Objective： To investigate the cell-cycle specificities of cytarabine and paclitaxel in different growing status of target cell. Methods： Using flow cytometry, we tested the cell-cycle specificities of cytarabine and paclitaxel on acute lymphocyte leukemia cell line Molt-4 in different growing status and on clinical acute lymphocyte leukemia specimens in vitro as well as in leukemia patients in vivo. Results： Cytarabine induced S phase specific cebcyde blockage and apoptosis in exponentially growing Molt-4, but showed G0/G1 phase specificity in high-density cultured Molt-4 and in clinical specimens. Paclitaxel induced G2/M phase specific cell-cycle blockage and apoptosis in exponential Molt-4, but showed G0/G1 phase specificity in high-density cultured Molt-4 and S phase specificity in clinical specimens. In the first day of clinical chemotherapy, cytarabine induced G0/G1 with a little S phase apoptosis in leukemia cells of acute lymphocyte leukemia patient in vivo. Cytarabine plus paclitaxel together had almost the same effect in the second day. Conclusion： The cell-cycle effects of cytarabine and paditaxel were different in different target cell growing status. It should be noted that the in vivo effect of these agents may be different from people usually anticipated during clinical chemotherapy. So the combined chemotherapeutic regimens may need to be redesigned.
Peng ZhangYi ZhouDeding TaoJianfeng ZhouJianping Gong
Objective： To analyze and discuss cell cycle＇s correlation of y-H2AX, so as to accumulate the data for the further studies of y-H2AX. Methods： MOLT-4 cells, and peripheral blood lymphocytes （PBLs）, with or without 48 h stimulation of phytohemagglutinin （PHA）, were irradiated by ultraviolet rays （UV rays）. Fluorescence-labeled y-H2AX antibody was used to detect γ-H2AX foci at the DNA double-strand breaks （DSBs） in chromatin, DNA damage was analyzed by flow cytometry, cell cycle and cell apoptosis were detected by sub-G1 peak method, the expression of γ-H2AX was detected by Western blot. Results： With the progression of time, sub-G1 peak emerged apparently in the DNA histograms, and the cells of apoptosis increased gradually; with the progression of time, the increase of γ-H2AX emerged and firstly raised, then decreased; PBLs with 48 h stimulation of PHA entered apparently cell cycle, cells of S and G2/M phase emerged, and PBLs without stimulation of PHA did not enter cell cycle; Western blot showed the increase of the expression of γ-H2AX, and the increase also firstly raised, then decreased. Conclusion： γ-H2AX expressed in the cells of stationary phase and proliferative phase, and with the progression of time, the increase of γ-H2AX firstly raised, and then decreased.
Yangping Yue Zhenchuang Zhu Dongdong Yu Yu Deng Dan Huang Xiaolan Li Wei Xiao Deding Tao Junbo Hu Jianping Gong
Objective： To investigate the apoptosis-inducing effect of Jinke on Molt-4 cells and its possible mechanism. Methods： The Molt-4 cells were treated with different concentrations of Jinke and then cultured for necessary time. The Annexin-V / PI method was used to detect the apoptosis rate. The cell cycle was analyzed by DNA content with flow cytometry. Double parameters analysis of cyclins / DNA was performed to detect the expression of cyclin E. API method was used to confirm the cell cycle-specific apoptosis. The expressions of Bcl-2 and Bax were detected by westem blot. Results： 24 h after the treatment of 0.5, 1.0, 1.5, 2.0 and 3.0 mg/mL Jinke, the apoptosis rate of Molt-4 cells was evaluated in a concentration-dependent manner, from 5.2% of the control group to 41.0% of the 3.0 mg/mL Jinke group. When the Molt-4 cells were cultured with 1.5 mg/mL Jinke, the apoptosis rate was evaluated in a time-dependent manner. DNA content analysis showed that G0/G1 phase of Molt-4 cells increased in a time-dependent manner. The expression of cyclin E increased gradually. API assay showed the apoptosis cells were almost in G0/G1 phase. Western blot showed the Bcl-2 was down-regulated and the Bax was up-regulated. Conclusion： Jinke could induce G1 phase-specific apoptosis in Molt-4 cells in time-and concentration-dependent manners involving G1 phase arrest. The mechanism of apoptosis inducing effect may be related to the upregulation of Bax and the down-regulation of Bcl-2.
Zhenchuang Zhu Yixin Tong Yangping Yue Yu Deng Dongdong Yu Wei Xiao Xiaolan Li Deding Tao Junbo Hu Jianping Gong
Objective： We investigated the influence of CDK1 and CDK2 expression inhibited by cotransfection of CDK1 and CDK2 siRNA on cell cycle and apoptosis, explored the exact role of cell cycle master regulator in tumor cell apoptosis process. Methods： The siRNA targeting the CDK1 and CDK2 genes were synthesized and simultaneously cotransfected into Hela cells by lipofectamine 2000.48 or 60 h after the cotransfection, CDK1 and CDK2 protein expressions were examined by Western blot. Cell cycle distribution was analyzed by flow cytometry. Cell apoptosis was detected by the Annexin V/PI method. The changes of the transfected cell morphological under a microscope after Wright-Giemsa Staining were studied. Results： CDK1 and CDK2 protein expression was decreased at 48 or 60 h after cotransfection. The accumulation of the G2/M and S phase population in cell cycle of the cotransfected cells at 48 or 60 h after transfection was enhanced obviously compared with control. The ratio of apoptotic cell of cotransfected cells at 48 or 60 h after transfection was increased significantly compared with control. More binucleate or multinucleate ceJls among cotransfected cells were observed under the microscope. Conclusion： The decreased expression of CDK1 and CDK2 by cotransfection of CDK1 and CDK2 siRNA not only leads to tumor cell cycle arrest in S phase and G2/M phase, but also induces tumor cell apoptosis.
Hui Xiao Wanjun Gong Jingpeng Cao Xiaolan Li Deding Tao Junbo Hu Jianping Gong
