title: Predictive value of SRC-1 for tamoxifen response of recurrent breast cancer.
abstract: Tamoxifen causes an objective response in about one-third of metastatic breast cancer and in only half of the breast cancer patients with estrogen receptor (ER) positive tumors. Steroid-receptor coactivator-1 (SRC-1) appears to be a general coactivator for steroid receptors and rate limiting factor necessary for efficient ER transactivation. We aimed to evaluate whether SRC-1 expression is an additional factor for prediction of response to first-line tamoxifen therapy in patients who developed recurrent disease. Here for the first time, we report on SRC-1 expression using a semi-quantitative RT-PCR in 21 primary breast tumors, seven mammary tumor cell-lines, 12 fibroblast cultures, and six normal breast tissues. The highest levels of SRC-1 were observed in normal tissues, intermediate levels in tumor tissues, and the lowest levels in breast tumor cell-lines. There was no relationship between the levels of SRC-1 in these primary tumors and the proportion of tumor cells within the surgical samples, nor with ER status. The median SRC-1 level was, however, lower in tumors from patients that did not respond to tamoxifen. Our findings suggest that high levels of SRC-1 indicate a favorable response to tamoxifen of patients with recurrent breast cancer.
authors.affiliation: Department of Medical Oncology, Rotterdam Cancer Institute (Daniel den Hoed Kliniek)/University Hospital Rotterdam, The Netherlands. berns@bidh.azr.nl
authors.forename: E M
authors.initials: EM
authors.lastname: Berns
authors.forename: I L
authors.initials: IL
authors.lastname: van Staveren
authors.forename: J G
authors.initials: JG
authors.lastname: Klijn
authors.forename: J A
authors.initials: JA
authors.lastname: Foekens
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018931:Antineoplastic Agents, Hormonal / Q000627:therapeutic use*; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D005260:Female; D051548:Histone Acetyltransferases; D006801:Humans; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000188:drug therapy; D056920:Nuclear Receptor Coactivator 1; D011379:Prognosis; D011987:Receptors, Steroid / Q000032:analysis; D013629:Tamoxifen / Q000627:therapeutic use*; D014157:Transcription Factors / Q000032:analysis*; D014407:Tumor Cells, Cultured
chemical_list: D018931:Antineoplastic Agents, Hormonal; D011987:Receptors, Steroid; D014157:Transcription Factors; D013629:Tamoxifen; D051548:Histone Acetyltransferases; C538859:NCOA1 protein, human; D056920:Nuclear Receptor Coactivator 1