Open AccessIntracellular Levels and Secretion of Insulin‐Like‐Growth‐Factor‐Binding Proteins in MCF‐7/6, MCF‐7/AZ and MDA‐MB‐231 Breast Cancer Cells
Author(s) -
Dubois Vincent,
Couissi Driss,
Schonne Edgard,
Remacle Claude,
Trouet André
Publication year - 1995
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1995.tb20779.x
Subject(s) - mcf 7 , antiestrogen , intracellular , secretion , endocrinology , estrogen receptor , estrogen , medicine , biology , cancer cell , insulin like growth factor binding protein , cell culture , receptor , cell growth , growth factor , insulin like growth factor , microbiology and biotechnology , cancer , breast cancer , biochemistry , human breast , genetics
The synthesis and secretion of insulin‐like growth factor binding proteins (IGFBPs) were studied in MDA‐MB‐231 (estrogen‐receptor‐negative), MCF‐7/6 (estrogen‐receptor‐positive, invasive) and in MCF‐7/AZ (estrogen‐receptor‐positive, non‐invasive) human breast carcinoma cell lines. Cells were grown or maintained in a chemically defined medium. Under these conditions, we found different patterns of IGFBPs in the three cell types. MDA‐MB‐231 cells secrete most of the IGFBPs they produce whereas MCF‐7/6 and MCF‐7/AZ cells maintain a high intracellular level. In MDA‐MB‐231 cells, the major IGFBP is IGFBP‐4 which is the minor form in MCF‐7/6 and MCF‐7/AZ cells. IGFBP‐2 and IGFBP‐5 are predominant in MCF‐7/6 cells while MCF‐7/AZ cells produce far less IGFBPs and do not contain detectable amounts of 29–32‐kDa forms (IGFBP‐5). In MCF‐7/6 cells, estradiol‐17β specifically decreases both the intracellular content and secretion of IGFBP‐2 and IGFBP‐5. Estrogen regulation of IGFBPs cell content and secretion was found to be tamoxifen‐resistant, and only slightly antagonized by ICI 182,780, a pure antiestrogen. The function of these regulations relative to the invasive phenotype and proliferation has now to be determined.