BRAF V600E disrupts AZD6244-induced abrogation of negative feedback pathways between extracellular signal-regulated kinase and Raf proteins

Bret B. Friday, Chunrong Yu, Grace K. Dy, Paul D. Smith, Liang Wang, Stephen N Thibodeau, Alex Adjei

Research output: Contribution to journalArticle

110 Citations (Scopus)

Abstract

AZD6244 (ARRY 142886) is a potent and selective mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) kinase (MEK) inhibitor currently in early clinical trials. We examined the activity of AZD6244 in a panel of non-small cell lung cancer and a panel of cell lines representing many cancer types using in vitro growth assays. AZD6244 induced G 0-G 1 cell cycle arrest in sensitive cell lines that primarily included cells containing the BRAF V600E mutation. In these cells, G 0-G 1 arrest is accompanied by the up-regulation of the cell cycle inhibitors p21 WAF1 and p27 Kip1 and downregulation of cyclin D1. In the majority of cell lines tested, including those with K-ras or non-V600E BRAF mutations, AZD6244 induced the accumulation of phospho-MEK, an effect not observed in the most sensitive BRAF V600E-containing cells. Accumulation of phospho-MEKin non-V600E-containing cell lines is due to abrogation of negative feedback pathways. BRAF V600E disrupts negative feedback signaling, which results in enhanced baseline phospho-MEKex pression. Exogenous expression of BRAF V600E disrupts feedback inhibition but does not sensitize cells to AZD6244. Specific suppression of endogenous BRAF V600E does not confer resistance to AZD6244 but enhances sensitivity to AZD6244. Thus, our findings show that BRAF V600E marks cells with an in vitro requirement for MAPK signaling to support proliferation. These cells are exquisitely sensitive to AZD6244 (IC 50, <100 nmol/L), have high baseline levels of phospho-MEK, and lack feedback inhibition between ERK and Raf. These data suggest an approach to identifying cells that may be sensitive to AZD6244 and other MEK inhibitors.

Original languageEnglish (US)
Pages (from-to)6145-6153
Number of pages9
JournalCancer Research
Volume68
Issue number15
DOIs
StatePublished - Aug 1 2008

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Extracellular Signal-Regulated MAP Kinases
Proteins
Mitogen-Activated Protein Kinase Kinases
Cell Line
Gastrin-Secreting Cells
Mitogen-Activated Protein Kinases
AZD 6244
MAP Kinase Kinase Kinases
Mutation
Cyclin D1
Cell Cycle Checkpoints
Non-Small Cell Lung Carcinoma
Cell Cycle
Up-Regulation
Down-Regulation
Clinical Trials

ASJC Scopus subject areas

  • Cancer Research
  • Oncology

Cite this

BRAF V600E disrupts AZD6244-induced abrogation of negative feedback pathways between extracellular signal-regulated kinase and Raf proteins. / Friday, Bret B.; Yu, Chunrong; Dy, Grace K.; Smith, Paul D.; Wang, Liang; Thibodeau, Stephen N; Adjei, Alex.

In: Cancer Research, Vol. 68, No. 15, 01.08.2008, p. 6145-6153.

Research output: Contribution to journalArticle

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abstract = "AZD6244 (ARRY 142886) is a potent and selective mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) kinase (MEK) inhibitor currently in early clinical trials. We examined the activity of AZD6244 in a panel of non-small cell lung cancer and a panel of cell lines representing many cancer types using in vitro growth assays. AZD6244 induced G 0-G 1 cell cycle arrest in sensitive cell lines that primarily included cells containing the BRAF V600E mutation. In these cells, G 0-G 1 arrest is accompanied by the up-regulation of the cell cycle inhibitors p21 WAF1 and p27 Kip1 and downregulation of cyclin D1. In the majority of cell lines tested, including those with K-ras or non-V600E BRAF mutations, AZD6244 induced the accumulation of phospho-MEK, an effect not observed in the most sensitive BRAF V600E-containing cells. Accumulation of phospho-MEKin non-V600E-containing cell lines is due to abrogation of negative feedback pathways. BRAF V600E disrupts negative feedback signaling, which results in enhanced baseline phospho-MEKex pression. Exogenous expression of BRAF V600E disrupts feedback inhibition but does not sensitize cells to AZD6244. Specific suppression of endogenous BRAF V600E does not confer resistance to AZD6244 but enhances sensitivity to AZD6244. Thus, our findings show that BRAF V600E marks cells with an in vitro requirement for MAPK signaling to support proliferation. These cells are exquisitely sensitive to AZD6244 (IC 50, <100 nmol/L), have high baseline levels of phospho-MEK, and lack feedback inhibition between ERK and Raf. These data suggest an approach to identifying cells that may be sensitive to AZD6244 and other MEK inhibitors.",
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AU - Dy, Grace K.

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AU - Adjei, Alex

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