αV integrins in angiogenesis and cancer

IL-32γ suppresses lung cancer stem cell growth via inhibition of ITGAV-mediated STAT5 pathway

The cancer stem cells (CSCs) are thought to be responsible for cancer initiation, recurrence, and metastasis via a multifactorial process. IL-32γ has been known to inhibit several tumor developments. However, the role of IL-32γ in CSCs is unknown. The role of IL-32γ on tumor development was assessed in IL-32γ transgenic (Tg) mice allograft and xenograft model. In the in vitro assay, we analyzed CSC growth and apoptosis in cells with IL-32γ overexpression by cell viability assay and tumor-sphere formation assay. In addition, expression of cell proliferation, apoptosis markers, and signaling molecules was determined by western blot analysis. IL-32γ suppressed CD133+ CSC-induced allograft model in IL-32γ Tg mice and xenograft model. Tumor-sphere formation and cell viability assay revealed a greater inhibition of CSC proliferation and antineoplastic activity of IL-32γ in CD133+ CSCs as compared with normal cancer cells. The inhibitory effects of IL-32γ on tumor development were associated with inhibition of the STAT5 pathway. In addition, inhibition of STAT5 increased cleavage of caspase-3, but suppressed CD133 expression and colony formation. Web-based gene network analysis showed that IL-32 is correlated with ITGAV, an integrin gene. Our result revealed that knockdown of ITGAV by siRNA inhibited the phosphorylation of STAT5. Moreover, we identified that ITGAV overexpression reversed the effect of IL-32γ on phosphorylation of STAT5 and the expression of CD133. Our results demonstrate that IL-32γ negatively regulates CD133+ CSC proliferation and tumor development and suggest that IL-32γ has great potential for use in the treatment of cancer progression.

Cell Adhesion Molecules and Their Roles and Regulation in the Immune and Tumor Microenvironment

The immune system and cancer have a complex relationship with the immune system playing a dual role in tumor development. The effector cells of the immune system can recognize and kill malignant cells while immune system-mediated inflammation can also promote tumor growth and regulatory cells suppress the anti-tumor responses. In the center of all anti-tumor responses is the ability of the immune cells to migrate to the tumor site and to interact with each other and with the malignant cells. Cell adhesion molecules including receptors of the immunoglobulin superfamily and integrins are of crucial importance in mediating these processes. Particularly integrins play a vital role in regulating all aspects of immune cell function including immune cell trafficking into tissues, effector cell activation and proliferation and the formation of the immunological synapse between immune cells or between immune cell and the target cell both during homeostasis and during inflammation and cancer. In this review we discuss the molecular mechanisms regulating integrin function and the role of integrins and other cell adhesion molecules in immune responses and in the tumor microenvironment. We also describe how malignant cells can utilize cell adhesion molecules to promote tumor growth and metastases and how these molecules could be targeted in cancer immunotherapy.

Role of Integrins in Resistance to Therapies Targeting Growth Factor Receptors in Cancer

Integrins contribute to cancer progression and aggressiveness by activating intracellular signal transduction pathways and transducing mechanical tension forces. Remarkably, these adhesion receptors share common signaling networks with receptor tyrosine kinases (RTKs) and support their oncogenic activity, thereby promoting cancer cell proliferation, survival and invasion. During the last decade, preclinical studies have revealed that integrins play an important role in resistance to therapies targeting RTKs and their downstream pathways. A remarkable feature of integrins is their wide-ranging interconnection with RTKs, which helps cancer cells to adapt and better survive therapeutic treatments. In this context, we should consider not only the integrins expressed in cancer cells but also those expressed in stromal cells, since these can mechanically increase the rigidity of the tumor microenvironment and confer resistance to treatment. This review presents some of these mechanisms and outlines new treatment options for improving the efficacy of therapies targeting RTK signaling.

Mechanically Defined Microenvironment Promotes Stabilization of Microvasculature, Which Correlates with the Enrichment of a Novel Piezo-1+ Population of Circulating CD11b+ /CD115+ Monocytes

Vascularization is a critical step in the restoration of cellular homeostasis. Several strategies including localized growth factor delivery, endothelial progenitor cells, genetically engineered cells, gene therapy, and prevascularized implants have been explored to promote revascularization. But, long-term stabilization of newly induced vessels remains a challenge. It has been shown that fibroblasts and mesenchymal stem cells can stabilize newly induced vessels. However, whether an injected biomaterial alone can serve as an instructive environment for angiogenesis remains to be elucidated. It is reported here that appropriate vascular branching, and long-term stabilization can be promoted simply by implanting a hydrogel with stiffness matching that of fibrin clot. A unique subpopulation of circulating CD11b⁺ myeloid and CD11b⁺ /CD115⁺ monocytes that express the stretch activated cation channel Piezo-1, which is enriched prominently in the clot-like hydrogel, is identified. These findings offer evidence for a mechanobiology paradigm in angiogenesis involving an interplay between mechanosensitive circulating cells and mechanics of tissue microenvironment.

Current Development of siRNA Bioconjugates: From Research to the Clinic

Small interfering RNAs (siRNAs) acting via RNA interference mechanisms are able to recognize a homologous mRNA sequence in the cell and induce its degradation. The main problems in the development of siRNA-based drugs for therapeutic use are the low efficiency of siRNA delivery to target cells and the degradation of siRNAs by nucleases in biological fluids. Various approaches have been proposed to solve the problem of siRNA delivery in vivo (e.g., viruses, cationic lipids, polymers, nanoparticles), but all have limitations for therapeutic use. One of the most promising approaches to solve the problem of siRNA delivery to target cells is bioconjugation; i.e., the covalent connection of siRNAs with biogenic molecules (lipophilic molecules, antibodies, aptamers, ligands, peptides, or polymers). Bioconjugates are "ideal nanoparticles" since they do not need a positive charge to form complexes, are less toxic, and are less effectively recognized by components of the immune system because of their small size. This review is focused on strategies and principles for constructing siRNA bioconjugates for in vivo use.

