[Inhibitory effect of progesterone P1-1 on glutathione-s-transferase and its antiproliferative effect on human erythroleukemia K562 cells].

Since glutathione S-transferase P1-1 (GST P1-1) is predominantly expressed in many types of tumor cells it is regarded as its marker protein. The report discusses data on a relationship between progesterone (PS) inhibition of GST P1-1 and proliferation of human erythroleukemia K562 cells. Unlike such steroids as estrone, dexamethasone, testosterone and hydrocortisone, PS showed significant inhibitory effect (I50 = 32.5(M) and noncompetitively (Ki = 25(M) inhibited GST P1-1 isolated from human placenta. Pronounced inhibition of K562 cell proliferation by PS was in inverse correlation with the intracellular activity of GST P1-1. Also, PS injected into culture suppressed GST P1-1 expression in leukemia cells. At concentrations of 10(-8)-10(-5) M, both effects proved dose-dependent. The correlation between PS antiproliferative effect on GST P1-1 activity and expression in K562 cells is discussed in terms of its possible role played in malignant growth regulation.