Different Concentrations of Titanium Dioxide Nanoparticles Induce Autophagy Followed by Growth Inhibition or Cell Death in A375 Melanoma Cells

Dysregulation of autophagy is currently known as a contributing factor to tumorigenesis. Accordingly, exploring novel compounds with autophagy - modulating properties is a priority in cancer research. While a number of synthetic compounds have been developed, autophagy - modulating Nanoparticles (NPs), such as titanium dioxide (TiO2), have been recently considered. This research investigated the effects of a well - dispersed form of TiO2 NPs on autophagic vesicle formation in human melanoma A375 cells. The cells were treated with different concentrations of TiO2 NPs (1 - 100 g/mL) for 24 hours, then growth, cell death, and autophagy were, respectively, evaluated by trypan blue exclusion test, MTT assay, and acridine orange staining. The results showed that well - dispersed TiO2 NPs induced growth inhibition in a dose dependent manner, while cell death was only observed at high concentrations (100 g/mL). In addition, a significant increase in Acidic Vesicular Organelles (AVO) formation was detected at all concentrations of NPs after 24 hours, suggesting that TiO2 NPs may induce both cytostatic and cytotoxic autophagic responses, depending on the concentration.