Mast Cell Protease 7 Promotes Angiogenesis by Degradation of Integrin Subunits

Previous studies from our laboratory have shown that during angiogenesis in vitro, rmMCP-7 (recombinant mouse mast cell protease-7) stimulates endothelial cell spreading and induces their penetration into the matrix. The ability of rmMCP-7 to induce angiogenesis in vivo was assessed in the present study using a directed in vivo angiogenesis assay (DIVAA™). Vessel invasion of the angioreactor was observed in the presence of rmMCP-7 but was not seen in the control. Since integrins are involved in endothelial cell migration, the relationship between rmMCP-7 and integrins during angiogenesis was investigated. Incubation with rmMCP-7 resulted in a reduction in the levels of integrin subunits αv and β1 on SVEC4-10 endothelial cells during angiogenesis in vitro. Furthermore, the degradation of integrin subunits occurs both through the direct action of rmMCP-7 and indirectly via the ubiquitin/proteasome system. Even in the presence of a proteasome inhibitor, incubation of endothelial cells with rmMCP-7 induced cell migration and tube formation as well as the beginning of loop formation. These data indicate that the direct degradation of the integrin subunits by rmMCP-7 is sufficient to initiate angiogenesis. The results demonstrate, for the first time, that mMCP-7 acts in angiogenesis through integrin degradation.

The Intersection between Tumor Angiogenesis and Immune Suppression

Both immune checkpoint inhibitors (ICI) and antiangiogenesis agents have changed the landscape of cancer treatment in the modern era. While antiangiogenesis agents have demonstrated activities in tumors with high vascularization, including renal cell carcinoma and colorectal cancer, the effect of ICIs has been seen mainly in immunologically recognized tumors, with highly immune-infiltrative lymphocytes. The main challenge in the drug development of ICIs is moving their activities to noninflamed tumors and overcoming resistance that is driven, in part, by the immune-suppressive microenvironment. Angiogenesis factors drive immune suppression by directly suppressing the antigen-presenting cells as well as immune effector cells or through augmenting the effect of regulatory T cells (Treg), myeloid-derived suppressor cells (MDSC), and tumor-associated macrophages (TAM). Those suppressive immune cells can also drive angiogenesis, creating a vicious cycle of impaired immune activation. The combination of bevacizumab and ipilimumab was the first to show the promising effect of antiangiogenesis and ICIs. A plethora of similar combinations has entered the clinic since then, confirming the promising effects of such approach.

An Inhibitor of Arginine-Glycine-Aspartate-Binding Integrins Reverses Fibrosis in a Mouse Model of Nonalcoholic Steatohepatitis

The presence and stage of liver fibrosis in patients with nonalcoholic steatohepatitis (NASH) is strongly associated with mortality. Thus, both preventing and reversing fibrosis are critically important approaches to prevent death or the need for liver transplantation from NASH. Recently, fibrosis in several mouse models of organ injury was shown to be prevented and reversed with the potent small molecule, arginine-glycine-aspartic acid tripeptide (RGD)-binding, integrin antagonist (3S)-3-(3-bromo-5-(tert-butyl)phenyl)-3-(2-(3-hydroxy-5-((5-hydroxy-1,4,5,6-tetrahydropyrimidin-2-yl)amino)benzamido)acetamido)propanoic acid (Center for World Health and Medicine [CWHM]-12). We hypothesized that RGD-binding integrins may play an important role in fibrosis progression in NASH. We assessed the efficacy of CWHM-12 in a choline deficient, amino-acid defined, high-fat diet (CDAHFD) mouse model of NASH. Mice were kept on the CDAHFD or a control diet for 10 weeks, and CWHM-12 was delivered by continuous infusion for the final 4 weeks. The parameters of NASH and liver fibrosis were evaluated before and after drug treatment. Hepatic steatosis, liver injury, and inflammation were significantly induced by the CDAHFD at week 6 and did not change by week 10. Hepatic profibrogenic gene expression was induced by the CDAHFD at week 6, further increased at week 10, and decreased by CWHM-12. Fibrosis measured by analysis of liver collagen was reduced by CWHM-12 to levels significantly less than found at 6 weeks, demonstrating the possibility of reversing already established fibrosis despite ongoing injury. Demonstrated mechanisms of the antifibrotic effect of CWHM-12 included loss of activated hepatic stellate cells through apoptosis and suppression of hepatic profibrotic signal transduction by transforming growth factor β. Conclusion: RGD-binding integrins may be critical in the development of fibrosis in NASH and may represent potential targets for treating patients with NASH to reverse advanced liver fibrosis.

Protein Corona Fingerprints of Liposomes: New Opportunities for Targeted Drug Delivery and Early Detection in Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) is the fourth cause of cancer-related mortality in the Western world and is envisaged to become the second cause by 2030. Although our knowledge about the molecular biology of PDAC is continuously increasing, this progress has not been translated into better patients' outcome. Liposomes have been used to circumvent concerns associated with the low efficiency of anticancer drugs such as severe side effects and damage of healthy tissues, but they have not resulted in improved efficacy as yet. Recently, the concept is emerging that the limited success of liposomal drugs in clinical practice is due to our poor knowledge of the nano⁻bio interactions experienced by liposomes in vivo. After systemic administration, lipid vesicles are covered by plasma proteins forming a biomolecular coating, referred to as the protein corona (PC). Recent studies have clarified that just a minor fraction of the hundreds of bound plasma proteins, referred to as "PC fingerprints" (PCFs), enhance liposome association with cancer cells, triggering efficient particle internalization. In this study, we synthesized a library of 10 liposomal formulations with systematic changes in lipid composition and exposed them to human plasma (HP). Size, zeta-potential, and corona composition of the resulting liposome⁻protein complexes were thoroughly characterized by dynamic light scattering (DLS), micro-electrophoresis, and nano-liquid chromatography tandem mass spectrometry (nano-LC MS/MS). According to the recent literature, enrichment in PCFs was used to predict the targeting ability of synthesized liposomal formulations. Here we show that the predicted targeting capability of liposome⁻protein complexes clearly correlate with cellular uptake in pancreatic adenocarcinoma (PANC-1) and insulinoma (INS-1) cells as quantified by flow-assisted cell sorting (FACS). Of note, cellular uptake of the liposomal formulation with the highest abundance of PCFs was much larger than that of Onivyde®, an Irinotecan liposomal drug approved by the Food and Drug Administration in 2015 for the treatment of metastatic PDAC. Given the urgent need of efficient nanocarriers for the treatment of PDAC, we envision that our results will pave the way for the development of more efficient PC-based targeted nanomaterials. Here we also show that some BCs are enriched with plasma proteins that are associated with the onset and progression of PDAC (e.g., sex hormone-binding globulin, Ficolin-3, plasma protease C1 inhibitor, etc.). This could open the intriguing possibility to identify novel biomarkers.

