Over-expression of RNA Processing, Heat Shock and DNA Repair Proteins in Breast Tumor Compared to Normal Tissue.

This study identifies the main changes in protein expression in human breast tumors compared to normal breast tissue. Malignant tumors (32) and normal breast tissue samples (23), from formaldehyde-fixed, paraffin-embedded specimens were subjected to discovery proteomics using LC/MS/MS, with spectral counts for quantitation. The dataset contains 1406 proteins. Differential expression was measured using a method that takes advantage of estimates of the percentage of tumor on a slide. This analysis shows that the major classes of proteins over-expressed by tumors are RNA-binding, heat shock and DNA repair proteins. RNA-binding proteins, HNRNPs, SRSF and elongation factors form the largest group. Comparison with results from another study demonstrate that the RNA-binding proteins are associated specifically with malignant transformation, rather than with cell proliferation. HNRNP and SRSF proteins help define splice sites in normal cells. Their over-expression may dysregulate splicing, which in turn has the potential to promote malignant transformation. This article is protected by copyright. All rights reserved.