RESUMO
Malignant and normal human breast tissue were compared by evaluating two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) maps of frozen tissue samples. Image analyzing software was used to scan and process 34 gels. Eight (8/34) of these gels (4 malignant breast tumor samples, 4 normal tissue samples) were selected on the basis of gel and image quality to build a database to identify and measure the expression of a previously unidentified proteome. Growth factor receptor proteins (GFRs), including ERBB2 (HER2) and ERBB3 (HER3), were expressed in the malignant tissue samples. Growth factor receptor proteins were not expressed in the normal tissue. Also, expression of PS2-protein (pS2) was detected in neither malignant nor normal tissue. In benign breast samples a higher intensity of protein expression could be observed for maspin, desmoglein 3 and keratin 8 than in malignant samples. Other proteins expressed in malignant breast tissue include mitogen-activated protein kinase 3 (MK03), heat shock protein 27 kDa (HS27), growth factor receptor-bound protein (GRB2), cathepsin D, G1/S specific cyclin E1 (CGEI), glucose transporter type 5 (GTR5), and a number of as yet unidentified proteins.