CCL2 Is a Vascular Permeability Factor Inducing CCR2-Dependent Endothelial Retraction during Lung Metastasis

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

BACKGROUND

Hematological 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.

METHODS

In 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.

RESULTS

Our 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.

CONCLUSIONS

Our 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.

Beyond the barrier: the immune-inspired pathways of tumor extravasation

Extravasation is a fundamental step in the metastatic journey, where cancer cells exit the bloodstream and breach the endothelial cell barrier to infiltrate target tissues. The tactics cancer cells employ are sophisticated, closely reflecting those used by the immune system for tissue surveillance. Remarkably, tumor cells have been observed to form distinct associations or clusters with immune cells where neutrophils stand out as particularly crucial partners. These interactions are not accidental; they are critical for cancer cells to exploit the immune functions of neutrophils and successfully extravasate. In another strategy, tumor cells mimic the behavior and characteristics of immune cells. They release a suite of inflammatory mediators, which under normal circumstances, guide the processes of endothelium reshaping and facilitate the entry and movement of immune cells within tissues. In this review, we offer a new perspective on the tactics employed by cancer cells to extravasate and infiltrate target tissues. We delve into the myriad mechanisms that tumor cells borrow, adapt, and refine from the immune playbook. Video Abstract.

Simultaneous Targeting of IL-1-Signaling and IL-6-Trans-Signaling Preserves Human Pulmonary Endothelial Barrier Function During a Cytokine Storm-Brief Report

BACKGROUND

Systemic inflammatory diseases, such as sepsis and severe COVID-19, provoke acute respiratory distress syndrome in which the pathological hyperpermeability of the microvasculature, induced by uncontrolled inflammatory stimulation, causes pulmonary edema. Identifying the inflammatory mediators that induce human lung microvascular endothelial cell barrier dysfunction is essential to find the best anti-inflammatory treatments for critically ill acute respiratory distress syndrome patients.

METHODS

We have compared the responses of primary human lung microvascular endothelial cells to the main inflammatory mediators involved in cytokine storms induced by sepsis and SARS-CoV2 pulmonary infection and to sera from healthy donors and severely ill patients with sepsis. Endothelial barrier function was measured by electric cell-substrate impedance sensing, quantitative confocal microscopy, and Western blot.

RESULTS

The human lung microvascular endothelial cell barrier was completely disrupted by IL (interleukin)-6 conjugated with soluble IL-6R (IL-6 receptor) and by IL-1β (interleukin-1beta), moderately affected by TNF (tumor necrosis factor)-α and IFN (interferon)-γ and unaffected by other cytokines and chemokines, such as IL-6, IL-8, MCP (monocyte chemoattractant protein)-1 and MCP-3. The inhibition of IL-1 and IL-6R simultaneously, but not separately, significantly reduced endothelial hyperpermeability on exposing human lung microvascular endothelial cells to a cytokine storm consisting of 8 inflammatory mediators or to sera from patients with sepsis. Simultaneous inhibition of IL-1 and JAK (Janus kinase)-STAT (signal transducer and activator of transcription protein), a signaling node downstream IL-6 and IFN-γ, also prevented septic serum-induced endothelial barrier disruption.

CONCLUSIONS

These findings strongly suggest a major role for both IL-6 trans-signaling and IL-1β signaling in the pathological increase in permeability of the human lung microvasculature and reveal combinatorial strategies that enable the gradual control of pulmonary endothelial barrier function in response to a cytokine storm.

CCR2: A characteristic chemokine receptor in normal and pathological intestine

C-C motif chemokine receptor 2 (CCR2), together with its ligands, especially C-C motif ligand 2 (CCL2), to which CCR2 has the highest affinity, form a noteworthy signaling pathway in recruiting macrophages for the immune responses among variegated disorders in vivo environment. Scientometric methods are used to analyze intestine-related CCR2 expression. We describe the current knowledge on biological function of CCR2 in physiological intestine in three dimensions, namely its effects on stromal cells, angiogenesis, and remodeling. However, anomalous expression of CCR2 has also been conveyed to correlate with detrimental outcomes in intestine, such as infective colitis, inflammatory bowel disease, carcinogenesis, and colon-related metastasis. In this article, we briefly summarize recent experimental works on CCR2 and its ligands, mostly CCL2, in intestinal-related physiological and pathological states to ravel out their working mechanisms in intestinal diseases.

SGK1 Target Genes Involved in Heart and Blood Vessel Functions in PC12 Cells

Serum and glucocorticoid-regulated kinase 1 (SGK1) is expressed in neuronal cells and involved in the pathogenesis of hypertension and metabolic syndrome, regulation of neuronal function, and depression in the brain. This study aims to identify the cellular mechanisms and signaling pathways of SGK1 in neuronal cells. In this study, the SGK1 inhibitor GSK650394 is used to suppress SGK1 expression in PC12 cells using an in vitro neuroscience research platform. Comparative transcriptomic analysis was performed to investigate the effects of SGK1 inhibition in nervous cells using mRNA sequencing (RNA-seq), differentially expressed genes (DEGs), and gene enrichment analysis. In total, 12,627 genes were identified, including 675 and 2152 DEGs at 48 and 72 h after treatment with GSK650394 in PC12 cells, respectively. Gene enrichment analysis data indicated that SGK1 inhibition-induced DEGs were enriched in 94 and 173 genes associated with vascular development and functional regulation and were validated using real-time PCR, Western blotting, and GEPIA2. Therefore, this study uses RNA-seq, DEG analysis, and GEPIA2 correlation analysis to identify positive candidate genes and signaling pathways regulated by SGK1 in rat nervous cells, which will enable further exploration of the underlying molecular signaling mechanisms of SGK1 and provide new insights into neuromodulation in cardiovascular diseases.

