Project description:We found that RANKL, expressed by cancer cells or derived from exogenous sources, consistently induced human prostate, breast, kidney, lung and liver cancer cells to colonize or metastasize to bone in an animal model of cancer bone metastasis. RANK-mediated signaling established a premetastatic niche through a forward feedback loop by inducing RANKL and c-Met expression and downstream signaling via upregulation of master regulator transcription factors regulating EMT (Twist1, Slug, Zeb1, Zeb2), stem cells (Sox2, Myc, Oct3/4 and Nanog), neuroendocrine cells (Sox 9, HIF-1α and FoxA2) and osteomimicry (c-Myc/Max, Sox2, Sox9, HIF1α and Runx2). Abrogating RANK or its downstream signaling network, c-Myc/Max or c-Met, abolished PCa skeletal metastasis in mice. We observed that a small number of RANKL-expressing PCa cells can initiate bone and soft tissue metastases by recruiting non-tumorigenic or bystander PCa or host cells from the circulation or at metastatic sites to co-colonize bone. The recruited bystander PCa cells assume the phenotypes of RANKL-expressing PCa cells by expressing increased c-Met, phosphorylated c-Met and RANKL. RANKL expression at a single cell level in primary PCa tissues predicted disease-specific survival, reflecting the significant role of RANKL-RANK signaling in the development of lethal bone metastasis.
Project description:We found that RANKL, expressed by cancer cells or derived from exogenous sources, consistently induced human prostate, breast, kidney, lung and liver cancer cells to colonize or metastasize to bone in an animal model of cancer bone metastasis. RANK-mediated signaling established a premetastatic niche through a forward feedback loop by inducing RANKL and c-Met expression and downstream signaling via upregulation of master regulator transcription factors regulating EMT (Twist1, Slug, Zeb1, Zeb2), stem cells (Sox2, Myc, Oct3/4 and Nanog), neuroendocrine cells (Sox 9, HIF-1α and FoxA2) and osteomimicry (c-Myc/Max, Sox2, Sox9, HIF1α and Runx2). Abrogating RANK or its downstream signaling network, c-Myc/Max or c-Met, abolished PCa skeletal metastasis in mice. We observed that a small number of RANKL-expressing PCa cells can initiate bone and soft tissue metastases by recruiting non-tumorigenic or bystander PCa or host cells from the circulation or at metastatic sites to co-colonize bone. The recruited bystander PCa cells assume the phenotypes of RANKL-expressing PCa cells by expressing increased c-Met, phosphorylated c-Met and RANKL. RANKL expression at a single cell level in primary PCa tissues predicted disease-specific survival, reflecting the significant role of RANKL-RANK signaling in the development of lethal bone metastasis. Global gene expression analysis perturbed by RANKL in LNRANKL compared to LNNeo cells.
Project description:We used microarrays to probe the global programme of gene expression under treatment with c-Met inhibitor and identified distinct classes of up- and down-regulated genes during this process We treated MET addicted EBC-1 and MKN-45 cells with selective c-Met kinase inhibitor SGX-523 at 1uM for 24 and 48 hours, using HCC827 cells with activated c-Met but lacking MET dependency as a negative control
Project description:MET amplification is present in 20% of gastric cancers and has been confirmed as a therapeutic target in clinical trials. The molecular mechanisms of response and resistance to MET inhibitors are not well understood. We investigated the determinants of MET dependency in human gastric cancer. MET inhibition inhibited proliferation and induced cell death only in MET-amplified gastric cancer cell lines. The effects on growth arrest were stronger than the effects on cell death. To identify possible resistance mechanisms, we performed whole-genome mRNA expression profiling. Molecular changes related to autophagy were among the top alterations observed. Consistent with these findings, autophagy levels increased in a concentration-dependent manner when MET-amplified cells were exposed to crizotinib. Autophagy inhibition caused a dramatic decrease in apoptosis in one of the MET-amplified cell lines (MKN45) but not in the other (SNU-5). Because autophagy may provide energy in cells subjected to growth factor deprivation, we explored the effects of MET or autophagy inhibition on cellular ATP levels. This revealed that autophagy-dependent ATP production was selectively required for apoptosis in the MKN45 cells and that chemical ATP depletion mimicked the effects of autophagy inhibition to block cell death. Overall, the data reveal a novel relationship between ATP depletion and resistance to MET inhibitor-induced cell death. Our observations suggest that autophagy inhibitors could have unintended consequences when they are combined with growth factor receptor inhibitors in tumors that require autophagy-dependent ATP production for apoptosis. 12 samples triplicate samples of SNU-5 and MKN45 +/- criztonib for 24 hours
Project description:Somatic hotspot mutations and structural amplifications and fusions affecting fibroblast growth factor receptor 2 (FGFR2) occur in multiple cancer types. However, clinical responses to FGFR inhibitors (FGFRi) have remained variable, emphasizing a need to better understand which FGFR2 alterations are oncogenic and targetable. Here we applied transposon-based screening and tumor modelling in mice to uncover truncation of exon (E) 18 of Fgfr2 as a potent driver mutation. Human oncogenomic datasets revealed a diverse set of FGFR2 alterations, including rearrangements (REs), E1-E17 partial amplifications, and E18 nonsense and frameshift mutations, each causing transcription of E18-truncated FGFR2 (FGFR2deltaE18). Somatic modelling in mice and human tumor cell lines using a compendium of FGFR2deltaE18 and full-length variants identified FGFR2deltaE18-truncation as potent single-driver alteration in cancer. Here we show the phosphoproteomic landscape of FGFR2 variants in murine epithelial cell (MEC) lines and mouse tumors. Global (STY) phosphoproteomics using IMAC and phosphotyrosine phosphoproteomics using pTyr IP’s are combined with DIA protein expression data to uncover oncogenic signaling of clinically-relevant FGFR2 variants.
