p21 WAF1/CIP1基因导入对p53突变人肺癌细胞系生长特性的影响

目的　探讨含突变ｐ５３ 基因癌细胞系表达ｐ２１ 基因的抗肿瘤作用。方法　构建人ｐ２１表达重组子，导入ｐ５３ 基因突变的人肺癌ＰＧ细胞系，建立稳定高表达ｐ２１ 的细胞系；然后观察其形态及生长特性的改变；ＣＤＫ４ ，ＰＣＮＡ水平；对基因毒性物的反应性。结果　在含ｐ５３ 基因突变的ＰＧ 细胞内导入外源性ｐ２１ 基因，其高表达ｐ２１ 约是ＰＧ 细胞的６ 倍；转染细胞出现核规则、核膜变薄等异型性降低；生长速度下降（５０％ ） ，叠落生长不明显；在０ ．５％ 血清条件下生长显著低于对照组；血清依赖性升高；软琼脂集落实验：转染细胞集落形成率降低为１ ％ （ 对照组为２８％ ） 。ｗｅｓｔｅｒｎ ｂｌｏｔ 显示，ｐ２１ 转染细胞的ＣＤＫ４ 和核仁组成区相关蛋白水平显著降低。但顺铂诱导下转染细胞凋亡发生延缓至４８ 小时以后（ 对照组２４ 小时）。结论　在有ｐ５３ 基因突变的肿瘤细胞ｐ２１ 的高表达仍能抑制癌细胞的生长，降低恶性表型；其作用可能与降低细胞ＣＤＫ４ 和ＰＣＮＡ 水平有关，而不依赖细胞凋亡机制。表达ｐ２１ 基因可作为恢复ｐ５３ 基因功能的旁路途径。

Effects of p21WAF1/CIP1 gene introduction on a human lung cancer cell line with p53 mutation

Objective To study the effects of p21WAF1/CIP1 gene expression on the biological hehavior of cancer cells with p53 gene mutation. Methods Expression of p21 vehicle was constructed and introduced into a human lung cancer cell ling PG with p53 gene mutation, the morphological and growth characteristics of the transfectant were then analysed. The CDK4 and PCNA levels were evaluated and the response to genotoxic agents were observed. Results The PG cells with mutant p53 were transfected with ectopic p21 gene which resulted in overexpression of p21 (6 fold of the control). The transfectants presented decreased nuclear irregularity and thinner membrane in nuclear atypia, with delayed growth rate and contact growth inhibition. The transfectant also displayed high serum requirement in culture and increased anchorage dependence. Both levels of CDK4 and PCNA were decreased. However, the cisplatin induced cell apoptosis was delayed. Conclusions Expression of p21WAF1/CIP1 gene was effective in cancer suppression even in p53 gene mutation. This may have been achieved through lowering of CDK4 or PCNA levels and not involving the apoptosis mechanism. Activation of p21WAF1/CIP1 gene may be considered a bypass for restoration of p53 gene function in cancer cells with p53 gene mutation