Metabolism of estradiol-17β, 5-androstene-3β,17β-diol and testosterone in human breast cancer cells in long-term culture

The human breast cancer cell line MCF-7 is able to metabolize steroids, which are added in order to study the growth rate of these cells. The following steroids: estradiol-17β, 5-androstene-3β,17β-diol and testosterone were incubated with these cells for 48 h under identical conditions used for growth-rate studies in our laboratory. The metabolites formed were identified. The conversion of estradiol-17β to estrone was 7% and no estriol was formed. The conversion of 5-androstene-3β-17β-diol to dehydroepiandrosterone was 8.1%, to testosterone 1.0% and to 5α-androstane-3β,17β-diol 3.2%. The conversion of testosterone to androstenedione was 6.5%, to etiocholanolone 0.4%, to 5α-dihydrotestosterone 0.7%, to 5-androstene-3β,17β-diol 0.5% and to androstenediol 0.2%. Some of these metabolites, due to their relative binding affinity, may have a biological effect on these cells that contain androgen and estrogen receptors

Increased phospholipase a activity and formation of communicative contacts between Acanthamoeba castellanii cells

1. 1. Exogenous 1-palmitoyl-sn-glycero-3-phosphorylcholine becomes incorporated into the membrane of A. castellanii within 2 min of incubation. 2. 2. Homogenates of A. castellanii are shown to contain phospholipase A activity. 3. 3. The phospholipase A activity is dependent on the population density of the culture. 4. 4. An increased phospholipase A activity in older cultures of A. castellanii, due to an increased population density, induces aggregation of these cells in a way that communicative contacts are formed. 5. 5. At pH 5.5, the pH value at which the cells were grown, the phospholipase A activity is stimulated by cAMP; at pH 8.0 no stimulation occurs