Pre-metastatic Niche Formation Research Articles

Mir-605-3p prevents liver premetastatic niche formation by inhibiting angiogenesis via decreasing exosomal nos3 release in gastric cancer.

Cancer-induced pre-metastatic niches (PMNs) play a decisive role in promoting metastasis by facilitating angiogenesis in distant sites. Evidence accumulates suggesting that microRNAs (miRNAs) exert significant influence on angiogenesis during PMN formation, yet their specific roles and regulatory mechanisms in gastric cancer (GC) remain underexplored. miR-605-3p was identified through miRNA-seq and validated by qRT-PCR. Its correlation with the clinicopathological characteristics and prognosis was analyzed in GC. Functional assays were performed to examine angiogenesis both in vitro and in vivo. The related molecular mechanisms were elucidated using RNA-seq, immunofluorescence, transmission electron microscopy, nanoparticle tracking analysis, enzyme-linked immunosorbent assay, luciferase reporter assays and bioinformatics analysis. miR-605-3p was screened as a candidate miRNA that may regulate angiogenesis in GC. Low expression of miR-605-3p is associated with shorter overall survival and disease-free survival in GC. miR-605-3p-mediated GC-secreted exosomes regulate angiogenesis by regulating exosomal nitric oxide synthase 3 (NOS3) derived from GC cells. Mechanistically, miR-605-3p reduced the secretion of exosomes by inhibiting vesicle-associated membrane protein 3 (VAMP3) expression and affects the transport of multivesicular bodies to the GC cell membrane. At the same time, miR-605-3p reduces NOS3 levels in exosomes by inhibiting the expression of intracellular NOS3. Upon uptake of GC cell-derived exosomal NOS3, human umbilical vein endothelial cells exhibited increased nitric oxide levels, which induced angiogenesis, established liver PMN and ultimately promoted the occurrence of liver metastasis. Furthermore, a high level of plasma exosomal NOS3 was clinically associated with metastasis in GC patients. miR-605-3p may play a pivotal role in regulating VAMP3-mediated secretion of exosomal NOS3, thereby affecting the formation of GC PMN and thus inhibiting GC metastasis.

Effects of small extracellular vesicles derived from normoxia- and hypoxia-treated prostate cancer cells on the submandibular salivary gland epithelium in vitro

ABSTRACT Small extracellular vesicles (sEVs) are an important part of intercellular communication. They are phospholipid bilayer particles that carry active biomolecules such as proteins, various nucleic acids, and lipids. In recipient cells, sEVs can alter cellular functions, including cancer development and premetastatic niche formation in distant organs. Moreover, sEVs can carry cancer-specific features, which makes them promising biomarker candidates. However, the interactions of sEVs with biological barriers and consequences thereof, are not clarified yet. The blood-saliva barrier is crucial for preventing the entry of pathogens and (in)organic substances into the bloodstream, as well as molecule filtration from blood to saliva. The effects of brain derived DU145 prostate cancer (PCa) sEVs on a human submandibular salivary gland barrier (SSGB) in vitro were investigated. Small EVs were harvested from normoxic (N, atmospheric O2) or hypoxic (H, 1% O2) conditions, fluorescently labeled with CellTrackerTM Orange and thoroughly characterized. HTB-41 B2 cells were used as SSGB model cultured on 24-well ThinCert® inserts. After model optimization indicating effects of serum and serum-sEVs on barrier properties, PCa sEVs were applied to the basolateral (blood) side in either 10% serum, or serum-free conditions, and barrier integrity was continuously monitored for 40 hours. This study found that H and N PCa sEVs were uptaken by the SSGB in vitro model in similar quantities regardless of the media composition in the basolateral compartment. Permeation of fluorescent PCa sEVs into the apical compartment was not detectable with the applied methods. However, treatment with H and N sEVs under different serum conditions revealed distinct molecular clusters after hierarchical analysis of mRNA data measured by high-throughput qPCR, which were partly reflected at the protein level. For example, serum-reduction dependent decrease of barrier properties was accompanied with the decrease of CDH1 or Claudin-7 expression. Interestingly, the presence of H sEVs significantly increased the number of sEV-sized particles in the apical compartment of the SSGB model compared to basolaterally added N sEVs. This functional effect on the number of particles in the saliva (apical) compartment induced by different sEVs applied in the blood (basolateral) compartment might be a new approach to understand one possible mechanism how differences of salivary EVs might occur which then could be used as biomarker.