Inhibition of skin carcinogenesis by suppression of NF-κB dependent ITGAV and TIMP-1 expression in IL-32γ overexpressed condition

BACKGROUND

Interleukin-32 (IL-32) has been associated with various diseases. Previous studies have shown that IL-32 inhibited the development of several tumors. However, the role of IL-32γ, an isotype of IL-32, in skin carcinogenesis remains unknown.

METHODS

We compared 7,12-Dimethylbenz[a]anthracene/12-O-Tetradecanoylphorbol-13-acetate (DMBA/TPA)-induced skin carcinogenesis in wild type (WT) and IL-32γ-overexpressing mice to evaluate the role of IL-32γ. We also analyzed cancer stemness and NF-κB signaling in skin cancer cell lines with or without IL-32γ expression by western blotting, quantitative real-time PCR and immunohistochemistry analysis.

RESULTS

Carcinogen-induced tumor incidence in IL-32γ mice was significantly reduced in comparison to that in WT mice. Infiltration of inflammatory cells and the expression levels of pro-inflammatory mediators were decreased in the skin tumor tissues of IL-32γ mice compared with WT mice. Using a genome-wide association study analysis, we found that IL-32 was associated with integrin αV (ITGAV) and tissue inhibitor of metalloproteinase-1 (TIMP-1), which are critical factor for skin carcinogenesis. Reduced expression of ITGAV and TIMP-1 were identified in DMBA/TPA-induced skin tissues of IL-32γ mice compared to that in WT mice. NF-κB activity was also reduced in DMBA/TPA-induced skin tissues of IL-32γ mice. IL-32γ decreased cancer cell sphere formation and expression of stem cell markers, and increased chemotherapy-induced cancer cell death. IL-32γ also downregulated expression of ITGAV and TIMP-1, accompanied with the inhibition of NF-κB activity. In addition, IL-32γ expression with NF-κB inhibitor treatment further reduced skin inflammation, epidermal hyperplasia, and cancer cell sphere formation and downregulated expression levels of ITGAV and TIMP-1.

CONCLUSIONS

These findings indicated that IL-32γ suppressed skin carcinogenesis through the inhibition of both stemness and the inflammatory tumor microenvironment by the downregulation of TIMP-1 and ITGAV via inactivation of NF-κB signaling.

Molecular Targets in Hepatocarcinogenesis and Implications for Therapy

Hepatocarcinogenesis comprises of multiple, complex steps that occur after liver injury and usually involve several pathways, including telomere dysfunction, cell cycle, WNT/β-catenin signaling, oxidative stress and mitochondria dysfunction, autophagy, apoptosis, and AKT/mTOR signaling. Following liver injury, gene mutations, accumulation of oxidative stress, and local inflammation lead to cell proliferation, differentiation, apoptosis, and necrosis. The persistence of this vicious cycle in turn leads to further gene mutation and dysregulation of pro- and anti-inflammatory cytokines, such as interleukin (IL)-1β, IL-6, IL-10, IL-12, IL-13, IL-18, and transforming growth factor (TGF)-β, resulting in immune escape by means of the NF-κB and inflammasome signaling pathways. In this review, we summarize studies focusing on the roles of hepatocarcinogenesis and the immune system in liver cancer. In addition, we furnish an overview of recent basic and clinical studies to provide a strong foundation to develop novel anti-carcinogenesis targets for further treatment interventions.

CD51 is an independent unfavorable prognostic factor in esophageal squamous cell carcinoma

BACKGROUND

Esophageal squamous cell carcinoma (ESCC) is a common cancer in East Asia and some other parts of the world with a dismal prognosis. CD51 (integrin αv),a transmembrane glycoprotein responsible for cell-to-matrix binding has been found to enhance tumor progression. However, its expression and clinicopathological significance in ESCC tumors are not fully understood. The purpose of this study was to investigate the expression level of CD51 and to explore its clinicopathological significance in ESCC.

METHODS

The expression of CD51 in 122 ESCC samples was examined by immunohistochemistry and its clinicopathological significance was evaluated.

RESULTS

The expression of CD51 was observed in tumor cell membrane and/or cytoplasm, with a positive rate of 48.36% (59/122). High expression of CD51 was significantly associated with lymph node metastasis (P =  0.031), tumor size (P =  0.028) and invasive depth (P =  0.027). Kaplan-Meier analysis revealed that positive expression of CD51 was correlated with poor overall survival of ESCC patients (P =  0.015). Multivariate analysis suggested that CD51 was an independent prognositic factor for ESCC (hazard ration = 1.604; 95% CI, 1.086-2.368; P =  0.017).

CONCLUSION

These data suggested CD51 was a predictor for the prognosis of ESCC patients.

Customizable biomaterials as tools for advanced anti-angiogenic drug discovery

The inhibition of angiogenesis is a critical element of cancer therapy, as cancer vasculature contributes to tumor expansion. While numerous drugs have proven to be effective at disrupting cancer vasculature, patient survival has not significantly improved as a result of anti-angiogenic drug treatment. Emerging evidence suggests that this is due to a combination of unintended side effects resulting from the application of anti-angiogenic compounds, including angiogenic rebound after treatment and the activation of metastasis in the tumor. There is currently a need to better understand the far-reaching effects of anti-angiogenic drug treatments in the context of cancer. Numerous innovations and discoveries in biomaterials design and tissue engineering techniques are providing investigators with tools to develop physiologically relevant vascular models and gain insights into the holistic impact of drug treatments on tumors. This review examines recent advances in the design of pro-angiogenic biomaterials, specifically in controlling integrin-mediated cell adhesion, growth factor signaling, mechanical properties and oxygen tension, as well as the implementation of pro-angiogenic materials into sophisticated co-culture models of cancer vasculature.

