ABSTRACT: The present study aimed at proposing a novel chemically-induced cirrhosis-associated rat hepatocarcinogenesis model, involving the characterization of histological, biochemical and molecular features. Male Wistar rats received a single dose of diethylnitrosamine (DEN, 200 mg/Kg body weight [b.wt.]), and were submitted to several cycles of thioacetamide (TAA, 200 mg/Kg b.wt.), during 23 weeks. Blood and liver were collected from untreated and DEN/TAA-treated groups. Liver samples were processed for global gene expression (cDNA microarray), histopathological (HE) and collagen content (picrosirius red) evaluations, immunohistochemical (Ki-67, GST-P and α-SMA), biochemical (catalase, glutathione peroxidase and glutathione-S-transferase) and gelatin zymography (MMP-2 and 9) analysis. Using a very stringent analysis (FDR<0.01 and fold change>3), gene expression array evidenced 359 differentially expressed genes upon DEN/TAA regimen. Gene Ontology and functional analyses showed several upregulated genes involved in extracellular matrix organization, mainly collagen type I α1 and 2 (Col1α1, Col1α2) and tissue inhibitor of metalloproteinase 1 and 2 (Timp1 and Timp2) genes. In addition, glutathione S-transferase, pi 1 and 2 (Gstp1 and Gstp2) genes were markedly upregulated. In contrast, functional analyses also revealed the downregulation of antioxidant response genes, as catalase, glutathione peroxidase 1 and glutathione S-transferase mu type 3 (Cat, Gpx1 and Gstm3). In agreement with gene expression data, our model presented extensive liver cirrhosis with increased α-SMA expression and collagen deposition, as well as marked development of preneoplastic GST-P positive hyperplastic lesions and some neoplasms. Besides, we observed a decrease in total glutathione peroxidase, total glutatione-S-tranferase and catalase activities. The characterization of a suitable cirrhosis-associated hepatocarcinogenesis model could provide insights into molecular characteristics of the human disease and be applied to evaluate potential preventive and therapeutic approaches.
