Potent Anti-angiogenic Compound Research Articles

Inhibition of angiogenesis and metastasis in colorectal cancer cell lines through KRAS-associated signaling pathways by 2-methoxy-6-undecyl-1,4-benzoquinone

Colorectal cancer (CRC), the third most prevalent cancer globally, presents formidable hurdles in treatment owing to factors such as therapeutic resistance and genetic mutations affecting primary drug targets. 2-methoxy-6-undecyl-1,4-benzoquinone (BQ), derived from Ardisia crispa roots, has emerged as a potent anti-inflammatory and anti-angiogenic compound with substantial potential, as evidenced by previous studies. This study aimed to explore the potential of BQ in suppressing angiogenesis and metastasis in the human CRC cell lines LoVo and HCT116. Various in vitro and in silico studies have been conducted to elucidate the potential pathway(s) of BQ. BQ was highly cytotoxic, with an IC50 of 7.01 ± 0.6 μM in HCT116 and 9.58 ± 0.8 μM in LoVo cells. Moreover, BQ induced notable apoptotic activity and suppressed migration, invasion, and adhesion in both cell lines. The inhibition of MMP-2 suggests the potential of BQ to impede extracellular matrix degradation and CRC cell metastasis. BQ inhibits the expression of key proteins involved in angiogenesis and metastasis, including VEGF-A, VEGF-C, BRAF, ERK, KRAS, PI3K, and AKT. Molecular docking simulations illustrated the robust binding of BQ to CRC protein receptors. BQ holds promise in impeding CRC progression by targeting angiogenesis and metastasis, particularly through inhibition of the KRAS/BRAF/ERK and KRAS/PI3K/AKT signaling pathways.

Danthron, an Anthraquinone Isolated from a Marine Fungus, Is a New Inhibitor of Angiogenesis Exhibiting Interesting Antitumor and Antioxidant Properties.

The role played by a sustained angiogenesis in cancer and other diseases stimulates the interest in the search for new antiangiogenic drugs. In this manuscript, we provide evidence that 1,8- dihydroxy-9,10-anthraquinone (danthron), isolated from the fermentation broth of the marine fungus Chromolaenicola sp. (HL-114-33-R04), is a new inhibitor of angiogenesis. The results obtained with the in vivo CAM assay indicate that danthron is a potent antiangiogenic compound. In vitro studies with human umbilical endothelial cells (HUVEC) reveal that this anthraquinone inhibits certain key functions of activated endothelial cells, including proliferation, proteolytic and invasive capabilities and tube formation. In vitro studies with human breast carcinoma MDA-MB231 and fibrosarcoma HT1080 cell lines suggest a moderate antitumor and antimetastatic activity of this compound. Antioxidant properties of danthron are evidenced by the observation that it reduces the intracellular reactive oxygen species production and increases the amount of intracellular sulfhydryl groups in endothelial and tumor cells. These results support a putative role of danthron as a new antiangiogenic drug with potential application in the treatment and angioprevention of cancer and other angiogenesis-dependent diseases.

New anti-angiogenic compound based on chemically modified heparin.

The purpose of this study was to measure the anti-angiogenic effect of N-desulfated Re-N-acetylated, a chemically modified heparin (mHep). In vitro assays (cell tube formation, viability, proliferation, and migration) with endothelial cells were performed after 24h of treatment with mHep at 10, 100, and 1000ng/mL or saline. In vivo tests were performed after laser-induced choroidal neovascularization (CNV) in rats, followed by an intravitreal injection (5 µL) of mHep (10, 100, 1000ng/mL) or balanced salt solution. Immunofluorescence analysis of the CNV was performed after 14days. mHep produced a statistically significant reduction in cell proliferation, tube formation, and migration, without cell viability changes when compared to saline. Mean measures of CNV area were 54.84 × 106 pixels/mm (± 12.41 × 106), 58.77 × 106 pixels/mm (± 17.52 × 106), and 59.42 × 106 pixels/mm (± 17.33 × 106) in groups 100, 1000, and 10,000ng/mL, respectively, while in the control group, mean area was 72.23 × 106 (± 16.51 × 106). The P value was 0.0065. Perimeter analysis also demonstrated statistical significance (P = 0.0235) with the mean measure of 93.55 × 104, 94.23 × 104, and 102 × 104 in the 100ng/mL, 1000ng/mL, and control groups, respectively. These results suggest that mHep N-DRN is a potent anti-angiogenic, anti-proliferative, and anti-migratory compound with negligible anticoagulant or hemorrhagic action and no cytotoxicity for retina cells. This compound may serve as a candidate for treating choroidal neovascularization.

