Rat Liver Epithelial Lines

The long-term rat liver epithelial lines are used for mutagenesis studies because of the need for cell proliferation in such studies. The mutation that has been studied is in the hypoxanthine-guanine phosphoribosyl transferase (HGPRT) locus. This locus is on the X chromosome, and therefore only one 

TABLE 4. Hepatocyte Primary Culture/DNA Repair Assay Results on Structural Types of Activation-Dependent Carcinogens 

TABLE 5. DNA Synthesis in Hepatocyte Primary Cultures in the Presence of 

To obtain the maximum number of mutants from mutagen exposure, the interval between exposure and mutant selection must be optimized. This interval, called the expression time or phenotypic lag, allows for replication of DNA and fixation of the mutations, but probably more important, reduction of the level of HGPRT present in cells at the time of mutation. For the rat liver lines, the expression time is about 10 days.  

the protocol for a typical mutagenesis study is exposure of proliferating cultures to a mutagen for 3 days, removal of the mutagen, subculture at confluency, subculture as required over the next 14 days, and finally subcul- 

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TABLE 6. Mutagenesis by Carcinogens in Rat Liver Epithelial Line ARL 6"... 

Hepatocyte-Mediated Mutagenesis of Rat Liver Epithelial Lines... 

In the heptatocyte-mediated mutagenesis studies, freshly isolated hepatocytes were mixed in a ratio of about 2 1 with liver epithelial cells before inoculation into culture flasks. After attachment, the two cell types were found to be well mixed and in close contact. Exposure of mixed cultures to several activation-dependent carcinogens that produce DNA repair in hepatocytes also produced mutagenesis in the cocultivated rat liver epithelial lines (Table 7) under conditions of exposure in which the carcinogens were not mutagenic to the lines in the absence of cocultivated hepatocytes. Thus, activated metabolites produced by the hepatocytes were transferred to the epithelial cells. Efforts to simplify this assay by the use of stored frozen hepatocytes are in progress. 

C. Tong and G. M. Williams, Induction of purine analog-resistant mutants in adult rat liver epithelial lines by metabolic activation-dependent and -independent carcinogens, Mutat. Res. 55,339-352 (1978). 

Kenne K, Fransson-Steen R, Honkasalo S, et al. 1994. Two inhibitors of gap junctional intercellular communication, TPA and endosulfan Different effects on phosphorylation of connexin 43 in the rat liver epithelial cell line, lAR 20. Carcinogenesis 15(6) 1161-1165. 

Briggs JA, Briggs RC. 1988. Characterization of chromium effects on a rat liver epithelial cell line and their relevance to in vitro transformation. Cancer Res 48 6484-6490. 

Upham BL, Rummel AM, Carbone JM, Trosko JE, Ouyang Y, Crawford RB, Kaminski NE (2003) Cannabinoids inhibit gap junctional intercellular communication and activate ERK in a rat liver epithelial cell line. Int J Cancer 104 12-18... 

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