title: The insulin-like growth factor binding protein BP-25 is expressed by human breast cancer cells.
abstract: Specific binding proteins are thought to modulate the effects of IGF-I. Previous work has demonstrated that media conditioned by human breast cancer cells contains IGF-I binding activity. Radiolabelled IGF-I incubated with serum-free conditioned media from the breast cancer cell line MDA-MB 231 eluted with an apparent M.W. of 35-40 kDa when analyzed by gel filtration chromatography at pH 7.4. The M.W. of this binding activity corresponded to that of BP-25, a binding protein cloned from the hepatocellular carcinoma cell line HepG2. Two breast cancer cell lines, MDA-MB 231 and Hs578T, were found to express BP-25 RNA. Specific BP-25 radioimmunoassay detected BP-25 production in the conditioned media of these two cell lines. Immunoprecipitation confirmed that metabolically labelled MDA-MB 231 released 30 kDa BP-25 into its medium. This study demonstrates that some breast cancer cells express the IGF-I binding protein, BP-25.
authors: Medicine Branch, National Cancer Institute, Bethesda, Maryland 20892.
authors: D
authors: D
authors: Yee
authors: R E
authors: RE
authors: Favoni
authors: R
authors: R
authors: Lupu
authors: K J
authors: KJ
authors: Cullen
authors: G S
authors: GS
authors: Lebovic
authors: K K
authors: KK
authors: Huff
authors: P D
authors: PD
authors: Lee
authors: Y L
authors: YL
authors: Lee
authors: D R
authors: DR
authors: Powell
authors: R B
authors: RB
authors: Dickson
mesh_terms: D001943:Breast Neoplasms / Q000378:metabolism*; D002352:Carrier Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D002460:Cell Line; D005260:Female; D006801:Humans; D018969:Insulin-Like Growth Factor Binding Proteins; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D008970:Molecular Weight; D012334:RNA, Neoplasm / Q000235:genetics; D013002:Somatomedins / Q000378:metabolism*
chemical_list: D002352:Carrier Proteins; D018969:Insulin-Like Growth Factor Binding Proteins; D012334:RNA, Neoplasm; D013002:Somatomedins; D007334:Insulin-Like Growth Factor I