Abstract: Objective To explore the effects of lentivirus-mediated RNA interference targeting HOXA10 gene combined with VCR on the proliferation and apoptosis of U937 cell line in vitro and in vivo. Methods U937 cells were divided into interference (lenti-shHOXA10,KD)group, negative control (lenti-NC,NC) group and blank control (BC)group.The infection efficiency of lentivirus for U937 was detected by flow cytometry,and HOXA10 gene expression of U937 cells at protein level was detected by Western blot. IC50 was determined by MTT assay.The apoptosis rates of KD,NC and BC group were detected by flow cytometry.The NC and KD group's GFP-positive cells were sorted by flow cytometry and then U937 xenografts were established by subcutaneous injection of U937 cells (viability>90%) into the flanks of nude mice.Tumor inhibition rate of KD group were calculated after VCR injection for four times. Results The ratio of GFP positive cells was up to 90%,and protein levels of HOXA10 in KD group decreased by 89.78% compared with the control group.Down-regulation of HOXA10 could reduce the IC₅₀ and improve the VCR-induced apoptosis rate of U937 cells.Compared to NC and BC group the differences were significant (P<0.05).In vivo tumor growth was inhibited in interference group mice. Conclusion Lentivirus vector-mediated RNA interference-targeted HOXA10 gene could enhance the sensitivity of U937 cells to VCR in vitro and in vivo.