Integrin Αvβ3 Antagonists Research Articles

Potential Benefits of Integrin αvβ3 Antagonists in a Mouse Model of Experimental Dry Eye.

The purpose of this study was to extensively evaluate the efficacy of integrin αvβ3 antagonists for the treatment of experimental dry eye (EDE). Vitronectin, an αvβ3 ligand, was used to induce tumor necrosis factor-α gene expression in human THP-1 macrophages. To induce EDE, C57BL/6 mice were housed in a low-humidity controlled environment chamber and injected subcutaneously with scopolamine for 7 days. Subsequently, αvβ3 antagonists, including RGDfD, c(RGDfD), c(RGDiD), c(RGDfK), ATN-161, SB273005, and cilengitide, were administered topically to EDE animals under controlled environment chamber conditions. Corneal epithelial damage in EDE was assessed by fluorescein staining. The density of conjunctival goblet cells and secretion of tears was measured by period acid-Schiff staining and phenol red-impregnated cotton threads, respectively. Inflammation markers, including tumor necrosis factor-α, interleukin (IL)-1β, IL-6, IL-17A, and metalloproteinase (MMP)-9, in the pooled cornea and conjunctiva tissues were examined by real-time polymerase chain reaction. The inhibitory effects of αvβ3 antagonists on the vitronectin-induced tumor necrosis factor-α gene expression and integrin-mediated inflammatory signaling were validated in THP-1 macrophages. αvβ3 antagonists ameliorated the impairment of the corneal epithelial barrier with varying therapeutic efficacies, compared with vehicle-treated mice. c(RGDfD) and c(RGDiD) significantly protected against goblet cell loss, tear reduction, and proinflammatory gene expression in EDE. Topical applications of αvβ3 antagonists yield therapeutic benefits in EDE by promoting corneal epithelial defect healing and reducing inflammation. Antagonistic targeting αvβ3 may be a novel promising strategy to treat patients with dry eye disease.

Abstract 3073: Action of thyroid hormones in sorafenib treatment of thyroid cancer

Abstract Background: Thyroid carcinoma (TC) is the most common endocrine neoplasia. Its incidence has increased in the last 40 years worldwide. Sorafenib (Sor), a tyrosine kinase inhibitor (TKI), was approved for the treatment of TC, being hypothyroidism the most frequent consequence of Sor-induced endocrine dysfunction. We have described that thyroid hormones (TH) increase cell proliferation in TC cell lines. Thus, hormone replacement therapy to treat Sor-induced hypothyroidism could negatively affect its antitumor action. We have also shown that the selective inhibition of the TH membrane receptor, integrin αVβ3, diminishes proliferation. Objective: To study integrin αVβ3 inhibition to enhance Sor antineoplastic activity in TC and the molecular mechanisms involved. Experimental Procedures: 8505C human anaplastic TC cell viability was evaluated by MTS assay. Sor was the TKI used, and Cilengitide (Cile) was used to inhibit integrin αVβ3. Protein modulation was measured by Western blot. Apoptosis induction was determined by APC-Annexin V Propidium iodide staining, followed by flow cytometry. In silico analysis on several databases were performed using CBioPortal (https://cbioportal.org/; TCGA, Cell 2014, n=504) and R2 (http://r2.amc.nl; GSE126729, n=28). Results: We first performed a bioinformatic analysis by cBioPortal on the PanCancer Atlas data and found that thyroid tumors are those with the highest integrin αVβ3 subunits expression. We then studied the role of integrin αVβ3 in Sor inhibition of TH-induced proliferation in TC cells. Treatment of 8505C cells with integrin αVβ3 antagonist Cile inhibits TH-induced proliferation (p&lt0.0001), confirming the participation of the integrin. As expected, Sor treatment decreases proliferation (p&lt0.05) while Cile addition did not change the inhibition level. Also, we found that Sor and Cile treatment diminished PCNA and Cyclin D1 expression levels. Cells were preincubated with Sor and Cile and then treated or not with TH for 48h to analyze apoptosis. Sor treatment increases the number of apoptotic cells relative to untreated control (p&lt0.0001) and the presence of TH reduces the rate of apoptosis (p&lt0.01). We then studied Sor target genes expression by R2 on an anaplastic TC patients’ database. FGFR is highly expressed among Sor targets, and it is correlated with integrin αVβ3 expression. Thus, FGFR expression modulation was studied by Western blot on cells treated as previously described. Finally, we found that TH treatment increased FGFR expression, Sor diminishes expression and in presence of TH, FGFR expression was rescued. Interestingly, Cile addition resensitized cells to Sor in presence of TH. Conclusion: Our results establish that the effective dual Sor and Cile treatment can significantly drive tumor proliferation inhibition and apoptosis, and it could provide alternatives to the treatments currently used for this disease. Citation Format: Mateo N. Campos Haedo, Maria C. Diaz Flaque, Helena A. Sterle, Johanna A. Diaz Albuja, Maria F. Cayrol, Maria M. Debernardi, Marina Perona, Guillermo J. Juvenal, Graciela A. Cremaschi, Cinthia Rosemblit. Action of thyroid hormones in sorafenib treatment of thyroid cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3073.

