Objective This study was designed to explore whether Tanshinone ⅡA (TanⅡA) could induce HL-60 and K562 cells differentiation and to assay the telomerase ativities before and after the leukemia cell differentiation induced by TanⅡA and All-trans retinoid acid (ATRA). Methods HL-60 and K562 cells were cultured with TanⅡA at concentration of 0.5μg/ml for 5 days and 6 days respectively. The cell differentiations were observed by morphology and nitroblue tetrazodium (NBT) test. The telomerase activities before and after TanⅡA and ATRA treatment were measured by PCR-TRAP, using ATRA as positive control, 0.01% DMSO as negative control. Results The results showed that TanⅡA inhibited both HL-60 and K562 cell growth. On the 5th day of TanⅡA action, the inhibiting rate of HL-60 cell growth was 79.9%. Also, it induced the cells to differentiate to terminal cells. Acted by TanⅡA for 5 days, the HL-60 cells differentiation rate was 72%, NBT test was positive and showed that the leukemia cells were differentiated. On the 6th day of TanⅡA action, the K562 cells differentiate rate was 76%. The telomerase activities decreased markedly; the inhibiting rates of HL-60 (5 days) and K562 (6 days) were 30.8% and 50.8% respectively. Conclusion These results indicate that TanⅡA induces leukemia cells to differentiate, and with the induction of leukemia cell differentiation, the telomerase activities decrease obviously.
