SELECTION OF A DEXAMETHASONE-RESISTANT H-4-IIE-C3 RAT HEPATOMA TISSUE-CULTURE LINE

Exposure of H-4-IIE-C3 rat hepatoma cell cultures to the synthetic glucocorticoid, dexamethasone, results in an inhibition of cellular proliferation which is not the result of steroid-induced cytolysis. A significant decrease in both the rat of DNA synthesis and DNA content precedes, a detectable effect on cell number. Continuous culture of H-4-IIE-C3 cells in medium containing 10-5m dexamethasone results in the selection of a steroid-resistant cell population that has the growth characteristics of unselected sensitive cultures and shows normal steroid induction of tyrosine transaminase. Selection is a slow process requiring 24 to 36 months to obtain, a phenotypically stable resitant cell line, and can be subdivided into three phases-a sensitive phase, adaptation and resistance. A comparison of the karyotypes of unselected and resistant cultures shows that the selection process enriches for a dexamethasone-resistant subpopulation. © 1979 Tissue Culture Association.