Shikonin-Mediated Anticancer Activity: Targeting Mitochondrial Dysfunction, DNA Damage and EMT to Suppress Oral Cancer

Abstract

Phytotherapy has provided a new insight into the treatment of many cancers, including oral cancer, over conventional chemotherapeutic agents, as it has lower side effects. Shikonin (Shk) is a naturally biologically active alkaloid found in the roots of the Lithospermum erythrorhizon plant, which exhibits strong cytotoxic effects against various cancers, including oral cancer. The present study evaluates the anticancer efficacy of Shk in SCC9 and H357 oral cancer cell lines, emphasising its antiproliferative, antimigratory and apoptosis-inducing mechanisms. We performed a series of assays, such as MTT, colony assay, wound healing, tumorsphere formation assay, AO/EtBr, DAPI, comet assay, western blotting, and measurements of reactive oxygen species (ROS) and mitochondrial membrane potential (MMP). As a result, we found that Shk reduced the viability, proliferation, and tumorigenicity of SCC9 and H357 cells in a time and concentration-dependent manner. It promotes apoptosis via overexpressing proapoptotic Bax and caspase 3 by enhancing ROS, that leads to MMP depletion and DNA damage. Moreover, Shk inhibited cell migration by regulating epithelial-mesenchymal transition (EMT) markers, including the upregulation of E-cadherin and ZO-1 expression and downregulation of N-cadherin and vimentin. Overall, our findings suggest that Shk possesses strong anticancer potential against oral cancer cells, highlighting its promise as a potential therapeutic agent for oral cancer treatment.