Antitumor activity of 5-hydroxy-3',4',6,7-tetramethoxyflavone in glioblastoma cell lines and its antagonism with radiotherapy.

5-Hydroxy-3',4',6,7-tetramethoxyflavone (TMF) is a plant-origin flavone known for its anti-cancer properties. In the present study, the cytotoxic effect of TMF was evaluated in the U87MG and T98G glioblastoma (GBM) cell lines. The effect of TMF on cell viability was assessed with trypan blue exclusion assay and crystal violet staining. In addition, flow cytometry was performed to examine its effect on the different phases of the cell cycle, and in vitro scratch wound assay assessed the migratory capacity of the treated cells. Furthermore, the effect of in vitro radiotherapy was also evaluated with a combination of TMF and radiation. In both cell lines, TMF treatment resulted in G0/G1 cell cycle arrest, reduced cell viability, and reduced cell migratory capacity. In contrast, there was an antagonistic property of TMF treatment with radiotherapy. These results demonstrated the antineoplastic effect of TMF in GBM cells in vitro, but the antagonistic effect with radiotherapy indicated that TMF should be further evaluated for its possible antitumor role post-radiotherapy.