Genetically modified animal models recapitulating molecular events altered in human hepatocarcinogenesis

Genetically Engineered Mouse Models of Liver Tumorigenesis Reveal a Wide Histological Spectrum of Neoplastic and Non-Neoplastic Liver Lesions

Genetically engineered mouse models (GEMM) are an elegant tool to study liver carcinogenesis in vivo. Newly designed mouse models need detailed (histopathological) phenotyping when described for the first time to avoid misinterpretation and misconclusions. Many chemically induced models for hepatocarcinogenesis comprise a huge variety of histologically benign and malignant neoplastic, as well as non-neoplastic, lesions. Such comprehensive categorization data for GEMM are still missing. In this study, 874 microscopically categorized liver lesions from 369 macroscopically detected liver "tumors" from five different GEMM for liver tumorigenesis were included. The histologic spectrum of diagnosis included a wide range of both benign and malignant neoplastic (approx. 82%) and non-neoplastic (approx. 18%) lesions including hyperplasia, reactive bile duct changes or oval cell proliferations with huge variations among the various models and genetic backgrounds. Our study therefore critically demonstrates that models of liver tumorigenesis can harbor a huge variety of histopathologically distinct diagnosis and, depending on the genotype, notable variations are expectable. These findings are extremely important to warrant the correct application of GEMM in liver cancer research and clearly emphasize the role of basic histopathology as still being a crucial tool in modern biomedical research.

Establishment of experimental implantation tumor models of hepatocellular carcinoma in Wistar rats

Our aims were to investigate and establish simple and reliable implanted hepatocellular carcinoma (HCC) models in Wistar rats. Concentrated suspensions of CBRH-7919 cancer cell lines were injected subcutaneously into the scapular regions of nude mice. The developing tumor tissues were then implanted into the livers of 45 adult Wistar rats. Dexamethasone (2.5 mg/day) was injected intramuscularly daily for 1 week preoperatively and 2 weeks postoperatively. After 4 weeks of implantation, ultrasonography and nuclear magnetic resonance imaging (MRI) were performed to identify model rats with liver tumor growth and to analyze the growth and characteristics of the tumors. Five of these model rats were then sacrificed, and the tumors were removed from the liver for pathological examination. Three rats died during the operation; among the remaining 42 rats, 36 possessed a total of 43 liver tumors. The success rate of tumor implantation was 85.7 % (36/42), and the diameters of the tumors ranged from 5 to 10 mm. All tumor specimens were confirmed to be HCC by pathological examination. This study provides a new approach for establishing implanted HCC models in Wistar rats, which can be used for studying numerous biological features of HCC.

Establishment of NOD/SCID mouse models of human hepatocellular carcinoma via subcutaneous transplantation of histologically intact tumor tissue

Hepatocellular carcinoma (HCC) is one of the most deadly human cancers, but it is very difficult to establish an animal model by using surgical specimens. In the present experiment, histologically intact fresh surgical specimens of HCC were subcutaneously transplanted in non-obese diabetic/severe combined immunodeficienccy (NOD/SCID) mice. The biological characteristics of the original and the corresponding transplanted tumors and cell lines were investigated. The results showed that 5 new animal models and 2 primary cell lines were successfully established from surgical specimens. Hematoxylin-eosin staining showed that xenografts retained major histological features of the original surgical specimens. The two new cell lines had been cultivated for 3 years and successively passaged for more than 100 passages in vitro. The morphological characteristics and biologic features of the two cell lines were genetically similar to the original tumor. The subcutaneous transplant animal models with histologically intact tumor tissue and primary cell lines could be useful for in vivo and in vitro testing of anti-cancer drugs and be ideal models to study various biologic features of HCC.