Nano neodymium oxide induces massive vacuolization and autophagic cell death in non-small cell lung cancer NCI-H460 cells

Abstract

Neodymium, a rare earth element, was known to exhibit cytotoxic effects and induce apoptosis in certain cancer cells. Here we show that nano-sized neodymium oxide (Nano Nd 2O 3) induced massive vacuolization and cell death in non-small cell lung cancer NCI-H460 cells at micromolar equivalent concentration range. Cell death elicited by Nano Nd 2O 3 was not due to apoptosis and caspases were not involved. Electron microscopy and acridine orange staining revealed extensive autophagy in the cytoplasm of the cells treated by Nano Nd 2O 3. Autophagy induced by Nano Nd 2O 3 was accompanied by S-phase cell cycle arrest, mild disruption of mitochondrial membrane potential, and inhibition of proteasome activity. Bafilomycin A1, but not 3-MA, induced apoptosis while inhibiting autophagy. Our results revealed a novel biological function for Nano Nd 2O 3 and may have implications for the therapy of non-small cell lung cancer.