ABSTRACT: The metastatic microenvironment. Brain-derived soluble factors alter the malignancy phenotype of cutaneous and brain- metastasizing melanoma cells
Project description:The present study deals with functional interactions of cutaneous and brain-metastasizing human melanoma cells with brain-derived molecules. In this study we employed the unique melanoma xenograft model developed by Izraely and described in Int J Cancer. 2011 Oct 25. doi: 10.1002/ijc.27324. The present study aims to determine if brain-derived soluble factors regulate malignancy-associated functions of cutaneous and brain-metastasizing melanoma cells and identify which functions are regulated by such factors. The working hypothesis of this study is that the interactions between the brain microenvironment and melanoma cells determine metastasis formation at this organ site. The aim of the study was to evaluate the contribution of such interactions to the formation of brain metastasis in nude mice xenografted with human melanoma cells. An insight into these interactions is an essential pre-requisite for the development of effective targeted therapy for melanoma brain metastasis. We assessed the effects of soluble factors present in supernatants of short-term cultures of normal mouse brain (referred here after as brain-derived soluble factors) on several characteristics linked to melanoma brain metastasis. It was found that brain-derived soluble factors affect differentially cutaneous and brain-metastasizing melanoma cells variants in-vitro. Such factors enhanced the viability of cutaneous melanoma cells but caused an S phase arrest followed by apoptosis of brain-metastasizing cells. Brain-derived soluble factors enhanced migration of melanoma cells metastasizing to the brain, but did not affect the migration of the cutaneous variants. Such factors up-regulated the expression of the chemokine receptor CCR4 in both cutaneous and brain metastasizing melanoma cells. It is not unlikely that CCR4 ligands expressed in the brain interact with the CCR4-expressing melanoma cells thereby directing them to the brain. Brain-derived soluble factors enhanced the transmigration, across human brain endothelial cells of cutaneous but not of brain metastasizing melanoma variants. This activity could promote the capacity of the cutaneous cells to metastasize to the brain. 4 Samples (arrays) were analyzed. There is 1 replicate for each variant and each treatment. We generated pairwise comparisons between cutaneous and brain metastatic variants of the same genetic background, using Partek Genomics Suite, in the three melanoma models. Genes with p≤5% and a fold-change difference of ≥2 or <-2 were selected.
Project description:The present study deals with functional interactions of cutaneous and brain-metastasizing human melanoma cells with brain-derived molecules. In this study we employed the unique melanoma xenograft model developed by Izraely and described in Int J Cancer. 2011 Oct 25. doi: 10.1002/ijc.27324. The present study aims to determine if brain-derived soluble factors regulate malignancy-associated functions of cutaneous and brain-metastasizing melanoma cells and identify which functions are regulated by such factors. The working hypothesis of this study is that the interactions between the brain microenvironment and melanoma cells determine metastasis formation at this organ site. The aim of the study was to evaluate the contribution of such interactions to the formation of brain metastasis in nude mice xenografted with human melanoma cells. An insight into these interactions is an essential pre-requisite for the development of effective targeted therapy for melanoma brain metastasis. We assessed the effects of soluble factors present in supernatants of short-term cultures of normal mouse brain (referred here after as brain-derived soluble factors) on several characteristics linked to melanoma brain metastasis. It was found that brain-derived soluble factors affect differentially cutaneous and brain-metastasizing melanoma cells variants in-vitro. Such factors enhanced the viability of cutaneous melanoma cells but caused an S phase arrest followed by apoptosis of brain-metastasizing cells. Brain-derived soluble factors enhanced migration of melanoma cells metastasizing to the brain, but did not affect the migration of the cutaneous variants. Such factors up-regulated the expression of the chemokine receptor CCR4 in both cutaneous and brain metastasizing melanoma cells. It is not unlikely that CCR4 ligands expressed in the brain interact with the CCR4-expressing melanoma cells thereby directing them to the brain. Brain-derived soluble factors enhanced the transmigration, across human brain endothelial cells of cutaneous but not of brain metastasizing melanoma variants. This activity could promote the capacity of the cutaneous cells to metastasize to the brain.
