ABSTRACT: Melanoma-derived exosomes educate bone marrow progenitor cells toward a pro-metastatic phenotype through upregulation of the MET oncoprotein.
Project description:Tumor-derived exosomes are emerging as mediators of tumorigenesis with a tissue-specific address and message. We explored the function of melanoma-derived exosomes in formation of primary tumors and metastatic progression in both murine models and patients. Whereas exosomes from highly metastatic melanoma cells increased the metastatic behavior of primary tumor cells by educating bone marrow (BM) progenitor cells via the MET receptor, exosomes from low metastatic melanoma cells did not alter the incidence of metastases. Melanoma-derived exosomes induced vascular leakiness at pre-metastatic sites, and reprogrammed BM progenitor cells towards a pro-vasculogenic phenotype (c-Kit+Tie2+MET+). Reducing MET expression in tumor-derived exosomes diminished the pro-metastatic behavior of BM cells. Importantly, MET expression was upregulated in circulating BM progenitor cells (CD45-CD117low and CD45-CD117lowTIE2+) isolated from stage III and stage IV melanoma patients. Rab1a, Rab5b, Rab7, and Rab27a were highly expressed in melanoma and Rab27a RNA interference decreased exosome production and/or soluble angiogenic factors in melanoma cells, thereby preventing mobilization of BM progenitor cells, tumor growth and metastasis. Finally, we identified a melanoma signature in exosomes isolated from metastatic melanoma patients, comprised of TYRP2, VLA-4, Hsp70, an Hsp90 isoform and MET oncoprotein, which together with Rab proteins, appear to represent exosome-specific proteins with prognostic potential, and may provide new therapeutic targets. Identification of molecular finger associated to exosome effects in metastatic organs Microarray analysis of genes differentially expressed in the lungs 24 and 48 hours after B16-F10 exosome tail vein injection compared to control.
Project description:Tumor-derived exosomes are emerging as mediators of tumorigenesis with a tissue-specific address and message. We explored the function of melanoma-derived exosomes in formation of primary tumors and metastatic progression in both murine models and patients. Whereas exosomes from highly metastatic melanoma cells increased the metastatic behavior of primary tumor cells by educating bone marrow (BM) progenitor cells via the MET receptor, exosomes from low metastatic melanoma cells did not alter the incidence of metastases. Melanoma-derived exosomes induced vascular leakiness at pre-metastatic sites, and reprogrammed BM progenitor cells towards a pro-vasculogenic phenotype (c-Kit+Tie2+MET+). Reducing MET expression in tumor-derived exosomes diminished the pro-metastatic behavior of BM cells. Importantly, MET expression was upregulated in circulating BM progenitor cells (CD45-CD117low and CD45-CD117lowTIE2+) isolated from stage III and stage IV melanoma patients. Rab1a, Rab5b, Rab7, and Rab27a were highly expressed in melanoma and Rab27a RNA interference decreased exosome production and/or soluble angiogenic factors in melanoma cells, thereby preventing mobilization of BM progenitor cells, tumor growth and metastasis. Finally, we identified a melanoma signature in exosomes isolated from metastatic melanoma patients, comprised of TYRP2, VLA-4, Hsp70, an Hsp90 isoform and MET oncoprotein, which together with Rab proteins, appear to represent exosome-specific proteins with prognostic potential, and may provide new therapeutic targets. Identification of molecular finger associated to exosome effects in metastatic organs
Project description:Clinical and genomic evidence support the view that the metastatic potential of a primary tumor may be dictated by transforming events acquired early in the tumorigenic process. It has been proposed that the presence of such pro-metastatic events in early-stage tumors reflects their additional capability to function as oncogenes. Here, to test this ‘deterministic’ hypothesis and identify potential pro-metastasis oncogenes, we adopted a comparative oncogenomics-guided functional genetic screening strategy involving (i) global transcriptomic data from two genetically engineered mouse models of melanoma with contrasting metastatic potential, (ii) genomic and transcriptomic profiles of human primary and metastatic melanoma and (iii) an invasion screen in TERT-immortalized human melanocytes and melanoma cells in vitro as well as (iv) evidence of expression selection in human melanoma tissues. This integrated effort led to the identification of 6 genes that are both potently pro-invasive and oncogenic. Further, we show that one such pro-invasion oncogene, ACP5, can confer spontaneous metastasis in vivo, engages a key pathway governing metastasis and is prognostic in human primary melanomas. The tetracycline-inducible MET-driven mouse (iMet) model (Tyr-rtTA;Tet-Met;Ink4a/Arf-/-) was constructed similar to the previously described iHRAS* model (Tyr-rtTA;Tet-HRASV12G;Ink4a/Arf-/-). RNA from cutaneous melanomas derived from iMet (n=6) or iHRAS* (n=6) models were profiled on Affymetrix M430A_2 chips and resultant transcriptomes were compared to generate a phenotype-based (metastatic capable or not) differentially expressed gene list. Cross-species triangulation to human gene expression and copy number aberrations was based on ortholog mapping.
