The effects of fractionation ~(60)Co gamma ray to the cell cycle kinetics of nasopharygeal carcinoma cell line CNE-2

Purpose:To study the effects of high-dose ()~(60)Co gamma ray to the cell cycles and cell cyclin D1,B1 and cyclin dependent kinase(CDK)1,4 of nasopharygeal carcinoma cell line CNE-2. Observe consecutively the mechanism of the action of high-dose gamma ray on cell cycle progress, in order So as to provide basic material for hypofractionated radiotherapy schedule for tumors.Methods:Propidium Iodide(PI) simple staining and flow cytometry(FC) were used to detect the cell cycle. The expression of cyclin D1、cyclinB1、CDK4 and CDK1 mRNA were detected by combining RT-PCR with semi-quantitative analysis.Results:Apparent G_(2)M phase arrest was observed first after CNE-2 cells were exposed to 4.0～8.0Gy fractionated radiation with gamma rays. G_(1) phase arrest was enhanced with increasing absorbed dose. Then all cell phase were arrested, but the dose-dependent relation was not obvious. The expression of cyclin D1、cyclin B1 mRNA was suppressed after CNE-2 cells were exposed to 4.0～8.0Gy gamma rays(P0.05). There was no significant difference between the expression of CDK4 mRNA and the control group(P0.05). But the CDK1 mRNA was not expressed in any of the irradiated groups.Conclusions:G_(1) phase, S phase and G_(2)M phase arrest were observed in CNE-2 cells exposed to 4.0～8.0Gy fractionated radiation in gamma rays. But the dose-dependent relation was not obvious. The main effects were that the cyclin D1 activity suppression lead to G_(1) phase arrest ,and G_(2)M arrest was correlated to the cyclin B1/CDK1 activity after 4.0～8.0 Gy gamma rays.[