Pan-Raf co-operates with PI3K-dependent signaling and critically contributes to myeloma cell survival independently of mutated RAS
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE75078 | GEO | 2016/11/21
SECONDARY ACCESSION(S): PRJNA302384
REPOSITORIES: GEO
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Project description:Oncogenic mutations within the RAS pathway are common in multiple myeloma (MM), an incurable malignancy of plasma cells. However, the mechanisms of pathogenic RAS signaling in this disease remain enigmatic and difficult to inhibit therapeutically. We employed an unbiased proteogenomic approach to dissect RAS signaling in MM by combining genome-wide CRISPR-Cas9 screening with quantitative mass spectrometry focused on RAS biology. We discovered that mutant isoforms of RAS organized a signaling complex with the amino acid transporter, SLC3A2, and MTOR on endolysosomes, which directly activated mTORC1 by co-opting amino acid sensing pathways. MM tumors with high expression of mTORC1-dependent genes were more aggressive and enriched in RAS mutations, and we detected interactions between RAS and MTOR in MM patient tumors harboring mutant RAS isoforms. Inhibition of RAS-dependent mTORC1 activity synergized with MEK and ERK inhibitors to quench pathogenic RAS signaling in MM cells. This study redefines the RAS pathway in MM and provides a mechanistic and rational basis to target this novel mode of RAS signaling.
2022-10-14 | PXD031662 | Pride
Project description:The RAF family kinases function in the RAS-ERK pathway to transmit signals from activated RAS to the downstream kinases MEK and ERK. This pathway regulates cell proliferation, differentiation, and survival enabling mutations in RAS and RAF to act as potent drivers of human cancers. Drugs targeting the prevalent oncogenic mutant BRAFV600E have shown great efficacy in the clinic but long-term effectiveness is limited by resistance mechanisms that often exploit the dimerization-dependent process by which RAF kinases are activated. Here, we investigated a proteolysis targeting chimera (PROTAC) approach to BRAF inhibition. The most effective PROTAC termed P4B displayed superior specificity and inhibitory properties relative to non-PROTAC controls in BRAFV600E cell lines. In addition, P4B displayed utility in two cell lines harboring alternate BRAF mutations that impart resistance to conventional BRAF inhibitors. This work provides a rationale for optimizing the drug-like properties of P4B to enable proof of concept studies in vivo.
2020-05-25 | GSE148500 | GEO
Project description:Mutation or deletion of Neurofibromin (NF1), an inhibitor of RAS signaling, frequently occurs in epithelial ovarian cancer (EOC), supporting therapies that target downstream RAS effectors, such as the RAF-MEK-ERK pathway. However, no comprehensive studies have been carried out testing the efficacy of MEK inhibition in NF1-deficient EOC. Here, we performed a detailed characterization of MEK inhibition in NF1-deficient EOC cell lines using kinome profiling and RNA sequencing. Our studies showed MEK inhibitors were ineffective at providing durable growth inhibition in NF1-deficient cells due to kinome reprogramming. MEKi-mediated destabilization of FOSL1 resulted in induced expression of RTKs and their downstream RAF and PI3K signaling overcoming MEKi therapy. MEKi synthetic enhancement screens identified BRD2 and BRD4 as integral mediators of the MEKi-induced RTK signatures. Inhibition of BET proteins using BET bromodomain inhibitors (BETi) blocked MEKi-induced RTK reprogramming, indicating BRD2 and BRD4 represent promising therapeutic targets in combination with MEKi to block resistance due to kinome reprogramming in NF1-deficient EOC.
2019-05-17 | GSE127886 | GEO
Project description:Neurofibromatosis Type 1 (NF1) patients develop benign neurofibromas and malignant peripheral nerve sheath tumors (MPNST). These incurable peripheral nerve tumors result from loss of NF1 tumor suppressor gene function, causing hyperactive Ras signaling. Activated Ras controls numerous downstream effectors, but specific pathways mediating effects of hyperactive Ras in NF1 tumors are unknown. Cross-species transcriptome analyses of mouse and human neurofibromas and MPNSTs identified global negative feedback of genes that regulate Ras-Raf- MEK- extracellular signal-regulated protein kinase (ERK) signaling in both species. Nonetheless, activation of ERK was sustained in mouse and human neurofibromas and MPNST. PD0325901, a highly selective pharmacological inhibitor of MEK, was used to test whether sustained Ras-Raf-MEK-ERK signaling contributes to neurofibroma growth in the Nf1fl/fl;Dhh-cre mouse model or in NF1 patient MPNST cell xenografts. PD0325901 treatment reduced aberrantly proliferating cells in neurofibroma and MPNST, prolonged survival of mice implanted with human MPNST cells, and shrank neurofibromas in >80% of mice tested. PD0325901 also caused effects on tumor vasculature. Our data demonstrate that deregulated Ras/ERK signaling is critical for the growth of NF1 peripheral nerve tumors and provide strong rationale for testing MEK inhibitors in NF1 clinical trials.
