Tin (IV) Oxide (SnO2 ) Nanoparticles Inhibit the Viability of Cervical Cancer HeLa Cells Through Induction of Apoptosis

Introduction: Resistance to chemotherapy and severe side effects have been reported as the main reasons for treatment failure in patients with cervical cancer. Therefore, it is necessary to find new treatment strategies with fewer side effects and more efficacy. This study aimed to investigate the cytotoxic property of tin (IV) oxide (SnO2) nanoparticles (NPs) against human cervical cancer cells (HeLa cells). In addition, the molecular mechanism of anticancer activity of SnO2 NPs was evaluated. 
Materials and Methods: The cytotoxicity of SnO2 NPs against HeLa cells and normal mouse fibroblast cells (L929) was studied using an MTT assay. To determine the mechanism of action of SnO2 NPs, the cells were treated with the half maximal inhibitory concentration values of SnO2 NPs for 24 h and apoptotic cell percentage was assessed by Annexin-PI and flow cytometry. In addition, real-time quantitative polymerase chain reaction (PCR) was used to evaluate the mRNA expression levels of apoptotic genes (Bax and Bcl-2). 
Results: SnO2 NPs suppress the viability of HeLa cells in a dose-dependent manner. This compound was more cytotoxic against HeLa cells than L929 cells. Flow-cytometry analysis revealed that SnO2 NPs significantly caused cell growth arrest. Moreover, real-time PCR results showed that SnO2 NPs treatment decreased Bcl-2 and increased Bax expression level. 
Conclusion: SnO2 NPs treatment significantly inhibit HeLa cells viability through the induction of apoptosis. Interestingly SnO2 NPs were more cytotoxic against HeLa cells than normal fibroblast cells, which may provide promising evidence for their applications as an anticancer drug.