ROS-responsive core–shell nano-inhibitor impedes pyruvate metabolism for reinforced photodynamic therapy and interrupted pre-metastatic niche formation

The formation of pre-metastatic niche (PMN) in a hospitable organ derived from the primary tumor requires the communication between the tumor cells and the host environment. Pyruvate is a fundamental nutrient by which the tumor cells metabolically reshape the extracellular matrix in the lung to facilitate their own metastatic development. Here we report a combination regimen by integrating the photo-sensitizer and the mitochondrial pyruvate carrier (MPC) inhibitor in a dendritic polycarbonate core-hyaluronic acid shell nano-platform with multivalent reversible crosslinker embedded in it (DOH-NI+L) to reinforce photodynamic therapy (PDT) toward the primary tumor and interrupt PMN formation in the lung via impeding pyruvate uptake. We show that DOH-NI+L mediates tumor-specific MPC inhibitor liberation, inhibiting the aerobic respiration for facilitated PDT and restraining ATP generation for paralyzing cell invasion. Remarkably, DOH-NI+L is demonstrated to block the metabolic crosstalk of tumor cell-host environment by dampening pyruvate metabolism, provoking a series of metabolic responses and resulting in the pulmonary PMN interruption. Consequently, DOH-NI+L realizes a significant primary tumor inhibition and an efficient pulmonary metastasis prevention. Our research extends nano-based anti-metastatic strategies aiming at PMN intervention and such a dendritic core–shell nano-inhibitor provides an innovative paradigm to inhibit tumor growth and prevent metastasis efficiently. Statement of significanceIn the progression of cancer metastasis, the formation of a pre-metastatic niche (PMN) in a hospitable organ derived from the primary tumor is one of the rate-limiting stages. The current nano-based anti-metastatic modalities mainly focus on targeted killing of tumor cells and specific inhibition of tumor cell invasion, while nanomedicine-mediated interruption of PMN formation has been rarely reported. Here we report a combination regimen by integrating a photo-sensitizer and an inhibitor of mitochondrial pyruvate carrier in a dendritic core–shell nano-platform with a reversible crosslinker embedded in it to reinforce PDT toward the primary tumor and interrupt PMN formation via impeding the uptake of pyruvate that is a fundamental nutrient facilitating aerobic respiration and PMN formation. Our research proposed a nano-based anti-metastatic strategy aiming at PMN intervention.

Cancer-derived small extracellular vesicles affect vascular endothelial cells and promote adhesiveness of pancreatic cancer cells

Abstract Objectives Pancreatic cancer (PC) is one of the most aggressive malignancies due to the high rate of metastasis. The mechanisms underlying metastasis need to be elucidated. Small extracellular vesicles (sEVs) mediate cell-to-cell communication, and cancer-derived sEVs contribute to the formation of pre-metastatic niches. The present study examined changes in adhesiveness by the internalization of PC-derived sEVs into vascular endothelial cells, and investigated the molecular mechanisms underlying metastasis. Methods PC-derived sEVs were internalized into vascular endothelial cells, and changes in adhesiveness were evaluated. We evaluated the effects of sEVs on the formation of liver metastasis in vivo. We also assessed molecular changes in vascular endothelial cells by the internalization of PC-derived sEVs. Results The internalization of PC-derived sEVs into vascular endothelial cells promoted the adhesiveness of vascular endothelial cells and PC cells. PC-derived sEVs contained high levels of transforming growth factor 1 mRNA and acted as its transporter. Once PC-derived sEVs were internalized into vascular endothelial cells, the expression of fibronectin 1 increased on the cell surface, and the adhesiveness of vascular endothelial cells was enhanced. Conclusions We investigated association between PC-derived sEVs and adhesiveness. Regulation of PC-derived sEVs has potential as a therapeutic modality to suppress the metastasis of PC.

NSCLC extracellular vesicles containing miR-374a-5p promote leptomeningeal metastasis by influencing blood‒brain barrier permeability.

Leptomeningeal metastasis (LM) is a devastating complication of advanced non-small cell lung cancer (NSCLC). Diagnosis and monitoring of LM can be challenging. Extracellular vesicles (EVs) microRNAs (miRNAs) have become a new noninvasive diagnostic biomarker. The purpose of this study was to examine the clinical value and role of EVs miRNAs in NSCLC-LM. According to next-generation sequencing (NGS), miRNAs with differential expression of EVs in serum of NSCLC patients with LM and non-LM were detected to find biological markers for the diagnosis of LM. Cellular and in vivo experiments were conducted to explore the pathogenesis of EVs miRNA promoting LM in NSCLC. In the present study, we first demonstrated the serum level of EV-associated miR-374a-5p in patients with LM of lung cancer was much higher than that in patients without LM and was correlated with the survival time of patients with LM. Further studies showed that EVs miR-374a-5p efficiently destroys tight junctions and the integrity of the cerebral microvascular endothelial cell barrier, resulting in increased blood-brain barrier (BBB) permeability. Mechanistically, miR-374a-5p regulates the distribution of ZO-1 and occludin in endothelial cells by targeting ADD3, increasing vascular permeability and promoting LM. Implications: These results suggest that serum NSCLC-derived EVs miR-374a-5p is involved in premetastatic niche formation by regulating the permeability of BBB to promote NSCLC-LM, and can be used as a blood biomarker for the diagnosis and prognosis of NSCLC-LM.

