Abstract: Objective  To study the molecular regulation mechanism of VEGF in the model of ATRA induced differentiation in HL-60 cells, and to provide new targets for leukemia anti-angiogenic therapy. Methods The morphology was observed by Wright-Gimesa staining; HL-60 cells differentiation was detected by NBT reduction experiment. VEGF,STAT3,c-myc mRNAs were measured by reverse transcription-PCR; VEGF,STAT3 and c-myc proteins were determined by Western blot. Results  The proliferation of HL-60 cells was inhibited obviously by ATRA(1 μmol/L) with the induction of differentiation, NBT positive rate was 82.59% (t =﹣24.157，P < 0.01); VEGF mRNA(t=7.339，P＜0.05), STAT3 mRNA (t =3.667，P＜0.05) and c-myc mRNA（t=6.858， P＜0.05） were all down-regulated. VEGF protein（t=3.386，P＜0.05）, STAT3 protein（t =4.074，P＜0.05）and c-myc protein （t =3.333，P＜0.05）were all down-regulated. Conclusion VEGF expression level is reduced with the procession of differentiation of HL-60 cells, which may be largely correlated with the down regulation of STAT3 and c-myc.

Key words: Tretinoin, Vascular endothelial growth factors, HL-60 cells