Inhibition of mTOR complex 2 restrains tumor angiogenesis in multiple myeloma

The mammalian Target of Rapamycin (mTOR) is an intracellular serine/threonine kinase that mediates intracellular metabolism, cell survival and actin rearrangement. mTOR is made of two independent complexes, mTORC1 and mTORC2, activated by the scaffold proteins RAPTOR and RICTOR, respectively. The activation of mTORC1 triggers protein synthesis and autophagy inhibition, while mTORC2 activation promotes progression, survival, actin reorganization, and drug resistance through AKT hyper-phosphorylation on Ser473. Due to the mTOR pivotal role in the survival of tumor cells, we evaluated its activation in endothelial cells (ECs) from 20 patients with monoclonal gammopathy of undetermined significance (MGUS) and 47 patients with multiple myeloma (MM), and its involvement in angiogenesis. MM-ECs showed a significantly higher expression of mTOR and RICTOR than MGUS-ECs. These data were supported by the higher activation of mTORC2 downstream effectors, suggesting a major role of mTORC2 in the angiogenic switch to MM. Specific inhibition of mTOR activity through siRNA targeting RICTOR and dual mTOR inhibitor PP242 reduced the MM-ECs angiogenic functions, including cell migration, chemotaxis, adhesion, invasion, in vitro angiogenesis on Matrigel^®, and cytoskeleton reorganization. In addition, PP242 treatment showed anti-angiogenic effects in vivo in the Chick Chorioallantoic Membrane (CAM) and Matrigel^® plug assays. PP242 exhibited a synergistic effect with lenalidomide and bortezomib, suggesting that mTOR inhibition can enhance the anti-angiogenic effect of these drugs. Data to be shown indicate that mTORC2 is involved in MM angiogenesis, and suggest that the dual mTOR inhibitor PP242 may be useful for the anti-angiogenic management of MM patients.

Integrin αVβ3 silencing sensitizes malignant glioma cells to temozolomide by suppression of homologous recombination repair

Integrins have been suggested as possible targets in anticancer therapy. Here we show that knockdown of integrins αVβ3, αVβ5, α3β1 and α4β1 and pharmacological inhibition using a cyclo-RGD integrin αVβ3/αVβ5 antagonist sensitized multiple high-grade glioma cell lines to temozolomide (TMZ)-induced cytotoxicity. The greatest effect was observed in LN229 cells upon integrin β3 silencing, which led to inhibition of the FAK/Src/Akt/NFκB signaling pathway and increased formation of γH2AX foci. The integrin β3 knockdown led to the proteasomal degradation of Rad51, reduction of Rad51 foci and reduced repair of TMZ-induced DNA double-strand breaks by impairing homologous recombination efficiency. The down-regulation of β3 in Rad51 knockdown (LN229-Rad51kd) cells neither further sensitized them to TMZ nor increased the number of γH2AX foci, confirming causality between β3 silencing and Rad51 reduction. RIP1 was found cleaved and IκBα significantly less degraded in β3-silenced/TMZ-exposed cells, indicating inactivation of NFκB signaling. The anti-apoptotic proteins Bcl-xL, survivin and XIAP were proteasomally degraded and caspase-3/−2 cleaved. Increased H2AX phosphorylation, caspase-3 cleavage, reduced Rad51 and RIP1 expression, as well as sustained IκBα expression were also observed in mouse glioma xenografts treated with the cyclo-RGD inhibitor and TMZ, confirming the molecular mechanism in vivo. Our data indicates that β3 silencing in glioma cells represents a promising strategy to sensitize high-grade gliomas to TMZ therapy.

Junctional Adhesion Molecules (JAMs): The JAM-Integrin Connection

Junctional adhesion molecules (JAMs) are cell surface adhesion receptors of the immunoglobulin superfamily. JAMs are involved in a variety of biological processes both in the adult organism but also during development. These include processes such as inflammation, angiogenesis, hemostasis, or epithelial barrier formation, but also developmental processes such as hematopoiesis, germ cell development, and development of the nervous system. Several of these functions of JAMs depend on a physical and functional interaction with integrins. The JAM – integrin interactions in trans regulate cell-cell adhesion, their interactions in cis regulate signaling processes originating at the cell surface. The JAM – integrin interaction can regulate the function of the JAM as well as the function of the integrin. Beyond the physical interaction with integrins, JAMs can regulate integrin function through intracellular signaling indicating an additional level of JAM – integrin cross-talk. In this review, we describe the various levels of the functional interplay between JAMs and integrins and the role of this interplay during different physiological processes.

The Effects of Isopropyl Methylphosphono-Fluoridate (IMPF) Poisoning on Tumor Growth and Angiogenesis in BALB/C Mice

Background

Acetylcholinesterase (AChE) and cholinergic receptors have an important role in the immune system and angiogenesis. This work evaluated the effects of isopropyl methylphosphonofluoridate (IMPF), an irreversible inhibitor of AChE, on tumor growth and selected parameters associated with tumor angiogenesis.

Material/Methods

Experiments were performed on male BALB/c mice exposed to IMPF (study group) or saline buffer (control group) and inoculated with L-1 sarcoma; the number of new blood vessels (TIA test) and the level of αvβ3 integrin (¹³¹I-MAb-antiβ3 assay) were analyzed at seven, 14, or 21 days after implantation of the tumor cells.

Results

The IMPF poisoning affected tumor angiogenesis (TIA test). There was a statistically significant increase in the number of newly forming blood vessels in the group subjected to IMPF and inoculated with tumor cells.

Conclusions

This study showed that IMPF had a significant effect on the regulation of lymphocyte-induced angiogenesis and the modulation of angiogenic and pro-inflammatory cytokines secretion. The observed effects suggest involvement of neuronal and/or non-neuronal cholinergic signaling pathway.