Project description:Genome-wide association studies have identified a locus within the second intron of the FGFR2 gene that is consistently the most strongly associated with estrogen receptor-poisive breast cancer risk. However, we know little about the mechanisms by which the FGFR2 locus mediates risk or the pathways in which multiple risk loci may combine to cause disease. Previously, a systems biology approach was adopted to elucidate the regulatory networks operating in MCF-7 breast cancer cells in order to examine the role of FGFR2 in mediating risk. Here, the same approach has been employed using MCF-7 cells that have been treated with siRNA directed against FGFR2, in order to knock-down FGFR2 expression, to confirm that the differential gene expression that we see when FGF10 signalling is perturbed, on a background of estrogen signalling, is mediated via FGFR2 stimulation.
Project description:MET amplification has been clinically credentialed as a therapeutic target in gastric cancer, but the molecular mechanisms underlying sensitivity and resistance to MET inhibitors are still not well understood. Using whole-genome mRNA expression profiling, we identified autophagy as a top molecular pathway that was activated by the MET inhibitor crizotinib in drug-sensitive human gastric cancer cells, and functional studies confirmed that crizotinib increased autophagy levels in the drug-sensitive cells in a concentration-dependent manner. We then used chemical and molecular approaches to inhibit autophagy in order to define its role in cell death. The clinically available inhibitor of autophagy, chloroquine, or RNAi-mediated knockdown of two obligate components of the autophagy pathway (ATG5 and ATG7) blocked cell death induced by crizotinib or RNAi-mediated knockdown of MET, and mechanistic studies localized the effects of autophagy to cytochrome c release from the mitochondria. Overall; the data reveal a novel relationship between autophagy and apoptosis in gastric cancer cells exposed to MET inhibitors. The observations suggest that autophagy inhibitors should not be used to enhance the effects of MET inhibitors in gastric cancer patients.
Project description:We used microarrays to probe the global programme of gene expression under treatment with c-Met inhibitor and identified distinct classes of up- and down-regulated genes during this process
Project description:Dysregulated FGF/FGFR signaling leads to a variety of pathologies. These include cancer as well as congenital syndromes that affect skeleton development, impair the response to injury, and/or result in metabolic disorders. In human cancers, the FGFR genes can be affected by hotspot missense mutations or structural alterations, such as amplifications and fusions/rearrangements. Missense mutations affecting the FGFR extracellular domains (e.g., FGFR3S249C) typically facilitate receptor dimerization and ligand-independent activation whereas kinase domain missense mutations frequently facilitate transition to (e.g., FGFR2N549K) or stabilization of (e.g., FGFR3K650E) an active kinase state. FGFR amplifications result in receptor overexpression. Notably, focal FGFR2 amplifications can also produce C-terminally truncated isoforms owing to genomic breakpoints that perturb intron or the FGFR2 C-terminus-encoding exon 18. FGFR2 and FGFR3 fusion/rearrangement breakpoints typically occur in the I17/E18 hotspot, thus also producing C-terminally truncated receptors. E18-truncated FGFR2 variants (FGFR2E18) indeed act as tumor driver genes. Hence, loss of the C-terminus is vital to render FGFR2 and potentially other FGFRs oncogenic.However, it has remained unclear, which motifs or amino acid residues within the C-terminal tail are most critical to suppress oncogenic FGFR2 signaling. Here we made us of a compendium of Fgfr2E18 and Fgfr2 C-terminal variants to functionally dissect FGFR2E18 signaling and the tumor suppressive nature of the FGFR2 C-terminus.
Project description:Translocations involving FGFR2 gene fusions are common in cholangiocarcinoma and predict response to FGFR kinase inhibitors. However, response rates and durability of are limited due to the emergence of resistance, typically involving FGFR2 kinase domain mutations, and to sub-optimal dosing, relating to drug adverse effects. Here, we develop biparatopic antibodies targeting the FGFR2 extracellular domain (ECD), as candidate therapeutics. Biparatopic antibodies can overcome drawbacks of bivalent monospecific antibodies, which often show poor inhibitory or even agonist activity against oncogenic receptors. We show that oncogenic transformation by FGFR2 fusions requires an intact ECD. Moreover, by systematically generating biparatopic antibodies targeting distinct epitope pairs in FGFR2 ECD, we identified antibodies that effectively block signaling and malignant growth driven by FGFR2-fusions. Importantly, these antibodies demonstrate efficacy in vivo, synergy with FGFR inhibitors, and activity against FGFR2 fusions harboring kinase domain mutations. Thus, biparatopic antibodies may serve as new treatment options for patients with FGFR2-altered cholangiocarcinoma.