PubMed | Marshfield Clinic Weston Center Weston, Marshfield Clinic Cancer Care at St Michaels Stevens Point, University of Wisconsin - Madison and McArdle Laboratory for Cancer Research Madison
Type: Journal Article | Journal: American journal of translational research | Year: 2015
Triple negative breast cancer (TNBC) is an aggressive breast cancer subtype for which there is a need to identify new therapeutic targets. Full-length estrogen receptor beta (ER1) may be a possible target given its antiproliferative effects on breast cancer cells. The prognostic significance of ER in breast cancer subtypes has remained elusive, and disparate results observed across previously published reports might be due to the detection of multiple ER isoforms, the lack of specific antibodies and the use of different cutoffs to define ERpositivity. The objective of this retrospective study was to determine the association between ER1 expression and disease-free and overall survival, as well as Ki67 expression, in non-metastatic TNBC. Immunohistochemical protocols were optimized using xenograft tissues obtained from a breast cancer cell line with inducible ER1 expression. ER1 localization and expression were assessed in two cohorts of TNBC using the VECTRA(TM) platform. There was a close relationship between nuclear and cytoplasmic ER1 expression. ER1 was expressed in a subset of TNBCs, but its expression was significantly associated with Ki67 in only one of the cohorts. There was no significant association between ER1 expression and disease-free and overall survival in either cohort. Although these results suggest that ER1 expression alone may not be informative in TNBCs, this study provides a new strategy for optimizing and objectively measuring ER1 expression in tissues, which may provide a standard for ER1 immunohistochemistry in future large-scale clinical studies aimed at better understanding the role of ER1 in breast cancer.