Effect of hydrocortisone on HeLa cells with special reference to the RNA metabolism.

Abstract

Hydrocortisone (HC) inhibited the growth of HeLa cells at the concentration of 0.01-10μg/ml but enhanced it at 0.001μg/ml.HC increased the β-glucuronidase and alkaline phosphatase activities of HeLa cells at 10μg/ml in 4 days, although it did not affect the acid phosphatase activity.Nucleic acids obtained from growing HeLa cells were fractionated by methylated bovine serum albumin column chromatography. Two peaks of rapidly labeled RNA were found in the chromatogram, and from the experiment of time course of 32P-labeling and base composition analysis, it was assumed that one was the precursor of r-RNA and the other d RNA possibly containing m-RNA.HC (10μg/ml) inhibited the synthesis of nucleic acid in HeLa cells; in early period of HC treatment, only the d-RNA synthesis was slightly inhibited, while with longer treatment the synthesis of r-RNA precursor was most strongly inhibited in contrast with the weak inhibition of DNA and d-RNA syntheses.From these data, the relationship between the catabolic action and enzyme-inducing action of HC was discussed.