Hacking macrophage-associated immunosuppression for regulating glioblastoma angiogenesis

Glioblastoma (GBM) is the most lethal primary adult brain tumor and its pathology is hallmarked by distorted neovascularization, diffuse tumor-associated macrophage infiltration, and potent immunosuppression. Reconstituting organotypic tumor angiogenesis models with biomimetic cell heterogeneity and interactions, pro-/anti-inflammatory milieu and extracellular matrix (ECM) mechanics is critical for preclinical anti-angiogenic therapeutic screening. However, current in vitro systems do not accurately mirror in vivo human brain tumor microenvironment. Here, we engineered a three-dimensional (3D), microfluidic angiogenesis model with controllable and biomimetic immunosuppressive conditions, immune-vascular and cell-matrix interactions. We demonstrate in vitro, GL261 and CT-2A GBM-like tumors steer macrophage polarization towards a M2-like phenotype for fostering an immunosuppressive and proangiogenic niche, which is consistent with human brain tumors. We distinguished that GBM and M2-like immunosuppressive macrophages promote angiogenesis, while M1-like pro-inflammatory macrophages suppress angiogenesis, which we coin "inflammation-driven angiogenesis." We observed soluble immunosuppressive cytokines, predominantly TGF-β1, and surface integrin (α_vβ₃) endothelial-macrophage interactions are required in inflammation-driven angiogenesis. We demonstrated tuning cell-adhesion receptors using an integrin (α_vβ₃)-specific collagen hydrogel regulated inflammation-driven angiogenesis through Src-PI3K-YAP signaling, highlighting the importance of altered cell-ECM interactions in inflammation. To validate the preclinical applications of our 3D organoid model and mechanistic findings of inflammation-driven angiogenesis, we screened a novel dual integrin (α_vβ₃) and cytokine receptor (TGFβ-R1) blockade that suppresses GBM tumor neovascularization by simultaneously targeting macrophage-associated immunosuppression, endothelial-macrophage interactions, and altered ECM. Hence, we provide an interactive and controllable GBM tumor microenvironment and highlight the importance of macrophage-associated immunosuppression in GBM angiogenesis, paving a new direction of screening novel anti-angiogenic therapies.

Ephrin receptor A2 is an epithelial cell receptor for Epstein-Barr virus entry

Epstein-Barr virus (EBV) is causally associated with nasopharyngeal carcinoma, 10% of gastric carcinoma and various B cell lymphomas ¹ . EBV infects both B cells and epithelial cells ² . Recently, we reported that epidermal growth factor and Neuropilin 1 markedly enhanced EBV entry into nasopharyngeal epithelial cells ³ . However, knowledge of how EBV infects epithelial cells remains incomplete. To understand the mechanisms through which EBV infects epithelial cells, we integrated microarray and RNA interference screen analyses and found that Ephrin receptor A2 (EphA2) is important for EBV entry into the epithelial cells. EphA2 short interfering RNA knockdown or CRISPR-Cas9 knockout markedly reduced EBV epithelial cell infection, which was mostly restored by EphA2 complementary DNA rescue. EphA2 overexpression increased epithelial cell EBV infection. Soluble EphA2 protein, antibodies against EphA2, soluble EphA2 ligand EphrinA1, or the EphA2 inhibitor 2,5-dimethylpyrrolyl benzoic acid efficiently blocked EBV epithelial cell infection. Mechanistically, EphA2 interacted with EBV entry proteins gH/gL and gB to facilitate EBV internalization and fusion. The EphA2 Ephrin-binding domain and fibronectin type III repeats domain were essential for EphA2-mediated EBV infection, while the intracellular domain was dispensable. This is distinct from Kaposi's sarcoma-associated herpesvirus infection through EphA2 ⁴ . Taken together, our results identify EphA2 as a critical player for EBV epithelial cell entry.

Collateral Damage Intended-Cancer-Associated Fibroblasts and Vasculature Are Potential Targets in Cancer Therapy

After oncogenic transformation, tumor cells rewire their metabolism to obtain sufficient energy and biochemical building blocks for cell proliferation, even under hypoxic conditions. Glucose and glutamine become their major limiting nutritional demands. Instead of being autonomous, tumor cells change their immediate environment not only by their metabolites but also by mediators, such as juxtacrine cell contacts, chemokines and other cytokines. Thus, the tumor cells shape their microenvironment as well as induce resident cells, such as fibroblasts and endothelial cells (ECs), to support them. Fibroblasts differentiate into cancer-associated fibroblasts (CAFs), which produce a qualitatively and quantitatively different extracellular matrix (ECM). By their contractile power, they exert tensile forces onto this ECM, leading to increased intratumoral pressure. Moreover, along with enhanced cross-linkage of the ECM components, CAFs thus stiffen the ECM. Attracted by tumor cell- and CAF-secreted vascular endothelial growth factor (VEGF), ECs sprout from pre-existing blood vessels during tumor-induced angiogenesis. Tumor vessels are distinct from EC-lined vessels, because tumor cells integrate into the endothelium or even mimic and replace it in vasculogenic mimicry (VM) vessels. Not only the VM vessels but also the characteristically malformed EC-lined tumor vessels are typical for tumor tissue and may represent promising targets in cancer therapy.

A First Report on [18F]FPRGD2 PET/CT Imaging in Multiple Myeloma

An observational study was set up to assess the feasibility of [¹⁸F]FPRGD₂ PET/CT for imaging patients with multiple myeloma (MM) and to compare its detection rate with low dose CT alone and combined [¹⁸F]NaF/[¹⁸F]FDG PET/CT images. Four patients (2 newly diagnosed patients and 2 with relapsed MM) were included and underwent whole-body PET/CT after injection of [¹⁸F]FPRGD₂. The obtained images were compared with results of low dose CT and already available results of a combined [¹⁸F]NaF/[¹⁸F]FDG PET/CT. In total, 81 focal lesions (FLs) were detected with PET/CT and an underlying bone destruction or fracture was seen in 72 (89%) or 8 (10%) FLs, respectively. Fewer FLs (54%) were detected by [¹⁸F]FPRGD₂ PET/CT compared to low dose CT (98%) or [¹⁸F]NaF/[¹⁸F]FDG PET/CT (70%) and all FLs detected with [¹⁸F]FPRGD₂ PET were associated with an underlying bone lesion. In one newly diagnosed patient, more [¹⁸F]FPRGD₂ positive lesions were seen than [¹⁸F]NaF/[¹⁸F]FDG positive lesions. This study suggests that [¹⁸F]FPRGD₂ PET/CT might be less useful for the detection of myeloma lesions in patients with advanced disease as all FLs with [¹⁸F]FPRGD₂ uptake were already detected with CT alone.

