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Evidence for Altered Gene Regulation in HeLa Cells Returned to Culture after Growing in Immunosuppressed Rats¹

Department of Anatomy, Fairleith Dickinson University School of Denistry, Hackensack, New Jersey 07601

HeLa TCRC-1 is a monophenotypic cell line for the production of the carcinoplacental Regan isoenzyme of alkaline phosphatase. It has been previously reported that, when this cell line is grown in immunosuppressed rats, there is an alteration of phenotypic expression in that an isoenzyme that is referred to as oncoamnion (FL) becomes the dominant enzyme form. This report describes the isoenzyme regulation after these cells are returned to culture for at least three months. These cells in culture demonstrate a density-dependent alteration in isoenzyme profiles. The Regan isoenzyme is the dominant isoenzyme form in new, sparsely populated cultures, while the oncoamnion isoenzyme predominates in the later high-density stages of growth. Prednisolone induction of enzyme activity is found to be most effective in the early stages of growth, and the previously reported specificity of hormone action on isoenzymes produced by cancer cells is maintained. Enzyme induction is restricted to the Regan isoenzyme, while hormone-mediated diminution in enzyme activity is confined to the oncoamnion (FL) isoenzyme.

¹ Presented at the Conference, "Regulation of Gene Expression in Development and Neoplasia," June 2 to 5, 1976, Santa Ynez, Calif. This work was supported by Grants-in-Aid CA-12924 and CA-13332 from the National Cancer Institute, NIH, Bethesda, Md., and by Grant CTR 935-M from the Council for Tobacco Research.