Interactions of cancer cells with the primary tumor microenvironment are important determinants of cancer progression toward metastasis but it is unknown whether additional prometastatic signals are ...provided during the intravascular transit to the site of metastasis. Here, we show that platelet-tumor cell interactions are sufficient to prime tumor cells for subsequent metastasis. Platelet-derived TGFβ and direct platelet-tumor cell contacts synergistically activate the TGFβ/Smad and NF-κB pathways in cancer cells, resulting in their transition to an invasive mesenchymal-like phenotype and enhanced metastasis in vivo. Inhibition of NF-κB signaling in cancer cells or ablation of TGFβ1 expression solely in platelets protects against lung metastasis in vivo. Thus, cancer cells rely on platelet-derived signals outside of the primary tumor for efficient metastasis.
► Platelet-tumor cell contacts induce a mesenchymal-like metastatic phenotype ► Platelet-derived TGFβ1 is necessary but not sufficient for efficient metastasis ► NF-κB signaling is also necessary but not sufficient and synergizes with TGFβ ► Signals provided outside the primary tumor microenvironment promote metastasis
The extracellular matrix (ECM) and ECM proteins are important in phenomena as diverse as developmental patterning, stem cell niches, cancer, and genetic diseases. The ECM has many effects beyond ...providing structural support. ECM proteins typically include multiple, independently folded domains whose sequences and arrangement are highly conserved. Some of these domains bind adhesion receptors such as integrins that mediate cell-matrix adhesion and also transduce signals into cells. However, ECM proteins also bind soluble growth factors and regulate their distribution, activation, and presentation to cells. As organized, solid-phase ligands, ECM proteins can integrate complex, multivalent signals to cells in a spatially patterned and regulated fashion. These properties need to be incorporated into considerations of the functions of the ECM.
The modular domain structure of extracellular matrix (ECM) proteins and their genes has allowed extensive exon/domain shuffling during evolution to generate hundreds of ECM proteins. Many of these ...arose early during metazoan evolution and have been highly conserved ever since. Others have undergone duplication and divergence during evolution, and novel combinations of domains have evolved to generate new ECM proteins, particularly in the vertebrate lineage. The recent sequencing of several genomes has revealed many details of this conservation and evolution of ECM proteins to serve diverse functions in metazoa.
During metastasis, host cells are recruited to disseminated tumor cells to form specialized microenvironments ("niches") that promote metastatic progression, but the mechanisms guiding the assembly ...of these niches are largely unknown. Tumor cells may autonomously recruit host cells or, alternatively, host cell-to-host cell interactions may guide the formation of these prometastatic microenvironments. Here, we show that platelet-derived rather than tumor cell-derived signals are required for the rapid recruitment of granulocytes to tumor cells to form "early metastatic niches." Granulocyte recruitment relies on the secretion of CXCL5 and CXCL7 chemokines by platelets upon contact with tumor cells. Blockade of the CXCL5/7 receptor CXCR2, or transient depletion of either platelets or granulocytes prevents the formation of early metastatic niches and significantly reduces metastatic seeding and progression. Thus, platelets recruit granulocytes and guide the formation of early metastatic niches, which are crucial for metastasis.
Tumor cells transit from the primary tumor via the blood circulation to form metastases in distant organs. During this process, tumor cells encounter a number of environmental challenges and stimuli ...that profoundly impact their metastatic potential. Here, we review the cooperative and dynamic host-tumor cell interactions that support and promote the hematogenous dissemination of cancer cells to sites of distant metastasis. In particular, we discuss what is known about the cross-talk occurring among tumor cells, platelets, leukocytes, and endothelial cells and how these cell-cell interactions are organized both temporally and spatially at sites of extravasation and in the early metastatic niche.
Metastasis is a function not only of tumor cells but also involves cooperative interactions of those cells with normal cells of the body, in particular platelets and leukocytes. These other cell types alter the behavior of the tumor cells themselves and of endothelial cells lining the vasculature and assist in tumor cell arrest and extravasation at sites of metastasis and subsequently in the establishment of tumor cells in the early metastatic niche. A better understanding of the important role that these contact and paracrine interactions play during metastasis will offer new opportunities for therapeutic intervention.
Extracellular matrix (ECM) proteins constitute >1% of the proteome and interact with many modifiers and growth factors to affect most aspects of cellular behaviour during development and normal ...physiology, as well as in diseases such as fibroses, cancer and many genetic disorders. In addition to biochemical signals provided to cells by ECM proteins, important cell–ECM interactions involve bidirectional mechanotransduction influences, which are dependent on the physical structure and organization of the ECM. These are beginning to be understood using twenty-first-century approaches, including biophysics, nanotechnology, biological engineering and modern microscopy. Articles in this issue of Nature Reviews Molecular Cell Biology review progress in our understanding of the ECM.