Development of Novel VEGFR2 Inhibitors Originating from Natural Product Analogues with Antiangiogenic Impact.

A novel natural small molecule, voacangine (Voa), has been discovered as a potent antiangiogenic compound. Notably, Voa directly binds the kinase domain of the vascular endothelial growth factor receptor 2 (VEGFR2) and thereby inhibits downstream signaling. Herein, we developed synthetic small molecules based on the unique chemical structure of Voa that directly and specifically target and modulate the kinase activity of VEGFR2. Among these Voa structure analogues, Voa analogue 19 (V19) exhibited increased antiangiogenic potency against VEGF-induced VEGFR2 phosphorylation without cytotoxic effects. Moreover, treatment with V19 resulted in significant tumor cell death in a mouse xenograft model. In conclusion, this new VEGFR2 modulator, inspired from the rigid scaffold of a natural compound, Voa, is presented as a potent candidate in the development of new antiangiogenic agents.

1337P Clinical study of apatinib combined with radiation therapy in advanced non-small cell lung cancer patients with brain metastasis

Radiotherapy of the whole brain has been the basis in the treatment of non-small cell lung cancer (NSCLC) patients (pts) with brain metastasis, which can improve the rate of survival and reduce the rate of local recurrence. However, the prognosis for such patients remains poor. Previous studies had suggested that antiangiogenic drugs combined with radiation therapy might prevent the progression of disease. Apatinib is a potent antiangiogenic compound directed at the vascular endothelial growth factor receptor-2 (VEGFR-2).

Reversible Bevacizumab Induced Vocal Fold Necrosis

As the use of anti-angiogenic treatments is gaining scope in the treatment of various malignancies, there are increasing reports of laryngeal side effects. We report two cases of laryngeal necrosis and dysphonia. Two patients with gynecological malignancies presented with severe dysphonia 11-24 months after initiation of bevacizumab therapy. Videostroboscopic examination of the larynx revealed bilateral ulcerations and eschar of the superior surface with absent mucosal waves. Patients were treated with discontinuation of the bevacizumab, vocal rest, and proton pump inhibitors. Both had improvement in voice and resolution of the eschar and ulceration. Shallow sulci and mild breathiness persisted in one patient. With increasing use of potent systemic anti-angiogenic compounds, clinicians should be vigilant of this important complication of therapy. Time to onset of symptoms and reversibility of symptoms vary by patient and require further study. There may be long-term voice sequelae.

The strigolactone analog GR-24 inhibits angiogenesis in vivo and in vitro by a mechanism involving cytoskeletal reorganization and VEGFR2 signalling

Phytohormones have shown great potential as natural anticancer compounds, being interesting in cancer prevention and therapy. Strigolactones are a class of plant hormones involved in the inhibition of root branching and sprouting. The antiproliferative capacity of the synthetic strigolactone analog GR-24 has been described against breast cancer cell lines in vitro. In this study, we show for the first time that GR-24 is a potent antiangiogenic compound in vivo and in vitro. In the in vivo tests, GR-24 shows a great inhibitory effect on vasculature formation in the chicken chorioallantoic membrane and in two different zebrafish models. Our in vitro results show that GR-24 inhibits the growth of endothelial cells and different cancer cell lines with a micromolar range of half inhibitory concentration (IC50) values. In addition, GR-24 inhibits key steps of the angiogenic process in vitro, such as tubulogenesis, invasion, extracellular matrix remodeling capacity, migration and adhesion of endothelial cells at non-cytotoxic concentrations. Our data point to an effect of GR-24 on cytoskeleton organization in endothelial cells, in addition to a decrease in focal adhesion kinase (FAK) presence in these cells. All these data, together with the observed increase in surface expression of vascular endothelial-cadherin (VE-cadherin) and platelet and endothelial cell adhesion molecule 1 (PECAM-1), suggest that GR-24 prevents angiogenesis by maintaining the quiescent phenotype in endothelial cells. The proposed mechanism of action underlying the antiangiogenic activity of GR-24 involves the inhibition of VEGFR2 phosphorylation, and the downstream reduction in activation of FAK, a key regulator protein implicated in angiogenesis. Our results suggest that GR-24 may be a promising new compound for antiangiogenic therapy of cancer and other angiogenesis-dependent diseases.

