ABSTRACT
AIM:To investigate the mechanism of the radiosensitizing effect of maximum non-cytotoxic doses of tetrandrine (Tet) on nasopharyngeal carcinoma cell lines CNE1 and CNE2.METHODS:The cells were treated with maximum non-cytotoxic doses of Tet (for CNE1 cells at 1.5 μmol/L and for CNE2 cells at 1.8 μmol/L),irradiation at 4 Gy,or combination of irradiation and maximum non-cytotoxic doses of Tet.The cell cycle distribution was analyzed by flow cytometry.The protein levels of γ-H2AX,cleaved caspase-3,p-CDC25C,CDK1,p-CDK1,cyclin B1,ERK and p-ERK were determined by Western blot.RESULTS:The expression of γ-H2AX was increased in CNE1 cells and CNE2 cells after combined treatment with irradiation and maximum non-cytotoxic doses of Tet.The percentages of CNE1 cells and CNE2 cells at G2/M phase in irradiation group were (18.09 ±0.42)％ and (18.48 ± 1.32)％,respectively,which were decreased to (15.88 ± 1.04) ％ and (13.80 ± 0.82) ％ in combined treatment group,respectively (P ＜ 0.05).Combined treatment enhanced the increase in the protein level of cleaved caspase-3 caused by irradiation.The protein levels of pCDC25C and p-CDK1 were increased in a dose-dependent manner by Tet treatment (P ＜ 0.05),while the expression of CDK1 showed no difference among different doses of Tet treatments.The protein levels of p-CDC25C,p-CDK1 and CDK1 showed no difference after the treatment with maximum non-cytotoxic doses of Tet.The combined treatment with irradiation and the maximum non-cytotoxic doses of Tet decreased the protein levels of p-CDC25C and p-CDK1 (P ＜0.05),increased the expression of cyclin B1,and had no influence on the expression of CDK1 （ P ＜0.05).The combined treatment resulted in an increase in the protein level of p-ERK1 (P ＜ 0.05).CONCLUSION:The maximum non-cytotoxic doses of Tet enhance the DNA damage and apoptosis in CNE1 cells and CNE2 cells caused by irradiation,and the mechanism might be associated with ending of G2/M arrest via activation of ERK/CDC25C/CDK1/cyclin B1 pathways.
ABSTRACT
In vitro method as indispensable biological research and testing tools, has been widely used in cosmetics compliance test, biological mechanism research and functional materials screening. These methods include alternative methods which have been accepted by reguations and standardized test guide, non-testing method used for risk assessment and prediction, and a lot more diversification and individualization of in vitro methods. With the consensus formation of the whole industry and increase of application experience, innovation and optimization in vitro method will be constantly emerge. These technologies will be beneficial to improve competitiveness and to develop products to meet the needs of consumers.
ABSTRACT
AIM:To investigate the mechanism of the radiosensitizing effect of maximum non-cytotoxic doses of tetrandrine (Tet) on nasopharyngeal carcinoma cell lines CNE1 and CNE2.METHODS:The cells were treated with maximum non-cytotoxic doses of Tet (for CNE1 cells at 1.5 μmol/L and for CNE2 cells at 1.8 μmol/L),irradiation at 4 Gy,or combination of irradiation and maximum non-cytotoxic doses of Tet.The cell cycle distribution was analyzed by flow cytometry.The protein levels of γ-H2AX,cleaved caspase-3,p-CDC25C,CDK1,p-CDK1,cyclin B1,ERK and p-ERK were determined by Western blot.RESULTS:The expression of γ-H2AX was increased in CNE1 cells and CNE2 cells after combined treatment with irradiation and maximum non-cytotoxic doses of Tet.The percentages of CNE1 cells and CNE2 cells at G2/M phase in irradiation group were (18.09 ±0.42)％ and (18.48 ± 1.32)％,respectively,which were decreased to (15.88 ± 1.04) ％ and (13.80 ± 0.82) ％ in combined treatment group,respectively (P ＜ 0.05).Combined treatment enhanced the increase in the protein level of cleaved caspase-3 caused by irradiation.The protein levels of pCDC25C and p-CDK1 were increased in a dose-dependent manner by Tet treatment (P ＜ 0.05),while the expression of CDK1 showed no difference among different doses of Tet treatments.The protein levels of p-CDC25C,p-CDK1 and CDK1 showed no difference after the treatment with maximum non-cytotoxic doses of Tet.The combined treatment with irradiation and the maximum non-cytotoxic doses of Tet decreased the protein levels of p-CDC25C and p-CDK1 (P ＜0.05),increased the expression of cyclin B1,and had no influence on the expression of CDK1 （ P ＜0.05).The combined treatment resulted in an increase in the protein level of p-ERK1 (P ＜ 0.05).CONCLUSION:The maximum non-cytotoxic doses of Tet enhance the DNA damage and apoptosis in CNE1 cells and CNE2 cells caused by irradiation,and the mechanism might be associated with ending of G2/M arrest via activation of ERK/CDC25C/CDK1/cyclin B1 pathways.
ABSTRACT
In vitro method as indispensable biological research and testing tools, has been widely used in cosmetics compliance test, biological mechanism research and functional materials screening. These methods include alternative methods which have been accepted by reguations and standardized test guide, non-testing method used for risk assessment and prediction, and a lot more diversification and individualization of in vitro methods. With the consensus formation of the whole industry and increase of application experience, innovation and optimization in vitro method will be constantly emerge. These technologies will be beneficial to improve competitiveness and to develop products to meet the needs of consumers.