Dicer expression in estrogen receptor-positive versus triple-negative breast cancer: an antibody comparison

Hum Pathol. 2016 Oct;56:40-51. doi: 10.1016/j.humpath.2016.05.014. Epub 2016 May 31.

Abstract

Dicer is an RNase III enzyme responsible for cleaving double-stranded RNAs into small interfering RNAs and microRNAs, which either target messenger RNA transcripts for degradation or inhibit translation. Dicer protein levels have been examined in breast cancer with contradictory results. Our goal was to resolve whether Dicer levels differ in breast cancer versus normal breast epithelium and between estrogen receptor-α-positive (ER+) or estrogen receptor-α-negative (ER-) primary breast cancers. We compared 3 different Dicer antibodies: Abcam 4A6, Abcam ab5818, and Sigma HPA000694, using immunohistochemistry and Western blot analyses. All 3 Dicer antibodies detected higher levels of Dicer in ER+ breast cancer cell lines versus ER-, and all 3 recognized exogenous overexpressed Dicer. In clinical specimens, all 3 antibodies detected higher Dicer in ER+ breast cancers versus triple-negative breast cancer (TNBC) but had very different staining patterns by immunohistochemistry on the same tumor samples. Using the optimal antibody, ab5818, selected for its sensitivity and specificity, Dicer protein expression was significantly higher in ER+ versus TNBC clinical specimens of primary tumor (P<.0001, unpaired t test). Dicer was also significantly higher in adjacent normal breast epithelium versus TNBC (P<.0001, paired t test; n=18 pairs). Differences in antibody performance may explain contrasting results observed in the literature regarding Dicer protein in breast cancer. If Dicer becomes more clinically relevant as a prognostic indicator, further antibody optimization and standardization will be critical.

Keywords: Breast cancer; Dicer; Estrogen receptor; Immunohistochemistry; TNBC.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Adult
  • Aged
  • Animals
  • Antibodies / immunology*
  • Antibody Specificity*
  • Biomarkers, Tumor / genetics
  • Biomarkers, Tumor / immunology
  • Biomarkers, Tumor / metabolism*
  • Breast Neoplasms / enzymology*
  • Breast Neoplasms / genetics
  • Breast Neoplasms / immunology
  • Breast Neoplasms / pathology
  • Cell Line, Tumor
  • DEAD-box RNA Helicases / genetics
  • DEAD-box RNA Helicases / immunology
  • DEAD-box RNA Helicases / metabolism*
  • Female
  • HEK293 Cells
  • Humans
  • Immunohistochemistry*
  • Mice
  • Middle Aged
  • Predictive Value of Tests
  • Receptor, ErbB-2 / analysis
  • Receptors, Estrogen / analysis*
  • Receptors, Progesterone / analysis
  • Reproducibility of Results
  • Ribonuclease III / genetics
  • Ribonuclease III / immunology
  • Ribonuclease III / metabolism*
  • Triple Negative Breast Neoplasms / enzymology*
  • Triple Negative Breast Neoplasms / genetics
  • Triple Negative Breast Neoplasms / immunology
  • Triple Negative Breast Neoplasms / pathology
  • Up-Regulation
  • Young Adult

Substances

  • Antibodies
  • Biomarkers, Tumor
  • Receptors, Estrogen
  • Receptors, Progesterone
  • ERBB2 protein, human
  • Receptor, ErbB-2
  • DICER1 protein, human
  • Ribonuclease III
  • DEAD-box RNA Helicases