Niraparib

Olaparib was purchased from TargetMol; rucaparib, niraparib, KU55933 (ATM inhibitor), AZD6738 (ATR inhibitor), AZD7762 (Chk1 inhibitor) and AZD1775 (Wee1 inhibitor) from Axon Medchem; cisplatin from Sigma Adrich; carboplatin from Adipogen; paclitaxel from ChemieTek; doxorubicin and verapamil from Merck. All the drugs were dissolved in DMSO as stock solutions and diluted in medium just before treatment. For cytotoxicity experiments, cells were seeded at 1000 cells/mL and treated with different drug concentrations in 96-well plates 48 h after seeding. After five days, cell viability was examined with the MTS assay system (Promega) and absorbance was acquired using a plate reader (GloMax Discover, Promega). Drug concentrations inhibiting growth in 50% of the cells (IC₅₀) were calculated for each cell line, with the interpolation method on Prism 8.3.0 (GraphPad Software).

The experimental setup has been described previously^{11 (link)}. In brief, 24 h after seeding, cells were treated with medium and antibiotics containing 0.1, 0.5, 1, 5, 10, 25, or 50 µM Niraparib (Selleckchem, Houston, TX), 0.1, 0.5, 1, 5, 10, 50, 100, or 200 µM Olaparib (Selleckchem, Houston, TX), 0.01, 0.05, 0.1, 0.25, 0.5, 0.75, or 1 µM Berzosertib (Axon Medchem, Groningen, NL), or a combination of the respective concentrations of Berzosertib and Niraparib (all final well concentrations) and were incubated at 37 °C with 5% CO₂ for six days. Medium containing the respective drug concentrations was replaced every 48 h. On day 6, 100 µM 5′-bromo-2′desoxyuridine (BrdU) labeling solution was added and the rate of proliferating cells was determined 24 h later (=d7) by means of a BrdU-ELISA (Roche, Basel, SUI), according to the manufacturer’s instructions. Optical density was measured at a wavelength of 370 nm and a reference wavelength of 492 nm using a microplate reader (Tecan Spark, Männedorf, SUI).

Cisplatin, metformin and fenformin were purchased from Sigma-Aldrich (St. Louis, MO, USA); carboplatin from Adipogen (San Diego, CA, USA); paclitaxel from ChemieTek (Indianapolis, IN, USA); doxorubicin and rotenone from Merck; Yondelis (ET-743) from PharmaMar (Madrid, Spain); olaparib from TargetMol (Boston, MA, USA); oxaliplatin, rucaparib, niraparib, KU55933 (ATM inhibitor), AZD6738 (ATR inhibitor), AZD7762 (Chk1 inhibitor) and AZD1775 (Wee1 inhibitor) from Axon Medchem (Groningen, The Netherlands). All the drugs were dissolved in DMSO or water as stock solutions and diluted in medium just before treatment. For cytotoxicity experiments, cells were seeded at 1000–2000 cells/mL and treated with different drug concentrations in 96-well plates 48 h after seeding. After five days of treatment, cell viability was examined with the MTS assay system (Promega Corporation, Madison, WI, USA), and absorbance was acquired using a microplate reader (GloMax Discover, Promega Corporation). Drug concentrations inhibiting growth in 50% of the cells (IC50) were calculated for each cell line, with the interpolation method on Prism 9.5.1 (GraphPad Software, La Jolla, CA, USA). All the experiments were run at least three times in sestuplicate.