Poly(ADP-Ribose) Polymerase Inhibition Sensitizes Colorectal Cancer-Initiating Cells to Chemotherapy

Awad Jarrar, Fiorenza Lotti, Jennifer DeVecchio, Sylvain Ferrandon, Gerald Gantt, Adam Mace, Georgios Karagkounis, Matthew Orloff, Monica Venere, Masahiro Hitomi, Justin Lathia, Jeremy N. Rich, Matthew F. Kalady

Research output: Contribution to journalArticlepeer-review

Abstract

Colorectal cancer (CRC) remains a leading killer in the U.S. with resistance to treatment as the largest hurdle to cure. Colorectal cancer-initiating cells (CICs) are a self-renewing tumor population that contribute to tumor relapse. Here, we report that patient-derived CICs display relative chemoresistance compared with differentiated progeny. In contrast, conventional cell lines failed model therapeutic resistance. CICs preferentially repaired chemotherapy-induced DNA breaks, prompting us to interrogate DNA damage pathways against which pharmacologic inhibitors have been developed. We found that CICs critically depended on the key single-strand break repair mediator, poly(ADP-ribose) polymerase (PARP), to survive treatment with standard-of-care chemotherapy. Small molecule PARP inhibitors (PARPi) sensitized CICs to chemotherapy and reduced chemotherapy-treated CIC viability, self-renewal, and DNA damage repair. Although PARPi monotherapy failed to kill CICs, combined PARPi therapy with chemotherapy attenuated tumor growth in vivo. Clinical significance of PARPi for CRC patients was supported by elevated PARP levels in colorectal tumors compared with normal colon, with further increases in metastases. Collectively, our results suggest that PARP inhibition serves as a point of fragility for CICs by augmenting therapeutic efficacy of chemotherapy. Stem Cells 2019;37:42–53.

Original languageEnglish
Pages (from-to)42-53
Number of pages12
JournalStem Cells
Volume37
Issue number1
DOIs
Publication statusPublished - Jan 2019

Keywords

  • Cancer-initiating cells
  • Chemotherapy
  • Colon cancer
  • DNA repair
  • PARP

ASJC Scopus subject areas

  • Molecular Medicine
  • Developmental Biology
  • Cell Biology

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