A Novel Model of Solitary Hepatic Tumor in Rats Using Ascites Hepatoma AH13: Suitability for Chemotherapeutic Studies

Abstract

A highly reproducible model of a solitary hepatic tumor in rats using ascites hepatoma AHI3 has been developed using a two-step method which was suitable for quantitative chemotherapeutic studies. Diffuse hepatic metastases were induced first by inoculation of three different ascites hepatomas, AHI3, AHI30 and AH7974 into the portal vein in a dose-dependent fashion. Second, the induced hepatic tumor (3 X 10' cells) was minced into I X I X 4 mm fragments and implanted in the liver of normal rats. In this procedure, the AHI3 strain proved best suited for the generation of a solitary hepatic tumor. The growth of the solitary liver tumor using AHI3 was highly reproducible. To demonstrate the suitability of this solitary hepatic tumor model for the evaluation of chemotherapy, the tumor-burdened rats were treated with adriamycin (A DR) and mitomycin C (MMC). The reduction in tumor size was proportional to dosage, and the statistical significance of the differences between the treatment group and control group was proportional to dosage. A synergistic effect of ADR and MMC on the tumor also was demonstrated. This model should prove to be a useful tool for the testing of newly developed treatments of hepatic cancer. Key words: Rat model -Solitary hepatic tumorThe liver is a major site of both primary and metastatic cancer. Hepatocellular carcinoma, which is the most common primary hepatic cancer,l) ranks third in incidence among all malignancies in Japan 2 ) and its prognosis remains disappointing. 3 -5 ) Hepatic metastases occur frequently in a variety of human cancers. 6 ) However, few animal models exist which are appropriate to evaluate the efficacy of hepatic cancer treatment.Previous hepatic tumor models in rats generally used long-term, continuous exposure to a carcinogen added to the diet'-l1) or injection of an established tumor cell line into the portal circulation. 12 -20 ) However, these preparations require a long time for tumor development and data concerning the "change in tumor size" are unavailable. Therefore, experiments designed to evaluate new approaches to the treatment of hepatic cancer have been hampered by the lack of an appropriate model.In this paper, we describe a two-step method of generating a solitary hepatic tumor using ascites hepatoma AH13 in rats,-and its suitability for chemotherapeutic studies. MATERIALS AND METHODSAnimals and tumor cell lines Male Donryu rats aged 5 to 6 weeks were obtained from Japan SLC Co., Ltd. (Shizuoka) and used in all experiments.I To whom reprint requests should be addressed.AH13, AH130 and AH7974 rat ascites hepatomas were generous gifts from Dr. H. Nagayama, Research Institute for Tuberculosis and Cancer, Tohoku University, Sendai. Cells were maintained in ascites in normal Donryu rats. Diffuse hepatic metastases induction by injection of tumor cells into the portal vein of rats Tumor cells used for injection were centrifuged twice in RPMI 1640 medium (M. A. Bioproducts, Walkersville, MD) at 250g for 6 min, and the cells to be injected, 1 X 10 6 to 3 X 10...