Evaluation of donafenib and radiotherapy application in temozolomide (TMZ) resistant and normal Glioblastoma Multiforme (GBM) cell lines in terms of cell survival

Objective: Glioblastoma Multiforme (GBM) is the most common and aggressive malignant brain tumor of the central nervous system (CNS). Donafenib (DNF) is a small molecule multikinase inhibitor. Based on the hypothesis that DNF may use Raf/MEK/ERK signaling pathway, our study was designed to evaluate the effect of DNF on tumor cell survival and this pathway with radiotherapy (RT) and Temozolomide (TMZ) administration. Method: The GBM cell lines used in our study were TMZ-sensitive U87MG and TMZ-resistant T98G cell lines. Our experimental groups consisted of Control (C), Vehicle (V), TMZ, DNF, TMZ+DNF, TMZ+DNF+RT and RT, TMZ+RT to mimic the clinical administration and DNF+RT. MTT assay was used to determine the proliferative effect of TMZ and DNF and to calculate IC50 values. For RT application, the cells were irradiated with a total of 10Gy for 5 days, 2Gy each day. In the same groups, the movement potentials of tumor cells were interpreted by migration analysis with the scar created on the cells. In addition, p-ERK 1/2 and Cleaved Caspase3 protein expression levels in the experimental groups were also evaluated by Western Blot analysis. Results: The IC50 value of DNF in GBM cell lines was determined for the first time. Individual and combined application of DNF and TMZ decreased tumor cell proliferation. At the same time, DNF, TMZ and simultaneous RT application decreased tumor cell survival. It was shown that tumor cell movement potential was restricted by the scar created on the cells. In addition, it was evaluated for the first time whether DNF uses p-ERK 1/2 signaling pathway and whether tumor cells went to apoptosis. Conclusion: Our study showed that DNF, which is administered both individually and in combination in addition to clinical treatments and whose efficacy on GBM cells has never been evaluated before, has anti-proliferative effects on tumor cells. Key words: Glioblastoma Multiforme, Temozolomide, Radiotherapy, Donafenib