Cytotoxic Effects of Titanium Dioxide Nanoparticles on Colon Cancer Cell Line (HT29) and Analysis of Caspase-3 and 9 Gene Expression Using Real Time PCR and Flow Cytometry

Background: Today, titanium dioxide (TiO2) nanoparticles present extensive therapeutic applications. The present study was conducted to investigate the cytotoxicity of TiO2 on colon cancer cell line (HT29), and analyze the expression of caspase-3 and 9 genes. Materials and Methods: The present experimental study used the MTT assay to examine the cytotoxicity of 3.125, 6.25, 12.5, 25, 50 and 100 µg/ml concentrations of TiO2 nanoparticles on cell line HT29. After the treatment of HT29 cells with IC50 concentration of TiO2, the gene expression levels of caspase-3 and caspase-9 were investigated and compared with the reference gene of GAPDH using real time PCR. DAPI staining and flow cytometry were ultimately used to confirm apoptosis in HT29 cells.  Results: The treatment of HT29 cells with different concentrations of TiO2 showed that TiO2 nanoparticles at 50 and 100 µg/ml concentrations present the highest cytotoxicity, which was statistically significant (P<0.05). Moreover, the expression of caspase-3 gene was found to be significantly upregulated by 2.0±69.13 (P<0.001) and that of caspase-9 gene by 3.0±46.29 (P<0.001) in HT29 cell lines treated with TiO2 nanoparticles for 24 hours. The results of DAPI staining and flow cytometry also confirmed apoptosis in HT29 cells.   Conclusion: According to the obtained results, TiO2 nanoparticles can be recommended as prospective medicinal candidates for pharmaceutical purposes, although further studies are required in this field