Early Detection of Myeloid-Derived Suppressor Cells in the Lung Pre-Metastatic Niche by Shortwave Infrared Nanoprobes.

Metastatic breast cancer remains a significant source of mortality amongst breast cancer patients and is generally considered incurable in part due to the difficulty in detection of early micro-metastases. The pre-metastatic niche (PMN) is a tissue microenvironment that has undergone changes to support the colonization and growth of circulating tumor cells, a key component of which is the myeloid-derived suppressor cell (MDSC). Therefore, the MDSC has been identified as a potential biomarker for PMN formation, the detection of which would enable clinicians to proactively treat metastases. However, there is currently no technology capable of the in situ detection of MDSCs available in the clinic. Here, we propose the use of shortwave infrared-emitting nanoprobes for the tracking of MDSCs and identification of the PMN. Our rare-earth albumin nanocomposites (ReANCs) are engineered to bind the Gr-1 surface marker of murine MDSCs. When delivered intravenously in murine models of breast cancer with high rates of metastasis, the targeted ReANCs demonstrated an increase in localization to the lungs in comparison to control ReANCs. However, no difference was seen in the model with slower rates of metastasis. This highlights the potential utility of MDSC-targeted nanoprobes to assess PMN development and prognosticate disease progression.

Destruction of vascular endothelial glycocalyx during formation of pre-metastatic niches

A special microenvironment called the “pre-metastatic niche” is thought to help primary tumor cells migrate to new tissues and invade them, in part because the normal barrier function of the vascular endothelium is compromised. While the primary tumor itself can promote the creation of such niches by secreting pro-metastatic factors, the underlying molecular mechanisms are still poorly understood. Here, we show that the injection of primary tumor-secreted pro-metastatic factors from B16F10 melanoma or 4T1 breast cancer cells into healthy mice can induce the destruction of the vascular endothelial glycocalyx, which is a polysaccharide coating on the vascular endothelial lumen that normally inhibits tumor cell passage into and out of the circulation. However, when human umbilical vein endothelial cultures were treated in vitro with these secreted pro-metastatic factors, no significant destruction of the glycocalyx was observed, implying that this destruction requires a complex in vivo microenvironment. The tissue section analysis revealed that secreted pro-metastatic factors could clearly upregulate macrophage-related molecules such as CD11b and tumor necrosis factor-α (TNF-α) in the heart, liver, spleen, lung, and kidney, which is associated with the upregulation and activation of heparanase. In addition, macrophage depletion significantly attenuated the degradation of the vascular endothelial glycocalyx induced by secreted pro-metastatic factors. This indicates that the secreted pro-metastatic factors that destroy the vascular endothelial glycocalyx rely primarily on macrophages. Our findings suggest that the formation of pre-metastatic niches involves degradation of the vascular endothelial glycocalyx, which may hence be a useful target for developing therapies to inhibit cancer metastasis.

Participation of suicide gene extracellular vesicles in metastasis prevention.

The incidence of distant metastases is associated with most cancer-related mortalities. Extracellular vesicles (EVs), secreted from tumors and cancer-associated fibroblasts, are involved in the metastatic process mediating their organotropism through their involvement in the pre-metastatic niche formation. We have been developing suicide gene therapy mediated by EVs secreted from mesenchymal stem/ stromal cells, tumor cells, and cancer-associated fibroblasts. Suicide gene EVs conjugated with prodrug are tumor tropic, penetrate tumor cells, and kill them by intracellular conversion of nontoxic prodrug to an efficient anti-cancer drug. Here, we discuss findings regarding the possibility of using suicide gene EVs as a novel therapeutic approach for metastases, via pre-metastatic niche modification. The suicide gene EVs provide a future perspective for metastasis prevention.

