Capsaicin Reduces Cancer Stemness and Inhibits Metastasis by Downregulating SOX2 and EZH2 in Osteosarcoma

Metastasis of osteosarcoma is an important adverse factor affecting patients' survival, and cancer stemness is the crucial cause of distant metastasis. Capsaicin, the main component of pepper, has been proven in our previous work to inhibit osteosarcoma proliferation and enhance its drug sensitivity to cisplatin at low concentrations. This study aims to further explore the anti-osteosarcoma effect of capsaicin at low concentrations (100 mu M, 24 h) on stemness and metastasis. The stemness of human osteosarcoma (HOS) cells was decreased significantly by capsaicin treatment. Additionally, the capsaicin treatment's inhibition of cancer stem cells (CSCs) was dose-dependent on both sphere formation and sphere size. Meanwhile, capsaicin inhibited invasion and migration, which might be associated with 25 metastasis-related genes. SOX2 and EZH2 were the most two relevant stemness factors for capsaicin's dose-dependent inhibition of osteosarcoma. The mRNAsi score of HOS stemness inhibited by capsaicin was strongly correlated with most metastasis-related genes of osteosarcoma. Capsaicin downregulated six metastasis-promoting genes and up-regulated three metastasis-inhibiting genes, which significantly affected the overall survival and/or diseasefree survival of patients. In addition, the CSC re-adhesion scratch assay demonstrated that capsaicin inhibited the migration ability of osteosarcoma by inhibiting its stemness. Overall, capsaicin exerts a significant inhibitory effect on the stemness expression and metastatic ability of osteosarcoma. Moreover, it can inhibit the migratory ability of osteosarcoma by suppressing its stemness via downregulating SOX2 and EZH2. Therefore, capsaicin is expected to be a potential drug against osteosarcoma metastasis due to its ability to inhibit cancer stemness.

Automated summary

Previous studies have shown that capsaicin can inhibit osteosarcoma proliferation and enhance its sensitivity to cisplatin. This study further explored the inhibitory effects of capsaicin at low concentrations on stemness and metastasis of osteosarcoma. The results demonstrated that capsaicin can significantly reduce the number of osteosarcoma cancer stem cells and inhibit their invasive and metastatic abilities. This has important implications for the prevention and treatment of osteosarcoma metastasis.