RAF inhibitors transactivate RAF dimers and ERK signaling in cells with wild-type BRAF

By P. Poulikakos, Chao Zhang, G. Bollag, Kevan M. Shokat, N. Rosen. Nature, 2010

1,791 citations recorded by the source corpus.

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.

Subfields: Computational Theory and Mathematics, Molecular Biology, Oncology

View Paper: https://www.semanticscholar.org/paper/c48468c28eebc952daa674dfb72d6158a0cd3caa

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Citations in the corpus

Integrated Genomic Characterization of Papillary Thyroid Carcinoma (2014, background): “Because BRAFV600E signals as a monomer, it is insensitive to feedback leading to ERK overactivation (Poulikakos et al., 2010).”
Targeting the RAS/RAF/MAPK pathway for cancer therapy: from mechanism to clinical studies (2023, background): “389 This paradoxical activation of RAFi-insensitive BRAF V600E – mutant dimers result in the formation of a new steady-state signaling network, even in the presence of RAFis.”
Rational, biologically based treatment of EGFR-mutant non-small-cell lung cancer (2010, background): “, and confers sensitivity to specific small-molecule V600E inhibitor”
Combined BRAF and MEK inhibition versus BRAF inhibition alone in melanoma. (2014, neutral): “Progressive disease 13 (6) 19 (9) 10 (6) 11 (6) 3 (10) 8 (27)”
Targeting the Mitogen-Activated Protein Kinase RAS-RAF Signaling Pathway in Cancer Therapy (2012, background): “The underlying mechanism for this paradoxical effect is probably related to the allosteric effect of the drug, which enforces the dimerization of endogenous BRAF with CRAF or ARAF [88-90].”
KRAS: The Critical Driver and Therapeutic Target for Pancreatic Cancer (2018, background): “In RAS-mutant cells, the BRAF-selective inhibitors cause paradoxical activation of ERK signaling (Hatzivassiliou et al. 2010; Heidorn et al. 2010; Poulikakos et al. 2010).”
A Comprehensive Review on MAPK: A Promising Therapeutic Target in Cancer (2019, background): “RAF inhibitors (GW5074, L779450, PLX4720, sorafenib, ZM336372) proved to activate RAF dimers, as mutant BRAF cells are dependent on the RAF/MEK/ERK signaling pathway for their growth [106].”
Widespread genetic heterogeneity in multiple myeloma: implications for targeted therapy (2014, neutral): “In addition, BRAF inhibition downregulated MAP kinase pathway activity only in BRAFmutant MM cells, whereas in BRAF-wild-type cells, the pathway was paradoxically upregulated (Figure 4A), similar to reports in melanoma (Poulikakos et al., 2010).”
Clinical characteristics of patients with lung adenocarcinomas harboring BRAF mutations. (2011, background): “Comprehensive prospective genotyping rather than clinical enrichment for future studies of drugs targeting this pathway is essential in light of recent data noting a paradoxical RAF inhibitor-mediated activation of the RAS signaling pathway in BRAF WT cell lines.(33)”
An Integrated Mechanistic Model of Pan-Cancer Driver Pathways Predicts Stochastic Proliferation and Death (2017, background): “Monotherapy can even activate the target pathway, depending on cellular context (Poulikakos et al., 2010).”
Targeting MAPK Signaling in Cancer: Mechanisms of Drug Resistance and Sensitivity (2020, background): “Vemurafenib Selective BRAF V600E inhibitor (ATP competitive) Activating mutations in NRAS or MEK [23,24]; BRAF/CRAF amplification [23,25]; BRAF alternative splicing [26,27]; RAF heterodimerization [28]; RTK upregulation [29]; Loss of NF1 [30]; COT upregulation [31] Dabrafenib”
EGFR-mediated re-activation of MAPK signaling contributes to insensitivity of BRAF mutant colorectal cancers to RAF inhibition with vemurafenib (2012, background): “Indeed, introduction of an activated RAS mutant into HT-29 cells led to sustained P-ERK levels and resistance to vemurafenib (11).”