Structure-Based Discovery of a Novel Class of Small-Molecule Pure Antagonists of Integrin αVβ3.

Inhibitors of integrin αVβ3 have therapeutic promise for a variety of diseases. Most αVβ3-targeting small molecules patterned after the RGD motif are partial agonists because they induce a high-affinity, ligand-binding conformation and prime the receptor to bind the ligand without an activating stimulus, in part via a charge-charge interaction between their aspartic acid carboxyl group and the metal ion in the metal-ion-dependent adhesion site (MIDAS). Building upon our previous studies on the related integrin αIIbβ3, we searched for pure αVβ3 antagonists that lack this typical aspartic acid carboxyl group and instead engage through direct binding to one of the coordinating residues of the MIDAS metal ion, specifically β3 E220. By in silico screening of two large chemical libraries for compounds interacting with β3 E220, we indeed discovered a novel molecule that does not contain an acidic carboxyl group and does not induce the high-affinity, ligand-binding state of the receptor. Functional and structural characterization of a chemically optimized version of this compound led to the discovery of a novel small-molecule pure αVβ3 antagonist that (i) does not prime the receptor to bind the ligand and does not induce hybrid domain swing-out or receptor extension as judged by antibody binding and negative-stain electron microscopy, (ii) binds at the RGD-binding site as predicted by metadynamics rescoring of induced-fit docking poses and confirmed by a cryo-electron microscopy structure of the compound-bound integrin, and (iii) coordinates the MIDAS metal ion via a quinoline moiety instead of an acidic carboxyl group.

Comparative Assessment of the Inhibitory Potential of the Herbicide Glyphosate and Its Structural Analogs on RGD-Specific Integrins Using Enzyme-Linked Immunosorbent Assays.

Transmembrane glycoprotein integrins play crucial roles in biochemical processes, and by their inhibition or activation, different signal pathways can be disrupted, leading to abnormal physiological functions. We have previously demonstrated the inhibitory effect of glyphosate herbicide’s active ingredient on cell adhesion and its αvβ3 integrin antagonist effect. Therefore, it appeared particularly exciting to investigate inhibition of glyphosate and its metabolites on a wider range of Arg-Gly-Asp (RGD) binding integrins, namely αvβ3, α5β1 and αllbβ3. Thus, the purpose of this study was to assess how extended the inhibitory effect observed for glyphosate on the integrin αvβ3 is in terms of other RGD integrins and other structurally or metabolically related derivatives of glyphosate. Five different experimental setups using enzyme-linked immunosorbent assays were applied: (i) αvβ3 binding to a synthetic polymer containing RGD; (ii) αvβ3 binding to its extracellular matrix (ECM) protein, vitronectin; (iii) α5β1 binding to the above polymer containing RGD; (iv) αllbβ3 binding to its ECM protein, fibrinogen and (v) αvβ3 binding to the SARS-CoV-2 spike protein receptor binding domain. Total inhibition of αvβ3 binding to RGD was detected for glyphosate and its main metabolite, aminomethylphosphonic acid (AMPA), as well as for acetylglycine on α5β1 binding to RGD.

Involvement of integrin αvβ3 in thyroid hormone-induced dendritogenesis.

