THE ROLE OF C AMP IN LEUKEMIC CELL DIFFERENTIATION

环磷酸腺苷在细胞增殖和分化中的关键作用 已经被很好地描述过了。添加维甲酸(RA)、霍乱毒素 (CT)或8-BrcAMP(8-BrcAMP)对人早幼粒细胞白血病细胞的作用 细胞株(HL60)在培养过程中可明显分化为 一种成熟的髓系表型，而佛波二酯的加入 12-0-十四酰佛波醇-13-乙酸酯(TPA)诱导分化 将细胞转化为巨噬细胞。我们检测到cAMP依赖和 -特定内源性蛋白的非依赖性改变的磷酸化 在RA和TPA诱导HL60细胞分化过程中 每条分化途径都是特定的。我们注意到了显著的变化 在cAMP依赖和非依赖的蛋白激酶活性中 沿巨噬细胞途径分化的细胞不同于 分化为成熟的髓系表型。维甲酸及其制剂 升高细胞内环磷酸腺苷协同诱导髓系 差异化。我们最近已经证明，Low的添加 二甲基甲酰胺、维甲酸、放线菌素D或次黄嘌呤的水平 在添加8-溴-环腺苷31-51，单磷酸， 霍乱毒素或磷酸二酯酶抑制剂异丁基甲基黄嘌呤， 结果HL60和HL60细胞的分化均明显增强 RDFD-白血病细胞，表现为获得OKM-1抗原， 还原硝基蓝四氮唑的能力或表达 趋化受体。这些结果进一步表明，cAMP在 髓系分化。蛋白质没有显著的调节作用 在HL60期间，检测到胞浆部分中的磷酸化 暴露于RA或AA和环状AMP提升剂。我们会调查的 CAMP依赖和非依赖蛋白磷酸化的调控 质膜组分并确定这些磷酸化是否也 在使用32PO4的体内磷酸化过程中注意到。此外, 从急性骨髓性白血病患者中分离出原始细胞形式 白血病、急性单核细胞白血病、慢性单核细胞白血病 和急性淋巴细胞性白血病。这些细胞将暴露在RA中 不同时间段和体内蛋白质磷酸化的测定。它 希望对这种生物分化的生化过程的理解 将使我们能够改进目前的临床治疗。(M)

The crucial role of cyclic AMP in cell proliferation and differentiation has been well-described. The addition of retinoic acid (RA), cholera toxin (CT), or 8-Br cyclic AMP (8-BrcAMP) to a human promyelocytic leukemia cell line (HL60) in culture results in a marked differentiation of the cells to a mature myeloid phenotype, while the addition of the phorbol diester 12-0-tetradecanoyl phorbol-13-acetate (TPA) results in the differentiation of the cells into macrophages. We have detected cAMP-dependent and -independent altered phosphorylations of specific endogenous proteins during RA-\and TPA-induced differentiation of HL60 cells which appear to be specific for each pathway of differentiation. We have noted marked changes in the cAMP-dependent and -independent protein kinase activities which are different in cells differentiated along the macrophage pathway from those differentiated to the mature myeloid phenotype. Retinoic acid and agents raising intracellular cyclic AMP synergistically induced myeloid differentiation. We have recently demonstrated that the addition of low levels of dimethyl formamide, retinoic acid, actinomycin D or hypoxanthine prior to the addition of 8-bromo-cyclic adenosine 31-51, monophosphate, cholera toxin or the phosphodisterase inhibitor isobutylmethyl-xanthine, results in marked potentiation of differentiation of both HL60 and the RDFD-leukemic cells as manifested by the acquisition of the OKM-1 antigen, the ability to reduce nitroblue tetrazolium or expression of the chemotactic receptor. These results further suggest a role for cAMP in myeloid differentiation. No significant modulations of protein phosphorylations have been detected in the cytosolic fraction during HL60 exposure to RA or AA and cyclic AMP elevating agents. We will investigate modulation of cAMP-dependent and -independent protein phosphorylations in plasma membrane fractions and determine if these phosphorylations are also noted during in vivo phosphorylation utilizing 32PO4. In addition, blast forms have been isolated from patients with acute myelogenous leukemia, acute myelomonocytic leukemia, chronic myelomonocytic leukemia and acute lymphocytic leukemia. These cells will be exposed to RA for various periods of time and in vivo protein phosphorylation determined. It is hoped that understanding of this biochemical process of differentiation will allow us to improve current clinical treatments. (M)