Four estrogen receptor-positive (ER+) [MCF-7, T47D, ZR75 and BT474 ] and 3 ER- [Hs578T, MDA-MB-468 and MDA-MB-231] human breast cancer cell lines were examined for expression of the IGFBP-5 and IGFBP-6 genes. Northern blot analysis revealed that all cell lines, except MDA-MB-231, expressed IGFBP-5 mRNA. IGFBP-6 mRNA, however, was expressed only by the ER- cell lines. Western immunoblotting indicated that the previously unidentified 31-kDa and 32-kDa IGF binding species secreted by these cell lines are IGFBP-5. The levels of IGFBP-4 and IGFBP-5 were increased in MCF-7 cells by estradiol and IGF-I, respectively, indicating that these BPs may contribute to the growth stimulatory response to these mitogens.
|Original language||English (US)|
|Number of pages||8|
|Journal||Biochemical and Biophysical Research Communications|
|State||Published - Mar 31 1992|
ASJC Scopus subject areas
- Molecular Biology
- Cell Biology