Regulation Of Tumor Angiogenesis Research Articles

Stathmin expression associates with vascular and immune responses in aggressive breast cancer subgroups

Studies indicate that stathmin expression associates with PI3K activation in breast cancer, suggesting stathmin as a marker for targetable patient subgroups. Here we assessed stathmin in relation to tumour proliferation, vascular and immune responses, BRCA1 germline status, basal-like differentiation, clinico-pathologic features, and survival. Immunohistochemical staining was performed on breast cancers from two series (cohort 1, n = 187; cohort 2, n = 198), and mass spectrometry data from 24 cases and 12 breast cancer cell lines was examined for proteomic profiles. Open databases were also explored (TCGA, METABRIC, Oslo2 Landscape cohort, Cancer Cell Line Encyclopedia). High stathmin expression associated with tumour proliferation, p53 status, basal-like differentiation, BRCA1 genotype, and high-grade histology. These patterns were confirmed using mRNA data. Stathmin mRNA further associated with tumour angiogenesis, immune responses and reduced survival. By logistic regression, stathmin protein independently predicted a BRCA1 genotype (OR 10.0, p = 0.015) among ER negative tumours. Cell line analysis (Connectivity Map) implied PI3K inhibition in tumours with high stathmin. Altogether, our findings indicate that stathmin might be involved in the regulation of tumour angiogenesis and immune responses in breast cancer, in addition to tumour proliferation. Cell data point to potential effects of PI3K inhibition in tumours with high stathmin expression.

A multifunctional MOF-based nanohybrid as injectable implant platform for drug synergistic oral cancer therapy

Toward eradicating tumor, it is crucial to facilitate the sustained delivery of encapsulated drugs and render enhancements of therapeutic effectiveness. Local cancer therapy with combined drugs has emerged as a promising therapeutic strategy. Herein, we put forward to construct a hybrid nanocomposite in which metal-organic frameworks (MOFs) were integrated with thermosensitive hydrogels to devise an injectable implant. Doxorubicin (Dox) and celecoxib (Cel) were coloaded into the system for localized oral cancer therapy (Dox/Cel/MOFs@Gel). In view of the antiangiogenetic activity of Cel, Cel was in alliance with Dox in order to improve treatment efficacy. The particle size, morphological characterization from SEM and TEM, stability, drug loading efficiency, drug release behaviors in vitro of Dox/Cel/MOFs@Gel were examined. The efficacy of Dox/Cel/MOFs@Gel in oral cancer cell lines as well as cell internalization was evaluated. This medical platform exhibited a high capacity for drug loading, steady and pH-responsive release of dual drugs, and enhanced toxic effects against oral cancer cells (KB and SCC-9) in vitro. The nanocomposites displayed outstanding tumor inhibition efficacy in vivo, inducing tumor apoptosis and regulating tumor angiogenesis due to the synergistic effects of Dox and Cel. It was found that this local treatment resulted in considerably lower systemic toxicity and no apparent injury to the other organs. The biocompatibility test of the MOFs indicated reasonable biosafety as no evidence of persistent toxicity in vivo was observed. The injectable nanocomposite (Dox/Cel/MOFs@Gel) possesses unique biological abilities in terms of pH-responsiveness, antitumor efficacy, biocompatibility, and simultaneously release hydrophobic and hydrophilic drug at the oral tumor site, suggesting that this nanocomposite is a promising vehicle for local oral cancer treatment.

Anti-Angiogenic Effects of Phytochemicals on miRNA Regulating Breast Cancer Progression.

