TY - JOUR
T1 - ERβ splice variant expression in four large cohorts of human breast cancer patient tumors
AU - Wimberly, Hallie
AU - Han, Gang
AU - Pinnaduwage, Dushanthi
AU - Murphy, Leigh C.
AU - Yang, Xiaohong Rose
AU - Andrulis, Irene L.
AU - Sherman, Mark
AU - Figueroa, Jonine
AU - Rimm, David L.
N1 - Funding Information:
Acknowledgments The authors of the study thank Pei Chao and Michael Stagner from Information Management Services (Silver Spring, MD) for data management support; the participants, physicians, pathologists, nurses, and interviewers from participating centers in Poland for their efforts during field-work; and Drs. Montserrat Garcia-Closas, Louise Brinton, Jolanta Lissowska, B. Peplonska for their contributions to the PBCS study design. Funding for this study was partially provided by the Breast Cancer Research Foundation.
PY - 2014/8
Y1 - 2014/8
N2 - Though the role of Estrogen Receptor (ER)α in breast cancer has been studied extensively, there is little consensus about the role of alternative ER isoform ERβ in breast cancer biology. ERβ has significant sequence homology to ERα but is located on a different chromosome and maintains both overlapping and unique functional attributes. Five variants exist, resulting from alternative splicing of the C-terminal region of ERβ. The relevance of ERβ variants in breast cancer outcomes and response to therapy is difficult to assess because of conflicting reports in the literature, likely due to variable methods used to assess ERβ in patient tumors. Here, we quantitatively assess expression of ERβ splice variants on over 2,000 breast cancer patient samples. Antibodies against ERβ variants were validated for staining specificity in cell lines by siRNA knockdown of ESR2 and staining reproducibility on formalin-fixed paraffin-embedded tissue by quantitative immunofluorescence (QIF) using AQUA technology. We found antibodies against splice variants ERβ1 and ERβ5, but not ERβ2/cx, which were sensitive, specific, and reproducible. QIF staining of validated antibodies showed both ERβ1 and ERβ5 QIF scores, which have a normal (bell shaped) distribution on most cohorts assessed, and their expression is significantly associated with each other. Extensive survival analyses show that ERβ1 is not a prognostic or predictive biomarker for breast cancer. ERβ5 appears to be a context-dependent marker of worse outcome in HER2-positive and triple-negative patients, suggesting an unknown biological function in the absence of ERα.
AB - Though the role of Estrogen Receptor (ER)α in breast cancer has been studied extensively, there is little consensus about the role of alternative ER isoform ERβ in breast cancer biology. ERβ has significant sequence homology to ERα but is located on a different chromosome and maintains both overlapping and unique functional attributes. Five variants exist, resulting from alternative splicing of the C-terminal region of ERβ. The relevance of ERβ variants in breast cancer outcomes and response to therapy is difficult to assess because of conflicting reports in the literature, likely due to variable methods used to assess ERβ in patient tumors. Here, we quantitatively assess expression of ERβ splice variants on over 2,000 breast cancer patient samples. Antibodies against ERβ variants were validated for staining specificity in cell lines by siRNA knockdown of ESR2 and staining reproducibility on formalin-fixed paraffin-embedded tissue by quantitative immunofluorescence (QIF) using AQUA technology. We found antibodies against splice variants ERβ1 and ERβ5, but not ERβ2/cx, which were sensitive, specific, and reproducible. QIF staining of validated antibodies showed both ERβ1 and ERβ5 QIF scores, which have a normal (bell shaped) distribution on most cohorts assessed, and their expression is significantly associated with each other. Extensive survival analyses show that ERβ1 is not a prognostic or predictive biomarker for breast cancer. ERβ5 appears to be a context-dependent marker of worse outcome in HER2-positive and triple-negative patients, suggesting an unknown biological function in the absence of ERα.
KW - Antibody validation
KW - Breast cancer prognosis and prediction
KW - Estrogen receptors
KW - Quantitative immunofluorescence
KW - Triple-negative breast cancer
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U2 - 10.1007/s10549-014-3050-3
DO - 10.1007/s10549-014-3050-3
M3 - Article
C2 - 25007965
AN - SCOPUS:84907597187
SN - 0167-6806
VL - 146
SP - 657
EP - 667
JO - Breast Cancer Research and Treatment
JF - Breast Cancer Research and Treatment
IS - 3
ER -