Temporal profiling of lapatinib-suppressed phosphorylation signals in EGFR/HER2 pathways

Koshi Imami, Naoyuki Sugiyama, Haruna Imamura, Masaki Wakabayashi, Masaru Tomita, Masatoshi Taniguchi, Takayuki Ueno, Masakazu Toi, Yasushi Ishihama

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23 Citations (Scopus)

Abstract

Lapatinib is a clinically potent kinase inhibitor for breast cancer patients because of its outstanding selectivity for epidermal growth factor receptor (EGFR) and EGFR2 (also known as HER2). However, there is only limited information about the in vivo effects of lapatinib on EGFR/HER2 and downstream signaling targets. Here, we profiled the lapatinib-induced time- and dose-dependent phosphorylation dynamics in SKBR3 breast cancer cells by means of quantitative phosphoproteomics. Among 4953 identified phosphopeptides from 1548 proteins, a small proportion (5-7%) was regulated at least twofold by 1-10 μM lapatinib. We obtained a comprehensive phosphorylation map of 21 sites on EGFR/HER2, including nine novel sites on HER2. Among them, serine/threonine phosphosites located in a small region of HER2 (amino acid residues 1049-1083) were up-regulated by the drug, whereas all other sites were down-regulated. We show that cAMP-dependent protein kinase is involved in phosphorylation of this particular region of HER2 and regulates HER2 tyrosine kinase activity. Computational analyses of quantitative phosphoproteome data indicated for the first time that protein-protein networks related to cytoskeletal organization and transcriptional/translational regulation, such as RNP complexes (i.e. hnRNP, snRNP, telomerase, ribosome), are linked to EGFR/HER2 signaling networks. To our knowledge, this is the first report to profile the temporal response of phosphorylation dynamics to a kinase inhibitor. The results provide new insights into EGFR/HER2 regulation through region-specific phosphorylation, as well as a global view of the cellular signaling networks associated with the anti-breast cancer action of lapatinib.

Original languageEnglish
Pages (from-to)1741-1757
Number of pages17
JournalMolecular and Cellular Proteomics
Volume11
Issue number12
DOIs
Publication statusPublished - 2012 Dec 1

ASJC Scopus subject areas

  • Analytical Chemistry
  • Biochemistry
  • Molecular Biology

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    Imami, K., Sugiyama, N., Imamura, H., Wakabayashi, M., Tomita, M., Taniguchi, M., Ueno, T., Toi, M., & Ishihama, Y. (2012). Temporal profiling of lapatinib-suppressed phosphorylation signals in EGFR/HER2 pathways. Molecular and Cellular Proteomics, 11(12), 1741-1757. https://doi.org/10.1074/mcp.M112.019919