Chloroquine sensitises hypoxic colorectal cancer cells to ROS-mediated cell death via structural disruption of pyruvate dehydrogenase kinase 1

Free Radic Biol Med. 2025 Feb 1:227:656-666. doi: 10.1016/j.freeradbiomed.2024.12.026. Epub 2024 Dec 8.

Abstract

Chloroquine (CQ), an autophagy antagonist, has been recently explored as a repurposable medicine for cancer; however the exact mechanism of its action is still not known. The present study investigated the effect of CQ on colorectal cancer cells to elucidate the underlying molecular mechanisms. We report for the first time that CQ suppresses hypoxia-induced growth and survival of HCT-116 cells by reducing glycolytic capacity and NAD+ production through inhibition of PDK1. Furthermore, in silico and in vitro studies revealed that CQ induces structural alteration in the PDK1 protein, leading to its destabilization and promotes its enhanced degradation by proteases. This degradation is in turn inhibited by the MG-132 protease inhibitor. Moreover, CQ-induced suppression of PDK1 results in mitochondrial damage through excessive production of ROS, as reflected by the reduction in mitochondrial membrane potential, which in turn triggers apoptosis through PARP cleavage and Caspase activation. These findings advocate CQ as a promising repurposable chemotherapeutic for colorectal cancer and a novel inhibitor of PDK1.

Keywords: And apoptosis; CQ-Binding; CQ-Repositioning; Colorectal cancer; Glycolysis; Hypoxia; MMP; PDK1; ROS.

MeSH terms

  • Apoptosis* / drug effects
  • Autophagy / drug effects
  • Cell Hypoxia / drug effects
  • Cell Proliferation / drug effects
  • Chloroquine* / pharmacology
  • Colorectal Neoplasms* / drug therapy
  • Colorectal Neoplasms* / genetics
  • Colorectal Neoplasms* / metabolism
  • Colorectal Neoplasms* / pathology
  • Glycolysis / drug effects
  • HCT116 Cells
  • Humans
  • Membrane Potential, Mitochondrial* / drug effects
  • Mitochondria / drug effects
  • Mitochondria / metabolism
  • Mitochondria / pathology
  • Protein Serine-Threonine Kinases / antagonists & inhibitors
  • Protein Serine-Threonine Kinases / genetics
  • Protein Serine-Threonine Kinases / metabolism
  • Pyruvate Dehydrogenase Acetyl-Transferring Kinase* / genetics
  • Pyruvate Dehydrogenase Acetyl-Transferring Kinase* / metabolism
  • Reactive Oxygen Species* / metabolism

Substances

  • Reactive Oxygen Species
  • Pyruvate Dehydrogenase Acetyl-Transferring Kinase
  • PDK1 protein, human
  • Chloroquine
  • Protein Serine-Threonine Kinases