Molecular and cellular study of the human cellular aging factors

正常人二倍体成纤维细胞在体外具有有限的增殖能力。相反，来自肿瘤的细胞通常表现出无限的增殖潜力（永生）。人类细胞的永生化与细胞衰老过程有关。我们从肾母细胞瘤患者的成纤维细胞中建立了一个永生化敏感细胞系，染色体11 p部分缺失。该细胞系显示出比由SV 40 T永生化的正常人成纤维细胞高50倍的永生化频率。这种产生SV 40 T蛋白的11 β细胞在衰老期表现出异常危象，而T抗原阳性的正常细胞则没有。该11 p细胞的危机培养显示出比正常细胞极高的自发突变和染色体畸变频率。通过差异杂交，我们试图鉴定在危机时优先在11 p细胞中表达的人类基因，并获得了在衰老细胞中上调的克隆C-1基因。在某些永生细胞中发现了C-1基因的部分缺失。这些结果表明，衰老基因在细胞衰老危机期的失活可能与细胞永生化有关。

Normal human diploid fibroblasts have a limited proliferative capacity in vitro. In contrast, cells derived from tumors often exhibit unlimited proliferative potential (immortality). Immortalization of the human cells is associated with the process of cellular aging. We established an immortalization sensitive cell line from the fibroblasts of Wilms' tumor patients with a partial deletion of chromosome 11p. This cell line showed 50 times higher imortalization frequency than normal human fibroblasts immortalized by SV40T. This type of 11p-cells which produced SV40T protein showed an abnormal crisis at the senescent period, whereas T-antigen positive normal cells did not. The crisis culture of this 11p-cells showed a extremely higher frequency of spontaneous mutation and chromosomal aberrations than normal cells. By differential hybridization, we tried to identify the human genes that would be preferentially expressed in 11p-cells at the time of the crisis, and obtained a clone, C-1 gene, that was up-regulated in the senescent cells. A partial loss of C-1 gene was found in some kinds of immortal cells. These results indicate that the inactivation of senescent genes at the crisis phase of the cellular aging may be associated with the cellular immortalization.