Strategy for SRM-based verification of biomarker candidates discovered by iTRAQ method in limited breast cancer tissue samples

J Proteome Res. 2012 Aug 3;11(8):4201-10. doi: 10.1021/pr300322q. Epub 2012 Jul 9.

Abstract

Since LC-MS-based quantitative proteomics has become increasingly applied to a wide range of biological applications over the past decade, numerous studies have performed relative and/or absolute abundance determinations across large sets of proteins. In this study, we discovered prognostic biomarker candidates from limited breast cancer tissue samples using discovery-through-verification strategy combining iTRAQ method followed by selected reaction monitoring/multiple reaction monitoring analysis (SRM/MRM). We identified and quantified 5122 proteins with high confidence in 18 patient tissue samples (pooled high-risk (n=9) or low-risk (n=9)). A total of 2480 proteins (48.4%) of them were annotated as membrane proteins, 16.1% were plasma membrane and 6.6% were extracellular space proteins by Gene Ontology analysis. Forty-nine proteins with >2-fold differences in two groups were chosen for further analysis and verified in 16 individual tissue samples (high-risk (n=9) or low-risk (n=7)) using SRM/MRM. Twenty-three proteins were differentially expressed among two groups of which MFAP4 and GP2 were further confirmed by Western blotting in 17 tissue samples (high-risk (n=9) or low-risk (n=8)) and Immunohistochemistry (IHC) in 24 tissue samples (high-risk (n=12) or low-risk (n=12)). These results indicate that the combination of iTRAQ and SRM/MRM proteomics will be a powerful tool for identification and verification of candidate protein biomarkers.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Biomarkers, Tumor / chemistry
  • Biomarkers, Tumor / isolation & purification
  • Biomarkers, Tumor / metabolism*
  • Breast Neoplasms / diagnosis
  • Breast Neoplasms / metabolism*
  • Carrier Proteins / chemistry
  • Carrier Proteins / isolation & purification
  • Carrier Proteins / metabolism*
  • Chromatography, Ion Exchange
  • Extracellular Matrix Proteins / chemistry
  • Extracellular Matrix Proteins / isolation & purification
  • Extracellular Matrix Proteins / metabolism*
  • Female
  • GPI-Linked Proteins / chemistry
  • GPI-Linked Proteins / isolation & purification
  • GPI-Linked Proteins / metabolism*
  • Glycoproteins / chemistry
  • Glycoproteins / isolation & purification
  • Glycoproteins / metabolism*
  • Humans
  • Molecular Sequence Data
  • Peptide Fragments / chemistry
  • Prognosis
  • Staining and Labeling
  • Statistics, Nonparametric
  • Tandem Mass Spectrometry

Substances

  • Biomarkers, Tumor
  • Carrier Proteins
  • Extracellular Matrix Proteins
  • GP2 protein, human
  • GPI-Linked Proteins
  • Glycoproteins
  • MFAP4 protein, human
  • Peptide Fragments