Impact of 6 month conjugated equine estrogen versus estradiol-treatment on biomarkers and enriched gene sets in healthy mammary tissue of non-human primates

• Type of Material: Article
• Authors: Gabriel Hobi, University of Bern; Mark J Cline, Wake Forest University; Kelly Ethun, Emory University; Cedric Simillion, University of Bern; Irene Keller, University of Bern; Petra Stute, University of Bern
• Language: English
• Date: 2022-03-17
• Publisher: Public Library of Science (PLoS)
• Publication Version: Final Published Version
• Copyright Statement: © 2022 Hobi et al
• License: Creative Commons Attribution 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1371/journal.pone.0264057
• Title of Journal or Parent Work: PLoS One
• Volume: 17
• Issue: 3
• Grant/Funding Information: This study was funded by the Department of Pathology Research Endowment, Wake Forest School of Medicine through a grant awarded to JMC (2016). The study was also supported by Pfizer Inc. through a grant awarded to TBC (2007). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
• Keywords: Conjugated equine estrogens; HT, Hormone Therapy; Hormone therapy (HT); Gonadotropin releasing hormone; GREB1; Marker of Proliferation Ki67
• Research Categories: Health Sciences, Obstetrics and Gynecology; Health Sciences, Pathology

Abstract

Objective To identify distinctly regulated gene markers and enriched gene sets in breast tissue of cynomolgus monkeys (Macaca fascicularis) treated for six months with either conjugated equine estrogens (CEE) or estradiol (E2) by analysis of corresponding mRNA levels of genes associated with breast development, carcinogenesis, apoptosis and immune regulation. Additionally, translation of three nuclear markers was analyzed. Methods RNA from breast biopsies and necropsies was isolated from two independent study trials from Ethun et al. (CEE) and Foth et al. (E2) after 6 month of treatment duration. RNA was subjected to qRT-PCR and MicroArray analysis. Immunohistochemical stainings were performed for the estrogen receptor alpha subunit (ERa), the progesterone receptor (PGR) and the proliferation marker Ki67. Results We identified a total of 36 distinctly enriched gene sets. Thirty-one were found in the CEE treatment group and five were found in the E2 treatment group, with no overlap. Furthermore, two individual genes IGFBP1 and SGK493 were upregulated in CEE treated animals. Additional targeted qRT-PCR analysis of ten specific estrogen-related genes showed upregulation of three genes (TFF1, PGR and GREB1) after CEE treatment, respectively one gene (TFF1) after E2 treatment. Immunohistochemical stains of breast biopsies showed a significant increase in expression of the PGR marker after CEE treatment. Conclusions In this study we identified enriched gene sets possibly induced by CEE or E2 treatment in various processes associated with cancer biology and immunology. This preliminary translational data supports the concept that different estrogen types have different effects on healthy breast tissue and may help generate hypotheses for future research.