Morin Inhibits Cell Proliferation and Induces Caspase-mediated Apoptotic Cell Death in Glioma C6 Cell Line

Abstract

Background: Glioma is a recurrent form of primary malignant cancer that occurs in the brain and central nervous system. The adults are the major victims of gliomas, and the men are mostly affected. At present, gliomas are treated with surgical resection followed by radiation and the administration of chemodrugs such as temozolomide. The invasive and high recurrence rate of gliomas often reduces the effectiveness of treatment, which leads to poor recovery. Hence, more potent drugs without side effects on long-term treatment need to be discovered to treat gliomas. Morin is one such promising phytochemical that possesses immense pharmacological properties. It is proven to exert anti-inflammatory, antioxidant, anticancer, antibacterial, antidiabetic, and neuroprotective properties. The current research focuses on examining the growth inhibition and apoptosis-inducing potency of morin against glioma C6 cells. Materials and Methods: Rat C6 glioma cells were treated with different concentrations of morin and analyzed for cytotoxicity using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. The intracellular reactive oxygen species (ROS) production and alteration of mitochondrial membrane potential (MMP) by morin in glioma cells were examined with dichlorodihydrofluorescein diacetate (DCHF-DA) and rhodamine 123 staining. The apoptotic induction in glioma cells was analyzed with dual staining and it was confirmed by quantifying the apoptotic protein using the enzyme-linked immunosorbent assay (ELISA) technique. The anti-inflammatory property of morin was assessed by the inflammatory cytokines tumor necrosis factor-α (TNF-α), nuclear factor-kappa B (NF-κB), cyclooxygenase-2 (COX-2), and interleukin-6 (IL-6) using the ELISA technique. Results: Our MTT results show that morin treatment significantly reduced the cell viability of rat C6 glioma cells. It also significantly increased ROS generation and decreased MMP in rat C6 glioma cells. Morin treatment also effectively increased caspase-3 and caspase-9, the proapoptotic protein Bax, and decreased the antiapoptotic protein Bcl2. The induction of apoptosis by morin in glioma cells was evident with our acridine orange/ethidium bromide (AO/EtBr) staining results. Morin also decreased the inflammatory cytokine levels in rat C6 glioma cells. Conclusion: Our findings have proven that morin significantly induces apoptosis by increasing the levels of apoptotic protein via the generation of ROS. It also effectively reduced inflammatory cytokine levels, thereby exerting anticancer activity against glioma cells. Therefore, morin can be subjected to further research to be designed as a potent anticancer drug to treat gliomas.