Influence of steroids and retinoic acid on peanut-lectin binding of human breast cancer cells.
Membrane binding sites for peanut lectin or peanut agglutinin (PNA) were investigated in the established mammary carcinoma cell lines MCF-7, 734-B, ZR-75.1 and BT-20. The determination of PNA binding sites was performed in a flow cytometer after staining with fluorescein(FITC)-labeled PNA. It appeared that only the estrogen-sensitive cell lines exhibited PNA binding sites, whereas the hormone-insensitive cell line BT-20 was clearly negative. Steroid hormones, when administered singly to the cells in physiological concentrations (10(-9)-10(-8) M) had no effect on PNA binding expression. Only the combination of estradiol and progesterone together increased PNA binding sites. Pharmacological doses (10(-6) M) of medroxyprogesteroneacetate (MPA) and dexamethasone increased the number of binding sites, whereas retinoic acid decreased them. A preliminary characterization of the binding sites revealed that they have high capacity and moderate affinity for PNA (KD greater than 10(-7) M). FITC-PNA binding could be inhibited selectively by fetuin (greater than 10(-5) M) and by galactose (greater than 10(-2) M). Cytosol from MCF-7 cells and from some primary breast cancer specimens were able to decrease PNA binding to the surface of 734-B cells.
D001943:Breast Neoplasms / Q000032:analysis*; D002460:Cell Line; D003907:Dexamethasone / Q000494:pharmacology; D005260:Female; D016650:Fluorescein-5-isothiocyanate; D005452:Fluoresceins; D006801:Humans; D008525:Medroxyprogesterone / Q000031:analogs & derivatives / Q000494:pharmacology; D017258:Medroxyprogesterone Acetate; D011975:Receptors, Mitogen / Q000032:analysis* / Q000187:drug effects; D013256:Steroids / Q000494:pharmacology*; D013861:Thiocyanates; D014212:Tretinoin / Q000494:pharmacology*
D005452:Fluoresceins; D011975:Receptors, Mitogen; D013256:Steroids; D013861:Thiocyanates; C038223:peanut agglutinin receptor; D014212:Tretinoin; D003907:Dexamethasone; D017258:Medroxyprogesterone Acetate; D008525:Medroxyprogesterone; D016650:Fluorescein-5-isothiocyanate