Investigating Chemokine-Matrix Networks in Breast Cancer: Tenascin-C Sets the Tone for CCL2

Bidirectional dialogue between cellular and non-cellular components of the tumor microenvironment (TME) drives cancer survival. In the extracellular space, combinations of matrix molecules and soluble mediators provide external cues that dictate the behavior of TME resident cells. Often studied in isolation, integrated cues from complex tissue microenvironments likely function more cohesively. Here, we study the interplay between the matrix molecule tenascin-C (TNC) and chemokine CCL2, both elevated in and associated with the progression of breast cancer and playing key roles in myeloid immune responses. We uncover a correlation between TNC/CCL2 tissue levels in HER2+ breast cancer and examine the physical and functional interactions of these molecules in a murine disease model with tunable TNC levels and in in vitro cellular and cell-free models. TNC supported sustained CCL2 synthesis, with chemokine binding to TNC via two distinct domains. TNC dominated the behavior of tumor-resident myeloid cells; CCL2 did not impact macrophage survival/activation whilst TNC facilitated an immune suppressive macrophage phenotype that was not dependent on or altered by CCL2 co-expression. Together, these data map new binding partners within the TME and demonstrate that whilst the matrix exerts transcriptional control over the chemokine, each plays a distinct role in subverting anti-tumoral immunity.

Combination therapy with bevacizumab and a CCR2 inhibitor for human ovarian cancer: An in vivo validation study

BACKGROUND

Anti-angiogenic therapy with bevacizumab (BEV), an anti-VEGF antibody, plays a critical role in the treatment of ovarian cancer. However, despite an encouraging initial response, most tumors become resistant to BEV over time, and a new strategy that enables sustainable treatment using BEV is therefore needed.

METHODS

To overcome the resistance to BEV in patients with ovarian cancer, we performed a validation study of combination therapy with BEV (10 mg/kg) and the CCR2 inhibitor BMS CCR2 22 (20 mg/kg) (BEV/CCR2i) using 3 consecutive patient-derived xenografts (PDXs) of immunodeficient mice.

RESULTS

BEV/CCR2i demonstrated a significant effect of growth suppression in the BEV-resistant serous PDX and BEV-sensitive serous PDX compared with BEV (30.4% after the second cycle and 15.5% after the first cycle, respectively), and treatment cessation did not attenuate this effect. Tissue clearing and immunohistochemistry with an anti-α-SMA antibody suggested that BEV/CCR2i suppressed angiogenesis from the host mice more than BEV. In addition, human CD31 immunohistochemistry revealed that BEV/CCR2i decreased microvessels originating from the patients to a significantly greater degree than BEV. Regarding the BEV-resistant clear cell PDX, the effect of BEV/CCR2i was unclear during the first five cycles, but the following two cycles of increased-dose BEV/CCR2i (CCR2i 40 mg/kg) significantly suppressed tumor growth compared with BEV (28.3%) by inhibiting the CCR2B-MAPK pathway.

CONCLUSIONS

BEV/CCR2i showed a sustained anticancer immunity-independent effect in human ovarian cancer that was more significant in serous carcinoma than in clear cell carcinoma.

The Role of Endothelial Barrier Function in the Fibrosis of Salivary Gland

In the salivary glands, fibrosis occurs in many pathological conditions. Endothelial tight junction (TJ)-based barrier function plays a vital role in maintaining the homeostasis of the salivary glands. However, whether endothelial barrier function is changed and involved in the pathogenesis of glandular fibrosis is unknown. Here, by using a mouse model in which the main excretory duct of the submandibular gland (SMG) was ligated to induce inflammation and fibrosis, endothelial barrier function and TJ protein expression and distribution were examined. Both 4-kDa and 70-kDa fluorescence-labeled dextrans permeated more in the 1-, 3-, and 7-d ligated SMGs. Meanwhile, the mRNA level of claudin-5 was increased with an obvious redistribution from apicolateral membranes to lateral membranes and cytoplasm in the fibrotic glands. Notably, the TJ sealer AT1001 significantly attenuated the disrupted endothelial barrier function and thereby ameliorated the glandular fibrosis. Cytokine array detection showed that monocyte chemoattractant protein-1 (MCP-1) was highly enriched in the 3-d ligated SMGs, and MCP-1 directly impaired barrier function, increased claudin-5 expression, induced the relocalization of claudin-5, and activated p-ERK1/2 in cultured human endothelial cells. Furthermore, the upregulation and disorganization of claudin-5 as well as the elevation of MCP-1 and p-ERK1/2 signaling were also confirmed in fibrotic SMGs from patients with chronic sialadenitis and immunoglobulin G4-related sialadenitis. Altogether, our findings revealed that disrupted endothelial barrier function contributed to the progression of glandular fibrosis, and targeting endothelial TJs might be a promising approach to alleviate salivary gland fibrosis-related diseases.

Role of CC-chemokine ligand 2 in gynecological cancer

Gynecological cancer is one of the most severe diseases that threaten the lives and health of women worldwide. Its incidence rate increases with each passing year and becomes more prevalent among young people. The prognosis of gynecological cancer remains poor despite significant advances in surgical removal and systemic chemotherapy. Several chemokines play a role in the progression of gynecologic cancers. CCL2 (CC-chemokine ligand 2), also termed MCP-1 (monocyte chemotactic protein 1), plays a significant physiological role in monocyte cell migration and the inflammatory response. Recent studies have demonstrated that CCL2 plays a pro-tumorigenic function in the tumor microenvironment. According to previous studies, CCL2 plays a significant role in the occurrence and development of gynecological cancers. Furthermore, recent studies noted that CCL2 could be a potential diagnostic biomarker and prognostic predictor. The purpose of this paper is to review the role of CCL2 in the occurrence and development of gynecological cancers and to discuss the potential therapeutic strategy of CCL2 for gynecological cancers, with a primary focus on breast cancer, ovarian cancer, cervical cancer, and endometrial cancer.

