Objective To detect the synergetic effect and mechanism of arsenic trioxide(As2O3)and Trichostatin A(TSA)during inducing apoptosis of HL-60 cells.Methods MTT method was used to test the proliferation of HL-60 cells.Cell cycle and apoptosis were detected by FCM.Semi-quantitative RT-PCR was used to detect the mRNA expression of Bax and Bcl-2 in the cells treated by As2O3 and(or)TSA.Results As2O3 combined with TSA could inhibit proliferation and induce cell cycle arrest at G0 and G1.The percent of apoptosis induced by combination of As2O3 and TSA was obviously higher than that of either As2O3 or TSA.Bax gene expression was increased,while Bcl-2 gene expression was decreased,Bax/Bel-2 ratio was up-regulated.Conclusion Synergetic effect by As2O3 and TSA is remarkable in inducing apoptosis of HL-60 cells.Cell cycte arrest and Bax/Bcl-2 ratio play an important role in apoptosis of HL-60 cells induced by As2O3,TSA or their combination.

Objective To study the molecular mechanism of different sensitivities to apoptosis induced by low concentration of As2O3 in PML-RARα negative HL-60 cells and PML-RARα positive NB4 cells. Meth-ods NB4 and HL-60 cells were cultured with As2O3 for 1 to 4 days; cell proliferation were detected by MTT method; the apoptosis was detected by flow cytometry,Bcl-2,Bax and Fas mRNA were determined by RT-PCR. Results The proliferation of NB4 cells was inhibited obviously by As2O3(1.0 μmol/L)with the induction of apoptosis( P <0.05) ,which was accompanied by the down-regulation of Bcl-2 mRNA expression( P <0.05)and the ratio of Bcl-2/Bax(P <0.05), but there was no obvious variation of Bax and Fas expression( P >0.05). Inhibition of proliferation and apoptosis were not obvious in PML-RARα negative HL-60 cells induced by low concentration As2O3 ( P >0.05), and there was no obvious variation of Bcl-2, Bax, Fas mRNA expres-sion or Bcl/Bax ratio( P >0.05). Conclusion The ratio of Bcl-2/Bax is contributed to the different sensitiv-ities of PML-RARα negative HL-60 cells and positive NB4 cells induced by low concentration of As2O3.

Objective To investigate the reversal effect of the monomer of traditional Chinese medicine on muhidrug resistance(MDR) and its possible mechanism in K562/ADM cell line in vitro. Methods With different concentrations of baicalin, geniposide administered to K562/ADM cells, the proliferation of K562/ ADM cells was detected by the MTY assay. Expression of mdr-1 mRNA, Topo Ⅱ mRNA was measured by semi-quantitive RT-PCR. Results Thatbaicalin and geniposide could increase the sensitivity of K562/ADM cells to adriamycin, multiples of reversion were 1.95 times and 1.46 times. The proliferation of K562/ADM cells was in-hibited obviously by baicalin and geniposide, the level of mdr-1 mRNA expression was down-regulated and the Topo Ⅱ mRNA was up-regulated(P<0.01 ). Conclusion Baicalin and geniposide may reverse the multi-drag-resistance of K562/ADM cells, which was related to the down-regulation of mdr-1 expression and up-reg-ulation of Topo Ⅱ beta expression.

Objective To explore molecular mechanism of expression of vascular endothelial growth factor (VEGF) mRNA and secretion of VEGF protein in HL-60 cells induced by all-trans refinoic acid (ATRA). Methods MTr method was used to detect the proliferation of HL-60 cells induced by ATRA,cell cycle and CD11b expression in HL-60 cells were detected by flow cytometry. Expression of VEGF, c-myc, by-poxia-inducible factor(HIF)-lα, matrix metalloproteinase (MMP)-9 and MMP-2 mRNA were detected by semi-quantitative RT-PCR. VEGF protein in HL-60 cells culture supernatant was measured by ELISA before and after being induced by ATRA. Results After treatment with ATRA,the proliferation of HL-60 cells was obviously inhibited, CD11b expression increased, trend of granulocyte directional differentiation emerged, and differentiation degree was increasd(P <0. 05) ;expression level of c-my and VEGF mRNA was down-regulated (P < 0. 05), but expression level of HIF-1α mRNA was up-regulated (P < 0. 05). VEGF protein level in HL-60 cells culture supernatant was decreased by blocking the expression of MMP-9 or MMP-2(P <0. 05).Conclusion VEGF expression has positive correlation with c-myc expression,but has negative correlation with HIF-1α expression. MMP-9 and MMP-2 may be the main factors regulating VEGF secretion in HL-60 cells.