Several phytochemicals have been identified for their role in modifying miRNA regulating tumor progression. miRNAs modulate the expression of several oncogenes and tumor suppressor genes including the genes that regulate tumor angiogenesis. Hypoxia inducible factor-1 alpha (HIF-1α) signaling is a central axis that activates oncogenic signaling and acts as a metabolic switch in endothelial cell (EC) driven tumor angiogenesis. Tumor angiogenesis driven by metabolic reprogramming of EC is crucial for tumor progression and metastasis in many different cancers, including breast cancers, and has been linked to aberrant miRNA expression profiles. In the current article, we identify different miRNAs that regulate tumor angiogenesis in the context of oncogenic signaling and metabolic reprogramming in ECs and review how selected phytochemicals could modulate miRNA levels to induce an anti-angiogenic action in breast cancer. Studies involving genistein, epigallocatechin gallate (EGCG) and resveratrol demonstrate the regulation of miRNA-21, miRNA-221/222 and miRNA-27, which are prognostic markers in triple negative breast cancers (TNBCs). Modulating the metabolic pathway is a novel strategy for controlling tumor angiogenesis and tumor growth. Cardamonin, curcumin and resveratrol exhibit their anti-angiogenic property by targeting the miRNAs that regulate EC metabolism. Here we suggest that using phytochemicals to target miRNAs, which in turn suppresses tumor angiogenesis, should have the potential to inhibit tumor growth, progression, invasion and metastasis and may be developed into an effective therapeutic strategy for the treatment of many different cancers where tumor angiogenesis plays a significant role in tumor growth and progression.

TRPM2 channel regulates tumor angiogenesis via interacting with Stat3

TRPM2 channel regulates tumor angiogenesis via interacting with Stat3

Calcium-Permeable Channels in Tumor Vascularization: Peculiar Sensors of Microenvironmental Chemical and Physical Cues.

Calcium (Ca2+)-permeable channels are key players in different processes leading to blood vessel formation via sprouting angiogenesis, including endothelial cell (EC) proliferation and migration, as well as in controlling vascular features which are typical of the tumor vasculature.In this review we present an up-to-date and critical view on the role of Ca2+-permeable channels in tumor vascularization, emphasizing on the dual communication between growth factors (mainly VEGF) and Ca2+ signals. Due to the complexity of the tumor microenvironment (TME) as a source of multiple stimuli acting on the endothelium, we aim to discuss the close interaction between chemical and physical challenges (hypoxia, oxidative stress, mechanical stress) and endothelial Ca2+-permeable channels, focusing on transient receptor potential (TRP), store-operated Ca2+ channels (SOCs), and mechanosensitive Piezo channels. This approach will depict their crucial contribution in regulating key properties of tumor blood vessels, such as recruitment of endothelial progenitors cells (EPCs) in the early steps of tumor vascularization, abnormal EC migration and proliferation, and increased vascular permeability. Graphical abstract depicting the functional role of Ca2+-permeable TRP, SOCs and Piezo channels in the biological processes regulating tumor angiogenesis in presence of both chemical (oxidative stress and oxygen levels) and mechanical stimuli (ECM stiffness). SOCs store-operated Ca2+ channels, TRPA transient receptor potential ankyrin, TRPV transient receptor potential vanilloid, TRPC transient receptor potential canonical, TRPM transient receptor potential melastatin, TRPM transient receptor potential vanilloid, O2 oxygen, ECM extracellular matrix.

MicroRNA-200c affects bladder cancer angiogenesis by regulating the Akt2/mTOR/HIF-1 axis.

BackgroundBladder cancer is one of the most frequent urologic tumours in the world. MicroRNA-200c (miR-200c) has been considered a regulator of tumour angiogenesis. Akt2/mTOR was considered a regulator of vascular endothelial growth factor (VEGF) and hypoxia-inducible factor 1α (HIF-1α). However, the mechanism by which miR-200c regulates bladder cancer angiogenesis remains unknown.MethodsWestern blotting and qRT-PCR were used to detect the expression of protein and mRNA, respectively. Cell proliferation, migration and invasion were detected using MTT, wound-healing and transwell assays, respectively. A dual luciferase reporter assay was used to identify the binding site between miR-200c and Akt2. A tube formation assay was also applied to detect the angiogenesis ability.ResultsSignificantly higher expression levels of HIF-1α and VEGF and lower levels of miR-200c were observed in three types of bladder cancer cell lines. Transfection with the miR-200c mimic markedly inhibited cell viability, angiogenesis, and the expression of VEGF and HIF-1α. Overexpression of miR-200c remarkably suppressed the expression of Akt2, and the binding site between them was identified. Knockdown of Akt2 remarkably decreased the expression of VEGF and HIF-1α by regulating mTOR. miR-200c influenced the expression of VEGF and HIF-1α through the Akt2/mTOR signalling pathway and further regulated angiogenesis in bladder cancer cells.ConclusionsWe proved that miR-200c could suppress HIF-1α/VEGF expression in bladder cancer cells and inhibit angiogenesis, and these regulations were achieved by targeting Akt2/mTOR. This study may provide new insight into the prevention and treatment of bladder cancer.

