Anti-Epo receptor antibodies do not predict Epo receptor expression.
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.
Elliott
Steve
S
Amgen Inc, One Amgen Center Dr, Thousand Oaks, CA 91320, USA. selliott@amgen.com
Busse
Leigh
L
Bass
Michael B
MB
Lu
Hsieng
H
Sarosi
Ildiko
I
Sinclair
Angus M
AM
Spahr
Chris
C
Um
Moonkyoung
M
Van
Gwyneth
G
Begley
C Glenn
CG
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
D000911:Antibodies, Monoclonal; D018840:HSP70 Heat-Shock Proteins; D010455:Peptides; D017467:Receptors, Erythropoietin