TY - JOUR
T1 - Posttranscriptional regulation of PARG mRNA by HuR facilitates DNA repair and resistance to PARP inhibitors
AU - Chand, Saswati N.
AU - Zarei, Mahsa
AU - Schiewer, Matthew J.
AU - Kamath, Akshay R.
AU - Romeo, Carmella
AU - Lal, Shruti
AU - Cozzitorto, Joseph A.
AU - Nevler, Avinoam
AU - Scolaro, Laura
AU - Londin, Eric
AU - Jiang, Wei
AU - Meisner-Kober, Nicole
AU - Pishvaian, Michael J.
AU - Knudsen, Karen E.
AU - Yeo, Charles J.
AU - Pascal, John M.
AU - Winter, Jordan M.
AU - Brody, Jonathan R.
N1 - Funding Information:
This work was supported by a seed grant from the Hirshberg Foundation for Pancreatic Cancer Research (J.R. Brody and J.M. Pascal), NIH-NCI R21 CA182692 01A1 (J.R. Brody), 1R01CA212600-01 (J.R. Brody), American Cancer Society MRSG-14-019-01-CDD (J.M. Winter and J.R. Brody), the Mary Halinski Pancreatic Cancer Research Fund (J.R. Brody and A. Nevler), and Fund A Cure and the Michele Barnett Rudnick Fund (J.R. Brody and S.N. Chand). A. Nevler was supported by a scholarship from the Dr. P. Borenstein Talpiot Medical Leadership Program (2012, Chaim Sheba Medical Center, Israel).
Publisher Copyright:
©2017 AACR.
PY - 2017/9/15
Y1 - 2017/9/15
N2 - The majority of pancreatic ductal adenocarcinomas (PDAC) rely on the mRNA stability factor HuR (ELAV-L1) to drive cancer growth and progression. Here, we show that CRISPR-Cas9–mediated silencing of the HuR locus increases the relative sensitivity of PDAC cells to PARP inhibitors (PARPi). PDAC cells treated with PARPi stimulated translocation of HuR from the nucleus to the cytoplasm, specifically promoting stabilization of a new target, poly (ADP-ribose) glycohydrolase (PARG) mRNA, by binding a unique sequence embedded in its 30 untranslated region. HuR-dependent upregulation of PARG expression facilitated DNA repair via hydrolysis of polyADP-ribose on related repair proteins. Accordingly, strategies to inhibit HuR directly promoted DNA damage accumulation, inefficient PAR removal, and persistent PARP-1 residency on chromatin (PARP-1 trapping). Immunoprecipitation assays demonstrated that the PARP-1 protein binds and posttranslationally modifies HuR in PARPi-treated PDAC cells. In a mouse xenograft model of human PDAC, PARPi monotherapy combined with targeted silencing of HuR significantly reduced tumor growth compared with PARPi therapy alone. Our results highlight the HuR–PARG axis as an opportunity to enhance PARPi-based therapies.
AB - The majority of pancreatic ductal adenocarcinomas (PDAC) rely on the mRNA stability factor HuR (ELAV-L1) to drive cancer growth and progression. Here, we show that CRISPR-Cas9–mediated silencing of the HuR locus increases the relative sensitivity of PDAC cells to PARP inhibitors (PARPi). PDAC cells treated with PARPi stimulated translocation of HuR from the nucleus to the cytoplasm, specifically promoting stabilization of a new target, poly (ADP-ribose) glycohydrolase (PARG) mRNA, by binding a unique sequence embedded in its 30 untranslated region. HuR-dependent upregulation of PARG expression facilitated DNA repair via hydrolysis of polyADP-ribose on related repair proteins. Accordingly, strategies to inhibit HuR directly promoted DNA damage accumulation, inefficient PAR removal, and persistent PARP-1 residency on chromatin (PARP-1 trapping). Immunoprecipitation assays demonstrated that the PARP-1 protein binds and posttranslationally modifies HuR in PARPi-treated PDAC cells. In a mouse xenograft model of human PDAC, PARPi monotherapy combined with targeted silencing of HuR significantly reduced tumor growth compared with PARPi therapy alone. Our results highlight the HuR–PARG axis as an opportunity to enhance PARPi-based therapies.
UR - http://www.scopus.com/inward/record.url?scp=85031414522&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85031414522&partnerID=8YFLogxK
U2 - 10.1158/0008-5472.CAN-16-2704
DO - 10.1158/0008-5472.CAN-16-2704
M3 - Article
C2 - 28687616
AN - SCOPUS:85031414522
SN - 0008-5472
VL - 77
SP - 5011
EP - 5025
JO - Cancer Research
JF - Cancer Research
IS - 18
ER -