Prospective study of the predictive power of mass spectrometric profiles of plasma proteins and peptides in detecting early stage breast cancer
Women with a high risk for breast cancer urgently need more effective and sensitive, early screening options. Promising advances in cancer detection using human blood plasma have recently been reported using surface-enhanced laser desorption ionization time-of-flight (SELDI-TOF) mass spectrometry. Using seed funding from the Susan G. Komen Breast Cancer Research Foundation we implemented this technology in our laboratory. Our major goal is to validate the Ciphergen PBSIIc SELDI-TOF platform for direct analysis of cancer-specific proteins in clinical samples collected at Stanford University Hospital and the General Hospital of Vienna, Austria.
Personnel
SGTC:
Peter Oefner (PI)
Georg Hölzl
Birgit Timischl
First, we will obtain SELDI-TOF mass spectra of plasma proteins from healthy volunteers, and from patients with a known cancer diagnosis. To establish both the sensitivity and specificity of the method, we will train the data analysis software with specimens from early stage breast cancer, and compare them with other cancers. Then, we will perform cluster analysis to identify proteomic patterns that correlate with early signs of breast cancer, or with an increased risk of breast cancer.
Second, we will evaluate the method as a screening tool by prospectively following 100-150 high-risk women in our comprehensive screening program. We will compare proteomic analysis with other early detection strategies, including magnetic resonance imaging (MRI), and ductal lavage cytology.
Third, we will begin chemical characterization of cancer-specific patterns using high-performance liquid chromatography coupled to electro-spray ionization tandem mass spectrometry. The more detailed, and accurate mass spectra afforded by ESI-MS/MS may allow a definitive identification of cancer-specific proteins.
Depletion of high abundance proteins:
Peptide fractionation – 2D liquid chromatography (2D LC):
Material assisted laser desorption ionization mass spectrometry (MALDI-MS):
Quantitative mass spectrometry:
- Ionization by MELDI; analysis by QSTAR (Q-TOF), Protein Chip Reader (TOF)
- Ionization by ESI-MS; analysis by QSTAR (Q-TOF), Ion trap (LCQ/LTQ), FT-ICR