1,4-dihydroxy quininib attenuates growth of colorectal cancer cells and xenografts and regulates the TIE-2 signaling pathway in patient tumours.

ABSTRACTColorectal cancer (CRC) is the second leading cause of cancer associated deaths in developed countries. Cancer progression and metastatic spread is reliant on new blood vasculature, or angiogenesis. Tumour-related angiogenesis is regulated by pro- and anti-angiogenic factors secreted from malignant tissue in a stepwise process. Previously we structurally modified the small anti-angiogenic molecule quininib and discovered a more potent anti-angiogenic compound 1, 4 dihydroxy quininib (Q8), an antagonist of cysteinyl leukotriene receptor-1 with VEGF-independent bioactivity. Here, Q8, quininib (Q1) and five structural analogues were assayed for anti-tumorigenic effects in pre-clinical cancer models. Q8 reduced clone formation of the human colorectal cancer cell line HT29-Luc2. Gene silencing of CysLT1 in HT29-Luc2 cells significantly reduced expression of calpain-2. In human ex vivo colorectal cancer tumour explants, Q8 significantly decreased the secretion of both TIE-2 and VCAM-1 expression. In vivo Q8 was well tolerated up to 50 mg/kg by Balb/C mice and significantly more effective at reducing tumour volume in colorectal tumour xenografts compared to the parent drug quininib. In tumour xenografts, Q8 significantly reduced expression of the angiogenic marker calpain-2. In summary, we propose Q8 may act on the TIE-2-Angiopoietin signalling pathway to significantly inhibit the process of tumour angiogenesis in colorectal cancer.

Design, synthesis and antitumour and anti-angiogenesis evaluation of 22 moscatilin derivatives.

Two series of moscatilin derivatives were designed, synthesized and evaluated as anti-tumor and anti-angiogenesis agents. Most of these compounds showed moderate-to-obvious cytotoxicity against five cancer cell lines (A549, HepG2, MDA-MB-231, MKN-45, HCT116). Among these cell lines, compounds had obvious effects on HCT116. Especially for 8Ae, the IC50 was low to 0.25 μM. 8Ae can inhibit the viability and induce the apoptosis of HCT116 cells but exhibit no cytotoxic activity in noncancerous NCM460 colon cells. 8Ae can also arrest the G2/M cell cycle in HCT116 cells by inhibiting the α-tubulin expression. Zebrafish bioassay-guided screen showed the 22 moscatilin derivatives had potent anti-angiogenic activities and compound 8Ae had better activities than positive compound. Molecular docking indicated 8Ae interacted with tubulin at the affinity of -7.2 Kcal/mol. In conclusion, compound 8Ae was a potential antitumor and anti-angiogenesis candidate for further development.

Efficacy of Melflufen, a Peptidase Targeted Therapy, and Dexamethasone in an Ongoing Open-Label Phase 2a Study in Patients with Relapsed and Relapsed-Refractory Multiple Myeloma (RRMM) Including an Initial Report on Progression Free Survival