Tumor-driven stromal reprogramming in the pre-metastatic lymph node

Background Metastatic dissemination is critically reliant on the formation of a receptive niche, a process which is thought to rely on signals derived from the primary tumor. Lymph nodes are continuously exposed to such signals through the flow of afferent lymph, allowing the potential reprograming of lymphoid tissue stroma in support of metastases or immunosuppression. The objective of this study was therefore to better characterize tumor-driven transcriptomic changes occurring to specific stromal populations within the tumor-draining lymph node. Methods We utilize single cell RNA sequencing of dissociated LN tissue extracted from tumor-bearing and naïve mice to profile the reprograming of tissue stroma within the pre-metastatic lymph node. Results Resulting data provides transcriptomic evidence of tumor-induced imprinting on marginal reticular cells (MRCs) and floor lymphatic endothelial cells (fLECs) populating the subcapsular sinus. These alterations appear to be unique to the tumor-draining LN and are not observed during inflammatory antigenic challenge. Notably, MRCs exhibit characteristics reminiscent of early desmoplastic CAF differentiation, fLECs engage distinct chemoattractant pathways thought to facilitate recruitment of circulating cancer cells, and both stromal populations exhibit signs of metabolic reprograming and immune-modulating potential. Conclusions Cumulatively, these findings build upon existing literature describing pre-metastatic niche formation and offer several promising avenues for future exploration.

Abstract 3725: Exosomal Galactin-3 promotes pre-metastatic niche formation that accelerates peritoneal metastases of gastric adenocarcinoma

Abstract Peritoneal carcinomatosis (PC) in gastric adenocarcinoma (GAC) lead to a short median survival (≤6 months). Pre-metastatic niche (PMN) formation, in a distant organ to prepare for tumor seeding and colonization, has long been recognized. However, the precise molecular and mechanistic contributions of exosomes in PMN formation of PC remain unclear. We identify that exosomes promote PMN formation in the peritoneal cavity by patient-derived orthotopic mouse model. Using an in-depth proteomic profiling of paired ascites cells and ascites-derived exosomes from PC patients, we discover that Galectin-3 as the exosomal payload is responsible for PC by promoting PMN formation in both patient-derived orthotopic model and syngeneic mouse model. Inhibition of exosomal Galectin-3 reverses PC. Furthermore, exosomal Galectin-3 activates cancer-associated fibroblasts (CAFs), which further activate the CXCL12/CXCR4 axis to orchestrate the immunosuppressive PMN. Simultaneous inhibition of exosomal Galectin-3, CXCR4, and PD-1 leads to tumor regression and durable anti-tumor responses. Thus, this study provides a rationale for the novel clinical strategy for GAC patients with PC. Citation Format: Yibo Fan, Shumei Song, Melissa Pool Pizzi, Katsuhiro Yoshimura, Jody V. Vykoukal, Samir Hanash, Jaffer Ajani. Exosomal Galactin-3 promotes pre-metastatic niche formation that accelerates peritoneal metastases of gastric adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3725.

Abstract 1396: Targeting immune suppressive myeloid cells in prostate cancer recurrence and metastasis

Abstract Metastatic prostate cancer is a leading cause of cancer-related deaths worldwide and therefore an urgent inadequately addressed clinical problem. We have approached this problem primarily by studying immune cells within the tumor microenvironment rather than the tumor cells themselves. One critical cell subset that seems to be contributing to the aggressive behavior of clinically significant prostate cancers is the immune suppressive myeloid cells (MDSC) within the tumor microenvironment. MDSC have been shown to promote tumor metastases by participating in the formation of pre-metastatic niche, promoting angiogenesis, tumor cell invasion, and mediating immune suppression. Understanding the heterogeneity and function of these myeloid cells is an essential step toward developing effective therapeutic strategies to target them and enhance anti-tumor immune responses that have thus far been so elusive. We utilized previously generated scRNAseq data and combined it with publicly available prostate cancer scRNAseq datasets. The analysis included a total of 96 samples at different disease stages, including healthy prostate tissue, adjacent-normal tissue, low-grade tumors, high-grade tumors, as well as local and bone metastatic tumors. In addition, GeoMx spatial profiling was performed on 24 high-grade prostate cancer patients to assess immune cell spatial infiltration. This meta-analysis provided comprehensive insights into the molecular characteristics of prostate cancer. We characterized multiple MDSC subpopulations and revealed the dynamics of tumor associated macrophages (TAMs) during tumor progression and metastasis. We found that a specific type of TAM, known as APOE+ SPP1+TAM, is significantly enriched in metastatic tumors. They are transcriptionally similar to the TAMs found in the bone metastasis niche of prostate cancer. Moreover, we found APOE+ SPP1+TAMs within primary/localized tumors tumors alone could predict prostate cancer recurrence despite curative-intent local therapy. We validated the accumulation of APOE+ SPP1+TAMs in a prostate cancer mice model. We are currently studying the role of the specific subset of TAMs in tumor metastases by focused analysis of the communication between these TAMs, T cells, and tumors. Additionally, we are exploring the therapeutic potential of blocking APOE+ SPP1+TAMs in a mice model of prostate cancer. Our analyses provide a comprehensive picture of myeloid cell linage across different prostate cancer stages, highlighting the potential for therapeutic targets that disrupt the metastatic process via their effects on tumor associated macrophages. Citation Format: Shenglin Mei, Hanyu Zhang, Taghreed Hirz, Nathan Elias Jeffries, Shulin Wu, Chin Lee Wu, Douglas M. Dahl, Philip J. Saylor, David B. Sykes. Targeting immune suppressive myeloid cells in prostate cancer recurrence and metastasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1396.