Chronic inflammation, cancer development and immunotherapy

Chronic inflammation plays a pivotal role in cancer development. Cancer cells interact with adjacent cellular components (pro-inflammatory cells, intrinsic immune cells, stromal cells, etc.) and non-cellular components to form the inflammatory tumor microenvironment (TME). Interleukin 6 (IL-6), macrophage migration inhibitory factor (MIF), immune checkpoint factors and other pro-inflammatory cytokines produced by intrinsic immune cells in TME are the main mediators of intercellular communication in TME, which link chronic inflammation to cancer by stimulating different oncogenic signaling pathways and improving immune escape to promote cancer development. In parallel, the ability of monocytes, T regulatory cells (Tregs) and B regulatory cells (Bregs) to perform homeostatic tolerogenic functions is hijacked by cancer cells, leading to local or systemic immunosuppression. Standard treatments for advanced malignancies such as chemotherapy and radiotherapy have improved in the last decades. However, clinical outcomes of certain malignant cancers are not satisfactory due to drug resistance and side effects. The clinical application of immune checkpoint therapy (ICT) has brought hope to cancer treatment, although therapeutic efficacy are still limited due to the immunosuppressive microenvironment. Emerging evidences reveal that ideal therapies including clearance of tumor cells, disruption of tumor-induced immunosuppression by targeting suppressive TME as well as reactivation of anti-tumor T cells by ICT. Here, we review the impacts of the major pro-inflammatory cells, mediators and their downstream signaling molecules in TME on cancer development. We also discuss the application of targeting important components in the TME in the clinical management of cancer.

From Tumor Cells to Endothelium and Gut Microbiome: A Complex Interaction Favoring the Metastasis Cascade

Metastasis is a complicated process through which tumor cells disseminate to distant organs and adapt to novel tumor microenvironments. This multi-step cascade relies on the accumulation of genetic and epigenetic alterations within the tumor cells as well as the surrounding non-tumor stromal cells. Endothelial cells constitute a major player in promoting metastasis formation either by inducing the growth of tumor cells or by directing them towards dissemination in the blood or lymph. In fact, the direct and indirect interactions between tumor and endothelial cells were shown to activate several mechanisms allowing cancer cells’ invasion and extravasation. On the other side, gastrointestinal cancer development was shown to be associated with the disruption of the gut microbiome. While several proposed mechanisms have been investigated in this regard, gut and tumor-associated microbiota were shown to impact the gut endothelial barrier, increasing the dissemination of bacteria through the systemic circulation. This bacterial dislocation allows the formation of an inflammatory premetastatic niche in the distant organs promoting the metastatic cascade of primary tumors. In this review, we discuss the role of the endothelial cells in the metastatic cascade of tumors. We will focus on the role of the gut vascular barrier in the regulation metastasis. We will also discuss the interaction between this vascular barrier and the gut microbiota enhancing the process of metastasis. In addition, we will try to elucidate the different mechanisms through which this bacterial dislocation prepares the favorable metastatic niche at distant organs allowing the dissemination and successful deposition of tumor cells in the new microenvironments. Finally, and given the promising results of the studies combining immune checkpoint inhibitors with either microbiota alterations or anti-angiogenic therapy in many types of cancer, we will elaborate in this review the complex interaction between these 3 factors and their possible therapeutic combination to optimize response to treatment.

Remodelling of the tumour microenvironment by the kallikrein-related peptidases

Kallikrein-related peptidases (KLKs) are critical regulators of the tumour microenvironment. KLKs are proteolytic enzymes regulating multiple functions of bioactive molecules including hormones and growth factors, membrane receptors and the extracellular matrix architecture involved in cancer progression and metastasis. Perturbations of the proteolytic cascade generated by these peptidases, and their downstream signalling actions, underlie tumour emergence or blockade of tumour growth. Recent studies have also revealed their role in tumour immune suppression and resistance to cancer therapy. Here, we present an overview of the complex biology of the KLK family and its context-dependent nature in cancer, and discuss the different therapeutic strategies available to potentially target these proteases.

Prognosis-related autophagy genes in female lung adenocarcinoma

To screen the prognosis-related autophagy genes of female lung adenocarcinoma by the transcriptome data and clinical data from The Cancer Genome Atlas (TCGA) database.In this study, screen meaningful female lung adenocarcinoma differential genes in TCGA, use univariate Cox proportional regression model to select genes related to prognosis, and establish the best risk model. In this study, Gene Ontology and Kyoto Encyclopedia of Genes and Genomes were applied for carrying out bioinformatics analysis of gene function.The gene expression and clinical data of 264 female lung adenocarcinoma patient samples were downloaded from TCGA. Twelve down-regulated genes: NRG3, DLC1, NLRC4, DAPK2, HSPB8, PPP1R15A, FOS, NRG1, PRKCQ, GRID1, MAP1LC3C, GABARAPL1. Up-regulated 15 genes: PARP1, BNIP3, P4HB, ATIC, IKBKE, ITGB4, VMP1, PTK6, EIF4EBP1, GAPDH, ATG9B, ERO1A, TMEM74, CDKN2A, BIRC5. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analysis showed that these genes were significantly associated with autophagy and mitochondria (animals). Multifactor Cox analysis of autophagy-related genes showed that ITGA6, ERO1A, FKBP1A, BAK1, CCR2, FADD, EDEM1, ATG10, ATG4A, DLC1, VAMP7, ST13 were identified as independent prognostic indicators. According to the multivariate Cox proportional hazard regression model, there was a significant difference in the survival rate observed between the high-risk group (n = 124) and the low-risk group (n = 126) during the 10-year follow-up (P < .05). Univariate Cox analysis showed that tumor stage, T, M, and N stages, and risk score were all related to the survival rate of female lung adenocarcinoma patients. Multivariate Cox analysis found that autophagy-related risk scores were independent predictors, with an area under curve (AUC) value of 0.842. At last, there is autophagy genes differentially expressed among various clinicopathological parameters: ATG4A, BAK1, CCR2, DLC1, ERO1A, FKBP1A, ITGA6.The risk score can be used as an independent prognostic indicator for female patients with lung adenocarcinoma. The autophagy genes ITGA6, ERO1A, FKBP1A, BAK1, CCR2, FADD, EDEM1, ATG10, ATG4A, DLC1, VAMP7, ST13 were identified as prognostic genes in female lung adenocarcinoma, which may be the targets of treatment in the future.

