Tissue proteome analysis revealed an association between cancer, immune system response, and the idiopathic granulomatous mastitis.

Idiopathic Granulomatous Mastitis (IGM) is a disease that clinically mimics breast cancers with symptoms of pain, edema, erythema, nipple discharge, nipple retraction, and fistula. Although IGM is considered to be formed by autoimmune responses or infections, the molecular mechanism behind formation and progress is unknown. Therefore, in this study, we aimed to investigate molecular mechanisms underlying IGM formation, progress, and recurrence by monitoring the changes at the proteome level. Protein extracts prepared from IGM (n = 15) and within-control tissues (n = 15) were subjected to nHPLC followed by LC-MS/MS proteomic analysis. Label-free quantitation analysis revealed that sixty differentially regulated between the two groups. Those proteins were classified based on their role in metabolic pathways using bioinformatics tools. Based on DAVID analysis, 16 of the differently regulated proteins were associated with the immune system, while 17 proteins were involved in cancer metabolism. STRING analysis showed that five of the differentially regulated proteins were associated with combined immune deficiency which were PNP, TAP1, ITGAL, PRKDC, and PTPRC while the other proteins were involved in insulin response and neutrophil degranulation. This study is one of the very few studies that investigated the changes in protein expressions of IGM tissues compared to controls. For the first time, we have shown the relationship of IGM with the immune system at the protein level and also underlined the cancer-like behavior of the disease. Furthermore, the proteins that were pointed out as combined immune deficiency-related proteins may have value as diagnostic markers for idiopathic granulomatous mastitis although further studies are needed to shed more light on the pathogenesis of the disease.