2012-12-28 | GSE41747 | GEO
Project description:The eIF4F translation initiation complex plays a critical role in melanoma resistance to clinical BRAF and MEK inhibitors. In this study, we uncover a novel function of eIF4F in the negative regulation of the RAS/RAF/MEK/ERK mitogen-activated protein kinase (MAPK) signaling pathway. We demonstrate that eIF4F is essential for maintaining optimal ERK signaling intensity in treatment-naïve melanoma cells harboring BRAF or NRAS mutations. Specifically, the dual-specificity phosphatase DUSP6/MKP3, which acts as a negative feedback regulator of ERK activity, requires continuous production in an eIF4F-dependent manner to limit excessive ERK signaling driven by oncogenic RAF/RAS mutations. Treatment with small molecule eIF4F inhibitors disrupts the negative feedback control of MAPK signaling, leading to ERK hyperactivation and EGR1 overexpression in melanoma cells in vitro and in vivo. Furthermore, our quantitative analyses reveal a high spare signaling capacity in the ERK pathway, suggesting that eIF4F-dependent feedback keeps the majority of ERK molecules inactive under normal conditions. Overall, our findings highlight the crucial role of eIF4F in regulating ERK signaling flux and suggest that pharmacological eIF4F inhibitors can disrupt the negative feedback control of MAPK activity in melanomas with BRAF and NRAS activating mutations.
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Project description:We discover drugs with a dual-inhibitory mechanism provides a unique pharmacological strategy against cancer and evidence of cross-activation between the Ras/Raf/MEK/ERK and PI3K/AKT/mTOR pathways via a Ras˧PIK3IP1˧PI3K signaling network Achieving robust cancer-specific lethality is the ultimate clinical goal. Here we identify a compound with dual-inhibitory properties, named a131, that selectively kills cancer cells, while protecting normal cells. Through an unbiased CETSA screen, we identify the PIP4K lipid kinases as the target of a131. Ablation of the PIP4Ks generates a phenocopy of the pharmacological effects of PIP4K inhibition by a131. Notably, PIP4Ks inhibition by a131 causes reversible growth arrest in normal cells by transcriptionally up-regulating PIK3IP1, a suppressor of the PI3K/Akt/mTOR pathway. Strikingly, Ras activation overrides a131-induced PIK3IP1 up-regulation and activates the PI3K/Akt/mTOR pathway. Consequently, Ras-transformed cells override a131-induced growth arrest and enter mitosis where a131’s ability to de-cluster supernumerary centrosomes in cancer cells eliminates Ras-activated cells through mitotic catastrophe. Our discovery of drugs with a dual-inhibitory mechanism provides a unique pharmacological strategy against cancer and evidence of cross-activation between the Ras/Raf/MEK/ERK and PI3K/AKT/mTOR pathways via a Ras˧PIK3IP1˧PI3K signaling network.
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Project description:Microarray expression analysis to identify global changes in transcription in response to RAF inhibition. Genes under RAF control were identified in a panel of BRAFV600E tumor cells, following the short-term inhibition of RAF using a pan-RAF kinase inhibitor, PLX4032 (Plexxikon). For comparison with changes in gene expression in response to MEK inhibition using PD0325901 (Pfizer), the following array data was referenced: (http://www.ncbi.nlm.nih.gov/geo/ (accession no. GSE10086)). Cell lines growing in culture (n=5) were treated with the RAF inhibitor PLX4032 (250nM or 1000nM) or vehicle alone (0.1% DMSO) as control, for eight hours.