Insights into the Regulation of Tumor Angiogenesis by Micro-RNAs.

One of the hallmarks of cancer is angiogenesis, a series of events leading to the formation of the abnormal vascular network required for tumor growth, development, progression, and metastasis. MicroRNAs (miRNAs) are short, single-stranded, non-coding RNAs whose functions include modulation of the expression of pro- and anti-angiogenic factors and regulation of the function of vascular endothelial cells. Vascular-associated microRNAs can be either pro- or anti-angiogenic. In cancer, miRNA expression levels are deregulated and typically vary during tumor progression. Experimental data indicate that the tumor phenotype can be modified by targeting miRNA expression. Based on these observations, miRNAs may be promising targets for the development of novel anti-angiogenic therapies. This review discusses the role of various miRNAs and their targets in tumor angiogenesis, describes the strategies and challenges of miRNA-based anti-angiogenic therapies and explores the potential use of miRNAs as biomarkers for anti-angiogenic therapy response.

EXTH-46. ALISERTIB POTENTIATES THE EFFECT OF CABOZANTINIB AND VANDETANIB AGAINST GLIOBLASTOMA CELLS

Abstract Glioblastoma is the most common primary malignant brain tumor in adults and has a poor prognosis with current standard of care. Aurora-A (AURKA) is a serine-threonine kinase critical for mitotic progression through its role in centrosome maturation and mitotic spindle assembly. Vascular endothelial growth factor (VEGF) is a regulator of tumor angiogenesis and vasculogenesis. Both AURKA and VEGF are commonly over-expressed in glioblastoma. The AURKA inhibitor alisertib and inhibitors of VEGF have been shown to inhibit glioblastoma cell proliferation in vitro and in vivo, and both have been used in clinical trials for glioblastoma. Here we tested the ability of alisertib to potentiate the effects of the VEGF receptor (VEGFR) inhibitors cabozantinib and vandetanib using colony formation assays in U1242 and U87 glioblastoma cell lines. Chou-Talalay and Bliss independence models demonstrated synergistic growth inhibition in some cases. Annexin V binding assays were performed to assess the extent that apoptosis could account for the inhibitory effects in U87 cells, and a concentration of alisertib that did not cause apoptosis as a single agent was found to increase the induction of apoptosis caused by cabozantinib. These results support the rationale for further in vitro and in vivo studies of the combined use of alisertib and VEGFR inhibitors, including possible future clinical trials.

Radioimmunoimaging of 125I-labeled anti-CD93 monoclonal antibodies in a xenograft model of non-small cell lung cancer.

Lung cancer, especially non-small cell lung cancer (NSCLC), is the most common malignant tumor associated with poor prognosis. Angiogenesis plays a vital role in NSCLC, and could be used in tumor staging and therapy evaluation. CD93 (C1q receptor) is reportedly a key regulator of tumor angiogenesis. In the present study, the efficacy and specificity of a 125I-labeled CD93-specific monoclonal antibody (125I-anti-CD93 mAb) in detecting NSCLC xenografts were analyzed, and the association between CD93 expression and 125I-anti-CD93 mAb uptake by tumors was evaluated. The targeting ability of 125I-anti-CD93 mAb enabled its rapid, continuous and highly specific accumulation in CD93-expressing tumors in vivo. These results revealed the potential applicability of 125I-anti-CD93 mAb for non-invasive imaging diagnosis of CD93-positive NSCLC.

Roles of p38α and p38β mitogen‑activated protein kinase isoforms in human malignant melanoma A375 cells.

