Expression of autophosphorylating protein kinase 500 in normal and neoplastic rat cells.
AUTOR(ES)
Majumdar, G
RESUMO
Autophosphorylating protein kinase 500 (AUT-PK 500) is a unique serine protein kinase that was originally purified and characterized from the rat adrenocortical carcinoma. A specific RIA with an assay sensitivity of 10 ng (0.02 pmol) was developed for AUT-PK 500 and applied to normal, embryonic, fetal, neonatal, immortal, and neoplastic tissues and cultured cells. As compared to normal rat tissues, the expression of AUT-PK 500 is elevated 100-fold in spontaneously occurring adrenocortical carcinoma 494, 50- to 60-fold in four chemically induced, rapidly growing hepatomas, 30-fold in the chemically induced mammary carcinoma, 20-fold in the cultured hepatoma cell line, and 4-fold in the Rat I and Rat II established tissue culture cell lines. There was also a 5-fold increase in the enzyme when freshly cultured rat skin epithelial-like cells were established. Furthermore, in vivo studies showed that when the rat liver was chemically transformed into its premalignant altered foci, there was a 7-fold elevation of AUT-PK 500. Embryonic cells and fetal and neonatal tissues contained barely detectable (less than 0.22 micrograms/mg of protein) amounts of the protein kinase. These results suggest that AUT-PK 500 is not involved in the differentiation process during fetal development but may be elevated during early steps of carcinogenesis and is further elevated during later stages.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=390493Documentos Relacionados
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