Arbutin exerts anticancer activity against rat C6 glioma cells by inducing apoptosis and inhibiting the inflammatory markers and P13/Akt/mTOR cascade

Abstract

Gliomas are a type of brain cancer that occurs in the supporting glial cells of the brain. It is highly malignant and accounts for 80% of brain tumors with high mortality and morbidity. Phytomedicines are potent alternatives for allopathic drugs which cause side effects. They have been used from ancient times by traditional Chinese, Ayurveda, and Siddha medicine. Arubtin is a glycoside phytochemical extracted from plants and belongs to the family of Ericaceae. Arbutin possesses various pharmacological properties such as anti-inflammatory, antioxidant, antitumor, and so on. Hence in the present study, we analyzed the anticancer potency of arbutin against rat C6 glioma cells. Rat C6 glioma cells were procured from American Type Culture Collection and the cells were cultured in Roswell Park Memorial Institute-1640 medium. To assess the cytotoxicity effect of the arbutin against C6 glioma cells, an 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide test was performed with different doses from 10 to 60 µM. Arbutin effectively induced apoptosis in the cells and the IC₅₀ dose was obtained at 30 µM. For further studies, we selected the 30 µM IC₅₀ dose and a higher dose of 40 µM. Reactive oxygen species (ROS) generated were analyzed with DCFDA/H2DCFDA stain and the destruction of mitochondrial membrane permeability which is the initiator of apoptosis was analyzed with a cationic stain Rhodamine 123. Dual staining with acridine orange and ethidium bromide was performed to assess the viable and dead cells. Cell adhesion properties of glioma cells were analyzed with Matrigel assay. The apoptotic, inflammatory, and phosphoinositide 3-kinase (PI3K)/mammalian target of rapamycin (mTOR) signaling molecules were analyzed with quantitative polymerase chain reaction (qPCR) analysis to confirm the anticancer effect of arbutin. Arbutin generated excessive ROS and disrupted the mitochondrial membrane, which induced apoptosis in cells, it also inhibited the cell adhesion property of C6 glioma cells. qPCR analysis clearly indicates arbutin increases the apoptotic genes and decreased the inflammatory and PI3K/mTOR signaling molecules. Overall, our results authentically confirm that arbutin can be a potent alternative for treating glioma.

Keywords: anticancer drug; arbutin; glioma; in vivo; phytomedicine; rat C6 glioma cells.