METHODS: We developed two distinct types of BC tumor spheroids from MDA-MB-231 and MCF-7 cells. The spheroids underwent treatment with a range of concentrations of pharmacological Vit-C (1, 5, 10, 15, and 20 mM). Assessments were conducted to determine the cell viability, H2O2 levels, glutathione-to-glutathione disulfide (GSH/GSSG) ratios, and apoptosis. Both flow cytometry analyses of Annexin V/PI staining and caspase3/7 activity assay were used to check apoptosis.
RESULTS: We showed that Vit-C induced dose-dependent cell death in both types of tumor spheroids, primarily driven by elevated H2O2 production and a concomitant oxidative stress imbalance induced by the GSH depletion. The high levels of H2O2 generated by Vit-C triggered the apoptosis of spheroids. In MCF-7 spheroids, Vit-C-induced H2O2 production was higher, with a more pronounced decrease in the GSH/GSSG ratio, indicating greater susceptibility to oxidative stress-induced cell death. However, MDA-MB-231 spheroids exhibited a more severe cytotoxic response.
CONCLUSIONS: This study reveals that Vit-C induces oxidative stress-mediated cell death in both non-aggressive and aggressive BC spheroids. Unlike traditional in vitro studies, this work provides novel insights into the response of two BC tumor subtypes to Vit-C, demonstrating its potential as a targeted common therapy for BC.