Furuya Y, Lin X S, Walsh J C, Nelson W G, Isaacs J T
Johns Hopkins Oncology Center, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
Endocrinology. 1995 May;136(5):1898-906. doi: 10.1210/endo.136.5.7720636.
Proliferating cells characteristically undergo programmed (i.e. apoptotic) death if their progression through the cell cycle is sufficiently perturbed. To determine whether androgen ablation-induced programmed death of prostatic glandular cells involves apoptosis triggered by recruitment of nonproliferating cells into a perturbed cell cycle, rat ventral prostates were assessed temporally after castration for several stereotypical molecular stigmata of entry into the proliferative cell cycle. Northern blot analysis was used to assess levels of transcripts from genes characteristically activated 1) during the transition from quiescence (G(0)) into G1 of the proliferative cell cycle (cyclin-D1 and cyclin-C), 2) during the transition from G1 to S (cyclin-E, cdk2, thymidine kinase, and H4-histone), and 3) during progression through S (cyclin-A). Although levels of each of these transcripts increased as expected in prostatic glandular epithelial cells stimulated to proliferate by the administration of exogenous androgen to previously castrated rats, levels of the same transcripts decreased in prostatic glandular cells induced to undergo apoptosis after androgen withdrawal. Northern and Western blot analyses also demonstrated that there was no increase in prostatic p53 messenger RNA or protein content per cell after androgen ablation. Likewise, after castration, there was no enhanced prostatic expression of the WAF1/CIP1 gene, a gene whose expression is known to be induced in both a p53-dependent and -independent manner during recruitment from G0 into G1. In addition, androgen ablation-induced apoptosis of prostatic glandular cells was not accompanied by retinoblastoma protein phosphorylation, which is characteristic of progression into late G1. Nuclear run-on assays demonstrated that there was no increase in the prostatic rate of transcription of the c-myc and c-fos genes after castration. These results demonstrate that prostatic glandular cells undergo programmed death in G(0) without recruitment into the G1 phase of a defective cell cycle, and that an increase in p53 protein or its function is not involved in this death process.
如果增殖细胞在细胞周期中的进程受到足够的干扰，其典型特征是经历程序性（即凋亡性）死亡。为了确定雄激素去除诱导的前列腺腺细胞程序性死亡是否涉及通过将非增殖细胞募集到受干扰的细胞周期而触发的凋亡，在阉割后对大鼠腹侧前列腺进行了一段时间的评估，以观察进入增殖细胞周期的几种典型分子标记。采用Northern印迹分析来评估以下基因转录本的水平：1）在从静止期（G(0)）过渡到增殖细胞周期的G1期时典型激活的基因（细胞周期蛋白D1和细胞周期蛋白C）；2）在从G1期过渡到S期时（细胞周期蛋白E、细胞周期蛋白依赖性激酶2、胸苷激酶和H4组蛋白）；3）在S期进程中（细胞周期蛋白A）。尽管在给先前阉割的大鼠施用外源性雄激素刺激其增殖的前列腺腺上皮细胞中，这些转录本的水平如预期的那样升高，但在雄激素撤除后诱导发生凋亡的前列腺腺细胞中，相同转录本的水平却降低了。Northern和Western印迹分析还表明雄激素去除后每个细胞中前列腺p53信使RNA或蛋白质含量没有增加。同样，阉割后，WAF1/CIP1基因在前列腺中的表达也没有增强，已知该基因在从G0期募集到G1期的过程中以p53依赖性和非依赖性方式被诱导表达。此外，雄激素去除诱导的前列腺腺细胞凋亡并不伴有视网膜母细胞瘤蛋白磷酸化，而这是进入G1晚期的特征。核转录分析表明阉割后前列腺中c-myc和c-fos基因的转录速率没有增加。这些结果表明前列腺腺细胞在G(0)期经历程序性死亡，而不被募集到有缺陷的细胞周期的G1期，并且p53蛋白或其功能的增加不参与这个死亡过程。
