ICG-001 affects DRP1 activity and ER stress correlative with its anti-proliferative effect

Mitochondria form a highly dynamic network driven by opposing scission and fusion events. DRP1 is an essential modulator of mitochondrial fission and dynamics within mammalian cells. Its fission activity is regulated by posttranslational modifications such as activating phosphorylation at serine 616. DRP1 activity has recently been implicated as being dysregulated in numerous human disorders such as cancer and neurodegenerative diseases. Here we describe the development of a cell-based screening assay to detect DRP1 activation. We utilized this to undertake focused compound library screening and identified potent modulators that affected DRP1 activity including ICG-001, which is described as WNT/β-catenin signaling inhibitor. Our findings elucidate novel details about ICG-001's mechanism of action (MOA) in mediating anti-proliferative activity. We show ICG-001 both inhibits mitochondrial fission and activates an early endoplasmic reticulum (ER) stress response to induce cell death in susceptible colorectal cancer cell lines.