Biegała Łukasz, Statkiewicz Małgorzata, Gajek Arkadiusz, Szymczak-Pajor Izabela, Rusetska Natalia, Śliwińska Agnieszka, Marczak Agnieszka, Mikula Michał, Rogalska Aneta
Department of Medical Biophysics, Institute of Biophysics, Faculty of Biology and Environmental Protection, University of Lodz, 141/143 Pomorska Street, 90-236 Lodz, Poland.
Department of Genetics, Maria Sklodowska-Curie National Research Institute of Oncology, 5 Roentgena Street, 02-781 Warsaw, Poland.
Biochim Biophys Acta Mol Basis Dis. 2025 Feb;1871(2):167574. doi: 10.1016/j.bbadis.2024.167574. Epub 2024 Nov 16.
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 BRCA1/2 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.
卵巢癌（OC）患者不可避免地会对奥拉帕利产生耐药性，这凸显了采取有效策略提高其疗效的必要性。在此，我们建立了一种具有BRCA1/2突变的高级别浆液性OC患者来源的奥拉帕利耐药异种移植模型，并在体内研究了初治肿瘤对奥拉帕利获得性耐药和再敏化的分子特征。用奥拉帕利、ATR抑制剂（ATRi，西拉司他）、CHK1抑制剂（CHK1i，MK-8776）或它们的组合处理奥拉帕利耐药异种移植瘤。通过RT-qPCR、蛋白质印迹和免疫组织化学检测增殖、凋亡、ATR/CHK1活性、PARP信号传导、DNA损伤反应（DDR）、上皮-间质转化（EMT）和MDR1表达。耐药肿瘤在PARP和ATR/CHK1信号传导方面存在缺陷，同时伴有DDR和EMT相关蛋白表达的改变。奥拉帕利再挑战联合ATR/CHK1抑制剂对肿瘤生长抑制显示出有前景的协同作用。机制上，联合治疗抑制肿瘤增殖但不增加凋亡或坏死，同时诱导肿瘤细胞空泡化，提示细胞死亡。ATRi联合奥拉帕利诱导或增强了ATR、CHK1、PARP1、PARG、BRCA1、γH2AX和PAR化蛋白表达的下调，同时逆转了奥拉帕利诱导的波形蛋白、BRCA2和53BP1的上调。我们的总体研究结果表明，抑制ATR/CHK1通路可恢复奥拉帕利在耐药BRCA1/2高级别浆液性OC中的疗效，凸显了对无反应患者进行奥拉帕利再挑战的有前景方法。所揭示的机制可能会增进我们对卵巢癌中奥拉帕利耐药的获得和克服的理解。
