‐sensitized cells to TMZ‐induced apoptosis, and suppressed glioma stem cell (GSC) properties, including sphere formation and expression of stemness factors (OCT4, ALDH1A1). Mechanistically, KPNA3 was associated with a dual pathway: it correlated with increased expression of the DNA repair enzyme MGMT and was linked to activation of the STAT3 signaling pathway. KPNA3 knockdown reduced both MGMT levels and STAT3 phosphorylation (Tyr705). Furthermore, pharmacological inhibition of STAT3 mirrored the effect of KPNA3 knockdown by potently inhibiting GSC generation. Clinically, KPNA3 and p ‐STAT3 protein levels were positively correlated in high‐grade glioma tissues. Collectively, our findings suggest that KPNA3 may play a role in concurrently enhances DNA repair and sustains the GSC population to foster TMZ resistance, identifying it as a candidate for further investigation for overcoming chemoresistance in GBM.