Manufacturing or using nanomaterials may result in exposure of workers to nanoparticles. Potential routes of exposure include skin, lung and gastrointestinal tract. The lack of health-based standards for nanomaterials combined with their increasing use in many different workplaces and products emphasize the need for a reliable temporary risk assessment tool. Therefore, the aim of this work was to explore the effects of different doses of titanium dioxide nanoparticles on human gastric epithelial cells in vitro. We analyzed proliferation by MTT assay, apoptosis by Tunel, migration by injury assay, oxidative stress by determining GSH/GSSG ratio and DNA damage by Comet assay on nanoparticle-treated AGS human gastric epithelial cell line in comparison to controls. We show and discuss the tumor-like phenotypes of nanoparticles-exposed AGS cells in vitro, as increased proliferation and decreased apoptosis. Our results demonstrate for the first time that nanoparticles induce tumor-like phenotypes in human gastric epithelial cells.