Project description:We established a model of human melanoma metastasis to identify differentially expressed genes in brain metastasis, compared to cutaneous melanoma from which they were developed. Such genes may control brain metastasis. The identification and characterization of these genes would advance the understanding of the metastatic process and may lead to new diagnostics and therapeutic approach. Brain metastases occur in almost 40% of melanoma patients. The median survival of such patients does not exceed a few months. Very little information is available on mechanisms underlying the progression of melanoma towards brain metastasis. The function, and significance of the various factors involved in melanoma progression must be deciphered using relevant models. Currently, most human melanoma brain metastasis models consist of xenografted cells inoculated into immune-deficient mice mainly by intracarotid or intra-cardiac administration. We generated a reproducible melanoma brain metastasis model, consisting of brain-metastasizing variants and local, sub-dermal variants that originate from the same melanomas thus sharing a common genetic background. The brain metastasizing variants were obtained by intra-cardiac inoculation. One of the brain metastasizing variants when inoculated sub-dermally yielded spontaneous brain dormant micrometastasis. Cells from the spontaneous brain micrometastasis when removed from the brain microenvironment proliferate very well in vitro and generate tumors in the skin being the orthotopic organ site. The brain metastasis and micro-metastasis cells expressed higher levels of ANGPTL4, COX-2, MMP1, MMP2 and PRAME and lower levels of CLDN1, CYR61 and IL-6R than the cutaneous variants. These gene products may be involved in melanoma brain metastasis and may serve as novel brain metastasis biomarkers and targets for therapy. 8 Samples (arrays) were analyzed. We generated pairwise comparisons between cutaneous and brain metastatic variants of the same genetic background, using Partek Genomics Suite, in the three melanoma models. Genes with pM-bM-^IM-$5% and a fold-change difference of M-bM-^IM-%1.25 or <-1.25 were selected.
Project description:We established a model of human melanoma metastasis to identify differentially expressed genes in brain metastasis, compared to cutaneous melanoma from which they were developed. Such genes may control brain metastasis. The identification and characterization of these genes would advance the understanding of the metastatic process and may lead to new diagnostics and therapeutic approach. Brain metastases occur in almost 40% of melanoma patients. The median survival of such patients does not exceed a few months. Very little information is available on mechanisms underlying the progression of melanoma towards brain metastasis. The function, and significance of the various factors involved in melanoma progression must be deciphered using relevant models. Currently, most human melanoma brain metastasis models consist of xenografted cells inoculated into immune-deficient mice mainly by intracarotid or intra-cardiac administration. We generated a reproducible melanoma brain metastasis model, consisting of brain-metastasizing variants and local, sub-dermal variants that originate from the same melanomas thus sharing a common genetic background. The brain metastasizing variants were obtained by intra-cardiac inoculation. One of the brain metastasizing variants when inoculated sub-dermally yielded spontaneous brain dormant micrometastasis. Cells from the spontaneous brain micrometastasis when removed from the brain microenvironment proliferate very well in vitro and generate tumors in the skin being the orthotopic organ site. The brain metastasis and micro-metastasis cells expressed higher levels of ANGPTL4, COX-2, MMP1, MMP2 and PRAME and lower levels of CLDN1, CYR61 and IL-6R than the cutaneous variants. These gene products may be involved in melanoma brain metastasis and may serve as novel brain metastasis biomarkers and targets for therapy.
Project description:Brain metastases of melanoma are associated with therapy resistance and poor prognosis. It is not fully understood whether and how the selection of cells capable of metastasizing into the brain is accompanied by the establishment of specific features. For the investigation of these questions, we made use of previously described xenograft mouse models for primary human melanoma cells distinguishing cutaneous from cerebellar metastases from the same genetic background. Previous experiments suggested that cultured cells derived from these xenografts still maintain properties characteristic for the microenvironment of the originating metastases. Such corresponding pairs of metastatic cells were obtained from four individual donors, resulting in eight cell-lines presently investigated with regard to molecular properties characteristic for metastasis. Label free proteome profiling revealed significant alterations when comparing corresponding pairs of cutaneous and cerebellar metastases from the same donor. Molecules previously associated with metastasis such as cell adhesion molecules, immune regulators, epithelial mesenchymal transition markers, stem cell markers, redox regulators and cytokines were found differently expressed. This was also observed with regard to eicosanoids considered relevant for metastasis such as PGE2 and 12-HETE. However, no commonalities in the molecular characteristics of cerebellar metastases were identified in all four donors. Multiparametric morphological analysis of cells also revealed alterations associated with the kind of metastases, while lacking uniformity. In conclusion, here we describe that xenografted melanoma cells derived from two different microenvironments, i.e. cutaneous and cerebellar metastases, display significant alterations in the expression of molecules associated with metastastic properties. The observed lack of uniformity suggests that metastatic cells may find individual strategies to adapt to their microenvironmental challenges accompanied by the establishment of individual cell characteristics.
