Then, cell cultures were pretreated for 24 hours before XRT with 1 μM simvastatin alone, C225
alone (10 nM C225 for FaDu cells or 30 nM for A431 cells), or with the two drugs. Next, cell cultures were either irradiated (2 Gy) or subjected to mock irradiation in the presence or absence of the drugs. Colonies were stained with crystal violet. Clonogenic cell survival was calculated as the ratio between the number Selumetinib of colonies presented after irradiation and the number of cells plated, which was then normalized by the clonogenic efficiency of the untreated controls. Note that when XRT was applied, clonogenic cell survival was the survival after 2 Gy, which is the most useful clinical marker of intrinsic radiosensitivity. To generate tumor xenografts, 106 cells suspended in 100 μl of medium were injected into subcutaneous tissues on the right hind limb of 6- to 8-week-old female athymic Swiss nu/nu mice (Harlan, Gannat, Selleckchem Ruxolitinib France). Cells were injected on a Monday and left to grow for 7 days, moment when the treatments began. Tumor growth was measured—π/6 × (large diameter) × (small diameter)2—twice weekly. Mice were killed when the tumor volume reached 1200 mm3, when the mice showed moderate to severe toxicities, or when significant differences between groups were observed. All experimental procedures were approved by the Institutional Animal
Care and Ethics Committee. The mice received fractionated XRT, C225, and simvastatin. XRT was selectively delivered from Monday to Friday for 2 weeks using the 6-MV X-ray beams at doses of 20 to 30 Gy depending on type of experiment, in 10 fractions, 1 fraction each day. On the first day of treatment, C225 was intraperitoneally injected 6 hours before
irradiation at doses of 1 mg per animal to allow the antibody to have time to saturate the EGFR. Next, C225 was administered on days 3, 7, and 10 at doses of 0.5 mg per animal 2 hours (together with simvastatin or its vehicle) before irradiation as a maintenance C225 dose. Simvastatin (50 mg/kg) was administered orally on a daily basis for 12 days 2 hours before irradiation. Mice were randomly allocated to receive XRT plus C225 or XRT, C225, and simvastatin as well as to receive single treatments with XRT, C225, or simvastatin alone. In addition, a group N-acetylglucosamine-1-phosphate transferase of mice treated in parallel was killed on day 4 to obtain tumor samples for immunofluorescence. Semi-confluent cell cultures were pretreated for 48 hours with C225 and simvastatin in FBS-free medium and then irradiated with a single dose of 5 Gy. Twenty minutes after irradiation, cell cultures were rinsed in ice-cold phosphate-buffered saline (PBS) and lysed in radioimmunoprecipitation assay buffer with protease and phosphatase inhibitors. Vehicle and mock irradiation were provided as controls. Protein concentration in the lysates was determined by the Pierce BCA Protein Assay Kit (Thermo Scientific, Rockford, IL).