Biological Basic Research Of High-dose Radiotherapy On Different Interval

Objects:To compare the effects of same high doses of X-irradiation on human lung cancer cell lines Anip973 at different time intervals,and the effect of same high doses of X-irradiation on lung cancer cells apoptosis from the cell and nude mice model levels,in order to reveal biological mechanism of this radiotherapy mode.Methods:(1)To culture and build the lung adenocarcinoma cell line Anip973 in vitro, Anip973 were irradiated with 6MV-X-ray at 20 Gy in one fraction at different time intervals of 24,72,168 hours.Light microscope and electron microscope were used to observe cell morphologic 24 hours after X ray irradiation;flow cytometry were used to detect the cells apoptosis;comet assay were used to test the DNA damage.(2) Inoculated subcutaneous tissue of nude mouse with human lung cancer cell lines Anip973,in order to build modle of transplantable tumor.Group randomly when the diameter of transplanted tumors were up to 10 millimetres.Nude mouse were irradiated with X-ray at 20 Gy in one fraction at different time intervals of 24,72,168 hours under the state of conscious.Keep on breeding nude mouse after irradiating. Observe the changes of tumor volume,draw tumor growth curve and calculate tumor growth delay time.Results:1,Light microscope observation:Compared to the control group,Anip973 cells in all groups showed changes in morphology after X ray irradiation,cell's volume was enlarged,and cell differentiation appeared obviously.2,Electron microscope observation:Compared to the control group,Anip973 cells in all groups showed changes in morphology after X ray irradiation,cell swelling,cell membrane injury,organelle expansion,rough endoplasmic reticulum degranulation, mitochondria swelling,mitochondrial cristae were short and small,which in the typical state of cell apoptosis.The intact cell structure was fewer as the intervals of time goes by.3,Cells apoptosis were detected by flow cytometry:Cell apoptosis and cell survival rate of 168 hours groups were decreased significantly contrast with 24 and 72 hours group.Cell death was mianly oncosis. 4,COMET assay:The index of tail DNA percentage,tail length,tail moment,Olive tail moment of Anip973 cells positively correlated with interval time.With the interval time prolonged,tail DNA percentage was highly rising,DNA fragment defement length was significant increase.5,Observe tumor growth:All groups had good biological effect after X ray irradiating,the effect of the skin of animal tumor mass give priority to wet skin reaction,which had yellow exudate.The tumor inhibition rate and tumor growth delay in 168h group were significantly higher than 24h and 72h groups,there was no statistical significance between the 24h and 72h groups.