Insulin and Temozolomide effects in a glioblastoma multiforme cell model (U-251)

Glioblastoma multiforme (GBM) is an astrocytoma classified among the most aggressive brain tumors. Currently considered incurable, patients have a median survival of 15 months after diagnosis. Treatment typically involves tumor resection followed by radiotherapy and chemotherapy. Temozolomide is the most commonly used chemotherapeutic agent for GBM. Given the short median survival and the development of drug resistance to temozolomide, enhancing the efficacy of current treatments is of paramount importance. In this context, insulin is suggested as a supportive therapy to chemotherapy. It is hypothesized that insulin enhances the effectiveness of antimetabolite chemotherapies by prolonging the S phase. While insulin has been observed to extend the S phase in various cancers in the literature, its direct effect on the cell cycle in GBM has not been explored despite studies examining the impact of insulin on GBM by inhibiting insulin and IGF receptor gene function.In the MTT assay, cell survival decreased in groups treated with temozolomide (p