Decreased Astrocytic CCL2 Accounts for BAF-312 Effect on PBMCs Transendothelial Migration Through a Blood Brain Barrier in Vitro Model

Disruption of the blood brain barrier (BBB) is a common event in several neurological diseases and in particular, in multiple sclerosis (MS), it contributes to the infiltration of the central nervous system by peripheral inflammatory cells. Sphingosine-1-phosphate (S1P) is a bioactive molecule with pleiotropic effects. Agonists of S1P receptors such as fingolimod and siponimod (BAF-312) are in clinical practice for MS and have been shown to preserve BBB function in inflammatory conditions. Using an in vitro BBB model of endothelial-astrocytes co-culture exposed to an inflammatory insult (tumor necrosis factor-α and interferon-γ; T&I), we show that BAF-312 reduced the migration of peripheral blood mononuclear cells (PBMCs) through the endothelial layer, only in the presence of astrocytes. This effect was accompanied by decreased expression of the adhesion molecule ICAM-1. BAF-312 also reduced the activation of astrocytes, by controlling NF-kB and NLRP3 induction and preventing the increase of proinflammatory cytokine and chemokines. Reduction of CCL2 by BAF-312 may be responsible for the observed effects and, accordingly, addition of exogenous CCL2 was able to counteract BAF-312 effects and rescued T&I responses on PBMC migration, ICAM-1 expression and astrocyte activation. The present results further point out BAF-312 effects on BBB properties, suggesting also the key role of astrocytes in mediating drug effects on endothelial function.

Peripherally administered cannabinoid receptor 2 (CB2R) agonists lose anti-allodynic effects in TRPV1 knockout mice, while intrathecal administration leads to anti-allodynia and reduced GFAP, CCL2 and TRPV1 expression in the dorsal spinal cord and DRG

The transient receptor potential (TRP) superfamily of cation channels, of which the TRP vanilloid type 1 (TRPV1) receptor plays a critical role in inflammatory and neuropathic pain, is expressed on nociceptors and spinal cord dorsal horn neurons. TRPV1 is also expressed on spinal astrocytes and dorsal root ganglia (DRG) satellite cells. Agonists of the cannabinoid type 2 receptor (CB2R) suppress allodynia, with some that can bind TRPV1. The neuroimmune C-C class chemokine-2 (CCL2) expressed on injured DRG nociceptor cell bodies, Schwann cells and spinal astrocytes, stimulates immune cell accumulation in DRG and spinal cord, a known critical element in chronic allodynia. The current report examined whether two CB2R agonists, AM1710 and AM1241, previously shown to reverse light touch mechanical allodynia in rodent models of sciatic neuropathy, require TRPV1 activation that leads to receptor insensitivity resulting in reversal of allodynia. Global TRPV1 knockout (KO) mice with sciatic neuropathy given intrathecal or intraperitoneal AM1710 were examined for anti-allodynia followed by immunofluorescent microscopy analysis of lumbar spinal cord and DRG of astrocyte and CCL2 markers. Additionally, immunofluorescent analysis following intrathecal AM1710 and AM1241 in rat was performed. Data reveal that intrathecal AM1710 resulted in mouse anti-allodynia, reduced spinal astrocyte activation and CCL2 expression independent of TRPV1 gene deletion. Conversely, peripheral AM1710 in TRPV1-KO mice failed to reverse allodynia. In rat, intrathecal AM1710 and AM1241 reduced spinal and DRG TRPV1 expression, with CCL2-astrocyte and -microglial co-expression. These data support that CB2R agonists can impact spinal and DRG TRPV1 expression critical for anti-allodynia.

CCL2: An Important Mediator Between Tumor Cells and Host Cells in Tumor Microenvironment

Tumor microenvironment (TME) formation is a major cause of immunosuppression. The TME consists of a considerable number of macrophages and stromal cells that have been identified in multiple tumor types. CCL2 is the strongest chemoattractant involved in macrophage recruitment and a powerful initiator of inflammation. Evidence indicates that CCL2 can attract other host cells in the TME and direct their differentiation in cooperation with other cytokines. Overall, CCL2 has an unfavorable effect on prognosis in tumor patients because of the accumulation of immunosuppressive cell subtypes. However, there is also evidence demonstrating that CCL2 enhances the anti-tumor capability of specific cell types such as inflammatory monocytes and neutrophils. The inflammation state of the tumor seems to have a bi-lateral role in tumor progression. Here, we review works focusing on the interactions between cancer cells and host cells, and on the biological role of CCL2 in these processes.

