Revisiting two-stage models of chemically-induced cirrhosis-associated hepatocarcinogenesis in rodents: methodological and histopathological approaches

Abstract

Repeated exposure to hepatotoxins such as carbon tetrachloride (CCl4), thioacetamide (TAA), or diethylnitrosamine (DEN) has been frequently used to induce fibrosis/cirrhosis in rodents. In this narrative review, we compared two-stage medium-term protocols using different CCl4 or TAA regimens in DEN-initiated rats and mice. In addition, we revisited our previous two-stage DEN/CCl4 or DEN/TAA rat models to compare fibrosis grade, the mean number, and the percentage of liver area occupied by hepatocellular lesions positive for placental glutathione S-transferase (GST-P). Thus, we evaluated two groups of male Wistar rats that received DEN (a single dose), as an initiator agent for liver carcinogenesis, followed by CCl4 or TAA regimens (multiple doses) until week 25. Both male Wistar groups presented lower body weight gain and higher liver weight, serum alanine aminotransferase (ALT) levels, hepatocyte proliferation, and a frank development of fibrosis/cirrhosis, GST-P-positive preneoplastic lesions, and liver tumors. However, DEN/TAA protocol in male Wistar rats was more effective as a fibrosis/cirrhosis-associated hepatocarcinogenesis model since TAA effectively accelerates liver disease progression and carcinogenesis. In addition, these chemical regimens have been prospectively studied as a suitable and effective protocol that resembles the corresponding human disease with various molecular and morphological outcomes. In conclusion, two-stage DEN/CCl4 or DEN/TAA rodent models are effective in mimicking the progression of fibrosis-associated hepatocarcinogenesis and are suitable for prophylactic or therapeutic investigations.