PIG7 and valproic acid promote differentiation and apoptosis of human leukemia SKNO-1 cells

AIM: To investigate the synergistic effect of p53-inducible gene 7 (PIG7) and histone deacetylase (HDAC) inhibitor valproic acid (VPA) on the differentiation and apoptosis of human leukemia SKNO-1 cells.METHODS: The DNA fragments containing PIG7 open reading frame or antisense oligonucleotides were subcloned into lentiviral vector. SKNO-1 cells were transduced with prepared lentivirus. Transgene expression was detected by semi-quantitative RT-PCR and Western blotting. The expression of myeloid cell differentiation antigen CD11b and the apoptotic cells were analyzed by flow cytometry. DNA fragmentation analysis was also used to observe the apoptosis of SKNO-1 cells.RESULTS: VPA inhibited the proliferation of SKNO-1 cells in a dose-　and time-dependent manner. Compared with control group, the differentiation and apoptosis of SKNO-1 cells were significantly induced by ectopically expressed PIG7 (P<0.05). The apoptosis induced by ectopically expressed PIG7 was further enhanced by VPA treatment (P<0.05), and the typical DNA ladders were also observed. The proportion of CD11b+ SKNO-1 cells notably increased after infection with lentivirus containing PIG7 as compared with empty vector group (P<0.05). Up-regulation of PIG7 also enhanced the susceptibility of the cells to the induction of differentiation by VPA.CONCLUSION: VPA inhibits the proliferation and induces the differentiation and apoptosis of SKNO-1 cells. Enforced expression of PIG7 enhances the differentiation and apoptosis of SKNO-1 cells and promotes the sensitivity of SKNO-1 cells to VPA. Over-expression of PIG7 combined with VPA may provide a new strategy for treatment of leukemia.