A methodological study on modified comet assay in predicting solid tumor radiosensitivity / 中华放射肿瘤学杂志

ABSTRACT

Objective To impmve the method of "modified comet assay" in predicting the radiosensitivitv of solid tumor. Methods A single cell suspension from biopsy sample was lmdlated on ice with a dose of 5 Gy.The microscope slide was spread with agarose,lysed for 50 minutes,rinsed 3 times rinse solution,and given electrophoresis for 20 minutes. After being stained with PI,cell images were collected through the microscope and analyzed with Lucia G software(Version 4.6).In order to check system/ background errors,every sample was made into control slide and irradiation slide.The end-points were cell DNA contents and tail moment. Results The factors influencing the results included(1)Sample was iaulty tor the biopsv taken from mucosa and no tumor cells were contained. (2)The slides with a high backgmund ( induced by necrosis) disturbed the measurement of comet assay. (3) Setting lymphocytes as control to check svstem errors was very important. (4)To separately collect images of the normal tissue cells and tumor cells from the biopsy sample improved the conformity between the clinical obscrvation and the lab result. Conclusions To increase the correlation between comet assay and clinical response,it is very helpful to set double control for checking system/background errors and to collect images of the normal tissue cells and tumor cells through the microscope,respectively.