Objective To explore the effect and its mechanism of tetramethylpyrazine （TMP） alone or combined with arsenic trioxide （As2O3） on the proliferation of cell line HL-60 in human promyelocytic leukemia （APL）. Methods The cell line HL-60 and ECV-304 were adopted and randomized into the blank group

TMP group

As2O3 group and TMP combined with As2O3 group. Four wells were established in each group. Methylthiazolyldiphenyl-tetrazolium bromide （MTT） was used to detect the proliferation of cell line HL-60. The expression of vascular endothelial growth factor （VEGF） mRNA was detected as well. Trypan blue staining method was used to draw the growth curve of cell line ECV-304. The early apoptosis rate of cell line ECV-304 was detected by flow cytometry. The adhesion degree of cell line ECV-304 was observed by inverted microscope. Results TMP could inhibit the proliferation of cell line HL-60 and ECV-304 and strengthen the effect of As2O3. The expression of VEGF mRNA and protein was significantly decreased after the combined treatment. Both TMP and As2O3 could induce the early apoptosis of cell line ECV-304 and reduce the ability of cell adhesion

and the combined treatment could strengthen the effect. Conclusion The combination of TMP and As2O3 has a synergistic effect on inhibiting cell proliferation. It is initially confirmed that anti-angiogenesis is the therapeutic mechanism for APL.