Transcriptomic profiling of freshly isolated mouse lung cancer LLC- and mouse breast cancer 4T1- derived leptomeningeal metastatic cancer cells from different anatomical locations [RNA-Seq]
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ABSTRACT: Cancer cells metastatic to the leptomeninges encounter a metabolically-challenging extreme microenvironment. To understand adaptations to this space, we subjected leptomeningeal-metastatic (LeptoM) mouse breast and lung cancers isolated from either the leptomeninges or orthotopic primary sites to ATAC- and RNA-sequencing. When inhabiting the leptomeninges, the LeptoM cells demonstrated transcription downstream of retinoid-X-receptors (RXRs). We found evidence of local retinoic acid (RA) generation in both human leptomeningeal metastasis and mouse models in the form of elevated spinal fluid retinol and expression of RA-generating dehydrogenases within the leptomeningeal microenvironment. Stimulating LeptoM cells with 9-cis RA induced expression of transcripts encoding de novo fatty acid synthesis pathway enzymes in vitro. In vivo, whereas knockout of Stra6 did not alter cancer cell leptomeningeal growth, knockout of Rxra/b/g interrupted cancer cell lipid biosynthesis and arrested cancer growth. These observations illustrate a mechanism whereby locally-generated developmental cues metabolically reprogram metastatic cancer cells and suggest novel therapeutic approaches.
Project description:Cancer cells metastatic to the leptomeninges encounter a metabolically-challenging extreme microenvironment. To understand adaptations to this space, we subjected leptomeningeal-metastatic (LeptoM) mouse breast and lung cancers isolated from either the leptomeninges or orthotopic primary sites to ATAC- and RNA-sequencing. When inhabiting the leptomeninges, the LeptoM cells demonstrated transcription downstream of retinoid-X-receptors (RXRs). We found evidence of local retinoic acid (RA) generation in both human leptomeningeal metastasis and mouse models in the form of elevated spinal fluid retinol and expression of RA-generating dehydrogenases within the leptomeningeal microenvironment. Stimulating LeptoM cells with 9-cis RA induced expression of transcripts encoding de novo fatty acid synthesis pathway enzymes in vitro. In vivo, whereas knockout of Stra6 did not alter cancer cell leptomeningeal growth, knockout of Rxra/b/g interrupted cancer cell lipid biosynthesis and arrested cancer growth. These observations illustrate a mechanism whereby locally-generated developmental cues metabolically reprogram metastatic cancer cells and suggest novel therapeutic approaches.
Project description:To understand transcriptional regulation of nuclear receptors, LXRs and RXRs, in leptomeningeal metastatic cancer cells, we use CRISPR-Cas9 to knockout Nr1h2/3 genes (encoding LXRβ/α) or RXRa/b/g genes (encoding RXRα/β/γ) in LLC LeptoM cell lines, with small guide RNA targeting lacZ as vector control. We then subjected these cell lines for bulk RNA sequencing with or without stimulation of 1μM 9 cis-RA. Pathway analysis of the differentially expressed genes between LLC LeptoM vector control with RA stimulation to DMSO treatment revealed upregulation of developmental related pathways and lipid metabolism pathways. Meanwhile, loss of function in LXR or RXR both resulted in dysregulation of multiple lipid metabolism pathways, in which RXR made a broader impact.
Project description:Metastasis to the cerebrospinal fluid (CSF)-filled leptomeninges, or leptomeningeal metastasis (LM), represents a fatal complication of cancer. Proteomic and transcriptomic analyses of human CSF reveal a substantial inflammatory infiltrate in LM. We find the solute and immune composition of CSF in the setting of LM changes dramatically, with notable enrichment in IFN-gamma signaling. To investigate the mechanistic relationships between immune cell signaling and cancer cells within the leptomeninges, we developed syngeneic lung, breast, and melanoma LM mouse models. We find that transgenic host mice, lacking IFN-gamma or its receptor, fail to control LM growth. Overexpression of Ifng through a targeted AAV system controls cancer cell growth independent of adaptive immunity. Instead, leptomeningeal IFN-gamma actively recruits and activates peripheral myeloid cells, generating a diverse spectrum of dendritic cell subsets. These migratory, CCR7+ dendritic cells orchestrate the influx, proliferation, and cytotoxic action of natural killer cells to control cancer cell growth in the leptomeninges. This work uncovers leptomeningeal-specific IFN-gamma signaling and suggests a novel immune-therapeutic approach against tumors within this space.
