title: Identification of a potential tumor differentiation factor receptor candidate in prostate cancer cells.
abstract: Tumor differentiation factor (TDF) is a pituitary protein that is secreted into the bloodstream and has an endocrine function. TDF and TDF-P1, a 20-residue peptide selected from the ORF of TDF, induce differentiation in human breast and prostate cancer cells, but not in other cells. TDF has no known mechanism of action. In our recent study, we identified heat shock 70 kDa proteins (HSP70s) as TDF receptors (TDF-Rs) in breast cancer cells. Therefore, we sought to investigate whether TDF-R candidates from prostate cancer cells are the same as those identified in breast cancer cells. Here, we used TDF-P1 to purify the potential TDF-R candidates by affinity purification chromatography from DU145 and PC3 steroid-resistant prostate cancer cells, LNCaP steroid-responsive prostate cancer cells, and nonprostate NG108 neuroblastoma and BLK CL.4 fibroblast-like cells. We identified the purified proteins by MS, and validated them by western blotting, immunofluorescence microscopy, immunoaffinity purification chromatography, and structural biology. We identified seven candidate proteins, of which three were from the HSP70 family. These three proteins were validated as potential TDF-R candidates in LNCaP steroid-responsive and in DU145 and PC3 steroid-resistant prostate cancer cells, but not in NG108 neuroblastoma and BLK CL.4 fibroblast-like cells. Our previous study and the current study suggest that GRP78, and perhaps HSP70s, are strong TDF-R candidates, and further suggest that TDF interacts with its receptors exclusively in breast and prostate cells, inducing cell differentiation through a novel, steroid-independent pathway.
authors.affiliation: Department of Chemistry and Biomolecular Science, Clarkson University, Potsdam, NY 13699-5810, USA.
authors.forename: Izabela
authors.initials: I
authors.lastname: Sokolowska
authors.forename: Alisa G
authors.initials: AG
authors.lastname: Woods
authors.forename: Mary Ann
authors.initials: MA
authors.lastname: Gawinowicz
authors.forename: Urmi
authors.initials: U
authors.lastname: Roy
authors.forename: Costel C
authors.initials: CC
authors.lastname: Darie
mesh_terms: D000595:Amino Acid Sequence; D015153:Blotting, Western; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D002460:Cell Line; D045744:Cell Line, Tumor; D000091342:Endoplasmic Reticulum Chaperone BiP; D005260:Female; D018840:HSP70 Heat-Shock Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006360:Heat-Shock Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008297:Male; D018613:Microscopy, Confocal; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000378:metabolism; D010455:Peptides / Q000737:chemistry / Q000378:metabolism*; D011471:Prostatic Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011956:Receptors, Cell Surface / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D000091342:Endoplasmic Reticulum Chaperone BiP; D018840:HSP70 Heat-Shock Proteins; C000717247:HSPA5 protein, human; D006360:Heat-Shock Proteins; D009419:Nerve Tissue Proteins; C483315:PDF protein, human; D010455:Peptides; D011956:Receptors, Cell Surface