Combined in vitro effects of temozolomide and erucic acid on U87 MG cell viability, oxidative stress, and expression of genes involved in apoptotic signalling Kombinirano djelovanje temozolomida i eruka kiseline na vijabilnost stanica glioblastoma U-87 MG, oksidacijski stres i ekspresiju gena koji sudjeluju u signalizaciji apoptoze

Limited efficacy of glioblastoma treatment with temozolomide (TMZ) due to resistance has prompted researchers to look for adjuvants capable of enhancing TMZ-associated cytotoxicity. The aim of our in vitro study was to evaluate such effects of erucic acid when combined with TMZ in human U87 MG cells. Cells were treated for 24 or 72 h with vehicle (control), TMZ (200 ng/mL), or TMZ plus EA (20, 40, 80, or 160 μg/mL). Cell viability was assessed using the MTT assay, membrane integrity with lactate dehydrogenase (LDH) release, and intracellular redox balance by measuring total antioxidant capacity (TAC) and total oxidant status (TOS). The mRNA expression of apoptosis-related genes (p53, p21, Bax, Bcl-2, Bcl-xL, and caspase-3) was analysed by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Compared with the vehicle control, TMZ plus EA reduced cell viability and increased LDH release, with more pronounced effects at higher EA concentrations and at 72 h. These changes were accompanied by lower TAC and higher TOS, indicating a shift toward a pro-oxidant intracellular environment. At the transcriptional level, the combination induced increased pro-apoptotic Bax, caspase-3, p53, and p21 expression and reduced Bcl-2 and Bcl-xL expression. In conclusion, EA potentiated TMZ-associated cytotoxic responses in U87 MG cells with accompanying oxidative imbalance and apoptosis-related transcriptional changes.