Expression of Endogenous Oncogenic<i>V600EB-raf</i>Induces Proliferation and Developmental Defects in Mice and Transformation of Primary Fibroblasts

Mercer, Kathryn; Giblett, Susan; Green, Stuart; Lloyd, D. J.; Dias, Silvy DaRocha; Plumb, Mark; Marais, Richard; Pritchard, Catrin

doi:10.1158/0008-5472.can-05-2211

Cited by 158 publications

(205 citation statements)

References 41 publications

Supporting

Mentioning

194

Contrasting

Order By: Relevance

“…Our findings are of particular interest as aberrant b-Catenin signalling and EMT have been implicated as important processes in the metastatic progression of tumours with a high incidence of BRAF V600E mutations such as melanomas, thyroid and colorectal carcinomas (Thiery, 2002). Likewise, as EMT and its opposite process are crucial and tightly regulated events during metazoan development, our finding that B-Raf V600E induces EMT might help to explain the embryonic lethal phenotype of mouse embryos with an induced B-raf V600E allele (Mercer et al, 2005).…”

Section: Regulation Of B-raf Signallingmentioning

confidence: 80%

“…Expression of B-Raf V600E has been shown to transform fibroblasts and melanocytes as well as to induce haematopoietic dysplasia in mice and invasive melanomas in p53À/À zebrafish (Davies et al, 2002;Ikenoue et al, 2004;Wellbrock et al, 2004b;Mercer et al, 2005;Patton et al, 2005). Likewise, suppression of BRAF V600E expression in melanoma lines abrogates their transformed phenotype (Hingorani et al, 2003;Karasarides et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Functional analysis of the regulatory requirements of B-Raf and the B-RafV600E oncoprotein

et al. 2006

View full text Add to dashboard Cite

The BRAF V600E mutation is found in approximately 6% of human cancers and mimics the phosphorylation of the kinase domain activation segment. In wild-type B-Raf (B-Raf wt ), activation segment phosphorylation is thought to cooperate with negative charges within the N-region for full activation. In contrast to Raf-1, the N-region of B-Raf is constitutively negatively charged owing to the presence of residues D447/D448 and the phosphorylation of S446. Therefore, it has been suggested that this hallmark predisposes B-Raf for oncogenic activation. In this study, we demonstrate that neutralizing mutations of these residues (in particular S446 and S447), or uncoupling of B-Raf from Ras-guanine 5 0 -triphosphate (GTP), strongly reduce the biological activity of B-Raf in a PC12 cell differentiation assay. We also confirm that S365 is a 14-3-3 binding site, and determine that mutation of this residue rescues the impaired biological activity of B-Raf proteins with a neutralized N-region, suggesting that the N-region opposes a 14-3-3-mediated transition into an inactive conformation. However, in the case of B-Raf V600E , although complete N-region neutralization resulted in a 2.5-fold reduction in kinase activity in vitro, this oncoprotein strongly induced PC12 differentiation or transformation and epithelial-mesenchymal transition of MCF-10A cells regardless of its N-region charge. Furthermore, the biological activity of B-Raf V600E was independent of its ability to bind Ras-GTP. Our analysis identifies important regulatory differences between B-Raf wt and B-Raf V600E and suggests that B-Raf V600E cannot be inhibited by strategies aimed at blocking S446 phosphorylation or Ras activation. Keywords: Ras; 14-3-3 proteins; b-Catenin; E-cadherin; mammary epithelial cells IntroductionThe Ras/Raf/mitogen-activated/extracellular-regulated kinase (MEK)/extracellular signal regulated kinase (ERK) pathway plays a pivotal role in control of proliferation and differentiation and, owing to its role as a gatekeeper of this pathway, Raf appears an attractive therapeutic target (O'Neill and Kolch, 2004;Wilhelm et al., 2004). The Raf-kinase family comprises the A-Raf, B-Raf and Raf-1 isoforms in vertebrates as well as D-Raf and LIN-45 in Drosophila and Caenorhabditis, respectively. B-Raf, the major ERK activator in vertebrates, is required for the maintenance of basal ERK activity and displays the most potent transforming activity (Papin et al., 1998;Brummer et al., 2002;Mercer and Pritchard, 2003). All isoforms share three highly conserved regions (CRs; Figure 1a): the N-terminal CR1 contains the Ras-guanine 5 0 -triphosphate (GTP)-binding domain (RBD), which initiates the interaction with Ras-GTP through a conserved arginine residue (R188 in B-Raf) that is required for the recruitment and activation of Raf at the plasma membrane. Consequently, mutation of this residue prevents Ras/Raf interaction and renders D-Raf, B-Raf and Raf-1 unresponsive to most extracellular signals (Hou et al., 1995;Marais et al., 1997;Brummer et al., 2002). The ...

show abstract

Section: Regulation Of B-raf Signallingmentioning

confidence: 80%

Section: Introductionmentioning

confidence: 99%

Functional analysis of the regulatory requirements of B-Raf and the B-RafV600E oncoprotein

et al. 2006

View full text Add to dashboard Cite

show abstract

“…So far, only 2 transgenic mouse models with either constitutive 77 or conditional 78 expression of mutant B-Raf have been published. Constitutive expression of the mutant human V600E B-RAF under the control of the bovine thyroglobulin promoter induced goiter and invasive papillary thyroid cancers (PTC) with tall-cell features, which later transitioned to poorly differentiated carcino- mas.…”