Abstract 1385: Crosstalk between hepatocyte and myeloid-specific IL17 signaling in colorectal cancer metastasis

Abstract Advanced colorectal cancer (CRC) is resistant to current immunotherapies and prone to metastasis. Chronic inflammation mediated by cytokines such as interleukin (IL)17 activates the oncogenic pathways in cancer cells, promoting sporadic and inflammation-associated CRC. Increased levels of IL17A in early stages of CRC portends poor prognosis indicating its potential involvement into metastasis. We and others previously showed that IL17A signaling is required for early CRC tumorigenicity in a variety of models and that in early CRC, its ability to signal to epithelial cells is essential. What remains unknown is whether IL17 signaling to other cell types within the tumor microenvironment (TME) is essential to control tumor progression and metastasis. Using a model of colitis-associated cancer (CAC) we found that “late” IL17A neutralization decreases tumor burden, possibly acting through regulation of myeloid cells and chemokine network essential for the control of immunosuppressive TME. Next, using models of colorectal cancer liver metastasis (CRLM) including intraportal cell injection and cecum transplantation of organoids with distinct set of oncogenic mutation we found that IL17 neutralization reduces metastasis. FACS analysis revealed that IL17A promotes the recruitment of tumor-associated macrophages and other key myeloid subsets into the metastatic liver environment. Interestingly, ablation of IL17RC (receptor) in myeloid cells only (using Il17rcf/f -LysMCre mice) led to reduction in metastasis and reshaping of metastatic myeloid cell compartments. Meanwhile, IL17 signaling in hepatocytes was required for early metastasis and pre-metastatic niche formation, as the ablation of IL17RC in hepatocytes (using Il17rcf/f -AlbCre mice) led to a reduction of metastatic numbers but not growth. This coincided with reduced neutrophil recruitment and enhanced activation of cytotoxic innate lymphoid cells and CD8 T lymphocytes, indicating the role of hepatocyte specific IL17 signaling in blunting anti-tumor immunity. Our findings illuminate the role of inflammatory cytokine IL17 into CRC progression and metastasis and imply its distinct cell type specific role within the metastatic liver TME. Citation Format: Katarzyna Chojnacka, Dan Kamen, Katrina M. Reyes, Hana Tomizawa, Sergei I. Grivennikov. Crosstalk between hepatocyte and myeloid-specific IL17 signaling in colorectal cancer metastasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1385.

Abstract 1498: TGFβ signaling in cancer-associated fibroblasts drives a hepatic gp130-dependent pro-metastatic inflammatory program in CMS4 colorectal cancer

Abstract Background: Colorectal cancer (CRC) is characterized by a metastatic pattern that shows tropism towards the liver which is the major cause of CRC-related deaths. The current CRC classification, Consensus Molecular Subtypes (CMS), suggests an association between transforming growth factor (TGF)-β signaling, cancer-associated fibroblasts (CAFs), and the risk of liver metastasis. However, the key downstream effectors of TGFβ signaling in CAFs and their role in hepatic metastases remain poorly understood. Methods: The aim of this study was to investigate the TGF-β/CAF dependent cross talk with the hepatocytes in pre-metastatic niche formation. CAFs from 18 primary CRC tissues and 7 liver-metastasized CRC were stimulated with TGFβ1 and qPCR arrays/ELISAs were performed to identify differentially expressed genes. Results were cross-referenced with RNAseq expression data of CMS-classified CRC and in fresh samples from CRC patients. To investigate CAF-liver crosstalk hepatocytes were stimulated with the TGFβ primed CAF-derived cytokines and the effect on pro-inflammatory gene expression and neutrophil migration was determined. Subsequently, blockade of these pathways via chemical inhibition and CRISPR/Cas9 genetic ablation was performed to study the molecular mechanism involved in the induction of this hepatic pro-inflammatory program. Results: TGFβ signaling in primary CRC-derived CAFs leads to increased expression of different IL-6 cytokine family members, which was also reflected in human CRC samples. CAF-derived IL6 family members induce upregulation of myeloid chemoattractants, including SAA1, in hepatocytes and increased neutrophil-to-hepatocyte migration in vitro. Chemical blockade and genetic ablation of the IL-6 family cytokine signaling pathway showed the critical role of the gp130 co-receptor in the regulation of this inflammatory response in hepatocytes and the potential formation of a premetastatic niche. Conclusion: TGFβ signaling in CAFs actively contributes to the formation of a neutrophil-dependent, pre-metastatic hepatic niche, and this mechanism might play a role in CMS4 subtype CRC. Citation Format: Subinuer Abudukelimu, Tom J. Harryvan, Stef G. Janson, Imke Stouten, Els M. Verdegaal, Lukas JAC Hawinkels. TGFβ signaling in cancer-associated fibroblasts drives a hepatic gp130-dependent pro-metastatic inflammatory program in CMS4 colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1498.

