Autocrine Proliferation and Differentiation-Capacities of Leukemic Cells, and Molecular Analyses of Leukemic Phenotypes

正常的造血祖细胞的增殖和分化产生成熟的功能细胞，这取决于各种造血生长因子，最近已经克隆了这些因子的基因。相反，自分泌生长机制(S)被认为是由造血祖细胞的转化和克隆性增殖发展而来的，特别是在白血病这一血液系统恶性肿瘤的发病过程中。细胞增殖的自分泌机制(S)的概念认为，细胞既可以产生特定的生长因子，也可以对特定的生长因子做出反应。然后，在某些条件下，这样的细胞可能会以一种导致恶性转化的方式独立于外部生长调节。为了阐明造血细胞恶性转化的机制，我们研究了…后建立的依赖IL-3的小鼠成髓细胞系FDC-P2的致瘤性。进一步通过电穿孔的方法将编码小鼠IL-3的基因导入小鼠。建立了两个在无生长因子条件下生长的亚系。用IL-3基因探针进行Southern杂交分析表明，一个细胞系含有一个整合的IL-3基因拷贝，另一个细胞系含有2-3个拷贝。在这些细胞系的培养上清液中检测到大量的IL-3。这些结果提示IL-3基因的表达和IL-3的分泌将IL-3依赖的细胞转化为IL-3非依赖的细胞。将这些细胞皮下转移到裸鼠体内，持续产生肿瘤。转基因细胞产生IL-3的能力似乎赋予这些细胞致瘤表型。在另一种小鼠骨髓单核细胞系--NFS-60细胞中也得到了类似的结果。在后者中，将IL-3基因导入亲代IL-3依赖细胞系后，建立了10个不依赖IL-3的克隆。不同的克隆株在细胞外产生IL-3的能力不同。然而，细胞内的IL-3活性被发现在克隆之间并没有太小的差异。因此，细胞内IL-3活性对转化细胞的自分泌生长至关重要。较少

Normal hemopoietic progenitors proliferate and differentiate to produce mature functioning cells, depending on a variety of hemopoietic growth factors, of which genes have been recently cloned. In contrast, autocrine growth mechanism(s) have been proposed especially at the onset of leukemia, a type of hemopoietic malignancy, since leukemia have been considered to develop from the transformation and clonal proliferation of hemopoietic precursors. The concept of autocrine mechanism(s) of cellular proliferation suggests that a cell can both produce and respond to a particular growth factor. Then, under certain conditions, such a cell might become independent of external growth regulation in a manner that would lead to malignant transformation. In order to elucidate the mechanism of malignant transformation of hemopoietic cells, we investigated the tumorigenicity of FDC-P2, an IL-3-dependent murine myeloblastic cell line established from a long-term culture of normal bone marrow cells, aft … More er transfection of the cDNA encoding murine IL-3 by electroporation. Two sublines growing in the absence of growth factors were established. Southern blot analysis using the probe of IL-3 gene showed that one cell line contained one copy of the integrated IL-3 gene, and the other contained 2-3 copies. A significant amount of IL-3 was detected in cutured media of these cell lines. These results suggest that the expression of IL-3 gene and the secretion of IL-3 transformed IL-3-dependent cells to IL-3-independent cells. Subcutaneous transfer of these cells into nude mice consistently produced tumors. The capacity of the transfected cells producing IL-3 appeared to confer a tumorigenic phenotype to these cells. Similar results were obtained with another murine myelomonocytic cell line, NFS-60 cells. In the latter case, 10 clones which became independent of IL-3 were established after transfection with IL-3 gene into the parental IL-3-dependent cell line. The capacities to produce IL-3 outside the cell were varied with different clones. However, the IL-3 activity inside the cell was found not to be much less different among the clones. Thus, the intracellular IL-3 activity was considered to be crucial for the autocrine growth of the transformed cells produced by transfection of the growth factor gene. Less