Proteomic Analysis of Human Breast Milk to Reveal Potential Protein Biomarkers for Breast Cancer

Breast cancer (BC), one of the most common cancers, is a leading cause of death for women in the United States. An estimated 1 in 8 women in the United States will develop BC in their lifetime. Early diagnosis and treatment of BC is crucial, and protein biomarkers for this disease could make this possible. Mass spectrometry (MS)-based proteomic methods are ideal for the investigation of protein biomarkers. This study employs MS-based proteomics to study the protein differences in human breast milk from women with BC and matched controls. If significant protein dysregulations are revealed, they could be considered potential future protein biomarkers of BC for diagnosis and treatment. In this study, six human breast milk samples were analyzed by performing a 2D-SDS-PAGE and further analyzed via nanoLC-MS/MS. The human breast milk samples consisted of three comparison pairs of BC vs. control. There were one Coomassie blue-stained gel (6 total gels) and two replicate silver-stained gels (12 total gels) for each sample of breast milk. The silver-stained gels were scanned using a laser densitometer and the images were analyzed using Progenesis Same Spots and Progenesis PG240 software. The spot percentages were measured for each dysregulated spot., An in-gel trypsin digestion was performed for each spot with statistically significant dysregulation. This was followed by nanoLC-MS/MS, data processing, database search and statistical analysis. The dysregulated proteins found in this study can be investigated as BC biomarkers for future clinical methods for early diagnosis and treatment of BC.