ERβ1: characterization, prognosis, and evaluation of treatment strategies in ERα-positive and -negative breast cancer

Abstract

BackgroundThe role and clinical value of ERβ1 expression is controversial and recent data demonstrates that many ERβ antibodies are insensitive and/or non-specific. Therefore, we sought to comprehensively characterize ERβ1 expression across all sub-types of breast cancer using a validated antibody and determine the roles of this receptor in mediating response to multiple forms of endocrine therapy both in the presence and absence of ERα expression.MethodsNuclear and cytoplasmic expression patterns of ERβ1 were analyzed in three patient cohorts, including a retrospective analysis of a prospective adjuvant tamoxifen study and a triple negative breast cancer cohort. To investigate the utility of therapeutically targeting ERβ1, we generated multiple ERβ1 expressing cell model systems and determined their proliferative responses following anti-estrogenic or ERβ-specific agonist exposure.ResultsNuclear ERβ1 was shown to be expressed across all major sub-types of breast cancer, including 25% of triple negative breast cancers and 33% of ER-positive tumors, and was associated with significantly improved outcomes in ERα-positive tamoxifen-treated patients. In agreement with these observations, ERβ1 expression sensitized ERα-positive breast cancer cells to the anti-cancer effects of selective estrogen receptor modulators (SERMs). However, in the absence of ERα expression, ERβ-specific agonists potently inhibited cell proliferation rates while anti-estrogenic therapies were ineffective.ConclusionsUsing a validated antibody, we have confirmed that nuclear ERβ1 expression is commonly present in breast cancer and is prognostic in tamoxifen-treated patients. Using multiple breast cancer cell lines, ERβ appears to be a novel therapeutic target. However, the efficacy of SERMs and ERβ-specific agonists differ as a function of ERα expression.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2407-14-749) contains supplementary material, which is available to authorized users.

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

“…The cancer cell line MDA-MB-231 with doxycycline-inducible ERβ expression (MDA-MB-231-ERβ) (Reese et al., 2014) was cultured in Dulbeccos Modified Eagle Medium with F12 supplement (DMEM/F12) with 10% heat-inactivated tetracycline-free fetal bovine serum (FBS) (Fisher-Scientific), 2 mM L-glutamine, 50 U/ml penicillin, 50 μg/ml streptomycin, 5 μg/ml blasticidin S (Invivogen) to select for the tetracycline repressor and 500 μg/ml zeocin (Invitrogen) to select for the ERβ expression vector. To induce ERβ expression in MDA-MB 231-ERβ cells, 15 cm 2 plates were seeded with 5 × 10 6  cells and doxycycline added at either 0.1 μg/ml (for Western blot, real-time polymerase chain reaction (qRT-PCR) and PRM) or 0.5 μg/ml (for RIME) for 24 h. The MCF-7 breast cancer cell line was cultured in Dulbecco's Modified Eagle Medium (DMEM) with 10% heat-inactivated FBS (Fisher-Scientific), 2 mM L-glutamine, 50 U/ml penicillin and 50 μg/ml streptomycin.…”

Tyrosine phosphorylation regulates ERβ ubiquitination, protein turnover, and inhibition of breast cancer

“…ERβ is expressed in a significant percentage of breast tumors across all subtypes [42, 43], making it a potential target in anticancer therapies. In addition, several natural and synthetic ERβ-selective agonists were well tolerated in clinical trials [44] (ClinicalTrials.gov), further elevating therapeutic feasibility of rallying ERβ antitumor activity.…”

The prognostic significance of estrogen receptor β in head and neck squamous cell carcinoma

“…The most comprehensive analysis was performed on patients with breast cancer where positive expression of ERβ was associated with increased response rates to ER antagonist therapy with tamoxifen (12,22). However, the role of ER signaling in other malignancies remains unclear.…”

“…Recent data suggests that there is an association between the intranuclear overexpression of estrogen receptor (ER) β and higher survival rates in patients with lung (9,10), prostate (11), breast (12) and colon cancer (13). A number of studies have demonstrated that nuclear receptors are expressed in head and neck cancer (14–20).…”