Project description:Development of melanoma brain metastasis is caused by an interaction between tumor cells and normal cells in the brain microenvironment. miRNAs delivered by exosomes derived from the tumor cells seem to prime the brain microenvironment, prior to extravasation of tumor cells into the brain. We investigated miRNA in exosomes extracted from normal (astrocytes, melanocytes) and metastatic melanoma cells (brain, skin and lymph node metastasis). We have discovered that miR-146a-5p is an important player in brain metastatic development: this miRNA was highly upregulated in exosomes from melanoma brain metastasis cells, compared to normal cells.
Project description:Thousands of enhancers are characterized in the human genome, yet few have been shown important in cancer. Inhibiting oncokinases, such as EGFR, ALK, HER2, and BRAF, is a mainstay of current cancer therapy but is hindered by innate drug resistance mediated by upregulation of the HGF receptor, MET. The mechanisms mediating such genomic responses to targeted therapy are unknown. Here, we identify lineage-specific MET enhancers for multiple common tumor types, including a melanoma lineage-specific MET enhancer that displays inducible chromatin looping and MET gene induction upon BRAF inhibition. Epigenomic analysis demonstrated that the melanocyte-specific transcription factor, MITF, mediates this enhancer function. Targeted genomic deletion (<7bp) of the MITF motif within the MET enhancer suppressed inducible chromatin looping and innate drug resistance, while maintaining MITF-dependent, inhibitor-induced melanoma cell differentiation. Epigenomic analysis can thus guide functional disruption of regulatory DNA to decouple pro- and anti-oncogenic functions of tumor lineage-enriched transcription factors mediating innate resistance to oncokinase therapy. COLO829 human melanoma cell line harboring the BRAFV600E mutation was treated with BRAF inhibtior PLX4032 (Vemurafenib) and/or a hairpin against MITF
Project description:Thousands of enhancers are characterized in the human genome, yet few have been shown important in cancer. Inhibiting oncokinases, such as EGFR, ALK, HER2, and BRAF, is a mainstay of current cancer therapy but is hindered by innate drug resistance mediated by upregulation of the HGF receptor, MET. The mechanisms mediating such genomic responses to targeted therapy are unknown. Here, we identify lineage-specific MET enhancers for multiple common tumor types, including a melanoma lineage-specific MET enhancer that displays inducible chromatin looping and MET gene induction upon BRAF inhibition. Epigenomic analysis demonstrated that the melanocyte-specific transcription factor, MITF, mediates this enhancer function. Targeted genomic deletion (<7bp) of the MITF motif within the MET enhancer suppressed inducible chromatin looping and innate drug resistance, while maintaining MITF-dependent, inhibitor-induced melanoma cell differentiation. Epigenomic analysis can thus guide functional disruption of regulatory DNA to decouple pro- and anti-oncogenic functions of tumor lineage-enriched transcription factors mediating innate resistance to oncokinase therapy. MITF ChIP-seq was performed in primary human melanocytes with overexpression of BRAFV600E or a lentiviral control (RFP), and in COLO829 melanoma cells treated with DMSO, or PLX4032
Project description:Pancreatic cancers (PCs) are highly metastatic with poor prognosis, mainly due to delayed detection. We hypothesized that intercellular communication is critical for metastatic progression. Here, we show that PC-derived exosomes induce liver pre-metastatic niche formation in naïve mice and consequently increase liver metastatic burden. Uptake of PC-derived exosomes by Kupffer cells caused transforming growth factor β secretion and upregulation of fibronectin production by hepatic stellate cells. This fibrotic microenvironment enhanced recruitment of bone marrow-derived macrophages. We found that macrophage migration inhibitory factor (MIF) was highly expressed in PC-derived exosomes, and its blockade prevented liver pre-metastatic niche formation and metastasis. Compared to patients whose pancreatic tumors did not progress, MIF was markedly higher in exosomes from stage I PC patients who later developed liver metastasis. These findings suggest that exosomal MIF primes the liver for metastasis and may be a prognostic marker for the development of PC liver metastasis.
