title: Differential effects of estrogen and antiestrogen on in vitro clonogenic growth of human breast cancers in soft agar.
abstract: Of 534 human primary breast cancers provided for clonogenic assay in vitro, 276 (51.7%) developed distinctive colony formation by the soft-agar method. Estrogen receptors (ERs) were assayed by dextran-coated charcoal methods. A total of 65 (23.7%) of 274 breast cancers responded to added 10 nM 17 beta-estradiol (E2) by an increase in the number of colonies per dish of 150% or more of that in the controls treated with dextran-coated charcoal. The ER-positive and ER-negative tumors differed significantly in their response to E2: 55 (29.9%) of 184 ER-positive tumors responded versus 10 (11.1%) of 90 ER-negative tumors. The cancers in which the number of colonies increased to 150% or more of that of the controls were considered to be estrogen dependent; those in which the number of colonies increased to less than 150% of the control values were considered to be estrogen independent. When 1 microM tamoxifen (TMX) was added to the medium, 48 (21.3%) of 225 cancers showed a decreased in the number of colonies to 50% or less of that of the controls. Thus, we could separate breast cancers that were TMX sensitive (No. of colonies less than or equal to 50% of that of controls) from those that were TMX resistant (No. of colonies greater than 50% of that of controls). The response to TMX of the ER-positive cancers was significantly higher than that of the ER-negative tumors: 39 (25.5%) of 153 ER-positive tumors responded versus nine (12.5%) of 72 ER-negative tumors. In 153 ER-positive and 71 ER-negative tumors, we evaluated the correlation between the response to E2 and the response to TMX. ER-positive and ER-negative tumors differed significantly in their sensitivities to the two drugs. The TMX sensitivity did not completely correlate with the E2 dependence.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Breast Surgery, National Kyushu Cancer Center Hospital, Fukuoka, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Nomura
authors.forename: H
authors.initials: H
authors.lastname: Tashiro
authors.forename: K
authors.initials: K
authors.lastname: Hisamatsu
mesh_terms: D001943:Breast Neoplasms / Q000188:drug therapy* / Q000473:pathology; D002455:Cell Division / Q000187:drug effects; D004958:Estradiol / Q000494:pharmacology*; D004967:Estrogens; D005260:Female; D006801:Humans; D009376:Neoplasms, Hormone-Dependent / Q000188:drug therapy* / Q000473:pathology; D013268:Stimulation, Chemical; D013629:Tamoxifen / Q000494:pharmacology*; D014407:Tumor Cells, Cultured; D014410:Tumor Stem Cell Assay
chemical_list: D004967:Estrogens; D013629:Tamoxifen; D004958:Estradiol