Alternative splicing of CNOT7 diversifies CCR4-NOT functions

The CCR4-associated factor CAF1, also called CNOT7, is a catalytic subunit of the CCR4–NOT complex, which has been implicated in all aspects of the mRNA life cycle, from mRNA synthesis in the nucleus to degradation in the cytoplasm. In human cells, alternative splicing of the CNOT7 gene yields a second CNOT7 transcript leading to the formation of a shorter protein, CNOT7 variant 2 (CNOT7v2). Biochemical characterization indicates that CNOT7v2 interacts with CCR4–NOT subunits, although it does not bind to BTG proteins. We report that CNOT7v2 displays a distinct expression profile in human tissues, as well as a nuclear sub-cellular localization compared to CNOT7v1. Despite a conserved DEDD nuclease domain, CNOT7v2 is unable to degrade a poly(A) tail in vitro and preferentially associates with the protein arginine methyltransferase PRMT1 to regulate its activity. Using both in vitro and in cellulo systems, we have also demonstrated that CNOT7v2 regulates the inclusion of CD44 variable exons. Altogether, our findings suggest a preferential involvement of CNOT7v2 in nuclear processes, such as arginine methylation and alternative splicing, rather than mRNA turnover. These observations illustrate how the integration of a splicing variant inside CCR4–NOT can diversify its cell- and tissue-specific functions.

Insufficient Radiofrequency Ablation Treated Hepatocellular Carcinoma Cells Promote Metastasis by Up-Regulation ITGB3

Radiofrequency ablation (RFA) is one of the standards of care for early stage hepatocellular carcinoma (HCC). However, rapid progression of residual tumor after RFA has been confirmed. The aim of this study was to investigate the underlying mechanism of this phenomenon. Human HCC cell lines HCCLM3 and HepG2 were employed to establish insufficient RFA models in vivo and in vitro, respectively. The effects of insufficient RFA on metastatic potential of residual tumors were evaluated. The molecular changes after insufficient RFA were evaluated by PCR array, western blot, immunofluorescence, and immunohistochemistry. Results showed that insufficient RFA significantly promoted lung and intrahepatic residual tumor cells in vivo, and heat intervention promoted migration and invasion of hepatoma cells in vitro. PCR array revealed that the expression of integrin β3 (ITGB3) and MMP2 were up-regulated in the residual tumors of HCCLM3 xenograft model. The up-regulation of ITGB3 was confirmed by qRT-PCR, Western blot and immunohistochemistry. Knockdown ITGB3 expression in HCCLM3 cells by shRNA significantly lowered the pro-metastatic effects of insufficient RFA. Mechanism studies indicated that ITGB3 mediated the expression of MMP2 by activing FAK/PI3K/AKT signaling pathway. The up-regulation of ITGB3 contributed to enhanced metastatic potential of residual cancer in HCCLM3 model after insufficient RFA. Targeting ITGB3 expression may further improve the clinical effects of RFA.

Junctional Adhesion Molecules (JAMs): Cell Adhesion Receptors With Pleiotropic Functions in Cell Physiology and Development

Junctional adhesion molecules (JAM)-A, -B and -C are cell-cell adhesion molecules of the immunoglobulin superfamily which are expressed by a variety of tissues, both during development and in the adult organism. Through their extracellular domains, they interact with other adhesion receptors on opposing cells. Through their cytoplasmic domains, they interact with PDZ domain-containing scaffolding and signaling proteins. In combination, these two properties regulate the assembly of signaling complexes at specific sites of cell-cell adhesion. The multitude of molecular interactions has enabled JAMs to adopt distinct cellular functions such as the regulation of cell-cell contact formation, cell migration, or mitotic spindle orientation. Not surprisingly, JAMs regulate diverse processes such as epithelial and endothelial barrier formation, hemostasis, angiogenesis, hematopoiesis, germ cell development, and the development of the central and peripheral nervous system. This review summarizes the recent progress in the understanding of JAMs, including their characteristic structural features, their molecular interactions, their cellular functions, and their contribution to a multitude of processes during vertebrate development and homeostasis.

Modulating angiogenesis with integrin-targeted nanomedicines

Targeting angiogenesis-related pathologies, which include tumorigenesis and metastatic processes, has become an attractive strategy for the development of efficient guided nanomedicines. In this respect, integrins are cell-adhesion molecules involved in angiogenesis signaling pathways and are overexpressed in many angiogenic processes. Therefore, they represent specific biomarkers not only to monitor disease progression but also to rationally design targeted nanomedicines. Arginine-glycine-aspartic (RGD) containing peptides that bind to specific integrins have been widely utilized to provide ligand-mediated targeting capabilities to small molecules, peptides, proteins, and antibodies, as well as to drug/imaging agent-containing nanomedicines, with the final aim of maximizing their therapeutic index. Within this review, we aim to cover recent and relevant examples of different integrin-assisted nanosystems including polymeric nanoconstructs, liposomes, and inorganic nanoparticles applied in drug/gene therapy as well as imaging and theranostics. We will also critically address the overall benefits of integrin-targeting.

Increased Vascular Permeability in the Bone Marrow Microenvironment Contributes to Disease Progression and Drug Response in Acute Myeloid Leukemia

The biological and clinical behaviors of hematological malignancies can be influenced by the active crosstalk with an altered bone marrow (BM) microenvironment. In the present study, we provide a detailed picture of the BM vasculature in acute myeloid leukemia using intravital two-photon microscopy. We found several abnormalities in the vascular architecture and function in patient-derived xenografts (PDX), such as vascular leakiness and increased hypoxia. Transcriptomic analysis in endothelial cells identified nitric oxide (NO) as major mediator of this phenotype in PDX and in patient-derived biopsies. Moreover, induction chemotherapy failing to restore normal vasculature was associated with a poor prognosis. Inhibition of NO production reduced vascular permeability, preserved normal hematopoietic stem cell function, and improved treatment response in PDX.

Exploring the Role of RGD-Recognizing Integrins in Cancer

Integrins are key regulators of communication between cells and with their microenvironment. Eight members of the integrin superfamily recognize the tripeptide motif Arg-Gly-Asp (RGD) within extracelluar matrix (ECM) proteins. These integrins constitute an important subfamily and play a major role in cancer progression and metastasis via their tumor biological functions. Such transmembrane adhesion and signaling receptors are thus recognized as promising and well accessible targets for novel diagnostic and therapeutic applications for directly attacking cancer cells and their fatal microenvironment. Recently, specific small peptidic and peptidomimetic ligands as well as antibodies binding to distinct integrin subtypes have been developed and synthesized as new drug candidates for cancer treatment. Understanding the distinct functions and interplay of integrin subtypes is a prerequisite for selective intervention in integrin-mediated diseases. Integrin subtype-specific ligands labelled with radioisotopes or fluorescent molecules allows the characterization of the integrin patterns in vivo and later the medical intervention via subtype specific drugs. The coating of nanoparticles, larger proteins, or encapsulating agents by integrin ligands are being explored to guide cytotoxic reagents directly to the cancer cell surface. These ligands are currently under investigation in clinical studies for their efficacy in interference with tumor cell adhesion, migration/invasion, proliferation, signaling, and survival, opening new treatment approaches in personalized medicine.