Project description:V600E being the most common mutation in BRAF, leads to constitutive activation of the MAPK signaling pathway. The majority of V600E BRAF positive melanoma patients treated with the BRAF inhibitor vemurafenib showed initial good clinical responses but relapsed due to acquired resistance to the drug. The aim of the present study was to identify possible biomarkers associated with the emergence of drug resistant melanoma cells. To this end we analyzed the differential gene expression of vemurafenib-sensitive and vemurafenib resistant brain and lung metastasizing melanoma cells. The major finding of this study is that the in vitro induction of vemurafenib resistance in melanoma cells is associated with an increased malignancy phenotype of these cells. Resistant cells expressed higher levels of genes coding for cancer stem cell markers (JARID1B, CD271 and Fibronectin) as well as genes involved in drug resistance (ABCG2), cell invasion and promotion of metastasis (MMP-1 and MMP-2). We also showed that drug-resistant melanoma cells adhere better to and transmigrate more efficiently through lung endothelial cells than drug-sensitive cells. The former cells also alter their microenvironment in a different manner from that of drug-sensitive cells. Biomarkers and molecular mechanisms associated with drug resistance may serve as targets for therapy of drug-resistant cancer.
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: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:Brain metastasis (BrM) represents the most common and aggressive brain malignancy, predominantly arising from non-small cell lung cancer, breast cancer, and melanoma. Recent studies have revealed the importance of the brain tumor microenvironment (TME), notably diverse immune cells, which play important roles in regulating cancer progression in both primary and metastatic brain malignancies. The blood-brain barrier (BBB) is another critical TME component formed by endothelial cells, mural cells, astrocytic end-feet, and closely-associated microglial cells. Metastasizing cancer cells can utilize different strategies to traverse the BBB and once they have successfully seeded and colonized the brain, they can exploit the vasculature for their own benefit, forming the blood-tumor barrier. To explore the mechanisms underlying tumor vascularization in brain metastasis we performed a comprehensive multiomic analysis of the key components of the tumor vasculature. We integrated single-cell and/or bulk RNA sequencing of sorted endothelial and mural cells isolated from human and mouse BrM and non-tumor samples; immunofluorescence imaging analysis of the spatial architecture of the TME; and functional studies using BrM mouse models to target vascular regulators of tumor immunity. Our results provide a comprehensive understanding of the biology underlying vascularization in metastatic brain tumors, specifically highlighting the importance of vascular cells as immune regulators and proposing novel therapeutic strategies for these aggressive tumors.
Project description:Disseminated cancer cells (DCCs) that escape the primary site can seed in distal tissues, but may take several years, or even decades to grow out into overt metastases, a phenomenon termed tumor dormancy. Despite its importance in metastasis and residual disease, few studies have been able to successfully model or characterize dormancy within melanoma. Here, we show that age-related changes in the lung microenvironment facilitate a permissive niche for efficient outgrowth of disseminated dormant tumor cells, in contrast to the aged skin, where age-related changes suppress melanoma growth but drive dissemination. A model of melanoma progression that addresses these microenvironmental complexities is the phenotype switching model, which argues that melanoma cells switch between a proliferative cell state and a slower-cycling, invasive state1-3. We have previously shown that dermal fibroblasts are key orchestrators of promoting phenotype switching in primary melanoma tumors via changes in the secretion of soluble factors during aging4-8. Our new data identifies Wnt5A as a master regulator of activating melanoma DCC dormancy within the lung, which initially enables efficient dissemination and seeding of melanoma cells in metastatic niches. Age-induced reprogramming of lung fibroblasts increases their secretion of the soluble Wnt antagonist sFRP1, which inhibits Wnt5A, enabling efficient metastatic outgrowth. Further, we have identified the tyrosine kinase receptors AXL and MER as promoting a dormancy-toreactivation axis respectively. Overall, we find that age-induced changes in distal metastatic microenvironments promotes efficient reactivation of dormant melanoma cells in the lung.