G1 cell cycle regulatory proteins in chemically-induced rat mammary adenocarcinomas in vivo and tumor promotion-sensitive, -resistant and transformed mouse epidermal cells in vitro.
Tumor promotion is characterized by selective proliferation of initiated cells resulting in their clonal expansion. Cyclin Dl is frequently upregulated in this process, but its expression does not necessarily correlate positively with cyclin A. In the present article, expression of G1 cell cycle regulatory proteins was systematically analyzed using two models of carcinogenesis: (a) N-methyl-N-nitrosourea (MNU)-induced rat mammary adenocarcinomas and normal rat mammary epithelial cells in vivo and (b) promotion-sensitive, -resistant, and transformed JB6 mouse epidermal cells in vitro. The results of this analysis revealed that p27Kipl negatively correlated with cyclin Dl. In addition, there were two types of correlations between p27Kipl and cyclin A. First, p27Kipl negatively correlated with cyclin A (type-l correlation). This scenario was observed in normal rat mammary epithelial cells in vivo and promotion-sensitive (P+) JB6 mouse epidermal cells, stimulated with phorbol ester (TPA) in vitro. Second, p27Kipl positively correlated with cyclin A (type-ll correlation). This correlation was observed in MNU-induced rat mammary adenocarcinomas in vivo and TPA-stimulated (P+) JB6 cells, treated with retinoic acid in vitro.
Eto
Isao
I
Department of Nutrition Sciences and Chemoprevention Center, University of Alabama at Birmingham, 316 Suson Mott Webb Nutrition Sciences Building, 1675 University Boulevard, Birmingham, Alabama 35294, USA. etoi@shrp.uob.edu
D000230:Adenocarcinoma / Q000139:chemically induced* / Q000378:metabolism; D000818:Animals; D002273:Carcinogens; D018797:Cell Cycle Proteins / Q000378:metabolism*; D002461:Cell Line, Transformed; D002478:Cells, Cultured; D050760:Cyclin-Dependent Kinase Inhibitor p27; D000078404:Epidermal Cells; D004817:Epidermis / Q000187:drug effects / Q000378:metabolism; D005260:Female; D016193:G1 Phase / Q000187:drug effects; D008325:Mammary Neoplasms, Experimental / Q000139:chemically induced* / Q000378:metabolism; D008770:Methylnitrosourea; D051379:Mice; D051381:Rats; D017207:Rats, Sprague-Dawley; D014407:Tumor Cells, Cultured; D025521:Tumor Suppressor Proteins / Q000378:metabolism
D002273:Carcinogens; C493961:Cdkn1b protein, mouse; C493962:Cdkn1b protein, rat; D018797:Cell Cycle Proteins; D025521:Tumor Suppressor Proteins; D050760:Cyclin-Dependent Kinase Inhibitor p27; D008770:Methylnitrosourea