Activation and/or modulation of the membrane-associated receptors plays a critical role in brain development. Thyroid hormone (TH) acts on both nuclear receptors (thyroid hormone receptor, TR) and membrane-associated receptors, particularly integrin αvβ3 in neurons and glia. Integrin αvβ3-mediated signal transduction mediates various cellular events during development including morphogenesis, migration, synaptogenesis, and intracellular metabolism. However, the involvement of integrin αvβ3-mediated TH action during brain development remains poorly understood. Thus, we examined the integrin αvβ3-mediated effects of TH (T3, T4, and rT3) in the neurons and astrocytes using primary cerebellar culture, astrocyte-enriched culture, Neuro-2A clonal cells, and co-culture of neurons and astrocytes. We found that TH augments dendrite arborization of cerebellar Purkinje cells. This augmentation was suppressed by knockdown of integrin αvβ3, as well as TRα and TRβ. A selective integrin αvβ3 antagonist, LM609, was also found to suppress TH-induced arborization. However, whether this effect was a direct action of TH on Purkinje cells or due to indirect actions of other cells subset such as astrocytes was not clarified. To further study neuron-specific molecular mechanisms, we used Neuro-2A clonal cells and found TH also induces neurite growth. TH-induced neurite growth was reduced by co-exposure with LM609 or knockdown of TRα, but not TRβ. Moreover, co-culture of Neuro-2A and astrocytes also increased TH-induced neurite growth, indicating astrocytes may be involved in neuritogenesis. TH increased the localization of synapsin-1 and F-actin in filopodia tips. TH exposure also increased phosphorylation of FAK, Akt, and ERK1/2. Phosphorylation was suppressed by co-exposure with LM609 and TRα knockdown. These results indicate that TRs and integrin αvβ3 play essential roles in TH-induced dendritogenesis and neuritogenesis. Furthermore, astrocytes-neuron communication via TR-dependent and TR-independent signaling through membrane receptors and F-actin are required for TH-induced neuritogenesis.

Inhibition of angiogenesis and tumor progression of MK-0429, an integrin αvβ3 antagonist, on oral squamous cell carcinoma

PurposeIntegrin αvβ3 is an essential molecule for tumor angiogenesis. This study aimed to investigate the anti-tumor effect of MK-0429, an integrin αvβ3 antagonist, on oral squamous cell carcinoma (OSCC) through its inhibitory effect on angiogenesis.MethodsIn this study, we investigated the effect of MK-0429 on cellular function and angiogenesis in vitro with the use of an immortalized human umbilical vein endothelial cell, HUEhT-1, which is immortalized by the electroporatic transfection of hTERT. The effect of MK-0429 on the integrin αvβ3 signaling pathway was examined by FAK, MEK1/2 and ERK 1/2 phosphorylation. The anti-angiogenic effect of MK-0429 was evaluated by in vitro tube formation assay. The anti-tumor effect on OSCC was assessed by administrating MK-0429 to mouse oral cancer xenografts.ResultsMK-0429 inhibited cell proliferation, migration, and adhesion of HUEhT-1 in a dose-dependent manner. FAK, MEK and ERK phosphorylation were significantly blocked by MK-0429 treatment. Tube formation was suppressed by MK-0429 in dose-dependent manner. Tumor progression was significantly suppressed by MK-0429 administration in mouse oral cancer xenografts. Histological study revealed that MK-0429 decreased tumor vascularization.ConclusionThese results indicated integrin αvβ3 as a therapeutic target for OSCC and suggested that MK-0429 might be clinically applicable as an anti-tumor agent with potent anti-angiogenic activity.

Abstract 1314: A novel small molecule drug conjugate -avb3 integrin antagonist linked to a cytotoxic camptothecin derivative- for the treatment of multiple cancer types

Abstract To improve tumor selectivity of cytotoxic agents we designed small molecule drug conjugates leveraging two independent mechanisms of targeted delivery by utilizing an integrin binder for tumor homing and release of the active drug by proteases present in tumor stroma. Integrins are transmembrane receptors that mediate cell-extracellular matrix and cell-cell interaction. αvβ3 integrins in the tumor microenvironment are involved in critical events for tumor progression, cytotoxic therapy resistance and metastasis including angiogenesis, matrix remodeling and the recruitment of immune and inflammatory cells. Proteases in tumor stoma such as neutrophil elastase also contribute to cancer progression by enhancing tumor evasion and metastasis. The expectation is that small molecule drug conjugates could have better efficacy for solid tumors than antibody drug conjugates due to better tissue penetration. Following this rationale the small molecule drug conjugate is composed of a peptidomimetic αvβ3 integrin antagonist linked to a cytotoxic camptothecin derivative via a linker susceptible to cleavage by neutrophil elastase. Imaging studies with the αvβ3 antagonist conjugated with an IR-800 dye demonstrated efficient tumor targeting to 786-0 renal adenocarcinoma tumors, as compared with a weakly binding epimer used as a control conjugate. The targeted conjugate is highly stable in rat plasma and shows strong cytotoxic activity only in the presence of neutrophil elastase. The payload displays high cellular permeability and in contrast to SN38, the active metabolite of irinotecan, it is not a substrate of efflux transporters. The conjugate is highly efficacious in vivo effecting tumor regressions in SW480 (colon cancer), MX1 (breast cancer) and NCI-H69 (lung cancer) xenograft models with T/C ratios of 0.1, 0.03 and 0.06 (p<0.05 each, compared to vehicle control) respectively and it shows very good tolerability. Initial pharmacokinetic studies in tumor bearing mice demonstrate a more than 10-fold improved tumor/plasma ratio of free toxophore when administered as a conjugate as compared with direct administration of unconjugated toxophore. In summary, our results show potent, selective, in vivo anticancer activity against three solid tumor subtypes with a novel small molecule drug conjugate consisting of the conjugation of an integrin antagonist with a cytotoxic agent via a tailored linker enabling cleavage in tumor stroma. Citation Format: Hans-Georg Lerchen, Beatrix Stelte-Ludwig, Charlotte Kopitz, Melanie Heroult, Dmitry Zubov, Joerg Willuda, Thomas Schlange, Antje Kahnert, Raquel Izumi, Ahmed Hamdy. A novel small molecule drug conjugate -avb3 integrin antagonist linked to a cytotoxic camptothecin derivative- for the treatment of multiple cancer types [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1314.

