Email updates

Keep up to date with the latest news and content from BMC Cancer and BioMed Central.

Open Access Research article

Differential profiling of breast cancer plasma proteome by isotope-coded affinity tagging method reveals biotinidase as a breast cancer biomarker

Un-Beom Kang13, Younghee Ahn1, Jong Won Lee4, Yong-Hak Kim2, Joon Kim3, Myeong-Hee Yu2, Dong-Young Noh4* and Cheolju Lee1*

Author Affiliations

1 Life Sciences Division, Korea Institute of Science and Technology, Seoul 136-791, Korea

2 Functional Proteomics Center, Korea Institute of Science and Technology, Seoul 136-791, Korea

3 School of Life Sciences and Biotechnology, Korea University, Seoul 136-701, Korea

4 Cancer Research Institute, Seoul National University College of Medicine, Seoul 110-744, Korea

For all author emails, please log on.

BMC Cancer 2010, 10:114  doi:10.1186/1471-2407-10-114

Published: 26 March 2010

Abstract

Background

Breast cancer is one of the leading causes of women's death worldwide. It is important to discover a reliable biomarker for the detection of breast cancer. Plasma is the most ideal source for cancer biomarker discovery since many cells cross-communicate through the secretion of soluble proteins into blood.

Methods

Plasma proteomes obtained from 6 breast cancer patients and 6 normal healthy women were analyzed by using the isotope-coded affinity tag (ICAT) labeling approach and tandem mass spectrometry. All the plasma samples used were depleted of highly abundant 6 plasma proteins by immune-affinity column chromatography before ICAT labeling. Several proteins showing differential abundance level were selected based on literature searches and their specificity to the commercially available antibodies, and then verified by immunoblot assays.

Results

A total of 155 proteins were identified and quantified by ICAT method. Among them, 33 proteins showed abundance changes by more than 1.5-fold between the plasmas of breast cancer patients and healthy women. We chose 5 proteins for the follow-up confirmation in the individual plasma samples using immunoblot assay. Four proteins, α1-acid glycoprotein 2, monocyte differentiation antigen CD14, biotinidase (BTD), and glutathione peroxidase 3, showed similar abundance ratio to ICAT result. Using a blind set of plasmas obtained from 21 breast cancer patients and 21 normal healthy controls, we confirmed that BTD was significantly down-regulated in breast cancer plasma (Wilcoxon rank-sum test, p = 0.002). BTD levels were lowered in all cancer grades (I-IV) except cancer grade zero. The area under the receiver operating characteristic curve of BTD was 0.78. Estrogen receptor status (p = 0.940) and progesterone receptor status (p = 0.440) were not associated with the plasma BTD levels.

Conclusions

Our study suggests that BTD is a potential serological biomarker for the detection of breast cancer.