Project description:The tumor microenvironment plays a critical regulatory role in cancer progression, especially in metastases to the central nervous system. Cancer cells inhabiting the cerebrospinal spinal fluid (CSF)-filled leptomeningeal space face substantial microenvironmental challenges including inflammation and sparse extracellular iron. Unlike CSF leukocytes, we find that cancer cells within the CSF express the iron-binding protein LCN2 and its receptor SCL22A17. Employing mouse models of LM, we find that the LCN2/SLC22A17 system is necessary to support leptomeningeal cancer cell growth. We find that infiltrating CSF macrophages generate inflammatory cytokines that induce cancer cell LCN2 expression. This LCN2/SLC22A17 system provides cancer cells superior access to limiting extracellular iron, allowing LCN2-expressing cancer cells to outcompete CSF macrophages for this resource. Finally, pharmacologic interruption of these interactions prevents cancer cell growth within the leptomeninges.
Project description:The tumor microenvironment plays a critical regulatory role in cancer progression, especially in metastases to the central nervous system. Cancer cells inhabiting the cerebrospinal spinal fluid (CSF)-filled leptomeningeal space face substantial microenvironmental challenges including inflammation and sparse extracellular iron. Unlike CSF leukocytes, we find that cancer cells within the CSF express the iron-binding protein LCN2 and its receptor SCL22A17. Employing mouse models of LM, we find that the LCN2/SLC22A17 system is necessary to support leptomeningeal cancer cell growth. We find that infiltrating CSF macrophages generate inflammatory cytokines that induce cancer cell LCN2 expression. This LCN2/SLC22A17 system provides cancer cells superior access to limiting extracellular iron, allowing LCN2-expressing cancer cells to outcompete CSF macrophages for this resource. Finally, pharmacologic interruption of these interactions prevents cancer cell growth within the leptomeninges.
Project description:Ms4a3-Cre: R26-TdTomato: Cx3cr1-gfp mice allow discrimination between YS-derivd and monocyte-derived macrophages in the brain parenchyma and leptomeninges by color. We used single cell RNAseq for RNA profiling to compare YS-derived micrglia, monocyte-derived microglia, YS-derived leptomeningeal macrophages, and monocyte-derived leptomeningeal macrophages.
Project description:Leptomeningeal disease (LMD) remains a rapidly lethal complication for late-stage melanoma patients. The inaccessible nature of the disease site and lack of understanding of the biology of this unique metastatic site are major barriers to developing efficacious therapies for patients with melanoma LMD. This study aims to characterize the tumor microenvironment of the leptomeningeal tissues and patient-matched extra-cranial metastatic sites using spatial transcriptomic analyses.
Project description:Meninges, or the membranous coverings of the brain and spinal cord, play host to dozens of morbid pathologies. In this study we provide a method to isolate the leptomeningeal cell layer, identify leptomeninges in histologic slides, and maintain leptomeningeal fibroblasts in in vitro culture. Using an array of transcriptomic, histological, and cytometric analyses, we identified ICAM1 and SLC38A2 as two novel markers of leptomeningeal cells in vivo and in vitro. Our results confirm the fibroblastoid nature of leptomeningeal cells and their ability to form a sheet-like layer that covers the brain and spine parenchyma. These findings will enable researchers in central nervous system barriers to describe leptomeningeal cell functions in health and disease.
Project description:The meninges, comprising the leptomeninges (pia and arachnoid layers) and the pachymeninx (dura layer), participate in CNS autoimmunity but their relative contributions remain unclear. Here, we report on findings in animal models of CNS autoimmunity and in multiple sclerosis patients, where, in chronic disease, the leptomeninges were highly inflamed and showed structural changes, while the dura mater was only marginally affected. Although dural vessels were leakier than leptomeningeal vessels, effector T cells adhered more weakly to the dural endothelium. Furthermore, local antigen presenting cells presented myelin and neuronal autoantigens less efficiently and the activation of autoreactive T cells was lower in dural than leptomeningeal layers, preventing local inflammatory processes. Direct antigen application was required to evoke a local inflammatory response in the dura. Together, our data demonstrate an uneven involvement of the meningeal layers in CNS autoimmunity, in which effector T cell trafficking and activation are functionally confined to the leptomeninges, while the dura remains largely shielded from CNS autoimmune processes.
Project description:Medulloblastoma metastasis often occurs in the leptomeningeal spaces; however, the biology of the metastatic tumour cells and the local leptomeningeal niche are poorly characterized. We performed single-cell RNA sequencing to analyze the leptomeningeal metastatic niche in a medulloblastoma mouse model.