Regulation of vascular permeability in cancer metastasis

Enhancement of vascular permeability is indispensable for cancer metastasis. Weakened endothelial barrier function enhances vascular permeability. Circulating tumor cells moving in the microvasculature tend to invade into stromal tissue at the location where vascular permeability is enhanced. Many basic studies have identified permeability factors by using gene‐modified animals and cells. These factors directly/indirectly interact with endothelial cells. Here, we review vascular permeability factors and their molecular mechanisms. Interactions between tumor cells and endothelial cells are also discussed in the process of extravasation, one of the most critical steps in tumor metastasis. In some cases, primary tumors can manipulate permeability in a remote organ by secreting permeability factors. In addition, the importance of glycocalyx, which covers the endothelial cell surface, in controlling vascular permeability and tumor metastasis is also described. Furthermore, analysis of the hyperpermeable region found in a mouse model study is introduced. It clearly showed that tumor‐bearing mouse lungs had a hyperpermeable region due to the influence of a remote primary tumor, and fibrinogen deposition was observed in that region. Given that fibrinogen was reported to be a permeability factor and a key regulator of inflammation, eliminating fibrinogen deposition may prevent future metastasis.

The multifaceted roles of the chemokines CCL2 and CXCL12 in osteophilic metastatic cancers

Breast and prostate cancers have a great propensity to metastasize to long bones. The development of bone metastases is life-threatening, incurable, and drastically reduces patients' quality of life. The chemokines CCL2 and CXCL12 and their respective receptors, CCR2 and CXCR4, are central instigators involved in all stages leading to cancer cell dissemination and secondary tumor formation in distant target organs. They orchestrate tumor cell survival, growth and migration, tumor invasion and angiogenesis, and the formation of micrometastases in the bone marrow. The bone niche is of particular importance in metastasis formation, as it expresses high levels of CCL2 and CXCL12, which attract tumor cells and contribute to malignancy. The limited number of available effective treatment strategies highlights the need to better understand the pathophysiology of bone metastases and reduce the skeletal tumor burden in patients diagnosed with metastatic bone disease. This review focuses on the involvement of the CCL2/CCR2 and CXCL12/CXCR4 chemokine axes in the formation and development of bone metastases, as well as on therapeutic perspectives aimed at targeting these chemokine-receptor pairs.

Therapeutic Approaches Targeting the Natural Killer-Myeloid Cell Axis in the Tumor Microenvironment

Immunotherapy has transformed cancer treatment by promoting durable clinical responses in a proportion of patients; however, treatment still fails in many patients. Innate immune cells play a key role in the response to immunotherapy. Crosstalk between innate and adaptive immune systems drives T-cell activation but also limits immunotherapy response, as myeloid cells are commonly associated with resistance. Hence, innate cells have both negative and positive effects within the tumor microenvironment (TME), and despite investment in early clinical trials targeting innate cells, they have seen limited success. Suppressive myeloid cells facilitate metastasis and immunotherapy resistance through TME remodeling and inhibition of adaptive immune cells. Natural killer (NK) cells, in contrast, secrete inflammatory cytokines and directly kill transformed cells, playing a key immunosurveillance role in early tumor development. Myeloid and NK cells show reciprocal crosstalk, influencing myeloid cell functional status or antigen presentation and NK effector function, respectively. Crosstalk between myeloid cells and the NK immune network in the TME is especially important in the context of therapeutic intervention. Here we discuss how myeloid and NK cell interactions shape anti-tumor responses by influencing an immunosuppressive TME and how this may influence outcomes of treatment strategies involving drugs that target myeloid and NK cells.

c-Myb interferes with inflammatory IL1α-NF-κB pathway in breast cancer cells

The transcription factor c-Myb can be involved in the activation of many genes with protumorigenic function; however, its role in breast cancer (BC) development is still under discussion. c-Myb is considered as a tumor-promoting factor in the early phases of BC, on the other hand, its expression in BC patients relates to a good prognosis. Previously, we have shown that c-Myb controls the capacity of BC cells to form spontaneous lung metastasis. Reduced seeding of BC cells to the lungs is linked to high expression of c-Myb and a decline in expression of a specific set of inflammatory genes. Here, we unraveled a c-Myb-IL1α-NF-κB signaling axis that takes place in tumor cells. We report that an overexpression of c-Myb interfered with the activity of NF-κB in several BC cell lines. We identified IL1α to be essential for this interference since it was abrogated in the IL1α-deficient cells. Overexpression of IL1α, as well as addition of recombinant IL1α protein, activated NF-κB signaling and restored expression of the inflammatory signature genes suppressed by c-Myb. The endogenous levels of c-Myb negatively correlated with IL1α on both transcriptional and protein levels across BC cell lines. We concluded that inhibition of IL1α expression by c-Myb reduces NF-κB activity and disconnects the inflammatory circuit, a potentially targetable mechanism to mimic the antimetastatic effect of c-Myb with therapeutic perspective.

Activating Sphingosine-1-phospahte signaling in endothelial cells increases myosin light chain phosphorylation to decrease endothelial permeability thereby inhibiting cancer metastasis

Targeting the metastatic process to prevent disease dissemination in cancer remains challenging. One step in the metastatic cascade involves cancer cells transiting through the vascular endothelium after inflammation has increased the permeability of this cellular layer. Reducing inflammation-mediated gaps in the vascular endothelium could potentially be used to retard metastasis. This study describes the development of a novel ASR396-containing nanoparticle designed to activate the Sphingosine-1-Phosphate Receptor 1 (S1PR1) in order to tighten the junctions between the endothelial cells lining the vascular endothelium thereby inhibiting metastasis. ASR396 was derived from the S1PR1 agonist SEW2871 through chemical modification enabling the new compound to be loaded into a nanoliposome. ASR396 retained S1PR1 binding activity and the nanoliposomal formulation (nanoASR396) made it systemically bioavailable upon intravenous injection. Studies conducted in microvessels demonstrated that nanoASR396 significantly attenuated inflammatory mediator-induced permeability increase through the S1PR1 activation. Similarly, nanoASR396 inhibited gap formation mediated by inflammatory agents on an endothelial cell monolayer by decreasing levels of phosphorylated myosin light chain protein thereby inhibiting cellular contractility. In animal models, nanoASR396 inhibited lung metastasis by up to 80%, indicating its potential for retarding melanoma metastasis. Thus, a novel bioavailable nanoparticle-based S1PR1 agonist has been developed to negate the effects of inflammatory mediators on the vascular endothelium in order to reduce the metastatic dissemination of cancer cells.