Skin cancer is one of the most common cancers worldwide. Melanoma accounts for ~5% of skin cancers but causes the large majority of skin cancer-related deaths. Recent discoveries have shown that the mitogen-activated protein kinase (MAPK) signaling pathway is critical for melanoma development and progression. Many oncogenic pathways that cause melanoma tumorigenesis have been identified, most of which are due to RAF/MEK/ERK (MAPK) pathway activation. However, the precise role of p38 remains unclear. Using specific short hairpin (sh) RNA to silence p38α and p38β, the present findings demonstrated that p38α was a crucial factor in regulating cell migration in the A375 melanoma cell line. Silencing p38α downregulated the expression of epithelial-mesenchymal transition markers, such as matrix metallopeptidase (MMP) 2, MMP9, twist family bHLH transcription factor 1, snail family transcriptional repressor 1 and vimentin, while mesenchymal-epithelial transition markers, such as E-cadherin, were upregulated. Of note, the results also demonstrated that p38α silencing impaired vascular endothelial growth factor expression, which regulates tumor angiogenesis. Furthermore, p38α knockdown inhibited cell proliferation in melanoma cells. In addition, silencing p38α induced senescence-like features, but not cell cycle arrest. Expression of the senescence markers p16, p21, p53 and β-galactosidase was upregulated, and an increase in the number of senescence-associated β-galactosidase-positive cells was observed in a p38α knockdown stable clone. However, no significant difference was found between control and p38β stable knockdown cells. Taken together, the present results suggested that p38α knockdown impaired migration and proliferation, and increased senescence, in A375 melanoma cells. However, p38β may not be involved in melanoma tumorigenesis. Therefore, targeting p38α may be a valuable approach towards inhibiting tumor growth and metastasis in patients with melanoma.

Extracellular matrix: the gatekeeper of tumor angiogenesis.

The extracellular matrix is a network of secreted macromolecules that provides a harmonious meshwork for the growth and homeostatic development of organisms. It conveys multiple signaling cascades affecting specific surface receptors that impact cell behavior. During cancer growth, this bioactive meshwork is remodeled and enriched in newly formed blood vessels, which provide nutrients and oxygen to the growing tumor cells. Remodeling of the tumor microenvironment leads to the formation of bioactive fragments that may have a distinct function from their parent molecules, and the balance among these factors directly influence cell viability and metastatic progression. Indeed, the matrix acts as a gatekeeper by regulating the access of cancer cells to nutrients. Here, we will critically evaluate the role of selected matrix constituents in regulating tumor angiogenesis and provide up-to-date information concerning their primary mechanisms of action.

Metal-Organic Frameworks@Thermosensitive Hydrogel as Injectable Implant for Dual Drug Synergistic Oral Cancer Therapy

Local cancer therapy with multiple drugs has emerged as a novel therapeutic approach for facilitating the sustained delivery of therapeutic molecules that effectively suppress tumor growth. In this study, we developed a hybrid nanocomposite in which metal-organic frameworks (MOFs) were integrated with thermosensitive hydrogels to devise an injectable implant. Doxorubicin (Dox) and celecoxib (Cel) were coloaded into the system for localized oral cancer therapy (Dox/Cel/MOFs@Gel). This medical platform exhibited a high capacity for drug loading, steady and pH-responsive release of dual drugs, and enhanced toxic effects against oral cancer cells (KB and SCC-9) in vitro. The nanocomposites displayed outstanding tumor inhibition efficacy in vivo, inducing tumor apoptosis and regulating tumor angiogenesis due to the synergistic effects of Dox and Cel. It was found that this local treatment resulted in considerably lower systemic toxicity and no apparent injury to the other organs. The biocompatibility test of the MOFs that constructed the nanocomposite indicated reasonable biosafety in vivo as no evidence of persistent toxicity was observed. The results of this study demonstrate that the injectable nanocomposite (Dox/Cel/MOFs@Gel) possesses unique biological abilities in terms of pH-responsiveness, antitumor efficacy, and biocompatibility, suggesting that the nanocomposite is a promising vehicle for local oral cancer treatment.

Tumor Angiogenesis Is Differentially Regulated by Phosphorylation of Endothelial Cell Focal Adhesion Kinase Tyrosines-397 and -861.

