Anticancer Potential of Brucine against Oral Cancer Cells in vitro through Elevation of Reactive Oxygen Species

Abstract

Background: Oral cancer is one of the cancers that pose a great threat to life globally. Though a number of chemotherapeutic strategies have been followed to treat oral cancer, a number of adverse effects limit the usage of chemotherapeutic agents Purpose: In the current study, we evaluated the anticancer potential of brucine.Materials and Methods: KB cell line was treated with various concentrations of brucine (10–100 μg/ml) and the cytotoxicity and cell viability were measured. Acridine orange/ethidium bromide (AO/EB) staining was performed to assess apoptosis in cells. To evaluate the mechanism of brucine‑mediated apoptosis, gene expression studies were carried out (Bax and cMyc).Results: Brucine caused cytotoxicity and reduced cell viability as assessed by 3‑(4,5‑dimethylthiazol‑2‑yl)‑2,5‑diphenyl tetrazolium bromide (MTT) assay and trypan blue exclusion assay, respectively. The IC50 value of brucine was calculated to be 30 µg/ml. Further experiments were performed according to the IC50 value. Brucine‑treated cells were rounded up and detached from the surface. AO/EB staining revealed apoptotic mode of cell death. Further, our experiments revealed elevated levels of reactive oxygen species (ROS) within the cells, which might have caused apoptosis. A dose‑dependent rise in lipid peroxidation was evident from thiobarbituric acid reactive substance (TBARS) assay, which could be due to the oxidative stress caused by brucine. Nitric oxide levels were impaired by brucine, which correlated well with apoptosis. On the other hand, catalase activity was decreased by brucine in a dose‑dependent manner, implying the reason for oxidative stress. Polymerase chain reaction (PCR) analysis revealed increased expression of Bax and impaired expression of the oncogene cMyc.Conclusion: Brucine triggers oxidative stress, which leads to lipid peroxidation and induces the expression of the proapoptotic gene Bax, thereby causing apoptosis. In parallel, brucine‑mediated suppression of cMyc leads to impairment of metastasis.

Keywords: Brucine; Apoptosis; Cancer cells; Oxidative stress; pro- apoptotic gene; lipid peroxidation