Carboplatin

OS cell lines (MG63, ZK-58, SaOS-2, MNNG-HOS and U2OS) were kindly provided by M. Nathrath (München, Germany) and authenticated by STR profiles. Cells were maintained in RPMI 1640 medium (Life Technologies, Inc., Darmstadt, Germany), supplemented with 10% fetal calf serum (FCS), 1% penicillin/streptomycin, 1 mM sodium pyruvate (all from Life Technologies, Inc.). Cell lines were regularly tested for mycoplasma contamination to ensure that experiments were performed only with mycoplasma-free cell lines. Talazoparib was obtained from Selleckchem (Munich, Germany). TMZ, SN-38, cisplatin, doxorubicin and etoposide were purchased from Sigma-Aldrich (Taufkirchen, Germany), MTX and carboplatin were purchased from Medac (Hamburg, Germany), zVAD.fmk from Bachem (Heidelberg, Germany). Chemicals were purchased from Sigma-Aldrich or Carl Roth (Karlsruhe, Germany) unless otherwise indicated.

4-Methylumbelliferyl heptanoate (MUH) assays were performed as previously described^{22 (link)}. The cells were treated with cisplatin (Hexal, up to 20 µM), carboplatin (Medac, up to 250 µM), vemurafenib (LC Laboratories, up to 20 µM), trametinib (Selleck Chemicals, up to 250 nM), 5-fluorouracil (R&D Systems, up to 25 µM), paclitaxel (Merck, up to 500 nM) or temozolomide (TMZ; Merck, up to 50 µM) for 72 h.

Two types of myelosuppressive regimens were used: i) 500 cGy whole-body irradiation in combination with carboplatin administration and ii) 300 cGy whole-body irradiation. Clinac 2300 C-D\S linear accelerator (Varian Medical Systems, Palo Alto, CA) was used as a source of 500 cGy irradiation at a dose rate of <100 cGy/min. In this regimen, irradiation was followed by a single intraperitoneal injection of 1.2 mg/mouse of carboplatin (medac GmbH, Wedel, Germany). RS 2000 irradiator (Rad Source Technologies, Inc., Suwannee, GA) was used for 300 cGy irradiation at a dose rate of 103.6 cGy/min. After myelosuppression induction, mice were divided into 3 groups (each of 15 animals): treated with IL-11, treated with H11 or served as the vehicle control (treated with PBS). Mice subcutaneously received 100 μg/kg/day of each cytokine in 100 μl sterile PBS (Sigma-Aldrich Co., St. Louis, MO). The injections were performed for seven consecutive days, starting the day after irradiation (the first day of the experiment).