Delgado M D, Vaqué J P, Arozarena I, López-Ilasaca M A, Martínez C, Crespo P, León J
Grupo de Biología Molecular del Cáncer, Departamento de Biología Molecular y Unidad Asociada al Centro de Investigaciones Biológicas (CSIC), Universidad de Cantabria, Santander, Spain.
Oncogene. 2000 Feb 10;19(6):783-90. doi: 10.1038/sj.onc.1203384.
Mutated ras genes are frequently found in human cancer. However, it has been shown that oncogenic ras inhibits growth of primary cells, through pathways involving p53 and the cell cycle inhibitors p16INK4a and p19ARF. We have analysed the effect of the ectopic expression of the three mammalian ras genes on the proliferation of K562 leukemia cells, which are deficient for p53, p16INK4a, p15INK4b and p19ARF genes. We have found that high expression levels of both wild-type and oncogenic H-, K- and N-ras inhibit the clonogenic growth of K562 cells. Induction of H-rasV12 expression in K562 transfectants retards growth and this effect is accompanied with an increase of p21WAF1 mRNA and protein levels. Furthermore, p21WAF1 promoter is activated potently by oncogenic ras and less pronounced by wild-type ras. This induction is p53-independent since a p21WAF1 promoter devoid of the p53 responsive elements is still activated by Ras. Finally, inhibition of p21WAF1 expression by an antisense construct partially overcomes the growth inhibitory action of oncogenic H-ras. Altogether, these results indicate that the antiproliferative effect of ras in myeloid leukemia cells is associated to the induction of p21WAF1 expression and suggest the existence of p19ARF and p16INK4a-independent pathways for ras-mediated growth inhibition.
突变的ras基因在人类癌症中经常被发现。然而，已经表明致癌性ras通过涉及p53以及细胞周期抑制剂p16INK4a和p19ARF的途径抑制原代细胞的生长。我们分析了三种哺乳动物ras基因的异位表达对K562白血病细胞增殖的影响，K562细胞缺乏p53、p16INK4a、p15INK4b和p19ARF基因。我们发现野生型和致癌性的H-ras、K-ras和N-ras的高表达水平均抑制K562细胞的克隆形成生长。在K562转染子中诱导H-rasV12表达会延迟生长，并且这种效应伴随着p21WAF1 mRNA和蛋白水平的增加。此外，致癌性ras能有效激活p21WAF1启动子，而野生型ras的激活作用则较弱。这种诱导不依赖于p53，因为缺乏p53反应元件的p21WAF1启动子仍能被Ras激活。最后，反义构建体抑制p21WAF1表达可部分克服致癌性H-ras的生长抑制作用。总之，这些结果表明ras在髓系白血病细胞中的抗增殖作用与p21WAF1表达的诱导有关，并提示存在p19ARF和p16INK4a非依赖性的ras介导的生长抑制途径。