2010-07-18 | E-GEOD-20051 | biostudies-arrayexpress
Project description:Disruption of the MAPK pathway in cancer by kinase inhibition often fails due to pathway reactivation, causing clinical relapse. Among MAPK inhibitors, type I RAF inhibitors are only active against specific BRAF mutants; MEK inhibitor monotherapy is associated with limited clinical benefits but may serve as a foundation for combinatorial therapy. Here, we show that type II RAF plus allosteric MEK inhibitors durably blunt the development of acquired MEK inhibitor resistance among cancers with KRAS, NRAS, NF1, BRAFnon-V600 and BRAFV600 mutations, when compared to a combination of type II RAF plus ERK inhibitors. Type II RAF and MEK (versus ERK) inhibitors also display superior capacity to sequester MEK in RAF complexes and uncouple MEK and ERK interaction in acquired resistant tumor subpopulations. Systemically and intratumorally, type II RAF plus MEK inhibitors expand memory and activated/exhausted CD8+ T-cells. Whereas trametinib alone temporally reduces dominant intra-tumoral T-cell clones, type II RAF inhibitor co-treatment reverses this effect and promotes T-cell clonotypic expansion and convergence. Importantly, durably control of tumors by this combination requires CD8+ T-cells. Thus, the prolonged anti-tumor efficacy of type II RAF plus MEK inhibitors reveals exquisite MAPK addiction in common lethal cancer histologies, and the mechanisms include unexpected allosteric perturbation of the MAPK pathway and engagement of anti-tumor CD8+ T-cell immunity.
2021-06-06 | GSE158609 | GEO
Project description:Disruption of the MAPK pathway in cancer by kinase inhibition often fails due to pathway reactivation, causing clinical relapse. Among MAPK inhibitors, type I RAF inhibitors are only active against specific BRAF mutants; MEK inhibitor monotherapy is associated with limited clinical benefits but may serve as a foundation for combinatorial therapy. Here, we show that type II RAF plus allosteric MEK inhibitors durably blunt the development of acquired MEK inhibitor resistance among cancers with KRAS, NRAS, NF1, BRAFnon-V600 and BRAFV600 mutations, when compared to a combination of type II RAF plus ERK inhibitors. Type II RAF and MEK (versus ERK) inhibitors also display superior capacity to sequester MEK in RAF complexes and uncouple MEK and ERK interaction in acquired resistant tumor subpopulations. Systemically and intratumorally, type II RAF plus MEK inhibitors expand memory and activated/exhausted CD8+ T-cells. Whereas trametinib alone temporally reduces dominant intra-tumoral T-cell clones, type II RAF inhibitor co-treatment reverses this effect and promotes T-cell clonotypic expansion and convergence. Importantly, durably control of tumors by this combination requires CD8+ T-cells. Thus, the prolonged anti-tumor efficacy of type II RAF plus MEK inhibitors reveals exquisite MAPK addiction in common lethal cancer histologies, and the mechanisms include unexpected allosteric perturbation of the MAPK pathway and engagement of anti-tumor CD8+ T-cell immunity.
2021-06-06 | GSE158608 | GEO
Project description:Disruption of the MAPK pathway in cancer by kinase inhibition often fails due to pathway reactivation, causing clinical relapse. Among MAPK inhibitors, type I RAF inhibitors are only active against specific BRAF mutants; MEK inhibitor monotherapy is associated with limited clinical benefits but may serve as a foundation for combinatorial therapy. Here, we show that type II RAF plus allosteric MEK inhibitors durably blunt the development of acquired MEK inhibitor resistance among cancers with KRAS, NRAS, NF1, BRAFnon-V600 and BRAFV600 mutations, when compared to a combination of type II RAF plus ERK inhibitors. Type II RAF and MEK (versus ERK) inhibitors also display superior capacity to sequester MEK in RAF complexes and uncouple MEK and ERK interaction in acquired resistant tumor subpopulations. Systemically and intratumorally, type II RAF plus MEK inhibitors expand memory and activated/exhausted CD8+ T-cells. Whereas trametinib alone temporally reduces dominant intra-tumoral T-cell clones, type II RAF inhibitor co-treatment reverses this effect and promotes T-cell clonotypic expansion and convergence. Importantly, durably control of tumors by this combination requires CD8+ T-cells. Thus, the prolonged anti-tumor efficacy of type II RAF plus MEK inhibitors reveals exquisite MAPK addiction in common lethal cancer histologies, and the mechanisms include unexpected allosteric perturbation of the MAPK pathway and engagement of anti-tumor CD8+ T-cell immunity.
2021-06-06 | GSE158607 | GEO