A diploid rat liver cell culture

Abstract

Chronic exposure of a cloned rat hepatocyte culture (RL-PR-C) to a subtoxic, sublethal dose of aflatoxin B1 resulted in malignant transformation. Continuous exposure to aflatoxin B1 caused increasing tumorigenic potential as tested by back injection into isogenic animals. Control cultures exhibited spontaneous transformation, although approximately 20 passages beyond the chemically induced event. Neither aflatoxin-treated nor control cultures exhibited cytopathological morphology, formation of cell foci, growth in soft agar, or irregular fibroblast-like growth patterns that could be specifically related to the onset of tumorigenic potential. In general, those parameters commonly used to monitor fibroblast cultures for transformation in vitro were not applicable for assessing the tumorigenic potential of these epithelial cells. Karyotypic analyses revealed no specific chromosomal aberrations associated with aflatoxin treatment; however, chromosomal instability was a property of the tumorigenic cell populations. Injection of both aflatoxin-treated and control cultures at passage 56 resulted in tumors indicative of both carcinoma and sarcoma indicating to us the multipotency of these epithelial cells transformed in vitro.

Restoration of glucagon responsiveness in spontaneously transformed rat hepatocytes (RL-PR-C) by fusion with normal progenitor cells and rat liver plasma membranes.

“…Normal (70-150 population doublings) and transformed (300-400 population doublings) RL-PR-C hepatocytes were cultured as described (8,9). The criteria for spontaneous transformation were those of Schaeffer et al (6,7,12 The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U. S. C. §1734 solely to indicate this fact.…”

“…These cells represent a unique model system for investigating hormonal regulation of adenylate cyclase. For well over a year (over 200 population doublings) they remain stable culturally and karyotypically, during which time they display a wide variety of liver functions, including the production of many specific liver enzymes and structural proteins (7) and responsiveness to insulin (8), cholera toxin (9), catecholamines (10), and glucagon (11). After this stable periodi.e., between 200 and 300 population doublings-the cells spontaneously transform and acquire the cultural and chromosomal characteristics of cells transformed by artificial means, including loss of contact inhibition and tumorigenicity in isogenic animals (12), and also become insensitive to glucagon (11).…”

Biochemical effects of 12‐O‐tetradecanoylphorbol‐13‐acetate, retinoic acid, phenobarbital, and 5‐azacytidine on a normal rat liver epithelial cell line

“…Two important aspects of the "oval" cell are: (1) It may constitute the hepatocytic stem cell and under appropriate conditions may differentiate into a n hepatocyte (Inaoka, 1967;Lombardi, 1982); and (2) it may be the precursor cell of hepatocellular carcinoma induced by chemical carcinogens (Sell and Leffert, 1982). Rat liver epithelial cells in culture can be transformed in vitro by multiple brief (Tsao et al, 198413;Shimada et al, 1983) or prolonged and continuous (Williams et al, 1973;Borenfreund et al, 1975;Montesano et al, 1975;Schaeffer and Heintz, 1978;Brown et al, 1983) exposures to chemical carcinogens. Transformation experiments with multiple brief treatments of the diploid WB-F344 rat liver epithelial cell line with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) showed cellular phenotypic changes which suggested the existence of a multistage process (Tsao et al, 1984b).…”