Prabhu N S, Blagosklonny M V, Zeng Y X, Wu G S, Waldman T, El-Deiry W S
Howard Hughes Medical Institute, Laboratory of Molecular Oncology, Chicago, Illinois, USA.
Clin Cancer Res. 1996 Jul;2(7):1221-9.
p53 tumor suppression is deficient in the majority of human cancers. Efforts to understand this pathway have identified cyclin-dependent kinase (CDK) inhibitors and suggested a potential for their replacement in human cancer. In the present studies, expression of a C-terminal deletion mutant of the human p21(WAF1/CIP1) CDK inhibitor completely suppressed the growth of colon cancer cells, whereas full-length p21 only partially suppressed growth. We prepared a replication-deficient adenoviral recombinant which expresses the p21 C-terminal mutant (Ad-WAF1-341) and compared its tumor suppressive abilities with Ad-p53 and Ad-LacZ. Ad-WAF1-341- and Ad-p53-infected cancer cells, but not Ad-LacZ-infected cancer cells, expressed a nuclear protein recognized by anti-p21 antibody and were deficient in cell cycle progression. The exogenous p21 mutant interacted with CDK2 but not proliferating cell nuclear antigen following infection of p21-/- cancer cells. Ad-WAF1-341 was more potent than Ad-p53 in inhibiting DNA synthesis in human papillomavirus 16 E6-expressing cancer cells. Most importantly, the Ad-WAF1-341-infected E6-expressing cells died, whereas most of the Ad-p53-infected cells continued to proliferate. Endonucleolytic cleavage of DNA was observed in Ad-WAF1-341-infected cancer cells. These observations suggest that Ad-WAF1-341 should be evaluated in the treatment of human papillomavirus-associated neoplasia and other neoplasias resistant to p53.
p53肿瘤抑制功能在大多数人类癌症中存在缺陷。为了解这条通路所做的努力已鉴定出细胞周期蛋白依赖性激酶（CDK）抑制剂，并提示了它们在人类癌症中替代的潜力。在本研究中，人p21（WAF1/CIP1）CDK抑制剂的C末端缺失突变体的表达完全抑制了结肠癌细胞的生长，而全长p21仅部分抑制生长。我们制备了一种表达p21 C末端突变体的复制缺陷型腺病毒重组体（Ad-WAF1-341），并将其肿瘤抑制能力与Ad-p53和Ad-LacZ进行比较。Ad-WAF1-341和Ad-p53感染的癌细胞，而非Ad-LacZ感染的癌细胞，表达一种可被抗p21抗体识别的核蛋白，且细胞周期进程存在缺陷。在p21基因敲除的癌细胞感染后，外源性p21突变体与CDK2相互作用，但不与增殖细胞核抗原相互作用。在表达人乳头瘤病毒16 E6的癌细胞中，Ad-WAF1-341在抑制DNA合成方面比Ad-p53更有效。最重要的是，Ad-WAF1-341感染的表达E6的细胞死亡，而大多数Ad-p53感染的细胞继续增殖。在Ad-WAF1-341感染的癌细胞中观察到DNA的内切酶切割。这些观察结果表明，Ad-WAF1-341应在人乳头瘤病毒相关肿瘤及其他对p53耐药的肿瘤治疗中进行评估。
