Exp Mol Med.  2013 Nov;45(11):e64.

Phosphoproteomic analysis identifies activated MET-axis PI3K/AKT and MAPK/ERK in lapatinib-resistant cancer cell line

  • 1WCU Department of Molecular Medicine and Biopharmaceutical Sciences, Graduate School of Convergence Science and Technology and College of Medicine or College of Pharmacy, Seoul National University, Seoul, Republic of Korea. euyi@snu.ac.kr
  • 2Wide River Institute of Immunology, Seoul National University, Seoul, Republic of Korea.
  • 3Cancer Research Institute, Seoul National University, Seoul, Republic of Korea. kimty@snu.ac.kr
  • 4Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea.


Lapatinib, a dual inhibitor of epidermal growth factor receptor (EGFR) and human epidermal growth factor receptor 2 (HER2) tyrosine kinases, has shown promising results as a growth inhibitor of HER2-positive cancer cells in vitro. However, similar to other EGFR-targeting drugs, acquired resistance to lapatinib by HER2-positive cancer cells remains a major clinical challenge. To elucidate resistance mechanisms to EGFR/HER2-targeting agents, we performed a systematic quantitative comparison of the phosphoproteome of lapatinib-resistant (LR) human gastric cancer cells (SNU216-LR) versus parental cells (SNU216) using a titanium dioxide (TiO2) phosphopeptide enrichment method and analysis with a Q-Exactive hybrid quadrupole-Orbitrap mass spectrometer. Biological network analysis of differentially expressed phosphoproteins revealed apparent constitutive activation of the MET-axis phosphatidylinositide 3-kinase (PI3K)/alpha-serine/threonine-protein kinase (AKT) and mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) signaling pathways in SNU216-LR. Inhibition of the PI3K/AKT and MAPK/ERK signaling pathways in SNU216-LR also leads to cell cycle arrest, confirming the biological network analysis. Lapatinib sensitivity was restored when cells were treated with several molecular targeting agents in combination with lapatinib. Thus, by integrating phosphoproteomic data, protein networks and effects of signaling pathway modulation on cell proliferation, we found that SNU216-LR maintains constitutive activation of the PI3K/AKT and MAPK/ERK pathways in a MET-dependent manner. These findings suggest that pathway activation is a key compensatory intracellular phospho-signaling event that may govern gastric cancer cell resistance to drug treatment.


drug resistance; HER2-positive gastric cancer; lapatinib; phosphoproteins; Q-Exactive; therapeutic targets

MeSH Terms

Antineoplastic Agents/*pharmacology
Cell Line, Tumor
Drug Resistance, Neoplasm
*MAP Kinase Signaling System
Mitogen-Activated Protein Kinase Kinases/metabolism
Mitogen-Activated Protein Kinases/metabolism
Phosphatidylinositol 3-Kinases/*metabolism
Proto-Oncogene Proteins c-akt/*metabolism
Proto-Oncogene Proteins c-met/*metabolism
Antineoplastic Agents
Mitogen-Activated Protein Kinase Kinases
Mitogen-Activated Protein Kinases
Phosphatidylinositol 3-Kinases
Proto-Oncogene Proteins c-akt
Proto-Oncogene Proteins c-met
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