INVESTIGATING PMCA EXPRESSION AND HYPOXIA-INDUCED RESISTANCE IN GLIOBLASTOMA

Abstract AIMS Glioblastoma is highly therapy-resistant, partly due to its hypoxic microenvironment, which promotes cellular adaptations that drive treatment evasion. Plasma Membrane Calcium ATPases (PMCAs) were studied in various cancers, but their role in Glioblastoma remains unexplored. Furthermore, PMCAs were play a role in angiogen- esis regulation This study aims to characterise PMCA expression in patient-derived Glioblastoma cultures under normoxic and hypoxic conditions, investigate hypoxia-driven resistance mechanisms, and evaluate the poten- tial synergy of sunitinib and temozolomide (TMZ) in overcoming resistance. METHODS Patient-derived Glioblastoma cultures were authenticated using molecular biomarkers and cultured under nor- moxia and hypoxia. PMCA expression was analysed at the RNA (RT-qPCR) and protein (Western blot) levels. MTT viability assays to study TMZ responses across various concentrations and exposure durations. RESULTS Hypoxia significantly modulated PMCA expression, with PMCA1 and PMCA2 downregulated over time, while PMCA4 showed variable trends notably due to their long half-life, PMCA proteins were only seen to be reduced after long-term exposure to hypoxia. TMZ resistance was evident, particularly in unmethylated MGMT cul- tures, underscoring the challenge of overcoming therapy resistance. These results highlight PMCA’s role in hypoxia-driven resistance,emphasising the need for RNA sequencing and proteomic studies to explore its ther- apeutic potential in glioblastoma treatment strategies. This study provides new insights into the role of PMCAs in glioblastoma, particularly their modulation under hypoxia and impact on therapy resistance. The observed interplay between PMCA expression and hypoxia-induced resistance suggests targeting PMCAs may enhance treatment efficacy. CONCLUSION These findings suggest that PMCA modulation plays a crucial role in glioblastoma adaptation to hypoxia, poten- tially contributing to therapy resistance. Understanding the regulatory mechanisms governing PMCA expres- sion under hypoxic conditions could reveal novel therapeutic targets.