Abstract 1382: Activation of the cGAS-STING pathway by large oncosomes induces type I IFN inflammation in mesenchymal stem cells that triggers an immunosuppressive phenotype in neutrophils

Abstract Extracellular vesicles (EVs) have been recognized as key players in cancer progression and metastasis, particularly large oncosomes (LO), secreted by invasive cancer cells, represent a distinct class of EVs with unique features. Previous research by the Di Vizio lab revealed LO's ability to alter recipient cell behavior, induce vascular morphogenesis, and carry cancer-specific biomolecules. Our preliminary studies point to a new mechanism of intercellular communication that involves the release of LO-containing DNA from PC cells. Notably, LO from prostate cancer exhibits enhanced potency in reprogramming bone marrow-derived mesenchymal stem cells (BM-MSCs) compared to exosomes (Exo) as observed by RNAseq. When evaluating the response to LO and Exo of BM-MSC, which are emerging as important drivers of bone metastasis, LO induces a robust inflammatory response, including metastasis-relevant chemokines and transcription factors involved in type I IFN response such as IRF7 and RASD2. Further, REACTOME pathway analysis of the differentially expressed genes revealed enrichment of the cGAS-STING pathway in BM-MSCs treated with LO, indicating a potential link between DNA/RNA sensors and the inflammatory response. BM cells isolated from WT and mutant Sting1gt/J mice demonstrated that up-regulation of IRF3 and IFNA1 genes induced by LO is inhibited when STING is absent. Suggesting that nucleic acid sensors engage in the LO-induced immune response in BM cells. Gene ontology analysis (GO) also identified several chemokines involved in neutrophil chemotaxis. In line with the observation from GO, neutrophil chemotaxis was significantly promoted by PC-derived LO-treated BM-MSC. Interestingly, human blood-derived neutrophils exposed to a conditioned medium from EVs-treated BM-MSC significantly increased the percentage of a population of LOX-1high and CD62Llow/− after 6h of culture. This was observed in concert with increased expression of Arginase1 and IL-10, suggesting their differentiation into polymorphonuclear-myeloid-derived suppressor cells (PMN-MDSC). An experimental orthotopic model using the breast cancer bone metastatic 4T1.2 cell line, with increased capacity to shed LO, demonstrated an increase in the presence of PMN-MDSC in the bone marrow of tumor-bearing mice in addition to a complete lack of lymphocyte populations, indicating their immunosuppressive activity that could lead to a pre-metastatic niche formation. This comprehensive study unveils the molecular pathways underlying the immune response to LO in the bone marrow, shedding light on mechanisms that could influence metastatic progression in prostate cancer. The findings underscore the unique role of LO in modulating the BM microenvironment, providing potential targets for therapeutic intervention and biomarkers for early disease detection. Citation Format: Taylon F. Silva, Diana Kitka, Blandine Victor, Chen Qian, Minhyung Kim, Tatyana Vagner, Giorgia Guerra, Catherine Grasso, Sungyong You, Fayyazz Sutterwala, Caroline Jefferies, Paola de Candia, Michael Freeman, Helen Goodridge, Karen Cavassani, Jlenia Guarnerio, Dolores Di Vizio. Activation of the cGAS-STING pathway by large oncosomes induces type I IFN inflammation in mesenchymal stem cells that triggers an immunosuppressive phenotype in neutrophils [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1382.

Abstract 4273: Genetically engineered mesenchymal stromal cells degrade hyaluronic acid to disrupt the ECM and enhance cancer therapy outcomes

