Proteomic and phosphoproteomic profiling of ErbB2-dependent signalling

The mechanisms of ErbB2 signalling and the effects of its overexpression are not fully understood. Herein, SILAC expression profiling and phosphopeptide enrichment of a relevant, non-transformed, immortalized human mammary luminal epithelial cell model were used to profile ErbB2-dependent differences in protein expression and phosphorylation events triggered via EGFR (EGF treatment) and ErbB3 (HRGbeta1 treatment) in the context of ErbB2 overexpression. Bioinformatics analysis was used to infer changes in cellular processes and signalling events. We demonstrate the complexity of the responses to oncogene expression and growth factor signalling and identify protein changes relevant to ErbB2-dependent altered cellular phenotype, in particular cell cycle progression and hyper-proliferation, reduced adhesion and enhanced motility. Numerous novel sites of growth factor-regulated phosphorylation were also identified that were enhanced by ErbB2 overexpression and we putatively link these to altered cell behaviour. Moreover, we have defined a novel mechanism by which ErbB signalling suppresses basal interferon signalling that would promote the survival and proliferation of mammary luminal epithelial cells.