Discovery of dual targeting PEGylated BG-P1600-TAT to norepinephrine transporter (NET) and thyrointegrin αvβ3 in the treatment of neuroblastoma

Polymer-drug conjugates are growing in interest as novel anticancer agents for targeted cancer therapy. The aim of this study was to synthesize a poly(ethylene glycol) (PEG) conjugated anticancer drug for neuroblastoma, which is the most common extracranial solid tumor of childhood and the deadliest tumor of infancy. In our previous studies, we designed and synthesized a dual targeting agent using benzylguanidine (BG) conjugated with the high affinity thyrointegrin αvβ3 antagonist TriAzole Tetraiodothyroacetic acid (TAT) via non-cleavable bonding to PEG400 to make BG-P400-TAT and its derivatives as agents against neuroblastoma. Here, we improved the pharmacodynamic properties and increased the solubility by changing the polymer length to 1600 molecular weight. The TAT group, which acts as an integrin αvβ3 antagonist, and the BG group, which can be taken up by neuroblastoma cells through the norepinephrine transporter (NET) system, are conjugated to PEG1600 to make BG-PEG1600-TAT. The binding affinity of BG-PEG1600-TAT was 40-fold higher to integrin αvβ3 versus BG-P400-TAT and was associated with greater anticancer activities against neuroblastoma cells (SK-N-F1 and SKNAS) implanted in SCID mice along with broad spectrum anti-angiogenesis activities versus the FDA approved anti-Vascular Endothelial Growth Factor (VEGF) monoclonal antibody Avastin (bevacizumab). In conclusion, our novel dual targeting of NET and αvβ3 receptor antagonist, BG-P1600-TAT demonstrated broad spectrum anti-angiogenesis and anti-cancer activities in suppressing neuroblastoma tumor progression and metastasis. Thus, BG-PEG1600-TAT represents a potential clinical candidate for targeted therapy in neuroblastoma management.

Antagonizing αvβ3 Integrin Improves Ischemia-Mediated Vascular Normalization and Blood Perfusion by Altering Macrophages.

Background: αVβ3 integrin has been implicated in the physiological processes and pathophysiology of important angiogenesis-related disorders; however, the preclinical and clinical data on integrin αVβ3 antagonists have not demonstrated improved outcomes. Our goal was to test the hypothesis that inhibition of αVβ3 integrin improves blood flow in a mouse hindlimb ischemia model. Methods: In this study, we examined the effect of cilengitide, an αVβ3/αVβ5 integrin-specific RGD-mimetic cyclic peptide, on blood perfusion and angiogenesis after hindlimb ischemia. Blood flow was measured using Laser Doppler Scanner. Vascular density, and macrophages infiltration were examined by immunofluorescence. Macrophage polarization was measured by quantitative real time PCR. Results: We found that low-dose, not high-dose, cilengitide increased blood flow perfusion, capillary formation, and pericyte coverage, accompanied by an accumulation of macrophages and increased expression of the chemokine (C-C motif) ligand 2 (CCL2) in ischemic muscles. Macrophage depletion using clodronate liposomes resulted in a reduction in low-dose cilengitide-induced blood flow perfusion, macrophage accumulation, pericyte coverage, and CCL2 expression. Finally, in vitro assays showed that low-dose, not high-dose, cilengitide increased macrophage migration. Conclusion: These studies identified a novel role of the inhibition of αVβ3 integrin in modulating ischemia-induced angiogenesis, possibly through effects on macrophage infiltration and polarization, and revealed αVβ3 integrin inhibition to be a promising therapeutic strategy for peripheral artery disease.

