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RAF inhibitors transactivate RAF dimers and ERK signalling in cells with wild-type BRAF.
Nature. 2010 Mar 18; 464(7287):427-30.Nat

Abstract

Tumours with mutant BRAF are dependent on the RAF-MEK-ERK signalling pathway for their growth. We found that ATP-competitive RAF inhibitors inhibit ERK signalling in cells with mutant BRAF, but unexpectedly enhance signalling in cells with wild-type BRAF. Here we demonstrate the mechanistic basis for these findings. We used chemical genetic methods to show that drug-mediated transactivation of RAF dimers is responsible for paradoxical activation of the enzyme by inhibitors. Induction of ERK signalling requires direct binding of the drug to the ATP-binding site of one kinase of the dimer and is dependent on RAS activity. Drug binding to one member of RAF homodimers (CRAF-CRAF) or heterodimers (CRAF-BRAF) inhibits one protomer, but results in transactivation of the drug-free protomer. In BRAF(V600E) tumours, RAS is not activated, thus transactivation is minimal and ERK signalling is inhibited in cells exposed to RAF inhibitors. These results indicate that RAF inhibitors will be effective in tumours in which BRAF is mutated. Furthermore, because RAF inhibitors do not inhibit ERK signalling in other cells, the model predicts that they would have a higher therapeutic index and greater antitumour activity than mitogen-activated protein kinase (MEK) inhibitors, but could also cause toxicity due to MEK/ERK activation. These predictions have been borne out in a recent clinical trial of the RAF inhibitor PLX4032 (refs 4, 5). The model indicates that promotion of RAF dimerization by elevation of wild-type RAF expression or RAS activity could lead to drug resistance in mutant BRAF tumours. In agreement with this prediction, RAF inhibitors do not inhibit ERK signalling in cells that coexpress BRAF(V600E) and mutant RAS.

Authors+Show Affiliations

Program in Molecular Pharmacology and Chemistry and Department of Medicine, Memorial Sloan-Kettering Cancer Center, New York, New York 10065, USA.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

20179705

Citation

Poulikakos, Poulikos I., et al. "RAF Inhibitors Transactivate RAF Dimers and ERK Signalling in Cells With Wild-type BRAF." Nature, vol. 464, no. 7287, 2010, pp. 427-30.
Poulikakos PI, Zhang C, Bollag G, et al. RAF inhibitors transactivate RAF dimers and ERK signalling in cells with wild-type BRAF. Nature. 2010;464(7287):427-30.
Poulikakos, P. I., Zhang, C., Bollag, G., Shokat, K. M., & Rosen, N. (2010). RAF inhibitors transactivate RAF dimers and ERK signalling in cells with wild-type BRAF. Nature, 464(7287), 427-30. https://doi.org/10.1038/nature08902
Poulikakos PI, et al. RAF Inhibitors Transactivate RAF Dimers and ERK Signalling in Cells With Wild-type BRAF. Nature. 2010 Mar 18;464(7287):427-30. PubMed PMID: 20179705.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - RAF inhibitors transactivate RAF dimers and ERK signalling in cells with wild-type BRAF. AU - Poulikakos,Poulikos I, AU - Zhang,Chao, AU - Bollag,Gideon, AU - Shokat,Kevan M, AU - Rosen,Neal, PY - 2009/11/13/received PY - 2010/02/16/accepted PY - 2010/2/25/entrez PY - 2010/2/25/pubmed PY - 2010/4/30/medline SP - 427 EP - 30 JF - Nature JO - Nature VL - 464 IS - 7287 N2 - Tumours with mutant BRAF are dependent on the RAF-MEK-ERK signalling pathway for their growth. We found that ATP-competitive RAF inhibitors inhibit ERK signalling in cells with mutant BRAF, but unexpectedly enhance signalling in cells with wild-type BRAF. Here we demonstrate the mechanistic basis for these findings. We used chemical genetic methods to show that drug-mediated transactivation of RAF dimers is responsible for paradoxical activation of the enzyme by inhibitors. Induction of ERK signalling requires direct binding of the drug to the ATP-binding site of one kinase of the dimer and is dependent on RAS activity. Drug binding to one member of RAF homodimers (CRAF-CRAF) or heterodimers (CRAF-BRAF) inhibits one protomer, but results in transactivation of the drug-free protomer. In BRAF(V600E) tumours, RAS is not activated, thus transactivation is minimal and ERK signalling is inhibited in cells exposed to RAF inhibitors. These results indicate that RAF inhibitors will be effective in tumours in which BRAF is mutated. Furthermore, because RAF inhibitors do not inhibit ERK signalling in other cells, the model predicts that they would have a higher therapeutic index and greater antitumour activity than mitogen-activated protein kinase (MEK) inhibitors, but could also cause toxicity due to MEK/ERK activation. These predictions have been borne out in a recent clinical trial of the RAF inhibitor PLX4032 (refs 4, 5). The model indicates that promotion of RAF dimerization by elevation of wild-type RAF expression or RAS activity could lead to drug resistance in mutant BRAF tumours. In agreement with this prediction, RAF inhibitors do not inhibit ERK signalling in cells that coexpress BRAF(V600E) and mutant RAS. SN - 1476-4687 UR - https://www.unboundmedicine.com/medline/citation/20179705/RAF_inhibitors_transactivate_RAF_dimers_and_ERK_signalling_in_cells_with_wild_type_BRAF_ L2 - https://doi.org/10.1038/nature08902 DB - PRIME DP - Unbound Medicine ER -