title: Anti-Epo receptor antibodies do not predict Epo receptor expression.
abstract: Investigators using anti-EpoR antibodies for immunoblotting and immunostaining have reported erythropoietin receptor (EpoR) expression in nonhematopoietic tissues including human tumors. However, these antibodies detected proteins of 66 to 78 kDa, significantly larger than the predicted molecular weight of EpoR (56-57 kDa). We investigated the specificity of these antibodies and showed that they all detected non-EpoR proteins. C-20 detected 3 proteins in tumor cell lines (35, 66, and 100 kDa). Sequences obtained from preparative gels had similarity to the C-20-immunizing peptide. The 66-kDa protein was a heat shock protein (HSP70) to which antibody binding was abrogated in peptide competition experiments. Antibody M-20 readily identified a 59-kDa EpoR protein. However, neither M-20 nor C-20 was suitable for detection of EpoR using immunohistochemical methods. We concluded that these antibodies have limited utility for detecting EpoR. Thus, reports of EpoR expression in tumor cells using these antibodies should be viewed with caution.
authors.affiliation: Amgen Inc, One Amgen Center Dr, Thousand Oaks, CA 91320, USA. selliott@amgen.com
authors.forename: Steve
authors.initials: S
authors.lastname: Elliott
authors.forename: Leigh
authors.initials: L
authors.lastname: Busse
authors.forename: Michael B
authors.initials: MB
authors.lastname: Bass
authors.forename: Hsieng
authors.initials: H
authors.lastname: Lu
authors.forename: Ildiko
authors.initials: I
authors.lastname: Sarosi
authors.forename: Angus M
authors.initials: AM
authors.lastname: Sinclair
authors.forename: Chris
authors.initials: C
authors.lastname: Spahr
authors.forename: Moonkyoung
authors.initials: M
authors.lastname: Um
authors.forename: Gwyneth
authors.initials: G
authors.lastname: Van
authors.forename: C Glenn
authors.initials: CG
authors.lastname: Begley
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000737:chemistry* / Q000276:immunology; D000918:Antibody Specificity; D018840:HSP70 Heat-Shock Proteins / Q000737:chemistry / Q000276:immunology; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D051379:Mice; D009369:Neoplasms / Q000378:metabolism*; D010455:Peptides / Q000737:chemistry / Q000276:immunology; D011237:Predictive Value of Tests; D017467:Receptors, Erythropoietin / Q000096:biosynthesis* / Q000276:immunology
chemical_list: D000911:Antibodies, Monoclonal; D018840:HSP70 Heat-Shock Proteins; D010455:Peptides; D017467:Receptors, Erythropoietin