Objective To observe the cell proliferation inhibition of DNA methyltransferase (DNMT) inhibitors decitabine (DAC) combined with daunorubicin (DNR) in human leukemia cell line HL-60.Methods The effects of DNR and DAC were examined in HL-60 cells by cell viability using MTT method,and cell death using flow cytometric (FCM).Results DAC,DNR single drug application showed their effects on cell proliferation was dependent of dose and time,the inhibition effect of combined treatment group was much clearer [inhibition ratio of 72 hours was (80.23±1.71) ％,P ＜ 0.001].The highest apoptosis rate was at 5.0 μmol/L DAC combined with 1.0 μmol/L DNR for 72 hours,which was statistic significant (F =30.199,P ＜ 0.001).Combinations of different concentrations of DAC and DNR increased expression of PTEN mRNA in concentration-dependent manner,which was significantly higher than the control group and DNR single drug group (F =578.218,P ＜ 0.001).Conclusions DAC can significantly inhibit the proliferation of HL-60 cells and induce apoptosis,synergistic effect can be observed when DAC combined with DNR.The underlying mechanism can be due to DAC demethylation effect to increase PTEN mRNA expression.

[Objective] To detect the expression levels of connexin43(Cx43),P-gp and COX-2 in bone marrow of patients with acute leukemia (AL),and investigate their relationship with the pathogenesis,prognosis and resistance of this condition.[Methods]Using SYBR green real-time quantitativereverse transcription polymerase chain reaction (SYBR-RT-PCR),the expression of Cx43,P-gp and COX-2 mRNA were detected in 77 AL patients at different phases,including 36 initially-treated,20 complete-remission (CR)and 20 relapsed.A follow-up was done in those initially lreated.[Results]Expression levels of Cx43,P-gp and COX-2 mRNA from initially-treated were 0.52±0.57,1.42 ±1.06,1.14±0.95;those from relapse AL patients were 0.20±0.40,2.29 ±1.11,1.69±0.81,respectively,those from CR patients were 0.95±0.37,0.93±-0.73,0.79±0.58,respectively,those from normal patients were 1.16 ±0.67,0.86±0.63,0.61±0.57.Expression levels of Cx43 mRNA in initially-treated and relapse AL patients were significantly lower than those in normal patients and CR patients(initially-treated P were 0.001,0.005;relapse patients were P＜0.001),while the comparison between normal patients and CR patients showed no statistical significance(P=0.185).Cx43mRNA expression level was negatively correlated with P-gp and COX-2 mRNA,and a negative correlation was noted of both two expressions in initially-treated and relapse groups (Cx43 mRNA and P-gp mRNA r were -0.471,-0.362,-0.526;Cx43 mRNA and COX-2 mRNA r were -0.479,-0.344,-0.471).A follow-up of four months was conducted in 36 initially-treated patients,eight of them died.The expression Cx43 in those who died was lower than that who survived.The difference was significant(t=2.16,P=0.042).[Conclusion] Cx43mRNA expression levels of initially-treated and relapse AL patients were lower than those in normal patients and CR patients,P-gp and COX-2 mRNA expression levels of initially-treated and relapse AL patients were higher than those in normal patients and CR patients.Cx43 expre-ssion probably is a favorable prognostic factor.Cx43 is participation in the genesis,development and drug resistance of AL.