In Vivo Quantitation of Estrogen Receptor β Subtype Expression in Ovarian Surface Epithelium Using Immunofluorescence...

Immunohistochemistry using formalin-fixed, paraffin-embedded tissue, chromogen label, and light microscopy has traditionally been used to semiquantify estrogen receptor (ER) to guide diagnosis and management of breast cancer. Quantitation of ER for this purpose currently only assesses levels of the ER-alpha subtype. Considerable variability in results reported has been due to protocol and fixation variability, intraobserver and interobserver variability, and different scoring systems and thresholds for scoring ER positivity. Results can also vary with low expression levels of ER. ER-beta expression is reduced in breast and ovarian cancers and requires quantitation.Herein we describe a novel approach to quantifying ERβ using older mouse ovarian surface epithelium, where ERβ is expressed at lower levels than ERα and is therefore harder to detect. We use an antibody highly specific to the ERβ1 isoform, together with immunofluorescence, confocal microscopy, and imaging and statistical software to achieve clear, reproducible, and unbiased quantitation of ERβ.