Analysis of EGFR signaling pathway in nasopharyngeal carcinoma cells by quantitative phosphoproteomics

Abstract

BackgroundThe epidermal growth factor receptor (EGFR) is usually overexpressed in nasopharyngeal carcinoma (NPC) and is associated with pathogenesis of NPC. However, the downstream signaling proteins of EGFR in NPC have not yet been completely understood at the system level. The aim of this study was identify novel downstream proteins of EGFR signaling pathway in NPC cells.ResultsWe analyzed EGFR-regulated phosphoproteome in NPC CNE2 cells using 2D-DIGE and mass spectrometry analysis after phosphoprotein enrichment. As a result, 33 nonredundant phosphoproteins including five known EGFR-regulated proteins and twenty-eight novel EGFR-regulated proteins in CNE2 were identified, three differential phosphoproteins were selectively validated, and two differential phosphoproteins (GSTP1 and GRB2) were showed interacted with phospho-EGFR. Bioinformatics analysis showed that 32 of 33 identified proteins contain phosphorylation modification sites, and 17 identified proteins are signaling proteins. GSTP1, one of the EGFR-regulated proteins, associated with chemoresistance was analyzed. The results showed that GSTP1 could contribute to paclitaxel resistance in EGF-stimulated CNE2 cells. Furthermore, an EGFR signaling network based on the identified EGFR-regulated phosphoproteins were constructed using Pathway Studio 5.0 software, which includes canonical and novel EGFR-regulated proteins and implicates the possible biological roles for those proteins.ConclusionThe data not only can extend our knowledge of canonical EGFR signaling, but also will be useful to understand the molecular mechanisms of EGFR in NPC pathogenesis and search therapeutic targets for NPC.

Eukaryotic elongation factor 2 is a prognostic marker and its kinase a potential therapeutic target in HCC

“…The average number of spots we detected comparing the enriched phosphoproteins of 7 HCC-patients was in a similar range of resolution compared to other gel-based phosphoproteomic studies [12–15]. Comparison of untreated and dephosphorylated protein lysates after off-gel fractionation could point to different phosphorylation states as eEF2 is not only phosphorylated at regulating threonine 56 by the eEF2 kinase but also at serine 595 by Cyclin A-Cyclin-Dependent Kinase 2 serving as a “docking” phosphorylation for eEF2 kinase [16, 17].…”

Expression profiling of 21 biomolecules in locally advanced nasopharyngeal carcinomas of Caucasian patients

“…Although EBV presence is believed to induce EGFR [63], such a paired expression model was also not found. The paucity of EGFR-expression information in the present study could be interpreted in the context of the evolving understanding of EGFR role in NPC pathogenesis; EGFR downstream signaling molecules are numerous in NPC and are still being defined [64]. The relative inefficacy of EGFR-targeting attempts in NPC [65], in contrast to HNSCC [66], serves as a reminder of the underlying complexity.…”

Antitumor Effects of Interferon-Alpha on Cell Growth and Metastasis in Human Nasopharyngeal Carcinoma

“…Moreover, a specific hyperactivation of EGFR-depedent Ras/extracellular signalregulated kinase (ERK) 1/2 pathway was also reported to counteract IFN-α-induced apoptosis and could be stimulated by the addition of EGF. Interestingly, alterations in EGFR signaling had been correlated to NPC carcinogenesis [39], therefore we hypothesized that the activation of EGFR signaling had a prominent role in the anti-apoptotic effect in NPC cells. On the other hand, IFN-α1b is well known to potently stimulate immune response, such as stimulation of leukocytes to produce and secret cytokines in vivo.…”