Influence of VLA-4 antibody combined with VP_(16) upon childhood leukemic cells' apoptosis / 白血病·淋巴瘤

ABSTRACT

Objective To investigate the influence of very late antigen-4 (VLA-4) antibody and VLA-4 antibody combined with VP_(16) in vitro on childhood leukemic cells' apoptosis and explore the protection of bone marrow stromal cells (BMSC) upon leukemic cells and its related mechanisms. Methods Leukemic bone marrow stromal cells were isolated by human lymphocyte separation medium and in vitro culture of BMSC (adherent) and leukemia cells (suspended) BMSC+leukemic cells group were as control. Then VLA-4 antibody and/or VP_(16) were added respectively to VLA-4 antibody group, VP_(16) group and VLA-4 antibody combined with VP_(16) group to detect the apoptosis of leukemic cells in different groups through Annexin V-FITC double-labeled flow cytometry and the expression of Survivin, bcl-2 genes in each group of leukemic cells detected by RT-PCR. Results The results showed by flow cytometry that compared with the control groups, for 12 h or 24 h, the early and total apoptosis rates of leukemic cells of the three experimental groups were significantly increased(P <0.05); the early and total apoptosis rates of leukemic cells treated with VLA-4 antibody combined with VP_(16) group was markedly increased, compared with the control group (P <0.05); the comparison of the early and total apoptosis rates for the three experimental groups between 12 h and 24 h was significantly different (P<0.01). Moreover, RT-PCR results showed that the expression of Survivin and bcl-2 genes of leukemic cells in three experimental groups was reduced in varying degrees and the reduction of VLA-4 antibody combined with VP_(16) group was the most obvious. Conclusion BMSC plays a protective role on leukemic cells, and VLA-4 antibody can block the adhesion between BMSC and leukemic cells promoting leukemic cells apoptosis and enhance the sensibility of apoptosis of leukemic cells induced by chemotherapeutics.