Section: Raf Kinases and Mouse Cancer Modelsmentioning

confidence: 99%

“…Pritchard and coworkers applied a Cre/lox strategy to generate a conditional knock-in allele of V600E B-Raf. 78 Ubiquitous expression of V600E B-Raf resulted in embryonic death before E7.5, whereas expression in adult somatic tissues induced hyperproliferation and bone marrow failure. 78 Up to now, 2 Raf-dependent mouse tumor models have been generated that allow a preclinical evaluation of novel therapeutic modalities and potential anticancer drugs.…”

Section: Raf Kinases and Mouse Cancer Modelsmentioning

confidence: 99%

Raf kinases: Oncogenesis and drug discovery

Schreck

Rapp

2006

Intl Journal of Cancer

View full text Add to dashboard Cite

Raf kinase signaling has been thoroughly investigated over the last 20 years. A-Raf, B-Raf and C-Raf, the 3 mammalian members of the Raf family, are involved in a variety of cellular processes such as growth, proliferation, survival, differentiation and transformation. The detection of B-RAF mutations in a wide variety of human cancers, the description of wildtype and mutant B-RAF as tumor antigens in melanoma and the promising outcome of clinical trials evaluating the Raf inhibitor Nexavar 1 (Sorafenib, BAY 43-9006) have sparked a broad interest in the scientific community. After a short historical detour and an introduction into Raf kinase signaling, we are going to discuss here recent outcomes of Raf kinase research with respect to tumor formation and give an overview on current efforts to develop anticancer therapies interfering with aberrant Raf kinase signaling. ' 2006 Wiley-Liss, Inc.Key words: cancer; clinical trials; transformation; drug delivery; signal transduction; mitogenic cascade; Raf kinases Raf kinases: The historyIn 1983, the cloning of the acutely transforming replication-defective mouse type C virus 3611-MSV and characterization of its acquired oncogene was reported. 1 Since 3611-MSV induces rapidly growing f ibrosarcoma in mice, the transduced oncogene was called v-raf, whereas its cellular homologue was named c-raf. 1 Shortly thereafter, Bister and coworkers described the cloning of the avian acute leukemia retrovirus Mil Hill No. 2 (MH2). 2 MH2 was found to carry a second potential oncogene in addition to vmyc, which was termed v-mil, whereas its cellular counterpart was called c-mil. 3 Already a hybridization analysis and the gross comparison of restriction maps of v-raf and v-mil pointed at sequence homologies between these 2 genes. 4 By direct sequencing of both genes it was finally proven that 3611-MSV and MH2 have integrated orthologues of the same gene into their genomes. 5 In the following we are going to use the nomenclature for Raf kinases as proposed in a recent review from Wellbrock et al. 6 In contrast to all other oncogene kinases known at that time, no tyrosine kinase activity was detected in C-Raf. 7 Indeed, it was found that C-Raf is a serine/threonine kinase. 8,9 This and the observation that Raf coexists with the Myc oncogene in retroviruses 10 led to two novel concepts: (i) There is a tyrosine to serine phosphorylation switch as the growth factor signal enters the cell, and (ii) the mechanistic basis for cooperation between nuclear and cytoplasmic oncogenes as well as for signal transduction from cell surface receptors to the nucleus is the phosphorylation of transcription factor class oncogenes such as Myc. 11-13 Growth factor abrogation and oncogene cooperation studies were performed to corroborate this signaling scheme. 14-17 Additional important early findings were (i) the cooperation between Raf and Myc in growth factor independent proliferation, immortalization and tumor induction, 14,18,19 leading to the Raf-Myc balance model, 20 and (ii) the cell lineage-switch ...

show abstract

“…Experimental studies with mice harboring a knock-in allele of BRAF mutant kinase revealed that BRAF V600E was able to induce cell transformation and proliferation (Mercer et al, 2005). Hongbin et al developed a BRAF V600E mutant mice lineage, which presented lung adenocarcinomas, histologically resembling human adenocarcinomas (Jemal et al, 2009).…”

Section: Mutationmentioning

confidence: 99%

BRAF mutations in non-small cell lung cancer: has finally Janus opened the door?

Caparica

Castro

Gil-Bazo

et al. 2016

Critical Reviews in Oncology/Hematology

View full text Add to dashboard Cite

Expression of Endogenous OncogenicV600EB-rafInduces Proliferation and Developmental Defects in Mice and Transformation of Primary Fibroblasts

Cited by 158 publications

References 41 publications

Functional analysis of the regulatory requirements of B-Raf and the B-RafV600E oncoprotein

Functional analysis of the regulatory requirements of B-Raf and the B-RafV600E oncoprotein

Raf kinases: Oncogenesis and drug discovery

BRAF mutations in non-small cell lung cancer: has finally Janus opened the door?

Contact Info

Product

Resources

About