title: Influence of phomopsin and ivalin on steroid-hormone binding and growth of MCF-7 human breast cancer cells.
abstract: Ivalin is a plant alkaloid that inhibits the induction of tumors in animals. Phomopsin is a mycotoxin known to be carcinogenic. To determine if these compounds influence endocrine responsiveness, their effect on steroid receptors was measured. Neither of these toxins had a direct effect on either the binding capacity or the rate of steroid association of [3H]estradiol-17 beta, [3H]R5020, or [3H]dexamethasone to their respective receptors in cytosol of human breast cancer and rat liver. However, steroid receptor levels of MCF-7 cells, grown in tissue culture, were altered by ivalin and phomopsin. Ivalin at 10(-6) M depressed estrogen receptor levels, while glucocorticoid receptor levels were increased. At 10(-6) M, phomopsin was inhibitory of both progestin and glucocorticoid binding capacities. Data obtained from the proliferation of MCF-7 cells indicated that ivalin and phomopsin at 10(-6) M decreased the number of cells grown in tissue culture. Phomopsin exhibited an inhibitory effect on both [3H]thymidine and [3H]glycine incorporation, while ivalin stimulated [3H]glycine incorporation.
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology; D001943:Breast Neoplasms / Q000378:metabolism / Q000473:pathology*; D002455:Cell Division / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D003907:Dexamethasone / Q000378:metabolism; D004958:Estradiol / Q000378:metabolism; D005260:Female; D005998:Glycine / Q000378:metabolism; D006801:Humans; D007783:Lactones; D009183:Mycotoxins / Q000494:pharmacology*; D011397:Promegestone / Q000378:metabolism; D011987:Receptors, Steroid / Q000032:analysis / Q000187:drug effects*; D012717:Sesquiterpenes / Q000494:pharmacology*; D013936:Thymidine / Q000378:metabolism; D014316:Tritium; D009842:Oligopeptides
chemical_list: D000970:Antineoplastic Agents; D003907:Dexamethasone; D004958:Estradiol; D005998:Glycine; D007783:Lactones; D009183:Mycotoxins; D011397:Promegestone; D011987:Receptors, Steroid; D012717:Sesquiterpenes; D013936:Thymidine; D014316:Tritium; C049171:ivalin; C035753:phomopsin; D009842:Oligopeptides