Assess The Genetic Damage And Study Dose-effect Manner By Hprt Gene Mutation And Comet Assay In Cervical Cancer Patients Undergoing Radiotherapy

Objective : To assess the genetic damage and study dose-effect manner by hprt gene mutation and comet assay in cervical cancer patients undergoing radiotherapy.Method : Blood samples were collected from fifteen cervical cancer patients exposed to radiation at the accumulated dose of 0,10,20,30,40,50,60 Gy . To study hprt gene mutation by multinucleated cell assay and study DNA damage by comet assay.Result : 1 . Mutation frequency of hprt gene increased after radiation . The mutation frequency increased significantly at dose 30Gy , 40Gy and 50Gy compared to OGy ( P<0.05 ) . At the accumulated dose of 40Gy , the hprt gene mutation frequency achieved the max value (the mean value>l X10"3). There was a significant increase according to OGy and other accumulated dose groups ( P<0.01 ) . At the accumulated dose of 60Gy , the mutation frequency was also higher than 0 Gy . But there was not statistic significant . The increase of hprt gene mutation frequency was linear from 0-40 Gy . There was a good dose-effect manner between mutation frequency of hprt gene and accumulated dose r=0.900 , ( P<0.05 ) . The linear regression analysis showed a linear dose- effect manner .The regression equation was Y=0.459+0.01353X , r=0.900 ( P<0.05 ).2 . In the comet assay , the comet frequency of all the accumulated dose groups increased significantly according to OGy ( P<0.01 ) . The increase of the comet frequency was linear from 0-60 Gy . At the accumulated dose of 60 Gy , the comet frequency achieved the max value . The linear regression analysis3showed a linear dose-effect manner . The regression equation was Y=12.133+0.230X , r=0.964 ( PO.05 ).3 . In the comet assay , the tail length showed significant increase at all the accumulated dose groups ( P<0.01 ) . At the accumulated dose of 30 Gy , the tail length achieved the max value . The tail length decreased a little , but kept a high level still after 30Gy . There was a significant increase compared to the control ( 0 Gy ). There is not dose-effect manner between the tail length and the accumulated dose.4 . Tow methods had some changes following the dose response ,but they showed different sensitivities , the sequences of correlation with dose from high to low is as follows : the comet frequency ( r=0.924 ) , hprt ( r=0.900 ) , the tail length ( r=0.444 ) . The comet frequency and the tail length showed significant increase when only receiving lOGy if compared with untreated time point ( P<0.01 ). HPRT frequency showed significant increase when receiving 30 Gy if compared with untreated time point.Conclusion : 1 . Mutation frequency of hprt gene increased after radiation . There was significant increase according to OGy ( P<0.05 ) . The increase of mutation frequency wss dose-dependent . At the accumulated dose of 40Gy , the hprt gene mutation frequency achieved the max value . The increase of the hprt gene mutation frequency was linear from 0-40 Gy . There was a good dose-effect manner between mutation frequency of hprt gene and accumulated dose . The linear regression analysis showed a linear dose- effect manner .2 . In the comet assay , the comet frequency of all the accumulated dose groups increased significantly according to 0 Gy ( P<0.01 ) . At the accumulated dose of 60Gy , the comet frequency achieved the max value .The increase of the comet frequency was linear and dose-dependent . There was a good dose-effect manner . The linear regression analysis showed a linear dose- effect manner .3 . In the comet assay , the tail length showed significant increase at all the accumulated dose groups ( P<0.01 ) . At the accumulated dose of 30Gy , the tail length achieved the max value . There was not dose-effect manner between the tail length and accumulated dose .4.To assess the radiation-induced damage by hprt gene mutation and comet assay has a high sensitivity . Cornet assay was more sensitive than Hprt gene mutation . There were good dose-effect manners . Hprt gene mutation and comet assay are valuable biodosimeters to assess the gen...