Enantioselective Synthesis of cis and trans 4‐Aminopipecolic Acids as γ‐Amino Acids for the Construction of Cyclic RGD‐Containing Peptidomimetics Antagonists of αVβ3 Integrin

A stereodivergent strategy to obtain enantiopure cis and trans 4‐aminopipecolic acids (4‐APAs) in a suitably protected form for peptide synthesis has been devised starting from a common, known precursor in turn easily prepared from commercial (R)‐4‐cyano‐3‐hydroxybutyric acid ethyl ester. The two isomers were efficiently obtained in 40 % and 23 % overall yields, respectively, in seven and ten steps. To demonstrate their usefulness in peptidomimetic synthesis, both 4‐APA isomers were incorporated as γ‐amino acids in a cyclic RGD‐containing sequence, although for the trans 4‐APA isomer a further amino acid in the sequence (L‐Phe) was needed to allow ring closure. The two cyclopeptides were tested as αVβ3 integrin antagonists in comparison with cilengitide.

αvβ3 Integrin Antagonists Enhance Chemotherapy Response in an Orthotopic Pancreatic Cancer Model.

Pancreatic cancer decreases survival time and quality of life because of drug resistance and peripheral neuropathy during conventional treatment. This study was undertaken to investigate whether αvβ3 integrin receptor antagonist compounds NDAT and XT199 can suppress the development of cisplatin resistance and cisplatin-induced peripheral neuropathy in an orthotopic pancreatic SUIT2-luc cancer cell mouse model. Anticancer effects of these compounds and their combination with cisplatin were assessed in this tumor mouse model with bioluminescent signaling and histopathology, and a cytokine assay was used to examine expression of inflammatory cytokines IL-1β, IL-6, IL-10, and TNF-α from plasma samples. To determine the neuroprotective effects of the compounds on cisplatin-induced peripheral neuropathy, behavioral hind-limb posture of the mice was evaluated. The combination therapy of NDAT or XT199 with cisplatin elicited greater inhibition of tumor growth and increased tumor necrosis compared to cisplatin alone. NDAT and XT199 in combination with cisplatin significantly decreased expression of pro-inflammatory cytokines IL-1β, IL-6, and TNF-α and significantly increased expression of anti-inflammatory cytokine IL-10 in comparison to cisplatin alone. Cisplatin-treated groups showed stocking-glove hind-limb posture, whereas NDAT and XT199 with cisplatin-treated groups displayed normal hind-limb posture. Results clearly suggest that NDAT and XT199 treatment with cisplatin that inactivates NF-κB may contribute to increased antitumor and anti-inflammatory efficacy as well as alleviate cisplatin-mediated loss of motor function in this pancreatic tumor mouse model.

Novel Pure αVβ3 Integrin Antagonists That Do Not Induce Receptor Extension, Prime the Receptor, or Enhance Angiogenesis at Low Concentrations.

The integrin αVβ3 receptor has been implicated in several important diseases, but no antagonists are approved for human therapy. One possible limitation of current small-molecule antagonists is their ability to induce a major conformational change in the receptor that induces it to adopt a high-affinity ligand-binding state. In response, we used structural inferences from a pure peptide antagonist to design the small-molecule pure antagonists TDI-4161 and TDI-3761. Both compounds inhibit αVβ3-mediated cell adhesion to αVβ3 ligands, but do not induce the conformational change as judged by antibody binding, electron microscopy, X-ray crystallography, and receptor priming studies. Both compounds demonstrated the favorable property of inhibiting bone resorption in vitro, supporting potential value in treating osteoporosis. Neither, however, had the unfavorable property of the αVβ3 antagonist cilengitide of paradoxically enhancing aortic sprout angiogenesis at concentrations below its IC50, which correlates with cilengitide's enhancement of tumor growth in vivo.

