Posttranscriptional regulation of PARG mRNA by HuR facilitates DNA repair and resistance to PARP inhibitors

Saswati N. Chand, Mahsa Zarei, Matthew J. Schiewer, Akshay R. Kamath, Carmella Romeo, Shruti Lal, Joseph A. Cozzitorto, Avinoam Nevler, Laura Scolaro, Eric Londin, Wei Jiang, Nicole Meisner-Kober, Michael J. Pishvaian, Karen E. Knudsen, Charles J. Yeo, John M. Pascal, Jordan M. Winter, Jonathan R. Brody

Research output: Contribution to journalArticlepeer-review

58 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)5011-5025
Number of pages15
JournalCancer Research
Issue number18
StatePublished - Sep 15 2017
Externally publishedYes

ASJC Scopus subject areas

  • Oncology
  • Cancer Research


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