Cytotoxicity of Vanadium(IV) and Vanadium(V) on Caco-2 Cells: The Important Influence of Vanadium Speciation

Exposure to vanadium (V) occurs through the ingestion of contaminated water, polluted soil, V-containing foods and medications, and the toxicity and absorption during the small intestine phase after oral ingestion play crucial roles in the ultimate health hazards posed by V. In this study, the human colon adenocarcinoma (Caco-2) cells were selected as an intestinal absorption model to investigate the uptake and cytotoxicity of vanadyl sulfate (VOSO₄) and sodium orthovanadate (Na₃VO₄). Our results confirmed the cytotoxic effects of V(IV) and V(V) and revealed a greater toxicity of V(IV) than V(V) towards Caco-2 cells. Cell viability correlated linearly with V(V) concentration, whereas it exhibited a non-monotonic dose-response curve with V(IV) concentration. Moreover, exposures to V(IV) and V(V) induced oxidative stress in Caco-2 cells. Under experimental conditions, Caco-2 cells exhibited greater uptake of V(IV) compared to V(V). Morphological experiments further substantiated the adverse effects of V(IV) on Caco-2 cells, manifested as alterations in cellular morphology and disruption of cell monolayer structure. In conclusion, these results indicate that V(IV) exerts stronger negative effects on Caco-2 cells, with a more complex mechanism of action. Altogether, studying intestinal cytotoxicity of V provides deeper insights into the potential health risks posed by oral V exposure.