RETRACTED ARTICLE: Pharmacokinetics, Biodistribution, and Anti-Angiogenesis Efficacy of Diamino Propane Tetraiodothyroacetic Acid-conjugated Biodegradable Polymeric Nanoparticle

The anti-angiogenic agent, diamino propane tetraiodothyroacetic acid (DAT), is a thyro-integrin (integrin αvβ3) antagonist anticancer agent that works via genetic and nongenetic actions. Tetraiodothyroacetic acid (tetrac) and DAT as thyroid hormone derivatives influence gene expression after they transport across cellular membranes. To restrict the action of DAT to the integrin αvβ3 receptors on the cell surface, we used DAT-conjugated PLGA nanoparticles (NDAT) in an active targeting mode to bind to these receptors. Preparation and characterization of NDAT is described, and both in vitro and in vivo experiments were done to compare DAT to NDAT. Intracellular uptake and distribution of DAT and NDAT in U87 glioblastoma cells were evaluated using confocal microscopy and showed that DAT reached the nucleus, but NDAT was restricted from the nucleus. Pharmacokinetic studies using LC-MS/MS analysis in male C57BL/6 mice showed that administration of NDAT improved the area under the drug concentration curve AUC(0–48 h) by 4-fold at a dose of 3 mg/kg when compared with DAT, and Cmax of NDAT (4363 ng/mL) was 8-fold greater than that of DAT (548 ng/mL). Biodistribution studies in the mice showed that the concentrations of NDAT were higher than DAT/Cremophor EL micelles in heart, lung, liver, spleen, and kidney. In another mouse model using female NCr nude homozygous mice with U87 xenografts, tumor growth was significantly decreased at doses of 1 and 3 mg/kg of NDAT. In the chick chorioallantoic membrane (CAM) assay used to measure angiogenesis, DAT (500 ng/CAM) resulted in 48% inhibition of angiogenesis levels. In comparison, NDAT at low dose (50 ng/CAM) showed 45% inhibition of angiogenesis levels. Our investigation of NDAT bridges the study of polymeric nanoparticles and anti-angiogenic agents and offers new insight for the rational design of anti-angiogenic agents.

The anticancer properties and mechanism of action of tablysin-15, the RGD-containing disintegrin, in breast cancer cells.

αvβ3 integrin expressed on cancer cell surfaces is associated with important cancer hallmarks including survival and metastasis and is thus a potential anticancer drug target. Tablysin-15 contains the RGD motif and is a high-affinity αvβ3 integrin antagonist. The aim of this study was to investigate the antitumor effect and mechanism of action of tablysin-15 against αvβ3 integrin high-expressing breast cancer cell lines in vitro and in vivo. Tablysin-15 dose-dependently inhibited the proliferation, migration, and invasion of two breast cancer cell lines via the αvβ3 integrin in vitro. Proliferation inhibition was attributable to G0/G1 phase cell cycle arrest rather than apoptosis or necrosis. Furthermore, tablysin-15 downregulated the activity and mRNA expression of MMP-2/-9, VEGF, and COX-2 but upregulated TIMP-1/-2 mRNA in both cell lines. Further, tablysin-15 suppressed the expression of CDK2, CDK6, cyclin D1, and cyclin E, the phosphorylation of FAK, Akt, GSK-3β, and ERK, and the nuclear translocation of NF-κB while increasing the expression of the CDK inhibitor p21waf1/C1. Lastly, tablysin-15 provided effective antitumor protection in vivo. Thus, tablysin-15 inhibits the metastasis and proliferation of breast cancer cells through binding αvβ3 integrin and blocking FAK-associated signaling pathways as well as nuclear translocation of NF-κB.

Tenascin-C Produced by Intestinal Myofibroblasts Promotes Colitis-associated Cancer Development Through Angiogenesis.

Colitis-associated cancer (CAC) is one of the prognostic factors in inflammatory bowel disease (IBD), and prevention of CAC is a critical concern for patients with IBD. Component cells of the microenvironment, especially myofibroblasts, are known to affect tumor development, but the role of intestinal myofibroblasts (IMFs) in CAC has not been clarified. Here, we explored the role of IMFs in CAC and sought to identify candidate genes as novel therapeutic targets for the prevention of CAC. We used the azoxymethane (AOM)/dextran sodium sulfate (DSS) model for dysplasia and CAC. Flow cytometry and RNA sequencing (RNA-seq) were performed to obtain an unbiased gene expression profile of IMFs. The transcriptome of significantly differentially expressed genes was analyzed by RNA-seq, quantitative reverse transcriptase polymerase chain reaction, and immunohistochemistry. Comparison of normal intestinal fibroblasts and IMFs revealed 1045 genes with significantly differential expression. Among them, we focused on tenascin-C (TNC; q = 0.00232, Log2(Fold Change) = 3.87). Tenascin-C gene expression was markedly increased in the dysplasia model compared with control and CAC model (P < 0.05). Tenascin-C protein was barely expressed in normal and nondysplastic mucosa but strongly expressed in the stroma around dysplastic lesions. Moreover, TNC surrounded and enclosed integrin αvβ3-positive microvessels. Administration of ATN-161, an antagonist of αvβ3-integrin, significantly suppressed tumorigenesis of CAC through inhibition of angiogenesis (P < 0.05). In the early stages of CAC, TNC produced by IMFs affects tumor development via integrin αvβ3-mediated angiogenesis. Intestinal myofibroblasts might be a novel therapeutic target for preventing CAC.

