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  3. Molecular mechanisms restoring olaparib efficacy through ATR/CHK1 pathway inhibition in olaparib-resistant BRCA1/2MUT ovarian cancer models

Molecular mechanisms restoring olaparib efficacy through ATR/CHK1 pathway inhibition in olaparib-resistant BRCA1/2MUT ovarian cancer models

  • Biochim Biophys Acta Mol Basis Dis. 2025 Feb;1871(2):167574. doi: 10.1016/j.bbadis.2024.167574.
Łukasz Biegała 1,  Małgorzata Statkiewicz 2,  Arkadiusz Gajek 3,  Izabela Szymczak-Pajor 4,  Natalia Rusetska 5,  Agnieszka Śliwińska 6,  Agnieszka Marczak 7,  Michał Mikula 8,  Aneta Rogalska 9
Affiliations

Affiliations

  • 1 Department of Medical Biophysics, Institute of Biophysics, Faculty of Biology and Environmental Protection, University of Lodz, 141/143 Pomorska Street, 90-236 Lodz, Poland. Electronic address: lukasz.biegala@edu.uni.lodz.pl.
  • 2 Department of Genetics, Maria Sklodowska-Curie National Research Institute of Oncology, 5 Roentgena Street, 02-781 Warsaw, Poland. Electronic address: malgorzata.statkiewicz@nio.gov.pl.
  • 3 Department of Medical Biophysics, Institute of Biophysics, Faculty of Biology and Environmental Protection, University of Lodz, 141/143 Pomorska Street, 90-236 Lodz, Poland. Electronic address: arkadiusz.gajek@biol.uni.lodz.pl.
  • 4 Department of Nucleic Acid Biochemistry, Medical University of Lodz, 251 Pomorska Street, 92-213 Lodz, Poland. Electronic address: izabela.szymczak@umed.lodz.pl.
  • 5 Department of Experimental Immunology, Maria Sklodowska-Curie National Research Institute of Oncology, 5 Roentgena Street, 02-781 Warsaw, Poland. Electronic address: natalia.rusetska@nio.gov.pl.
  • 6 Department of Nucleic Acid Biochemistry, Medical University of Lodz, 251 Pomorska Street, 92-213 Lodz, Poland. Electronic address: agnieszka.sliwinska@umed.lodz.pl.
  • 7 Department of Medical Biophysics, Institute of Biophysics, Faculty of Biology and Environmental Protection, University of Lodz, 141/143 Pomorska Street, 90-236 Lodz, Poland. Electronic address: agnieszka.marczak@biol.uni.lodz.pl.
  • 8 Department of Genetics, Maria Sklodowska-Curie National Research Institute of Oncology, 5 Roentgena Street, 02-781 Warsaw, Poland. Electronic address: michal.mikula@nio.gov.pl.
  • 9 Department of Medical Biophysics, Institute of Biophysics, Faculty of Biology and Environmental Protection, University of Lodz, 141/143 Pomorska Street, 90-236 Lodz, Poland. Electronic address: aneta.rogalska@biol.uni.lodz.pl.
PMID: 39557132 DOI: 10.1016/j.bbadis.2024.167574
Abstract

Resistance to olaparib inevitably develops in ovarian Cancer (OC) patients, highlighting the necessity for effective strategies to improve its efficacy. Here, we established a novel olaparib-resistant patient-derived xenograft model of high-grade serous OC with BRCA1/2 mutations and examined the molecular characteristics of acquired resistance and resensitization to olaparib in treatment-naïve tumors in vivo. Olaparib-resistant xenografts were treated with olaparib, ATR Inhibitor (ATRi, ceralasertib), Chk1 Inhibitor (CHK1i, MK-8776) or their combinations. Proliferation, Apoptosis, ATR/Chk1 activity, PARP signaling, DNA damage response (DDR), epithelial-to-mesenchymal transition (EMT), and MDR1 expression, were examined via RT-qPCR, western blot, and immunohistochemistry. Resistant tumors exhibited defects in PARP and ATR/Chk1 signaling, accompanied by altered expression of proteins involved in DDR and EMT. Olaparib rechallenge combined with ATR/Chk1 inhibitors showed promising synergistic effects on tumor growth inhibition. Mechanistically, combined treatments suppressed tumor proliferation without increasing Apoptosis or necrosis, while inducing tumor cell vacuolization indicative of cell death. ATRi combined with olaparib induced or augmented downregulation of ATR, Chk1, PARP1, PARG, BRCA1, γH2AX, and PARylated protein expression, while reversing olaparib-induced upregulation of vimentin, BRCA2, and 53BP1. Our collective findings indicate that ATR/Chk1 pathway inhibition restores the olaparib efficacy in resistant BRCA1/2MUT high-grade serous OC, highlighting promising approach for olaparib rechallenge of non-responsive patients. Uncovered mechanisms might improve our understanding of acquisition and overcoming resistance to olaparib in ovarian Cancer.

Keywords

ATR/CHK1 pathway; Olaparib resistance; Ovarian cancer; Patient-derived xenograft; Resensitization.

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