冈田酸促进ATRA诱导NB4细胞的分化及增殖抑制

OKA augmented all-trans retinoic acid-induced proliferation inhibition and differentiation in NB4 leukemia cells by inhibiting serine/threonine protein phosphatase 2A

目的:研究蛋白磷酸酶抑制剂冈田酸(Okadaic acid,OKA)对全反式维甲酸(ATRA)诱导NB4细胞分化及增殖抑制作用的影响。方法:选用ATRA、OKA、ATRA+OKA分别作用于NB4细胞,采用MTT法测定细胞增殖率,瑞氏染色法和NBT还原实验观察细胞形态的变化,流式细胞仪分析细胞表面CD11b的表达,丝/苏氨酸磷酸化酶试剂盒检测细胞内PP2A活性。结果:(1)MTT结果显示,OKA对NB4细胞增殖的抑制作用不明显;ATRA、ATRA+OKA作用7天,对NB4细胞的增殖抑制率分别为25.1%、38.4%,ATRA+OKA组与其他两组相比差异具有统计学意义(P<0.05)。(2)细胞形态学、NBT及流式细胞仪结果显示,加入OKA能促进ATRA诱导的NB4细胞分化。(3)酶活性分析显示,ATRA诱导的NB4细胞分化过程中,PP2A活性较对照组明显下降,ATRA+OKA作用后PP2A活性下降更加明显。结论:OKA促进ATRA诱导的NB4细胞增殖抑制作用,可能通过抑制PP2A活性参与细胞分化过程。

Objective： To study the influence of Okadaic acid on proliferation inhibition and differentiation of NB4 leukemia cells induced by all-trans retinoic acid, and then to evaluate the role of PP2A during the process. Methods： ATRA, OKA and the combination of the two at the same doses as in the single-agent treatments were incubated with NB4. The proliferation of cells was measured by MTT method. Wright＇s staining and NBT reduction test were employed to evaluate the change of cell phenotype. The expression of CD11b was measured by flow cytometer. The activity of PP2A was evaluated by Serine/Threonine phosphatase assay system. Results： （1）MTT showed the growth inhibitory rates of ATRA, OKA and the combination of the two to NB4 for 7 days were 25.1%, 3.34% and 38.4%respectively.（2）Wright＇s staining, NBT reduction test and flow cytometer results showed OKA can augment the differentiation of NB4 induced by ATRA. （3）Phosphatase assay showed a decrease in PP2A phosphatase activity in NB4 after ATRA treatment. OKA augmented the inhibitory effect of ATRA on the activity in NB4. Conclusion： Serine/threonine protein phosphatase inhibitors OKA could increase the proliferation inhibition and differentiation of NB4 cells induced by all-trans retinoic acid, and inhibition of PP2A activity may be involved in the process.