PARP1-Inhibition Sensitizes Cervical Cancer Cell Lines for Chemoradiation and Thermoradiation.
By: Marloes IJff, Gregor G W van Bochove, Denise Whitton, Roy Winiarczyk, Celina Honhoff, Hans Rodermond, Johannes Crezee, Lukas J A Stalpers, Nicolaas A P Franken, Arlene L Oei

Laboratory for Experimental Oncology and Radiobiology (LEXOR), Center for Experimental Molecular Medicine, Amsterdam University Medical Centers, P.O. Box 22700, 1100 DE Amsterdam, The Netherlands.
2021-02-15; doi: 10.3390/cancers13092092
Abstract

Radiotherapy plus cisplatin (chemoradiation) is standard treatment for women with locoregionally advanced cervical cancer. Both radiotherapy and cisplatin induce DNA single and double-strand breaks (SSBs and DSBs). These double-strand breaks can be repaired via two major DNA repair pathways: Classical Non-Homologous End-Joining (cNHEJ) and Homologous Recombination. Besides inducing DNA breaks, cisplatin also disrupts the cNHEJ pathway. Patients contra-indicated for cisplatin are treated with radiotherapy plus hyperthermia (thermoradiation). Hyperthermia inhibits the HR pathway. The aim of our study is to enhance chemoradiation or thermoradiation by adding PARP1-inhibition, which disrupts both the SSB repair and the Alternative NHEJ DSB repair pathway. This was studied in cervical cancer cell lines (SiHa, HeLa, C33A and CaSki) treated with hyperthermia (42 °C) ± ionizing radiation (2-6 Gy) ± cisplatin (0.3-0.5 µM) ± PARP1-inhibitor (olaparib, 4.0-5.0 µM). Clonogenic assays were performed to measure cell reproductive death. DSBs were analyzed by γ-H2AX staining and cell death by live cell imaging. Both chemoradiation and thermoradiation resulted in lower survival fractions and increased unrepaired DSBs when combined with a PARP1-inhibitor. A quadruple modality, including ionizing radiation, hyperthermia, cisplatin and PARP1-i, was not more effective than either triple modality. However, both chemoradiation and thermoradiation benefit significantly from additional treatment with PARP1-i.





PMID:33926008






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