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Aim To investigate the effects of diallyl di-sulfide( DADS) on G2/M arrest in Chk1/MGC803 and Chk2/MGC803 cells so as to establish stable human gastric cancer MGC803 cells with overexpression of Chk1/2 gene. Methods The colony formation, flow cytometry, RT-PCR and Western blot were used to de-tect the proliferation, cell cycle, and expression of Chk1/2 mRNA and protein, p-Chk1/2, CDC25C and cyclinB1, respectively. Results The colony formation showed that the colony forming efficiency in Chk1/MGC803 and Chk2/MGC803 cells treated by 30 mg· L-1 DADS was lower than in control group and vector group ( P <0. 05 ) . Flow cytometry demonstrated that 41. 3%, 57. 4%, 68. 9% and 42. 9% of G2/M cells in Chk1/MGC803 were increased than in MGC803 and Chk2/MGC803 , respectively after treated by DADS in 12,24, 36 and 48 h(P <0. 05). At the same time, RT-PCR disclosed that expression of Chk1 and Chk2 mRNA had no marked change. Western blot showed that total proteins of Chk1 and Chk2 and p-Chk2 had invisible change, but expression of p-Chk1 was up-reg-ulated, and CDC25C and cyclinB1 were down-regula-ted time-dependently in Chk1/MGC803 cells ( P <0. 05 ) . Conclusion DADS arrests MGC803 cells at G2/M by increasing p-Chk1 expression to cause down-regulation of CDC25C and cyclinB1 simultaneously.
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Objective To investigate influence of cisplatin (DDP) on the tumor inhibition rate,transcriptional levels of CyclinB1 and CyclinD1 of CNE-1 xenograft in nude mice.Methods Tumor mode of nude mice CNE-1 xenograft was established.Then mice were divided into control arm,DDP arm,high speed irradiation arm,simulated intensity modulated radiation therapy (IMRT) arm and simulated IMRT + DDP arm,with 12 mice in each arm.Irradiation dose was 20 Gy with a single fraction.DDP was 15 μg/g weight.The maximum diameter of tumor base was measured every other day.The growth curve was drawn and tumor inhibition rate werevcalculated after 40 days.The transcriptional level of CyclinB1 and CyclinD1 of xenograft was measured by RT-PCR.The results of different groups were compared with one-factor analysis of variance.Results Tumor inhibition rates of the control arm,DDP arm,high speed irradiation arm,simulated IMRT arm and simulated IMRT + DDP arm were-129.1％,-71.2％,42.5％,35.3％ and 47.1％,respectively.There was significant difference between the high speed irradiation arm and simulated IMRT arm (P =0.034),but not between the high speed irradiation arm and simulated IMRT + DDP arm (P =0.222).The transcriptional levels of CyclinB1 in the arms were 0.429,0.386,0.322,0.354 and 0.268.There were significant differences between the high speed irradiation arm and the simulated IMRT arm or the simulated IMRT + DDP arm (P =0.007 and 0.000).The transcriptional levels of CyclinD1 in the arms were 0.716,0.583,0.348,0.495 and 0.296,respectively.There was significant difference between the acute irradiation arm and the simulated IMRT arm (P =0.000),but there was no significant difference between the high speed irradiation arm and the simulated IMRT + DDP arm (P =0.072).Conclusions Irradiation of 20 Gy single fraction,or combined with DDP are effective on the CNE-1 xenograft in nude mice,but DDP alone can only lower the tumor growth speed.Irradiation of 20 Gy single fraction,or combined with DDP,or DDP alone can reduce the transcriptional levels of CyclinB1 and CyclinD1.As the single therapeutic time is prolonged in IMRT mode,the tumor inhibition rate is reduce,and the reduce of the transcriptional levels of CyclinB1 and CyclinD1 is depressed,while combined DDP can compensate the decline of the biological effect.
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Objective: To investigate the effect of oridonin on G2/M phase arrest of human stomach cancer SGC-7901 cell growth in vitro and its molecular mechanism. Methods: The inhibition of oridonin on SGC-7901 cells was detected by MTT assay. Effect of oridonin on the phase distribution of SGC-7901 cell cycle was observed by flow cytometry (FCM). Western blotting was used to analyze the expression of Cdk1 and CyclinB1. Results: IC50 of oridonin on SGC-7901 cells was 15. 64 μmol/L. The effect of oridonin on SGC-7901 cells presented the increasing percentages of cells in G2/M phase as the concentration of oridonin increased. With the increase of oridonin dose, the expression of Cdk1 and CyclinB1 proteins was remarkably decreased. Conclusion: Oridonin can down-regulate the expression of Cdk1 and CyclinB1, which may be the mechanism of arresting SGC-7901 cells in G2/M phase.