Expression of focal adhesion kinase (FAK) in endothelial cells (EC) is essential for angiogenesis, but how FAK phosphorylation at tyrosine-(Y)397 and Y861 regulate tumor angiogenesis in vivo is unknown. Here, we show that tumor growth and angiogenesis are constitutively reduced in inducible, ECCre+;FAKY397F/Y397F -mutant mice. Conversely, ECCre+;FAKY861F/Y861F mice exhibit normal tumor growth with an initial reduction in angiogenesis that recovered in end-stage tumors. Mechanistically, FAK-Y397F ECs exhibit increased Tie2 expression, reduced Vegfr2 expression, decreased β1 integrin activation, and disrupted downstream FAK/Src/PI3K(p55)/Akt signaling. In contrast, FAK-Y861F ECs showed decreased Vegfr2 and Tie2 expression with an enhancement in β1 integrin activation. This corresponds with a decrease in Vegfa-stimulated response, but an increase in Vegfa+Ang2- or conditioned medium from tumor cell-stimulated cellular/angiogenic responses, mimicking responses in end-stage tumors with elevated Ang2 levels. Mechanistically, FAK-Y861F, but not FAK-Y397F ECs showed enhanced p190RhoGEF/P130Cas-dependent signaling that is required for the elevated responses to Vegfa+Ang2. This study establishes the differential requirements of EC-FAK-Y397 and EC-FAK-Y861 phosphorylation in the regulation of EC signaling and tumor angiogenesis in vivo. SIGNIFICANCE: Distinct motifs of the focal adhesion kinase differentially regulate tumor blood vessel formation and remodeling.

Controlling the Phenotype of Tumor-Infiltrating Macrophages via the PHD-HIF Axis Inhibits Tumor Growth in a Mouse Model.

SummaryThe tumor microenvironment (TME) polarizes tumor-infiltrating macrophages toward tumor support. Macrophage-abundant tumors are highly malignant and are the cause of poor prognosis and therapeutic resistance. In this study, we show that the prolyl hydroxylase (PHD) inhibitor FG-4592 (FG) inhibits tumor growth of macrophage-abundant tumors and prolongs mouse survival. FG not only normalizes tumor vessels and improves tumor oxygenation but also directly affects macrophages and activates phagocytosis through the PHD-hypoxia-inducible factor (HIF) axis. Remarkably, FG can promote phagocytic ability of the Ly6Clo subset of tumor-infiltrating macrophages, leading to tumor growth inhibition. Moreover, Ly6Cneg macrophages contributed to blood vessel normalization. Using a malignant tumor mouse model, we characterized macrophage function and subsets. Altogether, our findings suggest that the PHD inhibitor can promote the anti-tumor potential of macrophages to improve cancer therapy.

Regulation of tumor angiogenesis and mesenchymal\u2013endothelial transition by p38\u03b1 through TGF-\u03b2 and JNK signaling

The formation of new blood vessels is essential for normal development, tissue repair and tumor growth. Here we show that inhibition of the kinase p38α enhances angiogenesis in human and mouse colon tumors. Mesenchymal cells can contribute to tumor angiogenesis by regulating proliferation and migration of endothelial cells. We show that p38α negatively regulates an angiogenic program in mesenchymal stem/stromal cells (MSCs), multipotent progenitors found in perivascular locations. This program includes the acquisition of an endothelial phenotype by MSCs mediated by both TGF-β and JNK, and negatively regulated by p38α. Abrogation of p38α in mesenchymal cells increases tumorigenesis, which correlates with enhanced angiogenesis. Using genetic models, we show that p38α regulates the acquisition of an endothelial-like phenotype by mesenchymal cells in colon tumors and damage tissue. Taken together, our results indicate that p38α in mesenchymal cells restrains a TGF-β-induced angiogenesis program including their ability to transdifferentiate into endothelial cells.

SIX4 activates Akt and promotes tumor angiogenesis

Angiogenesis plays important roles in solid tumors progression. Growth factors such as vascular endothelial growth factors (VEGFs) can induce angiogenesis and hypoxia promotes the expression of VEGFs through activating hypoxia-inducible factor 1 (HIF-1α). However, the regulation of HIF-1α still not been fully understood. Here, we demonstrate that the Sine Oculis Homeobox Homolog 4 (SIX4) is up-regulated in colorectal cancer (CRC) and high expression of SIX4 predicts a poor prognosis. Overexpression of SIX4 enhances tumor growth and angiogenesis in vitro and in vivo, while knockdown of SIX4 inhibits tumor growth and angiogenesis. Furthermore, we show that SIX4 increases the expression of VEGF-A by coordinating with the HIF-1α. Mechanically, we explore that SIX4 up-regulates the expression of HIF-1α depending on Akt activation. Collectively, we demonstrate that SIX4 is functional in regulating tumor angiogenesis and SIX4 might be used as anti-angiogenic therapy in CRC.

