Comparative Proteomics of Tumor and Paired Normal Breast Tissue Highlights Potential Biomarkers in Breast Cancer

Background/Aim: Breast cancer is the most common type of cancer among women worldwide, and about 57,000 new cases are expected for the Brazilian population in 2015. Elucidation of protein expression and modification is essential for the biological understanding, early diagnosis and therapeutics of breast cancer. The main objectives of the study are comparison between the proteome of tumor and paired non-tumor breast cancer tissues, describing all identified proteins, highlighting the ones most differentially expressed and comparing the data with existing literature. Materials and Methods: The five paired samples from patients with invasive ductal carcinoma were analyzed by 2-DE and MS. Results: We collected 161 identified spots corresponding to 110 distinct proteins. Forty-three differentially-expressed spots were common to at least two samples, and the ten proteins with the highest-fold changes were CASPE, ENOG, TPM1, CAPG, VIME, TPM3, TRFE, PDIA6, WDR61 and PDIA3. Metabolic enzymes and proteins with binding functions were the most representative functional classes of proteins with increased and decreased expression in tumor tissue respectively. Conclusion: Taking the fold change as a parameter, we point to future targets to be studied by functional methods in a search for biomarkers for initiation and progress of breast cancer.