Pedrazzoli P, Bains M A, Watson R, Fisher J, Hoy T G, Jacobs A
Department of Haematology, University of Wales College of Medicine, Cardiff, United Kingdom.
Cancer Res. 1989 Dec 15;49(24 Pt 1):6911-6.
c-myc and c-myb mRNAs have been found to be tightly regulated during hemopoietic differentiation. We have studied nuclear c-myc and c-myb oncoproteins through the cell cycle, during macrophage, granulocyte, erythroid, and megakaryocytic differentiation of KG1, HL60, and HEL cells. p62c-myc and p75c-myb content of propidium iodide-stained nuclei was quantitated by flow cytometry using fluoresceinated antibodies CT14-G4 and MB4.3, respectively. In uninduced cells p62c-myc content is highest in HL60, followed by HEL, then KG1, while p75c-myb is highest in HEL, followed by HL60 and KG1. All lines showed a less than 2-fold increment in both oncoproteins over the cell cycle. Macrophage induction of KG1 and HL60 resulted in early increase in both oncoproteins, followed by a decline to less than starting values by 48 h, concurrent with a reduction of S phase cells and the appearance of adherent alpha-naphthyl acetate esterase-positive cells. p62c-myc changes were more pronounced in HL60 and p75c-myb changes in KG1. Different patterns of oncoprotein expression were found when different inducing agents were used for granulocyte differentiation of HL60. Under all conditions, however, both oncoproteins declined to basal levels before granulocyte maturity. Hemin-induced erythroid differentiation of HEL to hemoglobin-containing cells resulted in biphasic p62c-myc and p75c-myb kinetics. In contrast, dimethyl sulfoxide-induced megakaryocytic differentiation of HEL was accompanied by an early and steady decline in both oncoproteins. Despite considerable reduction in oncoprotein levels, HEL cells were still actively cycling at 120 h. It appears that c-myc and c-myb proteins decline with differentiation, well before proliferation ceases in some lineages. The kinetics of the decline differ between the two oncogenes and vary with the lineage induced and the nature of the inducing agent used. The cell cycle distribution of the oncoproteins does not change during maturation. These data suggest disparate roles for c-myc versus c-myb during hemopoietic differentiation and the existence of multiple signal transduction pathways for down-regulation of these genes.
已发现c-myc和c-myb信使核糖核酸在造血分化过程中受到严格调控。我们通过细胞周期，研究了KG1、HL60和HEL细胞在巨噬细胞、粒细胞、红细胞和巨核细胞分化过程中的细胞核c-myc和c-myb癌蛋白。分别使用荧光素化抗体CT14-G4和MB4.3，通过流式细胞术对碘化丙啶染色细胞核中的p62c-myc和p75c-myb含量进行定量。在未诱导的细胞中，p62c-myc含量在HL60中最高，其次是HEL，然后是KG1，而p75c-myb在HEL中最高，其次是HL60和KG1。所有细胞系在细胞周期中两种癌蛋白的增加均不到2倍。KG1和HL60的巨噬细胞诱导导致两种癌蛋白早期增加，随后在48小时时降至低于起始值，同时S期细胞减少，出现贴壁的α-萘乙酸酯酶阳性细胞。p62c-myc的变化在HL60中更明显，而p75c-myb的变化在KG1中更明显。当使用不同的诱导剂诱导HL60细胞向粒细胞分化时，发现了不同的癌蛋白表达模式。然而，在所有条件下，两种癌蛋白在粒细胞成熟前均降至基础水平。血红素诱导HEL细胞向含血红蛋白细胞的红细胞分化导致p62c-myc和p75c-myb呈现双相动力学。相反，二甲亚砜诱导HEL细胞向巨核细胞分化伴随着两种癌蛋白早期且持续的下降。尽管癌蛋白水平大幅降低，但HEL细胞在120小时时仍在活跃地进行细胞周期循环。似乎在某些谱系中，c-myc和c-myb蛋白在增殖停止之前就随着分化而下降。两种癌基因下降的动力学不同，并且随诱导的谱系和所用诱导剂的性质而变化。癌蛋白的细胞周期分布在成熟过程中不改变。这些数据表明在造血分化过程中c-myc与c-myb具有不同的作用，并且存在多种信号转导途径来下调这些基因。
