Abstract
The late endolysosomal compartment plays a crucial role in cancer cell metabolism by regulating lysosomal activity, essential for cell proliferation, and the degradation of cellular components during the final stages of autophagy. Modulating late endolysosomal function represents a new target for cancer therapy. In this study, we investigated the effects of bafilomycin A1 (BA1), a vacuolar H+-ATPase inhibitor, on colon cancer and normal colon fibroblasts (CCD-18Co) cells. We found that very low concentrations (~ 2 nM) of BA1 selectively induced cell death in colon cancer cells. This cytotoxicity was associated with lysosomal stress response and dysregulation of iron homeostasis. BA1 treatment resulted in significant alterations to the endolysosomal system, including an increased number and size of lysosomes, lysosomal membrane permeabilization, and autophagy flux blockade. These changes were accompanied by endoplasmic reticulum stress and lipid droplet accumulation. Furthermore, BA1 decreased intracellular Fe2+ levels, as measured using FerroOrange. Notably, iron (III)-citrate supplementation rescued cells from BA1-induced death. These findings suggest that BA1-induced endolysosomal dysfunction impairs iron homeostasis, ultimately leading to colon cancer cell death. Our results highlight the potential of targeting endolysosomal function and iron homeostasis as novel therapeutic strategies for colon cancer, paving the way for more selective and effective treatments.