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Improvement of breast-cancer detection through the identification of potential cancer biomarkers is considered as a promising strategy for effective assessment of the disease. The current study has used nonequilibrium pH gradient electrophoresis with subsequent analysis by mass spectrometry to identify protein alterations in invasive ductal carcinomas of the breast from Tunisian women. We have identified multiple protein alterations in tumor tissues that were picked, processed, and unambiguously assigned identities by matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF). The proteins identified span a wide range of functions and are believed to have potential clinical applications as cancer biomarkers. They include glycolytic enzymes, molecular chaperones, cytoskeletal-related proteins, antioxydant enzymes, and immunologic related proteins. Among these proteins, enolase 1, phosphoglycerate kinase 1, deoxyhemoglobin, Mn-superoxyde dismutase, α-B-crystallin, HSP27, Raf kinase inhibitor protein, heterogeneous nuclear ribonucleoprotein A2/B1, cofilin 1, and peptidylprolyl isomerase A were overexpressed in tumors compared with normal tissues. In contrast, the IGHG1 protein, the complement C3 component C3c, which are two newly identified protein markers, were downregulated in IDCA tissues.

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The aim of this study is to evaluate tropomyosin-4 (TM4) expression in infiltrating ductal breast carcinomas (IDCAs), as well as its prognostic significance. Using a 2-DE/MALDI-TOF mass spectrometry investigation coupled with an immunohistochemical approach, we have assessed the expression of TM4 in IDCAs, as well as in other types of breast tumors. Proteomic analyses revealed an increased expression of tropomyosin-4 in IDCA tumors. Using immunohistochemistry, overexpression of tropomyosin-4 was confirmed in 51 additional tumor specimens. Statistical analyses revealed, however, no significant correlations between tropomyosin-4 expression and clinicopathological parameters of the disease including tumor stage, patient age, estrogen and progesterone receptor status, and lymph node metastasis occurrence. A significant association was found, however, with a high Scarf-Bloom-Richardson (SBR) grade, a known marker of tumor severity. Additionally, the SBR component showing a correlation with TM4 expression was the tubular differentiation status. This study demonstrates the upregulation of tropomyosin-4 in IDCA tissues, which may highlight its involvement in breast cancer development. Our findings also support a link between tropomyosin-4 expression and aggressiveness of IDCA tumors.