Despite the established role of mitochondria in cancer, the mechanisms by which mitochondrial Ca2+ (mtCa2+) regulates tumorigenesis remain incompletely understood. The crucial role of mtCa2+ in tumorigenesis is highlighted by altered expression of proteins mediating mtCa2+ uptake and extrusion in cancer. Here, we demonstrate decreased expression of the mitochondrial Na+/Ca2+/Li+ exchanger NCLX (SLC8B1) in human colorectal tumors and its association with advanced-stage disease in patients. Downregulation of NCLX causes mtCa2+ overload, mitochondrial depolarization, decreased expression of cell-cycle genes and reduced tumor size in xenograft and spontaneous colorectal cancer mouse models. Concomitantly, NCLX downregulation drives metastatic spread, chemoresistance, and expression of epithelial-to-mesenchymal, hypoxia, and stem cell pathways. Mechanistically, mtCa2+ overload leads to increased mitochondrial reactive oxygen species, which activate HIF1α signaling supporting metastasis of NCLX-null tumor cells. Thus, loss of NCLX is a novel driver of metastasis, indicating that regulation of mtCa2+ is a novel therapeutic approach in metastatic colorectal cancer.
- Trayambak Pathak
- Martin T Johnson
- Mohamed Trebak
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Animal experimentation: This study was performed in strict accordance with the recommendations in the Guide for the Care and Use of Laboratory Animals of the National Institutes of Health. All of the animals were handled according to approved institutional animal care and use committee (IACUC) protocol # 47350/Trebak, which was approved by the IACUC at the Penn State University college of medicine . Every effort was made to minimize animal suffering.
Human subjects: The Pennsylvania State University College of Medicine institutional review board approved this study. Approval under IRB Protocol number HY98-057EP-A. Prior to surgery, patients are consented to have resected tissues collected and banked into the Penn State Hershey Colorectal Disease Biobank. As outlined in the consent form and IRB protocol
- Mark T Nelson, University of Vermont, United States
© 2020, Pathak et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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