In their roles as major adhesion receptors, integrins signal across the plasma membrane in both directions. Recent structural and cell biological data suggest models for how integrins transmit ...signals between their extracellular ligand binding adhesion sites and their cytoplasmic domains, which link to the cytoskeleton and to signal transduction pathways. Long-range conformational changes couple these functions via allosteric equilibria.
The extracellular matrix (ECM) is a complex meshwork of cross-linked proteins providing both biophysical and biochemical cues that are important regulators of cell proliferation, survival, ...differentiation, and migration. We present here a proteomic strategy developed to characterize the in vivo ECM composition of normal tissues and tumors using enrichment of protein extracts for ECM components and subsequent analysis by mass spectrometry. In parallel, we have developed a bioinformatic approach to predict the in silico “matrisome” defined as the ensemble of ECM proteins and associated factors. We report the characterization of the extracellular matrices of murine lung and colon, each comprising more than 100 ECM proteins and each presenting a characteristic signature. Moreover, using human tumor xenografts in mice, we show that both tumor cells and stromal cells contribute to the production of the tumor matrix and that tumors of differing metastatic potential differ in both the tumor- and the stroma-derived ECM components. The strategy we describe and illustrate here can be broadly applied and, to facilitate application of these methods by others, we provide resources including laboratory protocols, inventories of ECM domains and proteins, and instructions for bioinformatically deriving the human and mouse matrisome.
The extracellular matrix (ECM) is a fundamental component of multicellular organisms that provides mechanical and chemical cues that orchestrate cellular and tissue organization and functions. ...Degradation, hyperproduction or alteration of the composition of the ECM cause or accompany numerous pathologies. Thus, a better characterization of ECM composition, metabolism, and biology can lead to the identification of novel prognostic and diagnostic markers and therapeutic opportunities. The development over the last few years of high-throughput (“omics”) approaches has considerably accelerated the pace of discovery in life sciences. In this review, we describe new bioinformatic tools and experimental strategies for ECM research, and illustrate how these tools and approaches can be exploited to provide novel insights in our understanding of ECM biology. We also introduce a web platform “the matrisome project” and the database MatrisomeDB that compiles in silico and in vivo data on the matrisome, defined as the ensemble of genes encoding ECM and ECM-associated proteins. Finally, we present a first draft of an ECM atlas built by compiling proteomics data on the ECM composition of 14 different tissues and tumor types.
•The matrisome is defined as the ensemble of 1000+ genes encoding ECM and ECM-associated proteins.•Bioinformatic and experimental approaches to study the ECM/matrisome are discussed.•We introduce a novel website and database MatrisomeDB to centralize resources on the matrisome.•We present a draft of an ECM atlas compiling proteomics data on the ECM of 14 different tissues and tumors.•“Omics” data provide novel insights into ECM functions in development, homeostasis and disease.
Checkpoint blockade immunotherapies can be extraordinarily effective, but might benefit only the minority of patients whose tumors are pre-infiltrated by T cells. Here, using lung adenocarcinoma ...mouse models, including genetic models, we show that autochthonous tumors that lacked T cell infiltration and resisted current treatment options could be successfully sensitized to host antitumor T cell immunity when appropriately selected immunogenic drugs (e.g., oxaliplatin combined with cyclophosphamide for treatment against tumors expressing oncogenic Kras and lacking Trp53) were used. The antitumor response was triggered by direct drug actions on tumor cells, relied on innate immune sensing through toll-like receptor 4 signaling, and ultimately depended on CD8+ T cell antitumor immunity. Furthermore, instigating tumor infiltration by T cells sensitized tumors to checkpoint inhibition and controlled cancer durably. These findings indicate that the proportion of cancers responding to checkpoint therapy can be feasibly and substantially expanded by combining checkpoint blockade with immunogenic drugs.
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•Kras/Trp53 mutant tumors lack CD8+ T cells and resist chemo- and immunotherapies•Immunogenic chemotherapy elicits tumor T cell infiltration and controls cancer growth•Tumor control requires CD8+ T cells, TLR4+ cells, and drug actions on cancer cells•T cell influx sensitizes tumors to checkpoint inhibition and durably controls cancer
There is an urgent need to expand the proportion of patients that respond to immune checkpoint therapy. Using clinically relevant genetic mouse models and a combination of immunogenic drugs to trigger T cell infiltration into tumors, Pittet and colleagues are able to make unresponsive tumors sensitive to checkpoint blockade therapy.
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