Integrin-targeted quantitative optoacoustic imaging with MRI correlation for monitoring a BRAF/MEK inhibitor combination therapy in a murine model of human melanoma.

PurposeTo investigate αvβ3-integrin-targeted optoacoustic imaging and MRI for monitoring a BRAF/MEK inhibitor combination therapy in a murine model of human melanoma.Materials and methodsHuman BRAF V600E-positive melanoma xenograft (A375)-bearing Balb/c nude mice (n = 10) were imaged before (day 0) and after (day 7) a BRAF/MEK inhibitor combination therapy (encorafenib, 1.3 mg/kg/d; binimetinib, 0.6 mg/kg/d, n = 5) or placebo (n = 5), respectively. Optoacoustic imaging was performed on a preclinical system unenhanced and 5 h after i. v. injection of an αvβ3-integrin-targeted fluorescent probe. The αvβ3-integrin-specific tumor signal was derived by spectral unmixing. For morphology-based tumor response assessments, T2w MRI data sets were acquired on a clinical 3 Tesla scanner. The imaging results were validated by multiparametric immunohistochemistry (ß3 –integrin expression, CD31 –microvascular density, Ki-67 –proliferation).ResultsThe αvβ3-integrin-specific tumor signal was significantly reduced under therapy, showing a unidirectional decline in all animals (from 7.98±2.22 to 1.67±1.30; p = 0.043). No significant signal change was observed in the control group (from 6.60±6.51 to 3.67±1.93; p = 0.500). Immunohistochemistry revealed a significantly lower integrin expression (ß3: 0.20±0.02 vs. 0.39±0.05; p = 0.008) and microvascular density (CD31: 119±15 vs. 292±49; p = 0.008) in the therapy group. Tumor volumes increased with no significant intergroup difference (therapy: +107±42 mm3; control +112±44mm3, p = 0.841). In vivo blocking studies with αvβ3-integrin antagonist cilengitide confirmed the target specificity of the fluorescent probe.Conclusionsαvβ3-integrin-targeted optoacoustic imaging allowed for the early non-invasive monitoring of a BRAF/MEK inhibitor combination therapy in a murine model of human melanoma, adding molecular information on tumor receptor status to morphology-based tumor response criteria.

A dual-specific macrophage colony-stimulating factor antagonist of c-FMS and αvβ3 integrin for osteoporosis therapy.

There is currently a demand for new highly efficient and specific drugs to treat osteoporosis, a chronic bone disease affecting millions of people worldwide. We have developed a combinatorial strategy for engineering bispecific inhibitors that simultaneously target the unique combination of c-FMS and αvβ3 integrin, which act in concert to facilitate bone resorption by osteoclasts. Using functional fluorescence-activated cell sorting (FACS)-based screening assays of random mutagenesis macrophage colony-stimulating factor (M-CSF) libraries against c-FMS and αvβ3 integrin, we engineered dual-specific M-CSF mutants with high affinity to both receptors. These bispecific mutants act as functional antagonists of c-FMS and αvβ3 integrin activation and hence of osteoclast differentiation in vitro and osteoclast activity in vivo. This study thus introduces a versatile platform for the creation of new-generation therapeutics with high efficacy and specificity for osteoporosis and other bone diseases. It also provides new tools for studying molecular mechanisms and the cell signaling pathways that mediate osteoclast differentiation and function.

PO-517 Peptide-based diagnostic in vivo targeting of membrane Hsp70 positive tumours

