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ERK phosphorylation predicts synergism between gemcitabine and the epidermal growth factor receptor inhibitor AG1478

Peter P Luk1, Peter Galettis, Matthew Links

  • 1Cancer Pharmacology and Therapeutic Laboratory, Medical Oncology, St. George Hospital, Sydney, NSW, Australia. Peter.Luk@sesiahs.health.nsw.gov.au

Lung Cancer (Amsterdam, Netherlands)
|February 1, 2011
PubMed
Abstract

Insights

EGFR inhibitors combined with gemcitabine show antagonism in non-small cell lung cancer, influenced by ERK phosphorylation and KRAS mutations. Understanding these interactions is key for effective lung cancer treatment.

Area of Science:

  • Oncology
  • Molecular Biology
  • Pharmacology

Background:

  • Clinical trials combining EGFR inhibitors and gemcitabine in NSCLC lack survival benefits.
  • Potential antagonism between EGFR inhibitors and gemcitabine, possibly due to RAS mutations, is a concern.
  • ERK, a downstream regulator of RAS, may influence treatment outcomes.

Purpose of the Study:

  • To investigate the interplay between ERK, drug synergy/antagonism, and cell cycle arrest in NSCLC treated with gemcitabine and EGFR inhibitors.
  • To explore the role of KRAS mutations in the response to combination therapy.

Main Methods:

  • Utilized A549 (mutant KRAS) and H322 (wildtype KRAS) cell lines, plus siRNA-mediated KRAS knockdown.
  • Assessed drug interactions using median effect analysis, cell cycle distribution via flow cytometry, and ERK phosphorylation by ELISA.
  • Evaluated cytotoxicity after ERK inhibition using U0126.

Main Results:

  • Cytotoxic interaction was dose-dependent, showing antagonism at high EGFR inhibitor doses.
  • ERK phosphorylation increased with gemcitabine and was suppressed by the EGFR inhibitor, correlating with antagonism, especially in wildtype KRAS cells.
  • KRAS mutant cells exhibited greater antagonism, and KRAS knockdown enhanced sensitivity to EGFR inhibitors and combination therapy.

Conclusions:

  • ERK phosphorylation appears to promote synergy, with outcomes dependent on the balance of gemcitabine-induced and EGFR inhibitor-suppressed ERK phosphorylation.
  • KRAS mutation confers resistance to EGFR inhibitors and combination treatments in NSCLC.

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