Beyond adhesion: emerging roles for integrins in control of the tumor microenvironment

While integrins were originally discovered as cell adhesion receptors, recent studies have reinforced the concept that integrins have central roles in cancer that extend far beyond controlling cell adhesion and migration. Indeed, as transmembrane cell surface receptors that occupy a critical position at the interface of cellular and extracellular interactions and are capable of both "inside-out" and "outside-in" signaling, integrins are uniquely poised to regulate the cell's ability to promote, sense, and react to changes in the tumor microenvironment. Moreover, integrins are present on all cell types in the tumor microenvironment, and they have important roles in regulating intercellular communication. Decades of promising pre-clinical studies have implicated certain integrins as attractive therapeutic targets in the cancer clinic. Nevertheless, results of the few clinical trials that target integrins in cancer have thus far been disappointing. Importantly, these clinical failures likely reflect the emerging complexity of individual and combinatorial integrin function within both tumor cells and other cell types of the tumor microenvironment, together with a need to explore integrin-targeting agents not just as monotherapies but also as adjuvants to more conventional radiotherapies or chemotherapies. In this review, we will examine recent advances toward understanding how integrins regulate cancer progression, including their roles in intercellular communication and modulation of the tumor microenvironment. Additionally, we will discuss factors that underlie the limited efficacy of current efforts to target integrins in the cancer clinic as well as potential strategies to overcome these challenges.

Glioblastoma stem cells exploit the αvβ8 integrin-TGFβ1 signaling axis to drive tumor initiation and progression

Glioblastoma (GBM) is a primary brain cancer that contains populations of stem-like cancer cells (GSCs) that home to specialized perivascular niches. GSC interactions with their niche influence self-renewal, differentiation and drug resistance, although the pathways underlying these events remain largely unknown. Here, we report that the integrin αvβ8 and its latent transforming growth factor β1 (TGFβ1) protein ligand have central roles in promoting niche co-option and GBM initiation. αvβ8 integrin is highly expressed in GSCs and is essential for self-renewal and lineage commitment in vitro. Fractionation of β8^high cells from freshly resected human GBM samples also reveals a requirement for this integrin in tumorigenesis in vivo. Whole-transcriptome sequencing reveals that αvβ8 integrin regulates tumor development, in part, by driving TGFβ1-induced DNA replication and mitotic checkpoint progression. Collectively, these data identify the αvβ8 integrin-TGFβ1 signaling axis as crucial for exploitation of the perivascular niche and identify potential therapeutic targets for inhibiting tumor growth and progression in patients with GBM.

Integrin αvβ3 Signaling in Tumor-Induced Bone Disease

Tumor-induced bone disease is common among patients with advanced solid cancers, especially those with breast, prostate, and lung malignancies. The tendency of these cancers to metastasize to bone and induce bone destruction is, in part, due to alterations in integrin expression and signaling. Substantial evidence from preclinical studies shows that increased expression of integrin αvβ3 in tumor cells promotes the metastatic and bone-invasive phenotype. Integrin αvβ3 mediates cell adhesion to several extracellular matrix proteins in the bone microenvironment which is necessary for tumor cell colonization as well as the transmission of mechanical signals for tumor progression. This review will discuss the αvβ3 integrin receptor in the context of tumor-induced bone disease. Specifically, the focus will be the role of αvβ3 in modulating cancer metastasis to bone and tumor cell response to the bone microenvironment, including downstream signaling pathways that contribute to tumor-induced osteolysis. A better understanding of integrin dysregulation in cancer is critical to developing new therapeutics for the prevention and treatment of bone metastases.

Anti-angiogenic agents for the treatment of solid tumors: Potential pathways, therapy and current strategies - A review

Recent strategies for the treatment of cancer, other than just tumor cell killing have been under intensive development, such as anti-angiogenic therapeutic approach. Angiogenesis inhibition is an important strategy for the treatment of solid tumors, which basically depends on cutting off the blood supply to tumor micro-regions, resulting in pan-hypoxia and pan-necrosis within solid tumor tissues. The differential activation of angiogenesis between normal and tumor tissues makes this process an attractive strategic target for anti-tumor drug discovery. The principles of anti-angiogenic treatment for solid tumors were originally proposed in 1972, and ever since, it has become a putative target for therapies directed against solid tumors. In the early twenty first century, the FDA approved anti-angiogenic drugs, such as bevacizumab and sorafenib for the treatment of several solid tumors. Over the past two decades, researches have continued to improve the performance of anti-angiogenic drugs, describe their drug interaction potential, and uncover possible reasons for potential treatment resistance. Herein, we present an update to the pre-clinical and clinical situations of anti-angiogenic agents and discuss the most recent trends in this field.

Dual-targeted hybrid nanoparticles of synergistic drugs for treating lung metastases of triple negative breast cancer in mice

Lung metastasis is the major cause of death in patients with triple negative breast cancer (TNBC), an aggressive subtype of breast cancer with no effective therapy at present. It has been proposed that dual-targeted therapy, ie, targeting chemotherapeutic agents to both tumor vasculature and cancer cells, may offer some advantages. The present work was aimed to develop a dual-targeted synergistic drug combination nanomedicine for the treatment of lung metastases of TNBC. Thus, Arg-Gly-Asp peptide (RGD)-conjugated, doxorubicin (DOX) and mitomycin C (MMC) co-loaded polymer-lipid hybrid nanoparticles (RGD-DMPLN) were prepared and characterized. The synergism between DOX and MMC and the effect of RGD-DMPLN on cell morphology and cell viability were evaluated in human MDA-MB-231 cells in vitro. The optimal RGD density on nanoparticles (NPs) was identified based on the biodistribution and tumor accumulation of the NPs in a murine lung metastatic model of MDA-MB-231 cells. The microscopic distribution of RGD-conjugated NPs in lung metastases was examined using confocal microscopy. The anticancer efficacy of RGD-DMPLN was investigated in the lung metastatic model. A synergistic ratio of DOX and MMC was found in the MDA-MB-231 human TNBC cells. RGD-DMPLN induced morphological changes and enhanced cytotoxicity in vitro. NPs with a median RGD density showed the highest accumulation in lung metastases by targeting both tumor vasculature and cancer cells. Compared to free drugs, RGD-DMPLN exhibited significantly low toxicity to the host, liver and heart. Compared to non-targeted DMPLN or free drugs, administration of RGD-DMPLN (10 mg/kg, iv) resulted in a 4.7-fold and 31-fold reduction in the burden of lung metastases measured by bioluminescence imaging, a 2.4-fold and 4.0-fold reduction in the lung metastasis area index, and a 35% and 57% longer median survival time, respectively. Dual-targeted RGD-DMPLN, with optimal RGD density, significantly inhibited the progression of lung metastasis and extended host survival.

