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Comparative proteomics and transcriptomics study of signaling network proteins across multiple normal and cancer cell lines

ABSTRACT: It is not known whether cancer cells generally show quantitative differences in the expression of signaling pathway proteins that could dysregulate signal transduction. To explore this issue, we first defined the primary components of the EGFR-MAPK pathway in normal human mammary epithelial cells, identifying 16 core proteins and 10 feedback regulators. We then quantified their absolute abundance at both the protein and mRNA level across a panel of normal and breast cancer cell lines. We found that core pathway proteins were present at very similar levels across all cell types. In contrast, the EGFR and transcriptionally controlled feedback regulators were present at highly variable levels. The absolute abundance of most core proteins was between 50,000-70,000 copies per cell, but the adaptors SOS1, SOS2, and GAB1 were found at far lower levels (2,000-5,000 per cell). MAPK signaling showed saturation in all cells between 3,000-10,000 occupied EGFR, consistent with the idea that adaptors limit signaling. Our results suggest that the relative stoichiometry of core MAPK pathway proteins is very similar across different cell types, with cell-specific differences mostly restricted to variable levels of feedback regulators. The low abundance of adaptors relative to the EGFR could be responsible for previous observation of saturable signaling, endocytosis, and high affinity EGFR.

ORGANISM(S): Homo sapiens

PROVIDER: GSE81032 | GEO | 2016/05/03

SECONDARY ACCESSION(S): PRJNA320318

REPOSITORIES: GEO

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Project description:The highly conserved Epidermal Growth Factor-receptor (Egfr) pathway is required in all animals for normal development and homeostasis; consequently, aberrant Egfr signaling is implicated in a number of diseases. Genetic analysis of Drosophila melanogaster Egfr has contributed significantly to understanding this conserved pathway and has led to the discovery of new components and targets. Here we used microarray analysis of Drosophila third instar wing discs, in which Egfr signaling was perturbed, to identify new Egfr-responsive genes. Upregulated transcripts included five known targets suggesting the approach was valid. We investigated the function of 29 previously uncharacterized genes, which had pronounced responses. The Egfr pathway is important for wing-vein patterning and using reverse genetic analysis we identified five genes that showed venation defects. Three of these genes are expressed in vein primordia and all showed transcriptional changes in response to altered Egfr activity consistent with being targets of the pathway. Genetic interactions with Egfr further linked two of the genes, Sulfated (Sulf1), an endosulfatase gene, and CG4096, an ADAMTS (A Disintegrin And Metalloproteinase with ThromboSpondin motifs) gene, to the pathway. Sulf1 showed a strong genetic interaction with the neuregulin-like ligand vein (vn) and may influence binding of Vn to heparan-sulfated proteoglycans (HSPGs). Genetic evidence also shows that CG4096 functions by modulating activity of the Egfr ligands. The substrate(s) and how ligand activity is affected are unknown, but interestingly vertebrate EGF ligands are regulated by a related ADAMTS protein. We conclude Sulf1 and CG4096 are negative feedback regulators of Egfr signaling that function in the extracellular space to influence ligand activity. 3 replicates each of wing disc samples in which EGFR dominant negative (EGFR-DN) or EGFR activated (EGFR-TOP) transgenes were expressed with the 71B-Gal4 driver.

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Comparative proteomics and transcriptomics study of signaling network proteins across multiple normal and cancer cell lines

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