CCL2 in the Tumor Microenvironment

The C-C motif chemokine ligand 2 (CCL2) is a crucial mediator of immune cell recruitment during microbial infections and tissue damage. CCL2 is also frequently overexpressed in cancer cells and other cells in the tumor microenvironment, and a large body of evidence indicates that high CCL2 levels are associated with more aggressive malignancies, a higher probability of metastasis, and poorer outcomes in a wide range of cancers. CCL2 plays a role in recruiting tumor-associated macrophages (TAMs), which adopt a pro-tumorigenic phenotype and support cancer cell survival, facilitate tumor cell invasion, and promote angiogenesis. CCL2 also has direct, TAM-independent effects on tumor cells and the tumor microenvironment, including recruitment of other myeloid subsets and non-myeloid cells, maintaining an immunosuppressive environment, stimulating tumor cell growth and motility, and promoting angiogenesis. CCL2 also plays important roles in the metastatic cascade, such as creating a pre-metastatic niche in distant organs and promoting tumor cell extravasation across endothelia. Due to its many roles in tumorigenesis and metastatic processes, the CCL2-CCR2 signaling axis is currently being pursued as a potential therapeutic target for cancer.

Biomarkers for the clinical development of antiviral therapies

With the morbidity and mortality associated with the COVID-19 pandemic that we are witnessing this year, the risks posed by emerging viral diseases to global health are all too obvious. This pandemic highlights the importance of antiviral drug discovery, which targets emerging viral pathogens, as well as existing pathogenic viruses that undergo continuous evolution. Drug discovery and development is a long and resource intensive process; however, the use of biomarkers can accelerate clinical development of antivirals by providing information regarding diagnosis of specific viral infections, status of infection, potential safety parameters, and antiviral responses. In clinical practice, many of the biomarkers initially utilized to support clinical development are also used for patient care. While viral load is a standard and essential biomarker used to detect the desired viral suppression induced by an antiviral agent, it has become apparent that additional biomarkers, whether related to the virus, the host or as a consequence of the drug's mechanistic effects, are also important for monitoring clinical outcomes associated with an antiviral therapy. This review summarizes the biomarkers used in the clinical development (as well as in clinical practice, where appropriate) of antiviral therapies for hepatitis C virus, hepatitis B virus, human immunodeficiency virus, and severe acute respiratory syndrome coronavirus 2.

Is the C-C Motif Ligand 2-C-C Chemokine Receptor 2 Axis a Promising Target for Cancer Therapy and Diagnosis?

C-C motif ligand 2 (CCL2) was originally reported as a chemical mediator attracting mononuclear cells to inflammatory tissue. Many studies have reported that CCL2 can directly activate cancer cells through a variety of mechanisms. CCL2 can also promote cancer progression indirectly through increasing the recruitment of tumor-associated macrophages into the tumor microenvironment. The role of CCL2 in cancer progression has gradually been understood, and various preclinical cancer models elucidate that CCL2 and its receptor C-C chemokine receptor 2 (CCR2) are attractive targets for intervention in cancer development. However, clinically available drugs that regulate the CCL2-CCR2 axis as anticancer agents are not available at this time. The complete elucidation of not only the oncological but also the physiological functions of the CCL2-CCR2 axis is required for achieving a satisfactory effect of the CCL2-CCR2 axis-targeted therapy.

A High-Content Screen Identifies Drugs That Restrict Tumor Cell Extravasation across the Endothelial Barrier

Metastases largely rely on hematogenous dissemination of tumor cells via the vascular system and significantly limit prognosis of patients with solid tumors. To colonize distant sites, circulating tumor cells must destabilize the endothelial barrier and transmigrate across the vessel wall. Here we performed a high-content screen to identify drugs that block tumor cell extravasation by testing 3,520 compounds on a transendothelial invasion coculture assay. Hits were further characterized and validated using a series of in vitro assays, a zebrafish model enabling three-dimensional (3D) visualization of tumor cell extravasation, and mouse models of lung metastasis. The initial screen advanced 38 compounds as potential hits, of which, four compounds enhanced endothelial barrier stability while concurrently suppressing tumor cell motility. Two compounds niclosamide and forskolin significantly reduced tumor cell extravasation in zebrafish, and niclosamide drastically impaired metastasis in mice. Because niclosamide had not previously been linked with effects on barrier function, single-cell RNA sequencing uncovered mechanistic effects of the drug on both tumor and endothelial cells. Importantly, niclosamide affected homotypic and heterotypic signaling critical to intercellular junctions, cell-matrix interactions, and cytoskeletal regulation. Proteomic analysis indicated that niclosamide-treated mice also showed reduced levels of kininogen, the precursor to the permeability mediator bradykinin. Our findings designate niclosamide as an effective drug that restricts tumor cell extravasation through modulation of signaling pathways, chemokines, and tumor-endothelial cell interactions. SIGNIFICANCE: A high-content screen identified niclosamide as an effective drug that restricts tumor cell extravasation by enhancing endothelial barrier stability through modulation of molecular signaling, chemokines, and tumor-endothelial cell interactions. GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/81/3/619/F1.large.jpg.

