Yatsunami J, Komori A, Ohta T, Suganuma M, Yuspa S H, Fujiki H
Cancer Prevention Division, National Cancer Center Research Institute, Tokyo, Japan.
Cancer Res. 1993 Mar 1;53(5):992-6.
Okadaic acid, dinophysistoxin-1 (35-methylokadaic acid), and calyculin A are potent tumor promoters on mouse skin (H. Fujiki, M. Suganuma, S. Nishiwaki, S. Yoshizawa, J. Yatsunami, R. Matsushima, H. Furuya, S. Okabe, S. Matsunaga, and T. Sugimura. In: R. D'Amato, T. J. Slaga, W. Farland, and C. Henry (eds.), Relevance of Animal Studies to the Evaluation of Human Cancer Risk, pp. 337-350. New York: John Wiley and Sons, Inc., 1992). These tumor promoters, which are also inhibitors of protein phosphatases 1 and 2A, induced hyperphosphorylation of M(r) 60,000, M(r) 58,000, M(r) 56,000, M(r) 52,000, M(r) 42,000, and M(r) 27,000 proteins in PHK 16-I cells, human keratinocytes immortalized by human papillomavirus type 16. Except for the M(r) 27,000 protein, these hyperphosphorylated proteins were identified to be cytokeratin peptides (CK) CK 5, CK 6, CK 7, CK 16, and CK 19, by anti-cytokeratin antibodies. CK 5 and CK 6 were more strongly phosphorylated than CK 16 and CK 19. The in vitro hyperphosphorylation of these cytokeratins was also found by incubation with an enzyme fraction containing a mixture of protein phosphatase 2A and protein kinases isolated from mouse brain and various concentrations of dinophysistoxin-1. Indirect immunofluorescence microscopy with anti-cytokeratin antibodies revealed that the hyperphosphorylated cytokeratins had retracted to the perinuclear area. The hyperphosphorylated M(r) 27,000 protein was identified as a heat shock protein, HSP27. Hyperphosphorylation of HSP27 and intermediate filaments, such as cytokeratins, is one of the early biochemical changes, or pleiotropic effects, in cells induced by the okadaic acid class of tumor promoters.
冈田酸、鳍藻毒素 -1（35 - 甲基冈田酸）和花萼海绵诱癌素A是小鼠皮肤的强效肿瘤促进剂（藤木博、菅沼正、西胁和、吉泽史、八津浪治、松岛润、古屋文夫、冈部史、松永诚、杉村敏郎。载于：R. 达马托、T. J. 斯拉加、W. 法兰德和C. 亨利（编），《动物研究与人类癌症风险评估的相关性》，第337 - 350页。纽约：约翰威利父子出版公司，1992年）。这些肿瘤促进剂也是蛋白磷酸酶1和2A的抑制剂，它们在PHK 16 - I细胞（由人乳头瘤病毒16型永生化的人角质形成细胞）中诱导了分子量为60,000、58,000、56,000、52,000、42,000和27,000的蛋白质发生过度磷酸化。除了分子量为27,000的蛋白质外，通过抗细胞角蛋白抗体鉴定这些过度磷酸化的蛋白质为细胞角蛋白肽（CK）CK 5、CK 6、CK 7、CK 16和CK 19。CK 5和CK 6的磷酸化程度比CK 16和CK 19更强。通过与含有从鼠脑分离的蛋白磷酸酶2A和蛋白激酶混合物以及不同浓度鳍藻毒素 -1的酶组分一起孵育，也发现了这些细胞角蛋白的体外过度磷酸化。用抗细胞角蛋白抗体进行间接免疫荧光显微镜检查显示，过度磷酸化的细胞角蛋白已回缩至核周区域。过度磷酸化的分子量为27,000的蛋白质被鉴定为热休克蛋白HSP27。HSP27和细胞角蛋白等中间丝的过度磷酸化是冈田酸类肿瘤促进剂诱导细胞发生的早期生化变化或多效性效应之一。
