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Analysis on the mechanisms of growth, differentiation and malignant transformation <of megakaryocytic cells

巨核细胞生长、分化及恶变机制分析

基本信息

批准号：
12670986
负责人：
MATSUMURA Itaru
金额：
$ 2.37万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2001
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-12670986/
关键词：
megakaryocyte polyploidization AIM-1 Ras STAT5 PI3-K Ras 分化 GATA-1

项目摘要

In this project, we examined the mechanisms of growth, differentiation, and malignant transformation of megakaryocytic cells.During the late phase of megakaryopoiesis, megakaryocytes undergo polyploidization characterized by DNA duplication without concomitant cell division. We initially examined the roles of AIM-1 which is a member of Aurora/Ipl1 serine threonine kinase family and essential for mitosis in megakaryocytic polpyploidization. In a proliferative hematopoietic cells, the expression of AIM-1 mRNA was restrictedly observed at G_2/M phase of cell cycle. In contras its expression was continuously repressed during polyploidization in normal megakaryocytes as in erythro/megakaryocytic cell lines (F-36P, K562, and CMK). Supplement of AIM-1 activities by the induced express on of wild-type AIM-1 canceled TPA-induced polyploidizaTion of K562.Moreover, suppression of AIM-1 activities by the induced expression dominant-negative(DN) AIM-1 led to polyploidization of K562 and CMK. These results suggested that down-regulation of AIM-1 may be involved in polyploid formation of megakaryocytes.Next, we examined the mechanism of the growth and survival of a BCR/ABL-positive erythroid/magakaryocytic cell line, K562. We inducibly expressed DN Ras (N17), phosphatidylinositol 3-kinase(PI3-K)(Δp85) and STAT5 (694F) alone or ill combination in K562 The inducibly expressed N17, 694F and Δp85 inhibited the growth by 90% 55% and 40%, respectively. In addition, N17 induced apoptosis in a small proportion of K562, whereas 694F and Δp85 were hardly effective In contrast, coexpression of two DN mutants in any combinations induced severe apoptosis. Furthermore, although K562 was resistant to IFN-α- and dexamethasone-induced apoptosis, disruption of one pathway by N17 694F or Δp85 sensitized K562 to these reagents. These results suggest that cooperation among these molecules is required for full leukemogenic activities of BCR/ABL.

在这个项目中，我们研究了巨核细胞的生长、分化和恶性转化的机制。在巨核细胞生成的后期，巨核细胞经历以DNA复制为特征的多倍体化，但不伴随细胞分裂。我们最初研究了 AIM-1 的作用，AIM-1 是 Aurora/Ipl1 丝氨酸苏氨酸激酶家族的成员，对于巨核细胞多倍化中有丝分裂至关重要。在增殖性造血细胞中，AIM-1 mRNA的表达仅限于细胞周期的G_2/M期。相反，在正常巨核细胞的多倍化过程中，如红细胞/巨核细胞系（F-36P、K562 和 CMK）中，其表达持续受到抑制。通过诱导表达野生型AIM-1来补充AIM-1活性可以取消TPA诱导的K562多倍化。此外，通过诱导表达显性失活(DN) AIM-1来抑制AIM-1活性导致K562和CMK的多倍化。这些结果表明AIM-1的下调可能与巨核细胞的多倍体形成有关。接下来，我们研究了BCR/ABL阳性红系/巨核细胞系K562的生长和存活机制。我们在K562中单独或组合诱导表达DN Ras (N17)、磷脂酰肌醇3-激酶(PI3-K)(Δp85)和STAT5 (694F)。诱导表达的N17、694F和Δp85分别抑制生长90%、55%和40%。此外，N17 在一小部分 K562 中诱导细胞凋亡，而 694F 和 Δp85 几乎没有效果。相反，两种 DN 突变体以任何组合共表达都会诱导严重的细胞凋亡。此外，尽管 K562 对 IFN-α 和地塞米松诱导的细胞凋亡具有抗性，但 N17 694F 或 Δp85 对一种途径的破坏使 K562 对这些试剂敏感。这些结果表明，BCR/ABL 的完全致白血病活性需要这些分子之间的合作。