Phosphatome profiling of estrogen receptor negative breast cancer

Purpose: To characterize the expression of phosphatases in estrogen receptor negative breast cancer Little is known about the role of phosphatases in the major estrogen receptor negative breast cancer phenotypes (i.e. those overexpressing ERBB2 and the triple negative). We carried out microarray phosphatome profiling in 41 estrogen receptor negative (ER-) breast cancer patients (as determined by immunohistochemistry (IHC)) containing both ERBB2+ and ERBB2- in order to characterize the differences between these groups by Statistical Analysis of Microarrays (SAM). Our findings point to the importance of the MAPK and PI3K pathways in ER- BCs as some of the most differentially expressed phosphatases (like DUSP4 and DUSP6) share ERK as substrate, or regulate the PI3K pathway (INPP4B, PTEN). These observations are also confirmed by pathway and GSEA analysis. It is shown that both ER- ERBB2+ and triple negative breast cancers have a distinctive pattern of phosphatase RNA expression. Surgical specimens from primary breast cancers that were estrogen receptor negative according to immunohistochemistry