Integrin-targeted cancer immunotherapy elicits protective adaptive immune responses

Integrin targeting for cancer has primarily focused on antagonizing integrin function, which has been clinically ineffective to date. In this study, Kwan et al. repurpose integrins as a beacon for recruiting immune effector functions to bolster current cancer immunotherapy approaches.

Certain RGD-binding integrins are required for cell adhesion, migration, and proliferation and are overexpressed in most tumors, making them attractive therapeutic targets. However, multiple integrin antagonist drug candidates have failed to show efficacy in cancer clinical trials. In this work, we instead exploit these integrins as a target for antibody Fc effector functions in the context of cancer immunotherapy. By combining administration of an engineered mouse serum albumin/IL-2 fusion with an Fc fusion to an integrin-binding peptide (2.5F-Fc), significant survival improvements are achieved in three syngeneic mouse tumor models, including complete responses with protective immunity. Functional integrin antagonism does not contribute significantly to efficacy; rather, this therapy recruits both an innate and adaptive immune response, as deficiencies in either arm result in reduced tumor control. Administration of this integrin-targeted immunotherapy together with an anti–PD-1 antibody further improves responses and predominantly results in cures. Overall, this well-tolerated therapy achieves tumor specificity by redirecting inflammation to a functional target fundamental to tumorigenic processes but expressed at significantly lower levels in healthy tissues, and it shows promise for translation.

Reverse transendothelial cell migration in inflammation: to help or to hinder?

The endothelium provides a strong barrier separating circulating blood from tissue. It also provides a significant challenge for immune cells in the bloodstream to access potential sites of infection. To mount an effective immune response, leukocytes traverse the endothelial layer in a process known as transendothelial migration. Decades of work have allowed dissection of the mechanisms through which immune cells gain access into peripheral tissues, and subsequently to inflammatory foci. However, an often under-appreciated or potentially ignored question is whether transmigrated leukocytes can leave these inflammatory sites, and perhaps even return across the endothelium and re-enter circulation. Although evidence has existed to support "reverse" transendothelial migration for a number of years, it is only recently that mechanisms associated with this process have been described. Here we review the evidence that supports both reverse transendothelial migration and reverse interstitial migration within tissues, with particular emphasis on some of the more recent studies that finally hint at potential mechanisms. Additionally, we postulate the biological significance of retrograde migration, and whether it serves as an additional mechanism to limit pathology, or provides a basis for the dissemination of systemic inflammation.

Mimetic peptide of ubiquitin-interacting motif of epsin as a cancer therapeutic-perspective in brain tumor therapy through regulating VEGFR2 signaling

Epsins, endocytic adaptor proteins required for internalization of ubiquitylated receptors, are generally upregulated in human cancers. It has been characterized that mice deficient of epsins in the endothelium inhibit tumor growth by dysregulating vascular endothelial growth factor receptor-2 (VEGFR2) signaling and non-productive tumor angiogenesis. Binding of the epsin ubiquitin (Ub)-interacting motif (UIM) with ubiquitylated VEGFR2 is a critical mechanism for epsin-dependent VEGFR2 endocytosis and degradation, indicative of epsin UIM as a potential therapeutic target. A Computer Assisted Drug Design approach was utilized to create the UIM mimetic peptides for the functional competition of epsin binding sites in ubiquitylated VEGFR2 in vivo. Specifically targeting VEGFR2 in the tumor vasculature, the chemically synthesized chimeric UIM peptide, UPI, causes non-functional tumor angiogenesis, retards tumor growth, and increases survival rates in several tumor models. The authors showed that UPI binds ubiquitylated VEGFR2 to form a supercomplex in an Ub-dependent fashion. Collectively, the UPI targeting strategy offers a potentially novel treatment for cancer patients who are resistant to current anti-angiogenic therapies. In this review, the authors outline the main points of this research specifically as a potential application for glioma tumor therapy.

Tumor penetrating peptides for improved drug delivery

In vivo screening of phage libraries in tumor-bearing mice has been used to identify peptides that direct phage homing to a tumor. The power of in vivo phage screening is illustrated by the recent discovery of peptides with unique tumor-penetrating properties. These peptides activate an endocytic transport pathway related to but distinct from macropinocytosis. They do so through a complex process that involves binding to a primary, tumor-specific receptor, followed by a proteolytic cleavage, and binding to a second receptor. The second receptor, neuropilin-1 (or neuropilin-2) activates the transport pathway. This trans-tissue pathway, dubbed the C-end Rule (CendR) pathway, mediates the extravasation transport through extravascular tumor tissue of payloads ranging from small molecule drugs to nanoparticles. The CendR technology provides a solution to a major problem in tumor therapy, poor penetration of drugs into tumors. Targeted delivery with tumor-penetrating peptides has been shown to specifically increase the accumulation of drugs, antibodies and nanotherapeutics in experimental tumors in vivo, and in human tumors ex vivo. Remarkably the payload does not have to be coupled to the peptide; the peptide activates a bulk transport system that sweeps along a drug present in the blood. Treatment studies in mice have shown improved anti-tumor efficacy and less damage to normal tissues with drugs ranging from traditional chemotherapeutics to antibodies, and to nanoparticle drugs.

Peptides for tumor-specific drug targeting: state of the art and beyond

This review outlines the most recent advances in peptide-mediated tumor-targeting and gives insight into the direction of the field.