Regulatory Mochanisms For Proliferation, Differentiation, And Apoptosis of Leukemic Cells In Reference To Cell Cycle Phases.

在1994年至1995年期间，取得了下列新的调查结果，其中大部分在一些国际会议上作了介绍。（1）TGF-β对人单核细胞株JOSK-I细胞的生长抑制作用主要发生在G1期晚期，而对S期和G2/M期细胞无明显抑制作用。TGF-β对cdc 2基因的mRNA和蛋白水平无影响，但对cdc 2基因的翻译速率和cdc 2激酶活性有抑制作用。因此，TGF-β的生长抑制与RB蛋白（Rb）磷酸化的抑制（未磷酸化Rb的显著储存）密切相关，随后是DNA合成的抑制，并且未磷酸化Rb的储存被认为是通过TGF-β抑制cdc 2激酶活性而发生的。另一方面，在G1/S期观察到aphidicoline的生长抑制活性，几乎没有未磷酸化的Rb。不同点 ...更多信息 诱导剂佛波醇酯TPA也能使Rb蛋白去磷酸化，这被认为发生在分化诱导后的细胞周期阻滞中。所有这些数据一起，这表明，一些cdc 2基因产物或一个身份不明的Rb激酶可能密切参与Rb磷酸化。(2)建立了实验模型系统，其中，使用人髓性白血病细胞系HL-60细胞，分化诱导（分化定型和分化特性的表达）和凋亡诱导可以被分开分析。结果表明：诱导分化6小时后，NBT还原活性和细胞凋亡诱导作用独立存在，myc和bcl-2基因的表达均受到抑制。在诱导分化开始后24-36小时内，所有诱导凋亡所必需的事件都与bcl-2表达的抑制密切相关。(3)细胞外基质（ECM）糖蛋白腱生蛋白（tenascin）的生物学功能被研究，因为ECM糖蛋白通常最近已被阐明通过细胞与细胞的粘附和识别在调节细胞增殖和分化中起重要作用。生肿蛋白-C的表达在肿瘤形成中观察到的基质-上皮相互作用中以严格的方式在时间和空间上进行调节。虽然生腱蛋白-C表达诱导的生理调节剂仍然是未知的，但在基质-上皮相互作用中生腱蛋白-C的从头合成用可溶性上皮生长因子（EGF）诱导，并且这种诱导用类固醇激素如氢化可的松抑制。从tenascin-C基因敲除小鼠的骨髓中建立了一些tenascin-C表达缺陷的基质细胞系，然后用Less

During the period from 1994 to 1995, the following new findings were obtained, and most of them were presented in some of the international conferences. and published in the specialized journals : (1) The inhibitory activity of TGF-beta on the growth of human monoblastic cell line JOSK-I cells was observed at the late G1 phase, but not at the S or G2/M phase of cell cycle. TGF-beta did not affect the level of both mRNA and protein of cdc2 gene, but did inhibit the translation rate of cdc2 gene and the cdc2 kinase activity. Thus, the growth inhibition by TGF-beta was closely related to the inhibition of RB protein (Rb) phosphorylation (the significant storage of unphosphorylated Rb) followed by the inhibition of DNA synthesis, and the unphosphorylated Rb storage was suggested to occur through the inhibition of cdc2 kinase activity by TGF-beta. On the other hand, the growth inhibitory activity of aphidicoline was observed at the G1/S phase with little unphosphorylated Rb. The differentia … More tion-inducer, phorbol ester TPA,also did unphosphorylate Rb protein, which was suggested to occur in the differentiation induction followed by the cell cycle arrest. With all these data together, it was suggested that some cdc2 gene products or an unidentified Rb kinase might be intimately involved in the Rb phosphorylation. (2) The experimental model system was established, in which, using human myelogenous leukemia cell line HL-60 cells, the differentiation induction (the differentiation commitment and the expression of differentiation properties) and the apoptosis induction could be separately analyzed. The results obtained were as follows : the NBT reducing acitivity and the apoptosis induction were independently observed, and the expression of both myc and bcl-2 genes was inhibited 6 hrs after the initiation of differentiation induction. During the period of 24-36 hrs after the initiation of differentiation induction, all the events necessary for the apoptosis induction occurred closely relating to the inhibition of bcl-2 expression. (3) The biological function of the extracellular matrix (ECM) glycoprotein, tenascin, was investigated since ECM glycoproteins in general have recently become clarified to play an important role in the regulation of cell proliferation and differentiation through the cell-to-cell adhesion and recognition. The expression of tenascin-C was termporally and spatially regulated in the strict manner at the stromal-epithelial interactions observed in tumor formations. Although the physiological regulators for tenascin-C expression-induction are still unknown, the do novo synthesis of tenascin-C in the stromal-epithelial interactions was induced with the soluble epithelial growth factor (EGF), and this induction was inhibited with steroid hormons such as hydrocortisone. Some stromal cell lines, which were deficient in the tenascin-C expression, could be first established from the bone marrows of tenascin-C gene knock-out mice, and then, usi Less