VCP/p97, a pleiotropic protein regulator of the DNA damage response and proteostasis, is a potential therapeutic target in KRAS-mutant pancreatic cancer
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https://doi.org/10.18632/genesandcancer.231
Ye S. Lee1, Jennifer E. Klomp2, Clint A. Stalnecker1, Craig M. Goodwin2, Yanzhe Gao3, Gaith N. Droby4, Cyrus Vaziri3,4,5, Kirsten L. Bryant1,2, Channing J. Der1,2,4 and Adrienne D. Cox1,2,6
1 Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
2 Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
3 Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
4 Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
5 Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
6 Department of Radiation Oncology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
Correspondence:
Adrienne D. Cox, email:[email protected]
Keywords: autophagy; DNA damage response; KRAS; pancreatic cancer; VCP
Received: October 03, 2022 Accepted: February 26, 2023 Published: March 10, 2023
Abstract
We and others have recently shown that proteins involved in the DNA damage response (DDR) are critical for KRAS-mutant pancreatic ductal adenocarcinoma (PDAC) cell growth in vitro. However, the CRISPR-Cas9 library that enabled us to identify these key proteins had limited representation of DDR-related genes. To further investigate the DDR in this context, we performed a comprehensive, DDR-focused CRISPR-Cas9 loss-of-function screen. This screen identified valosin-containing protein (VCP) as an essential gene in KRAS-mutant PDAC cell lines. We observed that genetic and pharmacologic inhibition of VCP limited cell growth and induced apoptotic death. Addressing the basis for VCP-dependent growth, we first evaluated the contribution of VCP to the DDR and found that loss of VCP resulted in accumulation of DNA double-strand breaks. We next addressed its role in proteostasis and found that loss of VCP caused accumulation of polyubiquitinated proteins. We also found that loss of VCP increased autophagy. Therefore, we reasoned that inhibiting both VCP and autophagy could be an effective combination. Accordingly, we found that VCP inhibition synergized with the autophagy inhibitor chloroquine. We conclude that concurrent targeting of autophagy can enhance the efficacy of VCP inhibitors in KRAS-mutant PDAC.