IntroductionHeat shock protein 70 (Hsp70, HSP1A1), the major stress-inducible stress response protein, is frequently overexpressed in tumour cells of many entities. Hsp70 plays a promotive role in the development, viability and metastatic spread of tumour cells, in vivo. In contrast to normal cells, next to its cytoplasmic localization Hsp70 is additionally found on the plasma membrane of many different tumour types. For tumour cell-selective in vivo targeting, we developed an membrane Hsp70 specific, peptide-based tumour targeting probe, termed ‘Tumour cell penetrating peptide’ (TPP).Material and methodsThe internalisation kinetics of the Hsp70 peptide tracer into tumour cells was determined by flow cytometry. The in vivotumour targeting capacity of fluorescence- or 89Zr radio-labelled TPP based probes were assessed by near infrared fluorescence imaging and PET/CT measurements, following intravenous administration of the compounds. For in vivo imaging, preclinical tumour models of syngeneic, spontaneous, chemically or genetically induced as well as xenografted tumours were used.Results and discussionsBy mimicking the oligomerization domain of Hsp70, binding specificity and affinity (Kd=19 nM) of TPP was achieved. Following the rapid intracellular turnover rate of membrane bound Hsp70, TPP is continuously internalised into tumour cells, leading to a rapid intracellular accumulation. In accordance, following intravenous administration in tumour bearing mice, the tracer is effectively protected from body clearance, which results in a high tumor-to-normal tissue signal ratio and precise tumour delineation within 24 hour after injection. In vivo, TPP accumulation reliably reflects the mHsp70 expression profiles of differently Hsp70 expressing tumour types. The peptide thereby differentiates between tumour cells and cells of the tumour microenvironment, such as tumor-associated macrophages and fbroblasts, which were found to be membrane-Hsp70 negative. Compared to a small molecule αvβ3-integrin antagonist probe, TPP based probes offer preferably high tumor-to-background contrast and tumor-specific signal intensity in the tested tumour models.ConclusionTPP provides a useful tool for multimodal imaging of tumours and metastases that might help to improve our understanding of tumour biology and allow the establishment of improved diagnostic procedures and more accurate therapeutic monitoring. TPP might also be a promising platform for tumor-specific drug delivery and other Hsp70- based targeted therapies.

Ocular Distribution and Pharmacodynamics of SF0166, a Topically Administered αvβ3 Integrin Antagonist, for the Treatment of Retinal Diseases.

SF0166, a small-molecule αvβ3 antagonist, has physiochemical properties that allow distribution to the posterior segment of the eye after topical administration in an ophthalmic solution. The pharmacodynamics and ocular distribution of SF0166 were evaluated in several cell lines, chick chorioallantoic membrane assays, and models of ocular neovascularization in mice and pigmented rabbits. SF0166 inhibited cellular adhesion to vitronectin across human, rat, rabbit, and dog cell lines with IC50 values of 7.6 pM to 76 nM. SF0166 inhibited integrin-ligand interactions at IC50 values of 0.6-13 nM for human αvβ3, αvβ6, and αvβ8 SF0166 significantly decreased neovascularization in the oxygen-induced retinopathy mouse model. SF0166 distributed to the choroid and retina after topical ocular administration in amounts that substantially exceeded the cellular IC50 for adhesion to vitronectin; drug concentrations were maintained for >12 hours. In the laser-induced choroidal neovascularization model, topical ocular administration of SF0166 decreased lesion area compared with vehicle and was comparable to a bevacizumab injection. In the vascular endothelial growth factor-induced early neovascularization and vascular leakage model, topical ocular application of SF0166 resulted in a dose-dependent reduction in vascular leakage; the highest ocular doses tested showed comparable activity to a bevacizumab injection.

Inhibition of osteoporosis by the αvβ3 integrin antagonist of rhodostomin variants

Integrins are heterodimeric cell surface receptors that mediate cell–cell and cell–matrix interaction. The vitronectin and osteopontin receptor αvβ3 integrin has increased expression levels and is implicated in the adhesion, activation, and migration of osteoclasts on the bone surface as well as osteoclast polarization. αvβ3 integrin plays an important role in osteoclast differentiation and resorption. In addition, Arg-Gly-Asp (RGD)-containing peptides, small molecular inhibitors, and antibodies to αvβ3 integrin have been shown to inhibit bone resorption in vitro and in vivo. Here we examined the effects of a disintegrin HSA-ARLDDL a genetically modified mutant of rhodostomin conjugated with human serum albumin, which is highly selective of αvβ3, on RANKL-induced osteoclastogenesis and ovariectomy (OVX)-induced osteoporosis. In RANKL-induced osteoclastogenesis, HSA-ARLDDL significantly inhibited osteoclast formation, and IC50 was at nM range. Post-treatment HSA-ARLDDL also inhibits osteoclast formation. Furthermore, weekly administration of HSA-ARLDDL significantly inhibits the increase in serum bone resorption marker levels and decrease in cancellous bone loss in tibia and femur induced by OVX. On the other hand, HSA-ARLDDL did not affect the differentiation and calcium deposition of osteoblasts. These results indicate that the highly selective and long-acting αvβ3 integrin antagonists could be developed as effective drugs for postmenopausal osteoporosis.