Roles of Cyclin D3 Expression in PMA-induced Human Leukemia Cells (HL-60) Apoptosis

Human promyelocytic leukemia HL-60 cells can be induced to apoptosis by treatment with phorbol myristate acetate. Phorbol myristate acetate (10nM) treatment arrests the cell cycle in the G1 phase and subsequently leads to apoptosis. Addition of phorbol myrisatate acetate stimulated protein kinase C translocation in 5 minutes and the maximum response was seen 30 minutes after the phorbol ester was added. Protein kinase C down regulation was observed within 24 hours after phorbol myristate acetate treatment. Cyclin D3 and D1 but not D2 expression was induced by phorbol myristate acetate. Expression of cyclin D1 was increased at 4 h, maximal at 8 to 16 h after phorbol myristate acetate addition and decreased thereafter. Cyclin D3 was expressed after protein kinase C was depleted, was maximal at 16 h, decreased at 24 h and had completely disappeared at 36 h after phorbol myristate acetate was added to HL-60 cells. Treatment of HL-60 cells with cyclin D3 antisense-DNA prior to phorbol myristate acetate addition abolished the growth inhibition seen in the control and sense-DNA groups. Cyclin D3 antisense-DNA prevented the HL-60 cell apoptosis but had no effect on phorbol myristate acetate-induced HL-60 cell differentiation. These data suggest that cyclin D3 expression is important in the regulation of cell cycle arrest and apoptosis but not the expression of differentiated phenotype.