The Emerging Role of PPAR Beta/Delta in Tumor Angiogenesis

PPARs are ligand-activated transcriptional factors that belong to the nuclear receptor superfamily. Among them, PPAR alpha and PPAR gamma are prone to exert an antiangiogenic effect, whereas PPAR beta/delta has an opposite effect in physiological and pathological conditions. Angiogenesis has been known as a hallmark of cancer, and our recent works also demonstrate that vascular-specific PPAR beta/delta overexpression promotes tumor angiogenesis and progression in vivo. In this review, we will mainly focus on the role of PPAR beta/delta in tumor angiogenesis linked to the tumor microenvironment to further facilitate tumor progression and metastasis. Moreover, the crosstalk between PPAR beta/delta and its downstream key signal molecules involved in tumor angiogenesis will also be discussed, and the network of interplay between them will further be established in the review.

Exosomal MicroRNAs as Mediators of Cellular Interactions Between Cancer Cells and Macrophages

Tumor microenvironment consists of cancer cells and various stromal cells such as endothelial cells, cancer-associated fibroblasts (CAFs), myeloid-derived suppressor cells (MDSCs), neutrophils, macrophages, and other innate and adaptive immune cells. Of these innate immune cells, macrophages are an extremely heterogeneous population, and display both pro-inflammatory and anti-inflammatory functions. While M1 macrophages (classically activated macrophages) display anti-tumoral and pro-inflammatory functions, M2 macrophages display pro-tumoral and anti-inflammatory functions. Cellular interactions and molecular factors in the tumor microenvironment affect the polarization of macrophages. We review molecules and immune cells that influence the polarization status of macrophages. Tumor-associated macrophages (TAMs) generally express M2 phenotype, and mediate many processes that include tumor initiation, angiogenesis, and metastasis. A high number of TAMs has been associated with the poor prognosis of cancers. MicroRNAs (miRNAs) have been known to regulate cellular interactions that involve cancer cells and macrophages. Tumor-derived exosomes play critical roles in inducing the M1 or M2-like polarization of macrophages. The roles of exosomal miRNAs from tumor cells in the polarization of macrophages are also discussed and the targets of these miRNAs are presented. We review the effects of exosomal miRNAs from TAMs on cancer cell invasion, growth, and anti-cancer drug resistance. The relevance of exosomal microRNAs (miRNAs) as targets for the development of anti-cancer drugs is discussed. We review recent progress in the development of miRNA therapeutics aimed at elevating or decreasing levels of miRNAs.

Gefitinib Inhibits Invasion and Metastasis of Osteosarcoma via Inhibition of Macrophage Receptor Interacting Serine-Threonine Kinase 2

Most patients with osteosarcoma have subclinical pulmonary micrometastases at diagnosis. Mounting evidence suggests that macrophages facilitate metastasis. As the EGFR has been implicated in carcinoma-macrophage cross-talk, in this study, we asked whether gefitinib, an EGFR inhibitor, reduces osteosarcoma invasion and metastatic outgrowth using the K7M2-Balb/c syngeneic murine model. Macrophages enhanced osteosarcoma invasion in vitro, which was suppressed by gefitinib. Oral gefitinib inhibited tumor extravasation in the lung and reduced the size of metastatic foci, resulting in reduced metastatic burden. Gefitinib also altered pulmonary macrophage phenotype, increasing MHCII and decreasing CD206 expression compared with controls. Surprisingly, these effects are mediated through inhibition of macrophage receptor interacting protein kinase 2 (RIPK2), rather than EGFR. Supporting this, lapatinib, a highly specific EGFR inhibitor that does not inhibit RIPK2, had no effect on macrophage-promoted invasion, and RIPK2^-/- macrophages failed to promote invasion. The selective RIPK2 inhibitor WEHI-345 blocked tumor cell invasion in vitro and reduced metastatic burden in vivo In conclusion, our results indicate that gefitinib blocks macrophage-promoted invasion and metastatic extravasation by reprogramming macrophages through inhibition of RIPK2.

Effect of apigenin on whole transcriptome profile of TNFα-activated MDA-MB-468 triple negative breast cancer cells

The lack of hormone receptors in triple negative breast cancer (TNBC) is associated with the inefficacy of anti-estrogen chemotherapies, leaving fewer options for patient treatment and higher mortality rates. Additionally, as with numerous types of inflammatory breast cancer, infiltration of tumor associated macrophages and other leukocyte sub-populations within the tumor inevitably lead to aggressive, chemo-resistant, metastatic and invasive types of cancer which escape immune surveillance. These processes are orchestrated by the release of potent cytokines, including TNFα, IL-6 and CCL2 from the stroma, tumor and immune cells within the tumor microenvironment. The present study evaluated apigenin modulating effects on the pro-inflammatory activating action of TNFα in TNBC MDA-MB-468 cells, derived from an African American woman. Initially, cell viability was determined to establish an optimal sub-lethal dose of TNFα and apigenin in MDA-MB-468 cells. Subsequently, various treatments effects were evaluated using whole transcriptomic analysis of mRNA and long intergenic non-coding RNA with Affymetrix HuGene-2.1-st human microarrays. Gene level differential expression analysis was conducted on 48,226 genes where TNFα caused significant upregulation of 53 transcripts and downregulation of 11 transcripts. The largest upward differential shift was for CCL2 [+61.86 fold change (FC); false discovery rate (FDR), P<0.0001]; which was down regulated by apigenin (to +10.71 FC vs. Control; FDR P-value <0.001), equivalent to an 83% reduction. Several TNFα deferentially upregulated transcripts were reduced by apigenin, including CXCL10, C3, PGLYRP4, IL22RA2, KMO, IL7R, ROS1, CFB, IKBKe, SLITRK6 (a checkpoint target) and MMP13. Confirmation of CCL2 experimentally induced transcript alterations was corroborated at the protein level by ELISA assays. The high level of CCL2 transcript in the cell line was comparable to that in our previous studies in MDA-MB-231 cells. The differential effects of TNFα were corroborated by ELISA, where the data revealed a >10-fold higher releasing rate of CCL2 in MDA-MB-468 cells compared with in MDA-MB-231 cells, both of which were attenuated by apigenin. The data obtained in the present study demonstrated a high level of CCL2 in MDA-MB-468 cells and a possible therapeutic role for apigenin in downregulating TNFα-mediated processes in these TNBC cells.

