Identification of the insulin-like growth factor binding proteins 5 and 6 (IGFBP-5 and 6) in human breast cancer cells

M. Saeed Sheikh, Zhi Ming Shao, David R. Clemmons, Derek Leroith, Charles Roberts, Joseph A. Fontana

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Abstract

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 languageEnglish (US)
Pages (from-to)1003-1010
Number of pages8
JournalBiochemical and Biophysical Research Communications
Volume183
Issue number3
DOIs
Publication statusPublished - Mar 31 1992
Externally publishedYes

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ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Molecular Biology

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