Proteomic Profiling of Invasive Ductal Carcinoma (IDC) using Magnetic Beads-based Serum Fractionation and MALDI-TOF MS

Aim: To reveal the serum proteomic profiling of intraductal carcinoma (IDC) patients in China, establish a serum proteome fractionation technique for choosing magnetic beads for proteomic analysis in breast cancer research; and identify differentially expressed peptides (m/z; P < 0.0001) as potential biomarkers of early IDCs. Methods: We used two different kinds of magnetic beads (magnetic bead-based weak cation exchange chromatography (MB-WCX) and immobilized metal ion affinity chromatography (MB-IMAC-Cu)) to analyze 32 patients with early stage (stages I-II) IDC and 32 healthy control serum samples for proteomic profiling by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) analysis. The mass spectra, analyzed using ClinProTools software, distinguished between IDC patients and healthy individuals based on k-nearest neighbor genetic algorithm. Results: The serum samples purified in the MB-WCX group provided better proteomic patterns than the MB-IMAC-Cu group. The samples purified by MB-WCX had better average peak numbers, higher peak intensities, and better capturing ability of low abundance proteins or peptides in serum samples. In addition, the MB-WCX and MB-IMAC-Cu purification methods, followed MALDI-TOF MS identification and use of ClinProTools software accurately distinguished patients with early stage IDC from healthy individuals. Conclusion: Serum proteomic profiling by MALDI-TOF MS is a novel potential tool for the clinical diagnosis of patients with IDC in China.