Insights into cadmium-induced carcinogenesis through an in-vitro study using C3H10T1/2Cl8 cells: the multifaceted role of mitochondria

Abstract

In this paper we report the metabolic characterization of two foci, F1 and F3, obtained at the end of Cell Transformation Assay (CTA), performed by treating C3H10T1/2Cl8 mouse embryo fibroblasts with 1 µM CdCl2 for 24 h. The elucidation of cadmium action mechanism can be useful both to improve the in vitro CTA and to yield insights into carcinogenesis. We previously showed that, despite being both completely transformed type III foci, F1 and F3 foci display different morphologies, proliferative behaviors and gene expression patterns. In this work, the metabolism of the two foci was investigated through Seahorse and enzyme activity assays; moreover, mitochondria were studied in confocal microscopy and reactive oxygen species were detected by flow cytometry. Results showed that F1 focus has higher glycolytic and TCA fluxes compared to F3 focus, and a more negative mitochondrial membrane potential (Δψ), so that most ATP synthesis is performed through oxidative phosphorylation. Confocal microscopy showed mitochondria crowded in the perinuclear region. On the other hand, F3 focus showed lower metabolic rates, with ATP mainly produced by glycolysis and damaged mitochondria. On the whole, our results showed that cadmium treatment induced lasting metabolic alterations in both foci. Triggered by the loss of Pasteur effect in F1 focus and by mitochondrial impairment in F3 focus, these alterations lead to a loss of coordination among glycolysis, TCA and oxidative phosphorylation, which leads to malignant transformation.