Poly(ADP-Ribose) Polymerase Inhibition Sensitizes Colorectal Cancer-Initiating Cells to Chemotherapy. (12th November 2018)

• Record Type: Journal Article
• Authors: Jarrar, Awad; Lotti, Fiorenza; DeVecchio, Jennifer; Ferrandon, Sylvain; Gantt, Gerald; Mace, Adam; Karagkounis, Georgios; Orloff, Matthew; Venere, Monica; Hitomi, Masahiro; Lathia, Justin; Rich, Jeremy N.; Kalady, Matthew F.
• Is Part Of: Stem cells. Volume 37:Number 1(2019)
• Page Start: 42
• Page End: 53
• Publication Date: 2018-11-12
• Subjects: Colon cancer -- Chemotherapy -- Cancer-initiating cells -- PARP -- DNA repair; Cloning -- Periodicals; Clone cells -- Periodicals; Stem cells -- Periodicals; Cell Differentiation -- Periodicals; Cell Division -- Periodicals; Clone Cells -- Periodicals; Hematopoietic Stem Cells -- Periodicals; Stem Cells -- Periodicals; 571.84
• DOI: 10.1002/stem.2929
• Languages: English
• ISSNs: 1066-5099

Abstract

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 : Abstract : Colorectal cancer initiating cells (CIC) were resistant to conventional chemotherapy in cell-autonomous assays. This was partly mediated by Poly(ADP-Ribose) Polymerase (PARP) DNA repair. Small molecule PARP inhibitors (PARPi) monotherapy failed to kill CICs. However, in combination with chemotherapy, PARPi reduced CIC viability, self-renewal, and DNA damage repair. Combined PARPi therapy with chemotherapy attenuated tumor growth in vivo.