Comprehensive assessment of estrogen receptor beta antibodies in cancer cell line models and tissue reveals critical limitations in reagent specificity

Estrogen Receptor-beta (ER beta) has been implicated in many cancers. In prostate and breast cancer its function is controversial, but genetic studies implicate a role in cancer progression. Much of the confusion around ER beta stems from antibodies that are inadequately validated, yet have become standard tools for deciphering its role. Using an ER beta-inducible cell system we assessed commonly utilized ER beta antibodies and show that one of the most commonly used antibodies, NCL-ER-BETA, is non-specific for ER beta. Other antibodies have limited ERGS specificity or are only specific in one experimental modality. ER beta is commonly studied in MCF-7 (breast) and LNCaP (prostate) cancer cell lines, but we found no ER beta expression in either, using validated antibodies and independent mass spectrometry-based approaches. Our findings question conclusions made about ER beta using the NCL-ER-BETA antibody, or LNCaP and MCF-7 cell lines. We describe robust reagents, which detect ER beta across multiple experimental approaches and in clinical samples. (C) 2016 The Authors. Published by Elsevier Ireland Ltd.