Identifying and targeting angiogenesis-related microRNAs in ovarian cancer.

Current anti-angiogenic therapy for cancer is based mainly on inhibition of the vascular endothelial growth factor pathway. However, due to the transient and only modest benefit from such therapy, additional approaches are needed. Deregulation of microRNAs (miRNAs) has been demonstrated to be involved in tumor angiogenesis and offers opportunities for a new therapeutic approach. However, effective miRNA-delivery systems are needed for such approaches to be successful. In this study, miRNA profiling of patient data sets, along with in vitro and in vivo experiments, revealed that miR-204-5p could promote angiogenesis in ovarian tumors through THBS1. By binding with scavenger receptor class B type 1 (SCARB1), reconstituted high-density lipoprotein-nanoparticles (rHDL-NPs) were effective in delivering miR-204-5p inhibitor (miR-204-5p-inh) to tumor sites to suppress tumor growth. These results offer a new understanding of miR-204-5p in regulating tumor angiogenesis.

Potential Role of HMGCS2 in Tumor Angiogenesis in Colorectal Cancer and Its Potential Use as a Diagnostic Marker.

Objective HMGCS2 is the rate-limiting enzyme of ketogenesis, which is vital for tumor initiation or metastasis. The aim of this study is to determine the relationship between HMGCS2 and tumor angiogenesis. Materials and Methods The study consisted of 100 cases with colorectal cancer and healthy control, the expression of HMGCS2 and the microvessel density (MVD) (marker: CD31) were analyzed by immunohistochemistry and tube formation, and the centration of β-hydroxybutyrate in serum was assessed by biochemical analysis. Results The results showed that HMGCS2 expression is significantly reduced in colorectal cancer compared with healthy control, which is inversely correlated with MVD in colorectal cancer by IHC analysis. What is more, knockdown HMGCS2 expression in HT-29 cells significantly contributed endothelial cell tube formation. Conclusion These findings implying HMGCS2 may have a negative regulation of tumor angiogenesis and provide an approach to inhibit tumor angiogenesis.

Abstract 183: N-myc downstream regulated gene 1 (NDRG1) is indispensable for VEGF-A-induced tumor angiogenesis through PLCγ/ERK signaling activation in vascular endothelial cells

Abstract [Background] Vascular endothelial growth factor (VEGF)-A is a key regulator of tumor angiogenesis that is essential for tumor growth and progression. The unraveling of the precise mechanisms behind VEGF-A-induced tumor angiogenic process will further contribute to development of novel and potent anti-cancer therapeutics. N-myc downstream regulated gene 1 (NDRG1) has been shown to play essential roles in multiple biological processes including embryogenesis, tissue development, cell growth, differentiation, and tumorigenesis. We previously reported that NDRG1 expression levels in cancer cells are closely correlated with tumor angiogenesis and growth (Hosoi et al., Cancer Res., 2009; Murakami et al., J Biol Chem., 2013), and also that NDRG1 promotes tumor angiogenesis through enhanced VEGF-A production by tumor-associated macrophages (Watari et al., Sci Rep., 2016). However, it remains unclear whether NDRG1 expression in vascular endothelial cells (ECs) plays any crucial role in VEGF-A-induced tumor angiogenesis. In our present study, we further ask whether and how NDRG1 in ECs could specifically regulate tumor angiogenesis. We also present our finding of intrinsic importance that NDRG1 functions as an essential factor for VEGF-A-induced angiogenesis. [Methods] NDRG1 deficient mice: The NDRG1 deficient mice on C57BL6 background were purchased from Laboratory Animal Resource Bank, National Institutes of Biomedical Innovation, Health and Nutrition (Osaka, Japan). Isolation of mouse endothelial cells: CD31+ endothelial cells were isolated from mouse lung by magnetic sorting using CD31 MicroBeads. Aortic ring assay: 1 mm mouse aortic rings were embedded in 3-dimensional growth factor reduced Matrigel, treated with or without FGF-2 (50 ng/mL) or VEGF (25 ng/ml), and incubated at 37°C. Vascular length and branching point were measured at day 7. [Results] [1] Analysis of TCGA datasets revealed that NDRG1 expression was positively correlated with VEGF-A expression in patients with various cancer types. [2] In breast cancer patients in Kurume University hospital, NDRG1 was expressed in both cancer cells and ECs. In NDRG1 deficient mice, we observed following experimental results. [3] Both tumor growth and angiogenesis were all suppressed in syngeneic tumors. [4] VEGF-A-induced angiogenesis was specifically impaired in corneal micropocket assay and aortic ring assay, whereas FGF-2 could induce angiogenesis in both assays. [5] NDRG1 formed a complex with PLC-γ, and this complex formation was requisite for the VEGF-A-induced PLCγ/ERK activation in ECs. [Conclusion] We first present an indispensable role of NDRG1 in VEGF-A-induced angiogenesis through PLCγ/ERK activation in ECs. The NDRG1 could be a novel candidate target for development of therapeutics for VEGF-A-induced tumor angiogenesis and other vascular diseases. Citation Format: Kosuke Watari, Tomohiro Shibata, Ai Shinoda, Hideyuki Abe, Akihiko Kawahara, Yuichi Murakami, Eiji Oki, Jun Akiba, Yoshihiko Maehara, Michihiko Kuwano, Mayumi Ono. N-myc downstream regulated gene 1 (NDRG1) is indispensable for VEGF-A-induced tumor angiogenesis through PLCγ/ERK signaling activation in vascular endothelial cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 183.

