The medium selleck was replaced with a fresh one 24 hours after irradiation. Colonies were fixed and stained with 0.5% crystal violet,
and the number of colonies containing at least 50 cells, as examined by microscopy, was recorded 3 to 7 days later. In each irradiation dose group, surviving fraction (SF) of cells was calculated as plating efficiency of the irradiated cells divided by the plating efficiency of untreated samples. Apoptosis analyzed by flow cytometry After 48 hours exposed to 4 Gy radiation, Hep-2 cells were harvested, and centrifuged at 1500 rpm for 2 min. Then cells were washed with PBS twice, and fixed in ice-cold 70% ethanol at 4°C overnight. After rinsing 1 × 105-1 × 106 cells with 1× Binding Buffer, the cells were reharvested and resuspended in 200 μl of 1× Binding Buffer. 5 μl of Annexin V and 10 μl of Propidium Iodide (PI) were added in cells incubating at room temperature for 15 min in the dark. Cell apoptotic rate were analyzed by flow cytometry (Elite ESP, BeckmanCoulter, USA). Animal experiment Female BALB/c-nu/nu mice were used to investigate the effect of ATM AS-ODNs on radio-induced apoptosis of Hep-2 cells solid ZD1839 tumor. All surgical procedures and care administered to the animals were in accordance with institutional guidelines. Animal surgeries and radiotherapy were performed under general anesthesia, 50 mg/kg ip
injection of pentobarbital sodium. About 1 × 105 Hep-2 cells were subcutaneously inoculated in submental space of the mice. Tumor growth rates were determined by measuring two orthogonal dimensional diameters of each tumor thrice a week. Tumor volumes were calculated according to the formula V = π/6 × a2 × b, where a is the short axis, and b the long axis. When tumors reached an average volume of about 200 mm3, the tumor-bearing BALB/c-nu/nu mice were divided into four groups assigned 8 nude mice in each group: Protein Tyrosine Kinase inhibitor (a) control group, no treatment; (b) ATM AS-ODNs group, tumors were treated
with ATM AS-ODNs alone but not exposed to irradiation for each time; (c) irradiation group, tumors were exposed to X-ray of 2 Gy alone for each time; and (d) combination group, 2.5 mg/kg of ATM AS-ODNs was injected into the solid tumor the day find more before X-ray exposure, another dosage of ATM AS-ODNs was injected right before exposure to 2 Gy of X-ray for each time. The same treatment for each group was repeated 3 times (the interval time was 5 days). BALB/c-nu/nu mice were killed 3 weeks later. The ATM protein expression of the tumor in the different groups was analyzed by western blot using the procedures described as above. The tumor inhibition rate was calculated using the following formula: (1-average tumor volume of experimental group/average tumor volume of control group) ×100%.