Analysis of the breast cancer proteome

PURPOSE The discovery of the oestrogen and her-2 receptor proteins paved the way for the subsequent development of adjunctive therapeutic options for the treatment of breast cancer. The advancement of proteomic technology has enabled the identification of such unique proteins differentially expressed in a range of disease states including breast cancer. It is our aim to use this technique to identify potential target molecules for future therapy. METHODS Breast cancer samples weighing 100mg were obtained from patients in Tasmania and Greece. Normal breast tissue was obtained as control from patients undergoing reduction mammoplasty. Sample preparation was performed using a sequential extraction protocol to yield two solutions per tissue sample. This was followed by two-dimensional gel electrophoresis and resultant gels analyzed using PDQuest software. RESULTS Quantitative analysis revealed a 5-fold increased expression of 54 spots and decreased expression of 20 spots in breast cancer versus normal tissue using solution 2 and 3 extracted gel images. All such identified spots were located within pI (Iso-electric point) 6.0-8.2 and molecular weight 25-75kDa. Further detailed analysis enabled the identification of a number of spots showing differential expression by clinical stage including metastatic cancer, histological subtype, racial subgroup and amongst familial cancers. CONCLUSION The further characterization of identified spots will involve the exclusion of known markers using immunoblotting techniques with unknown spots subjected to mass spectrometric analysis or amino acid sequence determination. This approach may allow the identification of new diagnostic and/or therapeutic targets.