Azoxystrobin Reduces Oral Carcinogenesis by Suppressing Mitochondrial Complex III Activity and Inducing Apoptosis

PURPOSE: The five-year survival rate of patients with oral cancer is approximately 50%; thus, alternative drugs with higher efficacy are urgently required. Azoxystrobin (AZOX), a natural, novel methoxyacrylate fungicide isolated from mushrooms, has a broad-spectrum, with highly efficient bactericidal effect. However, studies on AZOX have focused on antifungal effects. Here, we explore the potential cancer-preventive effects of AZOX and the underlying mechanisms. MATERIALS AND METHODS: The effects of AZOX on oral carcinogenesis induced by 4-nitroquinoline-1-oxide (4NQO) were investigated in C57BL/6 mice. Cell proliferation and apoptosis were examined by Ki67 immunohistochemistry and TUNEL staining, respectively. The main organ coefficients of each group were calculated to evaluate the biosafety of AZOX. CCK8 and flow cytometry were used to detect the effects of AZOX on cell viability and apoptosis in oral cancer cell line CAL27 and SCC15 cells in vitro. Cell cycle, mitochondrial complex III activity, intercellular reactive oxygen species (ROS) level, mitochondrial ROS level, and mitochondrial membrane potential (MMP) were detected by flow cytometry in AZOX-treated CAL27 cells. RESULTS: AZOX significantly inhibited the occurrence of 4NQO-induced tongue cancer and delayed the progression of tongue precancerous lesions in mice. High-dose AZOX obviously inhibited cell viability and induced apoptosis in epithelial dysplastic and oral squamous cell carcinoma (OSCC) lesions in mouse tongue mucosa. AZOX was confirmed to have high biosafety. Similarly, in vitro cell viability was suppressed, and apoptosis was induced in AZOX-treated CAL27 and SCC15 cells. AZOX induced cell cycle arrest at the S phase. AZOX inhibited mitochondrial complex III activity, increased intracellular and mitochondrial ROS levels, and decreased MMP in CAL27 cells. CONCLUSION: AZOX inhibited the development of oral cancer through specific inhibition of the activity of mitochondrial complex III, which led to ROS accumulation, and MMP decrease, ultimately inducing apoptosis. AZOX may be a novel agent for the prevention and treatment of OSCC.