Abstract The extracellular matrix (ECM) is a vital component of cancer pathophysiology. However, little is known about how to modulate the ECM for therapeutic benefit effectively. Hyaluronic acid (HA) is a polysaccharide component of the ECM with increased deposition during tissue injury or inflammation. HA in the tumor microenvironment (TME) has been linked to aggressive cancer progression. We have found enhanced ECM remodeling behavior linked to pre-metastatic niche formation and metastatic progression. To remodel this ECM-enriched microenvironment, we developed HA-targeting genetically engineered mesenchymal stromal cells (GEMesys) expressing hyaluronidase (Hyal), the enzyme responsible for HA degradation. We examined the impact of Hyal-GEMesys in osteosarcoma (F42010), rhabdomyosarcoma (M-3-9M), and pancreatic cancer (Panc02) syngeneic murine models. Hyal-GEMesys delivered to tumor-bearing mice homed to primary tumor sites and successfully degraded HA in the TME. The degradation of HA also resulted in a significant remodeling of collagen. T cells in Hyal-GEMesy treated tumors display an activated CD4+CD44+ phenotype with a reduction of LAG3+PD1+ exhaustion markers. Additionally, Hyal-GEMesy treatment results in a significant decrease in hypoxic regions within tumors and reorganization of the tumor vasculature to a more normalized phenotype, marked by diminished CD31 expression. Hyal-GEMesy treatment reduces tumor volumes in osteosarcoma, rhabdomyosarcoma, and pancreatic cancer models and enhances chemotherapeutic efficacy. These findings suggest that reorganizing the tumor ECM with Hyal-GEMesys holds the potential to dismantle the protective stroma of the tumor, which often shields malignant cells from therapeutic reach, and combining anti-cancer and anti-stroma agents can enhance anti-tumor efficacy and patient outcomes. Citation Format: Alice T. Browne, Miranda Clements, Wei Ju, Rosandra Kaplan. Genetically engineered mesenchymal stromal cells degrade hyaluronic acid to disrupt the ECM and enhance cancer therapy outcomes [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4273.

Shuangshen Granules Suppress Myeloid-derived Suppressor Cell-mediated Lung Premetastatic Niche Development by Targeting Sphingosine-1-Phosphate Receptor-1/Signal Transducer, Activator of Transcription 3 Signaling

Abstract Background: Shuangshen granules (SSGs) are extensively utilized for the treatment of lung cancer in China and have been reported to possess tumor-protective and anti-metastatic effects. Therefore, it is crucial to understand the precise mechanism. Building upon the findings of our previous study, the objective of the present study was to explore the impact of SSGs on the sphingosine-1-phosphate receptor-1 (S1PR1)/signal transducer and activator of transcription 3 (STAT3) axis, as well as the recruitment of myeloid-derived suppressor cells (MDSCs) during the formation of the premetastatic niches (PMNs). Methods: In a mouse xenograft model utilizing Lewis lung carcinoma (LLC) cells that express green fluorescent protein (GFP), the initiation of lung metastasis was monitored every three days until day 35 following transplantation. Lung metastasis, MDSC recruitment, the expression of PMN and S1PR1/STAT3 axis biomarkers, as well as the blood levels of granulocyte-macrophage colony-stimulating factor (GM-CSF) and transforming growth factor-β (TGF-β) were assessed in the SSG treatment and control groups. Results: The LLC cells did not reach the lung until 14–17 days following subcutaneous implantation, which was concurrent with the formation of lung PMNs. SSG significantly postponed the initiation of lung metastasis and reduced the recruitment of MDSCs to the lung PMNs. SSG also suppressed the S1PR1/STAT3 axis in tumor tissues, bone marrow, and lung PMNs. Additionally, SSG suppressed the blood levels of GM-CSF and TGF-β, as well as the PMN markers, matrix metalloproteinase-9 and versican. Conclusion: Our findings suggested that SSG suppressed the development of MDSC-mediated PMNs by inhibiting the S1PR1/STAT3 axis, consequently postponing the initiation of lung metastasis.

Hypoxia induced exosomal Circ-ZNF609 promotes pre-metastatic niche formation and cancer progression via miR-150-5p/VEGFA and HuR/ZO-1 axes in esophageal squamous cell carcinoma

Exosomes derived from cancer are regarded as significant mediators of cancer-host crosstalk. Hypoxia, on the other hand, is one of the essential characteristics of solid tumors. This research set out to discover how circulating exosomes from hypoxic esophageal squamous cell carcinoma (ESCC) contribute to the formation of metastatic niches and distant metastasis. First, we noticed that human umbilical vein endothelial cells (HUVECs) had their tight connections disrupted and the expression of proteins involved in angiogenesis boosted by ESCC hypoxic exosomes. Hypoxia significantly induced Circ-ZNF609 expression in exosomes from ESCC, which was then internalized by HUVECs, as determined by circular RNA screening. High Circ-ZNF609 expression in HUVECs facilitated angiogenesis and vascular permeability, thereby promoting pre-metastatic niche formation, and enhancing distant metastasis in vitro and in vivo. Exosomal Circ-ZNF609 activated vascular endothelial growth factor A (VEGFA) mechanistically by sponging miR-150-5p. Exosomal Circ-ZNF609 also interacted with HuR and inhibited HuR binding to ZO-1, Claudin-1, and Occludin mRNAs, thereby reducing their translation. Collectively, our findings identified an essential function for exosomal Circ-ZNF609 from ESCC cells, suggesting the potential therapeutic value of exosomes for ESCC patients.

