Androgen receptor expression on circulating tumor cells in metastatic breast cancer

PLoS One. 2017 Sep 28;12(9):e0185231. doi: 10.1371/journal.pone.0185231. eCollection 2017.

Abstract

Purpose: Androgen receptor (AR) is frequently detected in breast cancers, and AR-targeted therapies are showing activity in AR-positive (AR+) breast cancer. However, the role of AR in breast cancers is still not fully elucidated and the biology of AR in breast cancer remains incompletely understood. Circulating tumor cells (CTCs) can serve as prognostic and diagnostic tools, prompting us to measure AR protein expression and conduct genomic analyses on CTCs in patients with metastatic breast cancer.

Methods: Blood samples from patients with metastatic breast cancer were deposited on glass slides, subjected to nuclear staining with DAPI, and reacted with fluorescent-labeled antibodies to detect CD45, cytokeratin (CK), and biomarkers of interest (AR, estrogen receptor [ER], and HER2) on all nucleated cells. The stained slides were scanned and enumerated by non-enrichment-based non-biased approach independent of cell surface epithelial cell adhesion molecule (EpCAM) using the Epic Sciences CTC platform. Data were analyzed using established digital pathology algorithms.

Results: Of 68 patients, 51 (75%) had at least 1 CTC, and 49 of these 51 (96%) had hormone-receptor-positive (HR+)/HER2-negative primary tumors. AR was expressed in CK+ CTCs in 10 patients. Of these 10 patients, 3 also had ER expression in CK+ CTCs. Single cell genomic analysis of 78 CTCs from 1 of these 3 patients identified three distinct copy number patterns. AR+ cells had a lower frequency of chromosomal changes than ER+ and HER2+ cells.

Conclusions: CTC enumeration and analysis using no enrichment or selection provides a non-biased approach to detect AR expression and chromosomal aberrations in CTCs in patients with metastatic breast cancer. The heterogeneity of intrapatient AR expression in CTCs leads to the new hypothesis that patients with AR+ CTCs have heterogeneous disease with multiple drivers. Further studies are warranted to investigate the clinical applicability of AR+ CTCs and their heterogeneity.

MeSH terms

  • Adult
  • Aged
  • Breast Neoplasms / genetics
  • Breast Neoplasms / metabolism*
  • Breast Neoplasms / pathology*
  • DNA Copy Number Variations / genetics
  • Female
  • Humans
  • Immunohistochemistry
  • Middle Aged
  • Neoplasm Metastasis
  • Neoplastic Cells, Circulating / metabolism*
  • Neoplastic Cells, Circulating / pathology*
  • Prevalence
  • Receptor, ErbB-2 / metabolism
  • Receptors, Androgen / metabolism*
  • Receptors, Estrogen / metabolism
  • Single-Cell Analysis

Substances

  • AR protein, human
  • Receptors, Androgen
  • Receptors, Estrogen
  • ERBB2 protein, human
  • Receptor, ErbB-2

Grant support

This study was funded by the Morgan Welch Inflammatory Breast Cancer Research Program; a grant from the State of Texas Rare and Aggressive Breast Cancer Research Program; MD Anderson Cancer Center’s Cancer Center Support Grant from the National Cancer Institute, CA016672, which supports the Biostatistics Shared Resource; and Epic Sciences. The Morgan Welch Inflammatory Breast Cancer Research Program and the National Cancer Institute had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Epic Sciences provided support in the form of salaries for authors RK, MVS, RPG, JLee, SG, AR, LD, JLouw, YW, ML, and RD but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of these authors are articulated in the ‘author contributions’ section. Epic Sciences employees contributed to study design (RD), data collection and analysis (RK, MVS, RPG, JLee, SG, AR, LD, JLouw, YW, ML, and RD), decision to publish (RD), and preparation of the manuscript (RK, MVS, RPG, JLee, SG, AR, LD, JLouw, YW, ML, and RD).