There is a growing interest in
protein expression profiling aiming to identify novel diagnostic markers in
breast cancer. Proteomic approaches such as two-dimensional differential gel electrophoresis coupled with tandem mass spectrometry analysis (2-D DIGE/MS/MS) have been used successfully for the identification of candidate
biomarkers for screening, diagnosis, prognosis and monitoring of treatment response in various types of
cancer. Identifying previously unknown
proteins of potential clinical relevance will ultimately help in reaching effective ways to manage the disease. We analyzed
breast cancer tissues from five
tumor and five normal tissue samples from ten
breast cancer subjects with infiltrating
ductal carcinoma (IDC) by 2-D DIGE using two types of immobilized pH gradient (IPG) strips:
pH 3-10 and pH 4-7. From all the spots detected, differentially expressed (p < 0.05 and ratio > 2) were 50 spots. Of these, 39
proteins were successfully identified by MS, representing 29 different
proteins. Ten
proteins were overexpressed in the
tumor samples. The 2-D DIGE/MS/MS analysis revealed an increase in the expression levels in
tumor samples of several
proteins not previously associated with
breast cancer, such as: macrophage-capping
protein (CAPG),
phosphomannomutase 2 (PMM2),
ATPase ASN1, methylthioribose-1-phosphate
isomerase (MRI1),
peptidyl-prolyl cis-trans isomerase FKBP4, cellular
retinoic acid-
binding protein 2 (CRABP2),
lamin B1 and
keratin, type II cytoskeletal 8 (KRT8). Ingenuity Pathway Analysis (IPA) revealed highly significant (p = 10(-26)) interactions between the identified
proteins and their association with
cancer. These
proteins are involved in many diverse pathways and have established roles in cellular metabolism. It remains the goal of future work to test the suitability of the identified
proteins in samples of larger and independent patient groups.