LSD1 modulates the bone metastasis of breast cancer cells through hnRNPA2B1-mediated sorting of exosomal miRNAs

Bone metastasis is a key contributor to morbidity and mortality of breast cancer patients. We have previously shown that exosomal miRNAs derived from LSD1 knockdown (KD) breast cancer cells inhibit osteoblast differentiation and promote osteoclast differentiation. However, how LSD1 regulates exosomal miRNAs and whether miRNAs promote bone metastasis through the formation of pre-metastatic niches remains unclear. In vivo experiments demonstrates that exosomes derived from LSD1 KD breast cancer cells significantly promoted bone metastasis. To explore the mechanism underlying the effect of LSD1 on exosomes in breast cancer cells, exosomal and cellular miRNAs from control, LSD1 KD, and rescue cells were sequenced. Interestingly, approximately 80% of LSD1-associated miRNAs were downregulated in exosomes from LSD1 KD cells. The consensus sequence UAGGGC, was identified in many miRNAs downregulated in LSD1 KD exosomes. We found that hnRNPA2B1 regulated the exosomal sorting of miR-6881-3p and some other miRNAs. LSD1 deficiency reduced hnRNPA2B1 expression in breast cancer cells by decreasing the level of H3K9me2 demethylation in the promoter region of the hnRNPA2B1 gene. Our study revealed that LSD1 plays a crucial role in the regulation of exosomal sorting of miRNA.

Extracellular vesicle-mediated pre-metastatic niche formation via altering host microenvironments.

The disordered growth, invasion and metastasis of cancer are mainly attributed to bidirectional cell-cell interactions. Extracellular vesicles (EVs) secreted by cancer cells are involved in orchestrating the formation of pre-metastatic niches (PMNs). Tumor-derived EVs mediate bidirectional communication between tumor and stromal cells in local and distant microenvironments. EVs carrying mRNAs, small RNAs, microRNAs, DNA fragments, proteins and metabolites determine metastatic organotropism, enhance angiogenesis, modulate stroma cell phenotypes, restructure the extracellular matrix, induce immunosuppression and modify the metabolic environment of organs. Evidence indicates that EVs educate stromal cells in secondary sites to establish metastasis-supportive microenvironments for seeding tumor cells. In this review, we provide a comprehensive overview of PMN formation and the underlying mechanisms mediated by EVs. Potential approaches to inhibit cancer metastasis by inhibiting the formation of PMNs are also presented.

Tumor-derived exosomal ADAM17 promotes pre-metastatic niche formation by enhancing vascular permeability in colorectal cancer

BackgroundHematological metastasis has been recognized as a crucial factor contributing to the high rates of metastasis and mortality observed in colorectal cancer (CRC). Notably, exosomes derived from cancer cells participate in the formation of CRC pre-metastatic niches; however, the mechanisms underlying their effects are largely unknown. While our preliminary research revealed the role of exosome-derived disintegrin and metalloproteinase 17 (ADAM17) in the early stages of CRC metastasis, the role of exosomal ADAM17 in CRC hematogenous metastasis remains unclear.MethodsIn the present study, we isolated and purified exosomes using ultracentrifugation and identified exosomal proteins through quantitative mass spectrometry. In vitro, co-culture assays were conducted to evaluate the impact of exosomal ADAM17 on the permeability of the blood vessel endothelium. Vascular endothelial cell resistance, the cell index, membrane protein separation, flow cytometry, and immunofluorescence were employed to investigate the mechanisms underlying exosomal ADAM17-induced vascular permeability. Additionally, a mouse model was established to elucidate the role of exosomal ADAM17 in the modulation of blood vessel permeability and pre-metastatic niche formation in vivo.ResultsOur clinical data indicated that ADAM17 derived from the circulating exosomes of patients with CRC could serve as a blood-based biomarker for predicting metastasis. The CRC-derived exosomal ADAM17 targeted vascular endothelial cells, thus enhancing vascular permeability by influencing vascular endothelial cadherin cell membrane localization. Moreover, exosomal ADAM17 mediated the formation of a pre-metastatic niche in nude mice by inducing vascular leakage, thereby promoting CRC metastasis. Nonetheless, ADAM17 selective inhibitors effectively reduced CRC metastasis in vivo.ConclusionsOur results suggest that exosomal ADAM17 plays a pivotal role in the hematogenous metastasis of CRC. Thus, this protein may serve as a valuable blood-based biomarker and potential drug target for CRC metastasis intervention.