Project description:About 50% of human malignancies exhibit unregulated signalling through the Ras-ERK1/2 (ERK) pathway, as a consequence of activating mutations in members of Ras and Raf families. However, the quest for alternative Ras-ERK pathway-directed therapies is desirable. Upon phosphorylation ERK dimerize. We had previously demonstrated that dimerization is essential for ERK extranuclear but not nuclear signaling. Furthermore, by molecular biology approaches, we showed that specifically inhibiting ERK extranuclear component, by impeding ERK dimerization, is sufficient for curtailing tumor progression. Here, we have identified a small molecule inhibitor for ERK dimerization in vitro and in vivo that, without affecting ERK phosphorylation, prevents tumorigenesis driven by Ras-ERK pathway oncogenes, both in cellular and animal models. Importantly, this compound is unaffected by resistance-acquisition processes that hamper “classical” Ras-ERK pathway inhibitors. Thus, ERK dimerization inhibitors provide the proof of principle for two novel concepts in cancer therapy: 1) The blockade of sublocalization-specific sub-signals, rather than total signals, as a means of effectively counteracting oncogenic Ras-ERK signaling. 2) Targeting regulatory protein-protein interactions such as dimerization, rather than catalytic activities, within a signaling route, as an approach for producing effective anti-tumoral agents. Strategies aimed at preventing aberrant flux through this route remain an attractive option for therapeutic intervention in cancer. In this respect, drugs inhibiting the kinase activities of BRaf and MEK have yielded promising results. A375p cells treated with10 μM of either DEL22379, SCH772984 or DMSO as a control for two hours. mRNA from A375p cells was extrated using RNeasy mini kit (Qiagen, Germany) according to the manufacturer's instructions. Cells were previously treated with10 μM of either DEL22379, SCH772984 or DMSO as a control for two hours.
Project description:About 50% of human malignancies exhibit unregulated signalling through the Ras-ERK1/2 (ERK) pathway, as a consequence of activating mutations in members of Ras and Raf families. However, the quest for alternative Ras-ERK pathway-directed therapies is desirable. Upon phosphorylation ERK dimerize. We had previously demonstrated that dimerization is essential for ERK extranuclear but not nuclear signaling. Furthermore, by molecular biology approaches, we showed that specifically inhibiting ERK extranuclear component, by impeding ERK dimerization, is sufficient for curtailing tumor progression. Here, we have identified a small molecule inhibitor for ERK dimerization in vitro and in vivo that, without affecting ERK phosphorylation, prevents tumorigenesis driven by Ras-ERK pathway oncogenes, both in cellular and animal models. Importantly, this compound is unaffected by resistance-acquisition processes that hamper “classical” Ras-ERK pathway inhibitors. Thus, ERK dimerization inhibitors provide the proof of principle for two novel concepts in cancer therapy: 1) The blockade of sublocalization-specific sub-signals, rather than total signals, as a means of effectively counteracting oncogenic Ras-ERK signaling. 2) Targeting regulatory protein-protein interactions such as dimerization, rather than catalytic activities, within a signaling route, as an approach for producing effective anti-tumoral agents. Strategies aimed at preventing aberrant flux through this route remain an attractive option for therapeutic intervention in cancer. In this respect, drugs inhibiting the kinase activities of BRaf and MEK have yielded promising results.
Project description:Aberrant RAS/MAPK signaling, a common driver of oncogenesis, can be therapeutically targeted with clinically approved MEK inhibitors. Single agent therapy ultimately results in tumor outgrowth in most settings and combination therapies are required to achieve significant clinical benefit in most advanced cancers. Here we focus on identifying MEK inhibitor-based combination therapies in RAS-mutant neuroblastoma. Mutations that activate the RAS/MAPK signaling pathway, while rare at diagnosis, are more frequent in relapsed neuroblastoma. More than 50% of children with high-risk neuroblastoma ultimately relapse and treatment options for relapsed neuroblastoma are limited so most children with relapsed disease do not survive. Here we use a genome-scale CRISPR-Cas9 functional genomic screen to identify genes that, when lost, sensitize RAS-mutant neuroblastoma to MEK inhibition. We discover that loss of either CCNC or CDK8, two members of the mediator kinase module, sensitizes neuroblastoma to MEK inhibition. Furthermore, we demonstrate that small molecule kinase inhibitors of CDK8 improve response to MEK inhibitors in vitro and in vivo in RAS-mutant neuroblastoma and other adult solid tumors, suggesting that the addition of CDK8 inhibitors could improve clinical outcome. Using transcriptional profiling, we unexpectedly find that loss of CDK8 or CCNC antagonizes the transcriptional signature induced by MEK inhibition. When combined, loss of CDK8 or CCNC prevents the compensatory upregulation of pro-growth gene expression induced by MEK inhibition. These findings propose a new therapeutic combination for RAS-mutant neuroblastoma and may have clinical relevance for other RAS-driven malignancies.
