ABSTRACT
In vitro assay for carcinogenesis, using mammalian cells, provide opportunity for rapid and inexpensive means, compared to in vivo assays, for studying carcinogenesis and for identifying potential carcinogens. These assays must, however, be shown to be reproducible, reliable and able to detect a variety of known carcinogens before they can be recommended for general use. We have, independently, reproduced a transformation assay which utilizes murine leukemia virus-infected rat embryo cells as targets. In the process a new culture, designated 2FR4(50), was generated to replace the F1706 line, of Freeman, which is no longer available. Through careful control of the assay parameters a readily reproducible test has been developed. In 2-4 culture passages after chemical treatment, morphologically transformed foci of cells are observed while no such foci are found in noncarcinogen treated or control cultures. Over 75 compounds have been tested in this assay; 20 of these are detailed here as representative of the chemically diverse types of carcinogens detected.
Subject(s)
Carcinogens/pharmacology , Cell Transformation, Neoplastic/drug effects , Leukemia, Experimental/pathology , Animals , Cell Line , Cells, Cultured , Embryo, Mammalian , Female , Rats , Rats, Inbred F344 , Rauscher VirusABSTRACT
A modified in vitro transformation assay demonstrated potential for use in the identification and study of tumor promoters. Rauscher murine leukemia virus-infected F344 rat embryo cells were transformable by various chemical carcinogens when they were administered at appropriate doses. Cells treated with subeffective doses of 3-methylcholanthrene did not transform. However, when these cells were regularly treated with 12-O-tetradecanoylphorbol 13-acetate, sodium phenobarbital, limonene, oleic acid, lauric acid, or saccharin, transformation was observed. Thus several dhemically diverse in vivo tumor promoters behaved as promoters in this in vitro system. This assay appeared to be useful for in vitro efforts to identify promoters and may be of value in studies on the mechanisms of action of these cocarcinogens.