The key events (KE) identified in the MOA are PPARα activation (KE1), alteration in cell growth pathways (KE2), perturbation of hepatocyte growth and survival (KE3), and selective clonal expansion of preneoplastic foci cells (KE4), which leads to the apical event-increases in hepatocellular adenomas and carcinomas (KE5).
Bioinformatics analyses revealed that genes with increased expression in PPFP-positive follicular carcinomas include known PPAR target genes; genes involved in fatty acid, amino acid, and carbohydrate metabolism; micro-RNA target genes; and genes on chromosome 3p.
Previous work in rat mammary gland epithelial cells showed significantly increased PPARalpha mRNA expression in carcinomas, suggesting the possible role of this isoform in rodent mammary gland carcinogenesis.
Normal Sprague-Dawley rat mammary gland epithelial cells and mammary gland carcinomas induced by 2-amino-1-methyl-6-phenylimidazo[4, 5-b]pyridine, a carcinogen found in the diet, were examined for the expression of peroxisome proliferator-activated receptor alpha (PPAR alpha).