Project description:The insulin-like growth factor (IGF) axis is an important signaling pathway in the growth and survival of many cell types and has been implicated in multiple aspects of cancer progression from tumorigenesis to metastasis. The multiple roles of IGF signaling in cancer suggest that selective inhibition of the pathway might yield clinically effective therapeutics. Here we describe A-928605, a novel small molecule inhibitor of the receptor tyrosine kinase responsible for IGF signal transduction. This small molecule is able to abrogate activation of the pathway as shown by effects on the target and downstream effectors and is shown to be effective at inhibiting the proliferation of an oncogene addicted tumor model cell line (CD8-IGF1R 3T3) both in vitro and in vivo. Experiment Overall Design: CD8-IGF1R 3T3 cells and 3T3 Vector control treated for 24 h with vehicle or IGF1R inhibitor A-928605, all with 3 replicates.
Project description:The insulin-like growth factor (IGF) axis is an important signaling pathway in the growth and survival of many cell types and has been implicated in multiple aspects of cancer progression from tumorigenesis to metastasis. The multiple roles of IGF signaling in cancer suggest that selective inhibition of the pathway might yield clinically effective therapeutics. Here we describe A-928605, a novel small molecule inhibitor of the receptor tyrosine kinase responsible for IGF signal transduction. This small molecule is able to abrogate activation of the pathway as shown by effects on the target and downstream effectors and is shown to be effective at inhibiting the proliferation of an oncogene addicted tumor model cell line (CD8-IGF1R 3T3) both in vitro and in vivo. Keywords: Treatment Response
Project description:MAPK scaffolds, such as IQGAP1, assemble pathway kinases together to effect signal transmission and disrupting scaffold function therefore offers a potentially orthogonal approach to MAPK cascade inhibition. Consistent with this possibility, we observed an IQGAP1 requirement in Ras-driven tumorigenesis in mouse and human tissue. Delivery of the IQGAP1 WW peptide sequence that mediates Erk1/4 binding, moreover, disrupted IQGAP1-Erk1/2 interactions, abolished Ras/Raf-driven tumorigenesis, bypassed acquired resistance to the B-Raf inhibitor vemurafinib (PLX- 4032), and acts as a systemically deliverable therapeutic to significantly increase lifespan of tumor bearing mice. Scaffold-kinase interaction blockade (SKIB) acts by a mechanism distinct from direct kinase inhibition and represents a strategy to target over-active oncogenic kinase cascades in cancer. Gene expression profiling: Fragmented cRNA was hybridized to the Mouse Gene 1.0 ST Array (Affymetrix). Iqgap1 wild-type and Iqgap1 knockout mouse treated with topical 4OHT for 0 days and 6 days days are compared.
Project description:KRAS is the most frequently mutated driver of pancreatic, colorectal, and non-small cell lung cancers. Direct KRAS blockade has proven challenging and inhibition of a key downstream effector pathway, the RAF-MEK-ERK cascade, has shown limited success due to activation of feedback networks that keep the pathway in check. We hypothesized that inhibiting SOS1, a KRAS activator and important feedback node, represents an effective approach to treat KRAS-driven cancers. We report the discovery of a highly potent, selective and orally bioavailable small-molecule SOS1 inhibitor, BI-3406, that binds to the catalytic domain of SOS1 thereby preventing the interaction with KRAS. BI-3406 reduces formation of GTP-loaded RAS and limits cellular proliferation of a broad range of KRAS-driven cancers. Importantly, BI-3406 attenuates feedback reactivation induced by MEK inhibitors and thereby enhances sensitivity of KRAS-dependent cancers to MEK inhibition. Combined SOS1 and MEK inhibition represents a novel and effective therapeutic concept to address KRAS-driven tumors.
Project description:MAPK scaffolds, such as IQGAP1, assemble pathway kinases together to effect signal transmission and disrupting scaffold function therefore offers a potentially orthogonal approach to MAPK cascade inhibition. Consistent with this possibility, we observed an IQGAP1 requirement in Ras-driven tumorigenesis in mouse and human tissue. Delivery of the IQGAP1 WW peptide sequence that mediates Erk1/4 binding, moreover, disrupted IQGAP1-Erk1/2 interactions, abolished Ras/Raf-driven tumorigenesis, bypassed acquired resistance to the B-Raf inhibitor vemurafinib (PLX- 4032), and acts as a systemically deliverable therapeutic to significantly increase lifespan of tumor bearing mice. Scaffold-kinase interaction blockade (SKIB) acts by a mechanism distinct from direct kinase inhibition and represents a strategy to target over-active oncogenic kinase cascades in cancer.