title: Phage display biopanning identifies the translation initiation and elongation factors (IF1α-3 and eIF-3) as components of Hsp70-peptide complexes in breast tumour cells.
abstract: The heat shock protein, HSP70, is over-expressed in many tumours and acts at the crossroads of key intracellular processes in its role as a molecular chaperone. HSP70 associates with a vast array of peptides, some of which are antigenic and can mount adaptive immune responses against the tumour from which they are derived. The pool of peptides associated with HSP70 represents a unique barcode of protein metabolism in tumour cells. With a view to identifying unique protein targets that may be developed as tumour biomarkers, we used purified HSP70 and its associated peptide pool (HSP70-peptide complexes, HSP70-PCs) from different human breast tumour cell lines as targets for phage display biopanning. Our results show that HSP70-PCs from each cell line interact with unique sets of peptides within the phage display library. One of the peptides, termed IST, enriched in the biopanning process, was used in a 'pull-down' assay to identify the original protein from which the HSP70-associated peptides may have been derived. The eukaryotic translation initiation factor 3 (eIF-3), a member of the elongation factor EF1α family, and the HSP GRP78, were pulled down by the IST peptide. All of these proteins are known to be up-regulated in cancer cells. Immunohistochemical staining of tumour tissue microarrays showed that the peptide co-localised with HSP70 in breast tumour tissue. The data indicate that the reservoir of peptides associated with HSP70 can act as a unique indicator of cellular protein activity and a novel source of potential tumour biomarkers.
authors: Moyne Institute for Preventive Medicine, School of Genetics and Microbiology, Trinity College Dublin, College Green, Dublin 2, Ireland.
authors: Christina
authors: C
authors: Siebke
authors: Tharappel C
authors: TC
authors: James
authors: Robert
authors: R
authors: Cummins
authors: Tony
authors: T
authors: O'Grady
authors: Elaine
authors: E
authors: Kay
authors: Ursula
authors: U
authors: Bond
mesh_terms: D015415:Biomarkers; D014408:Biomarkers, Tumor; D001943:Breast Neoplasms / Q000378:metabolism*; D045744:Cell Line, Tumor; D000091342:Endoplasmic Reticulum Chaperone BiP; D039621:Eukaryotic Initiation Factor-3 / Q000235:genetics / Q000378:metabolism*; D005260:Female; D005455:Fluorescent Antibody Technique; D018840:HSP70 Heat-Shock Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D013058:Mass Spectrometry; D046228:Microarray Analysis; D046912:Multiprotein Complexes / Q000737:chemistry; D019151:Peptide Library; D039665:Prokaryotic Initiation Factor-3 / Q000235:genetics / Q000378:metabolism*; D015854:Up-Regulation
chemical_list: D015415:Biomarkers; D014408:Biomarkers, Tumor; D000091342:Endoplasmic Reticulum Chaperone BiP; D039621:Eukaryotic Initiation Factor-3; D018840:HSP70 Heat-Shock Proteins; C000717247:HSPA5 protein, human; D046912:Multiprotein Complexes; D019151:Peptide Library; D039665:Prokaryotic Initiation Factor-3