Roman J. Pienta

Transformation of hamster embryo cells by cholesterol-α-epoxide and lithocholic acid*

Summary Cholesterol and its α -oxide have been tested for their ability to transform hamster embryo cells, but only the epoxide, a suspected carcinogen, was active. Similarly, tests with sulfolithocholic and lithocholic acids showed that sulfolithocholic was negative in this system, whereas lithocholic acid transformed the mammalian cells. These results indicate that the hamster embryo cell transformation system can detect the more active compound in a given substrate-metabolite series and may be useful for screening endogenously-formed steroid metabolites for their potential carcinogenicity.

Correlation of bacterial mutagenicity and hamster cell transformation with tumorigenicity induced by 2,4-toluenediamine*

In the presence of rat liver microsome enzymes, 2,4-toluenediamine (TDA) was mutagenic for several tester strains of Salmonella typhimurium. TDA induced morphological transformation in an in vitro carcinogenesis system using secondary culture target cells prepared from cryopreserved primary Syrian hamster embryo cells. These results now correlate bacterial mutagenicity and in vitro morphological transformation with the reported tumorigenicity of this compound.

Transformation of hamster embryo cells by neutral sterols and bile acids

Toxicity and cell transformation of Syrian hamster embryo cells in culture by certain neutral sterols and bile acids show interesting trends related to their structures: cholesterol-alpha-epoxide and cholestan-3 beta, 5 alpha, 6 beta-triol were more toxic and induced transformation to these cells, whereas their metabolic precursor, cholesterol, was inactive. The secondary bile acids, lithocholic and deoxycholic acids, were more toxic than their primary bile acid precursors, cholic and chenodeoxycholic acids and transformed the cells. These data suggest that mammalian cell transformation is a useful short-term assay to measure the potential toxicity and carcinogenicity of steroid derivatives.

Malignant transformation of cryopreserved early passage syrian golden hamster cells by 2-(2-furyl)-3-(5-nitro-2-furyl)-acrylamide

2-(2-Furyl)-3-(5-nitro-2-furyl)-acrylamide (AF-2) induced the malignant transformation of secondary cultures of Syrian golden hamster embryo cells prepared from cryopreserved primary cells. Transformed cells grew in semi-solid agar medium and formed sarcomas when inoculated subcutaneously into non-immunosuppressed suckling hamsters.

A High Pressure Liquid Chromatography Procedure for the Separation of Metabolites of 2-Acetylaminofluorene from Cells in Culture

Abstract A method is presented for the determination of pmole levels of the carcinogenic metabolite N-hydroxy-2-acetylaminofluorene (N-hydroxy-AAF) formed from N-2-acetylaminofluorene (AAF) by cells in culture. The extract from the cells and cell incubation medium was given a preliminary cleanup using thin layer chromatography. N-hydroxy-AAF was then isolated using high-pressure liquid chromatography (HPLC) with a Waters Bondapak C18/Corasil column and an acetonitrile-water elution system. Ring hydroxylation products were eluted with 23% acetonitrile, and AAF and the deacetylation product 2-aminofluorene (AF) were eluted with 33% acetonitrile. Resolution of N-hydroxy-AAF was accomplished using a linear gradient of from 33% to 99% acetonitrile. When cells in culture were incubated with 22 nmoles/ml of AAF for 6 h, 690 pmoles of N-hydroxy-AAF per 106 cells were formed by hamster hepatocytes compared with 13 and 8 pmoles/106 cells for human embryo and hamster embryo cells respectively. The rate of formation ...

Factors affecting the binding of polycyclic aromatic hydrocarbons to human embryo cells, and transformable and non-transformable hamster embryo cells☆

The effects of various factors, including population doubling number, percent of confluence, serum concentration and storage in liquid nitrogen on the binding of several polycyclic aromatic hydrocarbons to human and hamster embryo cells were studied. The binding of 7,12-dimethylbenz[a]-anthracene (DMBA) to hamster embryo cells DNA, RNA and protein was maximal after 22 h of treatment. In contrast, binding to human embryo cell macromolecules increased for at least 55 h. Treatment of hamster embryo cells at 100% confluence resulted in much less binding than treatment at 70% confluence, whereas with human embryo cells the binding increased, or remained constant, following treatment at the greater confluence. The transforming frequency of hamster embryo cells decreases with increasing population doubling number. Accordingly, we found that the binding of DMBA to hamster embryo DNA, RNA and protein decreased approximately 100-fold between population doubling numbers 8 and 20. In transformable cell cultures, DMBA was bound to hamster embryo cell DNA to a greater extent than to RNA or protein. The binding of DMBA to nucleic acids was much greater than binding by either dibenz[a,h]anthracene (DB[a,h]A) or dibenz-[a,c]anthracene (DB[a,c]A), both of which had low binding values at all population doubling numbers tested. Therefore, the best correlation of binding with carcinogenicity and transforming activity was observed with DMBA. Storage of hamster embryo cells in liquid nitrogen did not alter their binding characteristics. Binding of all three hydrocarbons to human embryo cell nucleic acids was low during all population doubling numbers studied, while binding to cellular protein increased until population doubling number 70 and then decreased sharply.