Abstract 206: miR551b-mediated tumor-specific angiogenesis in ovarian cancer

Abstract Background: Ovarian cancer is the most lethal gynecological cancer. Tumor angiogenesis is essential for the progression and metastasis of ovarian cancer. Our data shows that STAT3, HIF-1α and VEGFA are the key regulators of tumor-specific angiogenesis. Our studies have provided evidence that VEGF is directly regulated by STAT3 in miR551b-3p expressing cells, which indicates that STAT3 is an important regulator of angiogenesis in a subset of ovarian cancers. Recently, we showed that miR551b-3p acts as an upstream regulator of STAT3 in ovarian cancer cells. We identified that anti-miR551b-3p inhibit the expression of miR551b-3p disrupt tumor-specific angiogenesis by preventing the expression of HIF-1α and VEGFA through direct inhibition of STAT3. Methods: In this study, we explored the role of miR551b on angiogenesis in ovarian cancer cells by performing cell proliferation, western blot and qPCR of angiogenic markers, in vitro capillary tube formation, in vivo matrigel plug assay and ex-vivo aortic ring assays. Results: We found that miR551b-3p upregulates STAT3, HIF-1α, VEGFR and VEGF in ovarian cancer cells and increases the abilities of cell proliferation, migration and tube formation of human umbilical vein endothelial (HUVEC) cells. In conjunction, knockdown of miR-551b decreased the level of STAT3, HIF-1α and VEGFR2 proteins as well as the angiogenic activity; also increased cellular apoptosis. Altogether, our data suggest critical roles of miR-551b on STAT-3–mediated angiogenesis in ovarian cancer cells. In complement to our in vitro results, the delivery of anti-miR551b inhibited angiogenesis in the matrigel plug injected in nude mice. Furthermore, the treatment of anti-miR551b reduced the angiogenic sprouting from rat thoracic aorta in our ex vivo culture. Taken together, our findings provide the first evidence that miR-551b is a pivotal regulator of tumor angiogenesis and inhibiting miR551b could be used to inhibit tumor-specific angiogenesis in ovarian cancer. Conclusions: miR551b markedly augmented the pro-angiogenic effects in vitro, in vivo and ex-vivo models. Our data suggest that miR551b is an actionable target to disrupt tumor-specific angiogenesis in ovarian cancer. In our pre-clinical model, we are using anti-miR551b encapsulated in nanoliposomes for in vivo delivery to inhibit and sensitize anti- angiogenic therapy and chemotherapy. We expect that the completion of our studies will identify novel mechanisms regulate tumor-specific angiogenesis and novel targets to treat ovarian cancer patients. Citation Format: Deepak Parashar, Anjali Geethadevi, Jasmine George, Gopakumar Gopinathan Nair, Changliang Chen, Sunila Pradeep, Pradeep Chaluvally-Raghavan. miR551b-mediated tumor-specific angiogenesis in ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 206.