U251 MG/TMZ Cells

U251 MG/TMZ is a temozolomide-resistant derivative of the human glioblastoma cell line U251 MG. The parental U251 MG line was established from the malignant glioma of an adult patient and is widely used as a model of high-grade astrocytic tumors. U251 MG/TMZ cells are generated through stepwise, long-term exposure of parental U251 MG cells to increasing concentrations of temozolomide (TMZ), the standard alkylating chemotherapeutic agent used in glioblastoma treatment. This selection process results in a stable phenotype characterized by significantly reduced sensitivity to TMZ-induced cytotoxicity compared to the parental line.

Mechanistically, TMZ resistance in U251 MG/TMZ cells is commonly associated with upregulation of O6-methylguanine-DNA methyltransferase (MGMT), enhanced DNA damage repair capacity, alterations in mismatch repair pathways, and activation of pro-survival signaling cascades. Resistant cells frequently exhibit reduced apoptosis following TMZ exposure, with decreased caspase activation and attenuated mitochondrial pathway engagement. Additional molecular adaptations may include dysregulation of PI3K/AKT, MAPK, NF-κB, or STAT3 signaling pathways, as well as altered expression of drug transporters and stemness-associated markers, depending on the selection protocol used.

U251 MG/TMZ cells maintain adherent growth with astrocytic morphology similar to the parental line but demonstrate higher TMZ IC50 values and sustained proliferation under drug pressure. This model is widely used to investigate mechanisms of acquired chemoresistance, identify biomarkers predictive of therapeutic response, and evaluate novel combinatorial strategies aimed at overcoming TMZ resistance. As such, U251 MG/TMZ provides a clinically relevant in vitro platform for studying treatment failure and therapeutic vulnerability in glioblastoma.