Comparision Of Biological Effects Between Ultra-Microfractionated Radiotherapy And Conventional Radiotherapy On Glioma Cells

BackgroundGlioma is the most common malignant tumor in central nervous system, which is from40to60percent in intracranial tumour. Through the operation, radiotherapy, chemotherapyand molecular targeted therapy, The median survival for the patients was14months and theprognosis is poor. Radiotherapy is an important treatment for adjunct therapy after surgeryand patient who are inoperable. In order to protect brain organization, tolerance dose mustbe limited. So the efficacy of adjunct therapy after surgery is not significant, recurrence andlocal invasion are always out of control. The study showed that multiple tumor cells haveultra-microfractionated allergic phenomenon. So far, we adopt ultra-microfractionatedradiotherapy technology which based on ultra-microfractionated allergic reaction and SLDR.This method is to divide conventional fractionation into equal and inject at regular intervals.ObjectiveThe aim of this study is to explore the way of radiotherapy through comparing theeffect of ultra-microfractionated radiotherapy and conventional fractionation radiotherapyon GL261cell line.Methods1.Divided GL261cells in logarithmic growth phase into control group,ultra-microfractionated radiotherapy group and conventional radiotherapy group, with3bottles cells each group, radiated for3days. Exposed ultra-microfractionated group to0.6Gy,0.2Gy every3min; exposed conventional group to0.6Gy one time, in the first3daysafter the start of radiation, take one bottles cells from each group, the comet assay and flowcytometry were employed for detection of cell DNA damage, apoptosis and distribution ofcell cycle in control group.2. In glioma GL261cells, the DNA damage after the comet assay. 3. The survival rate of GL261after Annexin V-FITC.4. detected cell cycle after ultra-microfractionated radiotherapy and the conventionalradiotherapy.Results1. The comet assay showed that after the ultra-microfractionated radiotherapy and theconventional radiotherapy, DNA fragments increased along with days, the values cometTailLength and TailMoment were signficantly increaseing. The values of TailDNA%were0.441,0.791,0.21; TailLength were0.822,0.889,0.953; TailMoment were0.437,0.525,0.119, and they have no significant differences in diffferent time periods.2. Annexin V-FITC showed that ultra-microfractionated radiotherapy group’s survivalrates were72.1%,70.5%,51.3%on1stday,2nd,3rd. conventional radiotherapy group’ssurvival rates were80.8%,80.5%,70.0%, which was remarkably different from the former.3. The distributions of cell cycle of two groups in different time periods were notsignificantly different.Conclusions1. The damages of DNA after ultra-microfractionated radiotherapy and conventionalradiotherapy were not significantly different.2. the survival rates of cells after ultra-microfractionated radiotherapy andconventional radiotherapy were remarkably different.3. The distributions of cell cycle after ultra-microfractionated radiotherapy andconventional radiotherapy were not significantly different.