Increased wound-response revealed by proteomics of estrogen receptor-negative breast cancers

Besides the mitogenic action of estrogens in breast cancer cells there is also evidence that estrogen receptors mediate protective, anti-invasive effects. The aim of this project was to identify downstream ER-dependent proteins differentially expressed in fresh-frozen ER-positive and –negative breast cancer. Tissue sections from eight ER-positive and eight ER-negative cryo-preserved breast cancer specimen were analysed by differential multiplex ProteoTope imaging of 2D-PAGE gels. This method is based on labeling proteins with chemically identical iodine radio-isotopes (I–125, I–131) and provides a direct quantitative and multi color differential proteome display at the low-attomole level. Spots were matched across gels, and their intensities were analysed relative to ER status. The statistically most significant differential protein spots were identified by mass spectrometry using picked co-migrating non-radioactive tumor proteins. In total, proteins from 325 spots were identified by MALDI-TOF PMF with MASCOT scores greater than 70. 72 spots represented 16 proteins that were identified in more than one protein spot. Proteins significantly differentially abundant across all pools at the 0.1% level were consistent with previously published literature. We observed elevated levels of keratins 19, 18 and 8 in ER-positive tumors suggesting a luminal phenotype for ER-positive tumors. Additionally, proteins associated with increased inflammation and wound response were observed in ER-negative tumors. Our data are consistent with previously published literature, suggesting an altered keratin pool associated with increased inflammation and wound response in ER-negative tumors.

breast cancer - proteomics