Combinatorial Effect of Temozolomide and Naringenin in Human Glioblastoma Multiforme Cell Lines

Glioblastoma multiforme (GBM) is a grade IV, lethal, and the most common type of brain tumor. GBM can acquire resistance to temozolomide (TMZ) recommended for its treatment. Naringenin (NAG), a flavonoid generally found in grapefruit, has antioxidant, anti-proliferative, and anti-inflammatory properties. It has been reported that phytochemicals can reduce resistance and improve the efficacy of a chemo-resistant drug. The combinatorial effect of TMZ and NAG on cell proliferation was evaluated using 3-4,5-dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide (MTT) assay, and the apoptosis in the U87MG and LN229 GBM cells were evaluated by change in fluorescence intensity. The effect of NAG and TMZ on anchorage-independent single-cell colony formation and cell migration was investigated. NAG and TMZ demonstrated enhanced cytotoxic effects on U87MG and LN229 cell lines. The combination index value being less than one indicated the synergistic action of the two drugs in restricting the growth of the cells. The NAG and TMZ together resulted in higher fluorescence intensity as compared to the alone drug. Further, the study showed a marked reduction in the migration of the cells and the formation of a single cell colony. Supplemental data for this article is available online at https://doi.org/10.1080/01635581.2021.1952438