低剂量氧化砷治疗早幼粒细胞白血病的实验研究

背景与目的：低剂量三氧化二砷（arsenic trioxide,As2O3）是治疗急性早幼粒细胞性白血病（APL）的有效手段之一,它不仅对初发APL病人有效,而且对全反式维甲酸（ATRA）巳耐受的复发APL病人可获得完全缓解。然而,目前其诱导APL缓解的机制尚不清楚。为此,本研究试图探低剂量As2O3治疗APL的可能机制。方法：以APL细胞株NB4和来源于APL患者骨髓的原代细胞为模型。通过观察细胞形态、对四氮唑蓝的还原能力和细胞表面分化抗原的变化来鉴定细胞分化;并应用免疫荧光和Western blot分析细胞内PML-RARα融合蛋白的变化。结果：0.25μmol/L AS2O3联合环腺苷酸（cAMP）拟似物8-对氯苯硫基环腺苷酸（8-CPT-CAMP）可诱导NB4细胞和原代细胞分化,而且该效应能被蛋白激酶PKA的抑制剂H89抑制。进一步研究还显示8-CPT-CAMP可以促进AS2O3介导的PML-RARα融合蛋白降解。结论：cAMP可增强AS2O3对APL细胞的分化诱导效应。

Experimental study of low dose arsenic trioxide in treatment of patients with acute promyelocytic leukemia

BACKGROUND & OBJECTIVE: Low dose arsenic trioxide(As2O3) is one of the effective treatments for patients with acute promyelocytic leukemia (APL). As2O3 could induce complete remission in de novo APL patients as well as in relapsed APL patients who have been resistant to all-trans retinoic acid (ATRA). However, the underlying mechanisms of As2O3-induced remission remain obscure. Therefore, we designed this study to explore the possible mechanism of low dose As2O3 in treatment of the patients with APL. METHODS: The APL cell line NB4 and primary malignant cells isolated from APL patients were used as in vitro models. Cell differentiation was determined by cell morphology, NBT reduction test and cytometry assay of cell differentiation antigens. The change of PML-RAR alpha fusion protein was analyzed by immunofluorescence and Western blot. RESULTS: The 0.25 mumol/L As2O3 combined with cyclic adenosine monophosphate(cAMP) analogue, 8-(4-chlorophenylthio) adenosine 3', 5'-cyclic monophosphate (8-CPT-cAMP), had induced differentiation in NB4 cell line and primary cells. It was also found that this effect could be attenuated by H89, a specific PKA inhibitor. Moreover, 8-CPT-cAMP was able to facilitate the As2O3-mediated degradation of PML-RAR alpha. CONCLUSIONS: The 8-CPT-cAMP could enhance As2O3-induced differentiation in APL cells.