Vascular PPARβ/δ Promotes Tumor Angiogenesis and Progression

Peroxisome proliferator-activated receptors (PPARs) are nuclear receptors, which function as transcription factors. Among them, PPARβ/δ is highly expressed in endothelial cells. Pharmacological activation with PPARβ/δ agonists had been shown to increase their angiogenic properties. PPARβ/δ has been suggested to be involved in the regulation of the angiogenic switch in tumor progression. However, until now, it is not clear to what extent the expression of PPARβ/δ in tumor endothelium influences tumor progression and metastasis formation. We addressed this question using transgenic mice with an inducible conditional vascular-specific overexpression of PPARβ/δ. Following specific over-expression of PPARβ/δ in endothelial cells, we induced syngenic tumors. We observed an enhanced tumor growth, a higher vessel density, and enhanced metastasis formation in the tumors of animals with vessel-specific overexpression of PPARβ/δ. In order to identify molecular downstream targets of PPARβ/δ in the tumor endothelium, we sorted endothelial cells from the tumors and performed RNA sequencing. We identified platelet-derived growth factor receptor beta (Pdgfrb), platelet-derived growth factor subunit B (Pdgfb), and the tyrosinkinase KIT (c-Kit) as new PPARβ/δ -dependent molecules. We show here that PPARβ/δ activation, regardless of its action on different cancer cell types, leads to a higher tumor vascularization which favors tumor growth and metastasis formation.

Function of low ADARB1 expression in lung adenocarcinoma

Adenosine deaminase RNA-specific B1 (ADARB1), an adenosine-to-inosine (A-to-I) RNA-editing enzyme, has been found to play an essential role in the development of cancer. However, the specific function of ADARB1 in lung cancer, especially in lung adenocarcinoma (LUAD), is still not fully understood and requires further study. In our study, integrative bioinformatics were used to analyze the detailed function of ADARB1 in LUAD. By conducting bioinformatics analyses of several public databases, such as Gene Expression Profiling Interactive Analysis (GEPIA), GE-mini, and Oncomine, we found significantly decreased ADARB1 expression in LUAD cells and tissues. Moreover, RT-PCR and Western blot showed lower ADARB1 expression in H358 and A549 LUAD cells compared to human bronchial epithelial Beas-2B cells. Wound Healing Assay indicated that knockdown ADARB1 could promote LUAD cell metastasis. By using the Kaplan-Meier Plotter tool, we found that downregulation of ADARB1 was related to shorter first progression (FP), overall survival time (OS) and post-progression survival time (PPS). The relevant clinical data acquired from the Wanderer database indicated that the expression and methylation values of ADARB1 were significantly associated with the clinical characteristics of LUAD. Using DNA methylation inhibitor, we found DNMT inhibitor 5-aza-2-deoxycytidine (5-azaD) could promote the expression of ADARB1 and reverse the inhibition effect of ADARB1 in migration. In addition, functional enrichment analysis of ADARB1-associated coexpression genes was further conducted. Our investigation demonstrated that low levels of ADARB1 were specifically found in LUAD, and this gene might be a potential target in the diagnostic and prognostic evaluation of LUAD patients.

MCP-1 promotes detrimental cardiac physiology, pulmonary edema, and death in the cpk model of polycystic kidney disease

Polycystic kidney disease (PKD) is characterized by slowly expanding renal cysts that damage the kidney, typically resulting in renal failure by the fifth decade. The most common cause of death in these patients, however, is cardiovascular disease. Expanding cysts in PKD induce chronic kidney injury that is accompanied by immune cell infiltration, including macrophages, which we and others have shown can promote disease progression in PKD mouse models. Here, we show that monocyte chemoattractant protein-1 [MCP-1/chemokine (C-C motif) ligand 2 (CCL2)] is responsible for the majority of monocyte chemoattractant activity produced by renal PKD cells from both mice and humans. To test whether the absence of MCP-1 lowers renal macrophage concentration and slows disease progression, we generated genetic knockout (KO) of MCP-1 in a mouse model of PKD [congenital polycystic kidney (cpk) mice]. Cpk mice are born with rapidly expanding renal cysts, accompanied by a decline in kidney function and death by postnatal day 21. Here, we report that KO of MCP-1 in these mice increased survival, with some mice living past 3 mo. Surprisingly, however, there was no significant difference in renal macrophage concentration, nor was there improvement in cystic disease or kidney function. Examination of mice revealed cardiac hypertrophy in cpk mice, and measurement of cardiac electrical activity via ECG revealed repolarization abnormalities. MCP-1 KO did not affect the number of cardiac macrophages, nor did it alleviate the cardiac aberrancies. However, MCP-1 KO did prevent the development of pulmonary edema, which occurred in cpk mice, and promoted decreased resting heart rate and increased heart rate variability in both cpk and noncystic mice. These data suggest that in this mouse model of PKD, MCP-1 altered cardiac/pulmonary function and promoted death outside of its role as a macrophage chemoattractant.