Project description:Several studies have demonstrated that melanoma-derived exosomes home in sentinel lymph nodes favoring metastasis. Here, we determined the proteomic signature in exosomes derived from lymph node metastatic models. We found a signature of genes over-expressed and proteins hyper-secreted in exosomes related to lymph node metastasis in the B16 mouse melanoma model. Out of these candidates, we found that Emilin1, a protein with an important function in lymph node physiology, was hyper-secreted in exosomes. Interestingly, we found that Emilin1 is degraded and secreted in exosomes as a mechanism favoring metastasis. Indeed, we found that Emilin1 has a tumor suppressor-like role regulating negatively cell viability and migration. Importantly, our in vivo studies demonstrate that Emilin1 overexpression reduced primary tumor growth and metastasis in mouse melanoma models. Analysis in human melanoma samples showed that cells expressing high levels of EMILIN1 are reduced in metastatic lesions. Overall, our analysis suggests a novel mechanism involved in the inactivation of Emilin1 in melanoma favouring melanoma progression and metastasis.
Project description:Thousands of enhancers are characterized in the human genome, yet few have been shown important in cancer. Inhibiting oncokinases, such as EGFR, ALK, HER2, and BRAF, is a mainstay of current cancer therapy but is hindered by innate drug resistance mediated by upregulation of the HGF receptor, MET. The mechanisms mediating such genomic responses to targeted therapy are unknown. Here, we identify lineage-specific MET enhancers for multiple common tumor types, including a melanoma lineage-specific MET enhancer that displays inducible chromatin looping and MET gene induction upon BRAF inhibition. Epigenomic analysis demonstrated that the melanocyte-specific transcription factor, MITF, mediates this enhancer function. Targeted genomic deletion (<7bp) of the MITF motif within the MET enhancer suppressed inducible chromatin looping and innate drug resistance, while maintaining MITF-dependent, inhibitor-induced melanoma cell differentiation. Epigenomic analysis can thus guide functional disruption of regulatory DNA to decouple pro- and anti-oncogenic functions of tumor lineage-enriched transcription factors mediating innate resistance to oncokinase therapy.
Project description:Thousands of enhancers are characterized in the human genome, yet few have been shown important in cancer. Inhibiting oncokinases, such as EGFR, ALK, HER2, and BRAF, is a mainstay of current cancer therapy but is hindered by innate drug resistance mediated by upregulation of the HGF receptor, MET. The mechanisms mediating such genomic responses to targeted therapy are unknown. Here, we identify lineage-specific MET enhancers for multiple common tumor types, including a melanoma lineage-specific MET enhancer that displays inducible chromatin looping and MET gene induction upon BRAF inhibition. Epigenomic analysis demonstrated that the melanocyte-specific transcription factor, MITF, mediates this enhancer function. Targeted genomic deletion (<7bp) of the MITF motif within the MET enhancer suppressed inducible chromatin looping and innate drug resistance, while maintaining MITF-dependent, inhibitor-induced melanoma cell differentiation. Epigenomic analysis can thus guide functional disruption of regulatory DNA to decouple pro- and anti-oncogenic functions of tumor lineage-enriched transcription factors mediating innate resistance to oncokinase therapy.