Small Particles, Big Problems: Polystyrene nanoparticles induce DNA damage, oxidative stress, migration, and mitogenic pathways predominantly in non-malignant lung cells

Abstract Polystyrene micro-and nanoplastics (PS-MNPs) are emerging environmental pollutants with potential implications for human health. In this study, we used two different sizes of PS-MNPs (0.25 µm and 1 µm) on non-small cell lung cancer (A549, H460), small cell lung cancer (DMS53, H372), and normal lung epithelial (BEAS-2B) cells, as well as on human-derived lung organoids, to investigate the cytotoxic effects of PS particles. At lower concentrations (< 30 µg/cm 2 , equivalent to 50 µg/ml), neither PS-MPs nor PS-NPs did not interfere with cell viability or proliferation. Intracellular kinetic assays revealed that non-malignant (BEAS-2B) lung cells showed the strongest turnover of PS-NPs compared to malignant cells. Since PS-NPs exhibited more pronounced cellular effects, we focused further analyses on their impact. Furthermore, we observed significantly increased migration, prolonged S-phase arrest along with induced DNA damage, and oxidative stress in non-malignant (BEAS-2B) lung cells. Thus, our data suggest that BEAS-2B cells exhibit the highest sensitivity to PS-NPs. We also demonstrate that after PS-NP treatment, these cells displayed decreased base excision repair capacity and increased activation of survival pathways, including AKT and ERK phosphorylation. PS-NP internalization and increase of signal pathways were validated in a more physiological lung organoid setting. Altogether, our findings suggest that PS-NPs do not significantly affect the malignant behavior of cancer cells. However, they could promote tumor-like features in normal lung cells by inducing survival pathways, migration, and alterations in stress response mechanisms. Environmental Implications This study investigates the effects of polystyrene micro-and nanoplastics (PS-MNPs) at environmentally relevant concentrations. The tested concentrations of PS-MNPs (0, 15, 30, and 60 µg/cm 2 , equivalent to 0, 25, 50, and 100 µg/ml) are commonly studied in the literature in lung cells. While these findings provide insights into cellular responses, the overall environmental impact of PS-MNPs remains limited at realistic exposure levels. Highlights PS-MNPs are internalized into lung cells, with higher uptake in non-malignant cells. PS-NPs lead to increased migration, DNA damage, oxidative stress, and disturbed cell cycle progression. PS-NPs promote activation of survival pathways in non-malignant cells and lung organoids. Exposure of PS-NPs may cause potential implications for lung cancer development and progression.