title: Insulin-like growth factor binding protein-3 interacts with autocrine motility factor/phosphoglucose isomerase (AMF/PGI) and inhibits the AMF/PGI function.
abstract: Autocrine motility factor/phosphoglucose isomerase (AMF/PGI) was identified as a binding partner for insulin-like growth factor binding protein-3 (IGFBP-3) in solubilized T47D and MCF-7 human breast cancer cell membranes. The interaction between AMF/PGI and IGFBP-3 was verified by cross-linking biotinylated IGFBP-3 to intact cells. After solubilization of the membranes, the biotinylated complexes were precipitated with streptavidin-agarose conjugate and analyzed by SDS-PAGE. A M(r) approximately 80,000 complex was identified when the nitrocellulose membranes were probed either with streptavidin-horseradish peroxidase conjugate or AMF/PGI antiserum confirming the cross-linking of IGFBP-3 to AMF/PGI. The interaction between IGFBP-3 and AMF/PGI was also further confirmed by ligand blotting of purified AMF/PGI using biotinylated IGFBP-3. Both glycosylated and nonglycosylated IGFBP-3 inhibited the catalytic activity of AMF/PGI in a dose-dependent fashion. In addition, IGFBP-3 inhibited the binding of AMF/PGI to breast cancer cells and AMF/PGI-induced migration of both T47D and MCF-7 human breast cancer cells. IGFBP-3 also decreased the phosphorylation of AMF/PGI and reduced the translocation of AMF/PGI to the cell membrane and AMF/PGI. AMF/PGI resulted in a dose-dependent inhibition of IGFBP-3 induced apoptosis in T47D and MCF-7 cells. In summary, we have identified AMF/PGI as a membrane-associated binding partner for IGFBP-3 in breast cancer cells. The ability of IGFBP-3 to bind and inhibit the actions of AMF/PGI may have some role in the antiproliferative proapoptotic effects of IGFBP-3.
authors.affiliation: Department of Physiology, University of Manitoba, Winnipeg, Manitoba, Canada.
authors.forename: Suresh
authors.initials: S
authors.lastname: Mishra
authors.forename: Avrahram
authors.initials: A
authors.lastname: Raz
authors.forename: Liam J
authors.initials: LJ
authors.lastname: Murphy
mesh_terms: D017209:Apoptosis / Q000502:physiology; D001943:Breast Neoplasms / Q000378:metabolism / Q000473:pathology; D002384:Catalysis; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism; D002465:Cell Movement / Q000187:drug effects; D005956:Glucose-6-Phosphate Isomerase / Q000037:antagonists & inhibitors* / Q000302:isolation & purification / Q000378:metabolism*; D006801:Humans; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000037:antagonists & inhibitors / Q000302:isolation & purification / Q000378:metabolism* / Q000494:pharmacology; D010766:Phosphorylation; D011485:Protein Binding
chemical_list: D018972:Insulin-Like Growth Factor Binding Protein 3; D005956:Glucose-6-Phosphate Isomerase