Background:Melflufen is a highly potent anti-angiogenic compound that triggers rapid, robust and irreversible DNA damage and exerts its cytotoxicity through alkylation of DNA. The lipophilicity of melflufen leads to rapid and extensive distribution into tissues and cells where it binds directly to DNA or is readily metabolized by intracellular peptidases into hydrophilic alkylating metabolites. With targeted delivery of alkylating metabolites to tumor cells in vitro (such as multiple myeloma that are rich in activating peptidase), melflufen exerts a 20-100 fold higher anti-tumor potency and produces a 20 fold higher intracellular concentration of alkylating moieties compared with melphalan.Methods:Melflufen is evaluated in combination with dexamethasone (dex) 40 mg weekly in an ongoing Phase 1/2a study. RRMM patients with measurable disease and at least 2 prior lines of therapy are eligible (NCT01897714). Phase 1 established the maximum tolerated dose (MTD) of melflufen to be 40 mg every 3 weeks in combination with low dose dex. The primary objective of Phase 2a is the overall response rate and safety of the MTD in a total of 55 patients. Response was investigator assessed at the end of each cycle by IMWG criteria. Here we present the Phase 2 data as of 14 July 2015 data-cut.Results:Thirty-one patients were dosed at the MTD. The median time from initial diagnosis to first dose of melflufen was 6 years (1-15). The median number of prior therapies was 4 (2-9). 97% of patients were exposed to immunomodulatory drugs (IMiDs), 90% to proteasome inhibitors (PIs), 77% to melphalan, and 71% had received prior autologous stem cell transplant. 58% were double refractory (IMiDs and PIs) and 42% were triple refractory (IMiDs, PIs and alkylators). In total, 121 doses of melflufen have been given (1-11 cycles). Median treatment duration was 13 weeks with 9 patients still ongoing. One patient completed therapy as planned, 15 patients discontinued due to AEs (48%) and 6 due to progression (19%).Twenty-three patients were evaluable for response (protocol defined as ≥2 doses of melflufen with baseline and follow-up response assessments). One patient achieved a very good partial response and 10 patients achieved partial response (PR) (1 unconfirmed, still ongoing) for an overall response rate (ORR) of 48%. Three additional patients achieved minimal response (MR) for a clinical benefit rate (CBR) of 61%. Time to clinical benefit and response was rapid with 93% of patients achieving ≥ MR after 1-3 cycles and 64% achieving PR after only 1-3 cycles. Eight patients maintained stable disease and 1 patient had early progressive disease. Similar ORRs were seen in PI-refractory (43%), IMiD-refractory (40%), alkylator-refractory (62%), double-refractory (38%) and triple-refractory (50%) patients. The median progression free survival (PFS) is currently at 7.6 months (95% confidence interval: 3.4 - ∞) based on 14 events in 30 patients.The most frequent adverse events (AE), all grades, occurring in >10% of patients, regardless of relationship to study drug were thrombocytopenia (94%), anemia (84%), neutropenia (61%), leukopenia (42%), pyrexia (36%), asthenia (32%), fatigue and nausea (26%), bone pain (19%), cough, diarrhea, dyspnea, mucosal inflammation and upper respiratory infection (16%) and constipation and epistaxis (13%). Treatment-related Grade 3 or 4 AEs were reported in 27 patients (87%). Those occurring in >5% of patients were thrombocytopenia (68%), neutropenia (55%), anemia (42%), leukopenia (32%) and febrile neutropenia, fatigue, pyrexia, asthenia and hyperglycemia each occurred in 6% of patients. Serious AEs occurred in 9 patients (29%), but were only assessed as related to study drug in 5 patients (16%) including 3 febrile neutropenia, 1 fever and 1 pneumonia. Cycle length has recently been increased to 28 days to improve tolerability with respect to hematologic toxicity.Conclusion:Melflufen has promising activity in heavily pretreated RRMM patients where conventional therapies have failed. The current ORR is 48% and CBR is 61%. Similar results were seen across patient populations regardless of refractory status. The median PFS is encouraging at 7.6 months. Hematologic toxicity was common, but non-hematologic AEs were infrequent. Updated results will be presented at the meeting. DisclosuresVoorhees:Millennium/Takeda and Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Array BioPharma, Celgene, GlaxoSmithKline, and Oncopeptides: Consultancy; Janssen, Celgene, GlaxoSmithKline,Onyx Pharmaceuticals and Oncopeptides: Consultancy, Research Funding. Sonneveld:Janssen: Speakers Bureau; Takeda: Research Funding; Celgene and Onyx: Research Funding, Speakers Bureau. Plesner:Roche and Novartis: Research Funding; Janssen and Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Genmab: Membership on an entity's Board of Directors or advisory committees. Mellqvist:Celgene, Amgen, Mundipharma and Novartis: Honoraria. Byrne:Oncopeptides: Consultancy. Harmenberg:Oncopeptides: Consultancy. Nordstrom:Oncopeptides: Employment. Palumbo:Amgen: Consultancy, Honoraria; Onyx: Consultancy, Honoraria; Array BioPharma: Honoraria; Millennium: Consultancy, Honoraria; Bristol-Myers Squibb: Consultancy, Honoraria; Genmab A/S: Consultancy, Honoraria; Janssen-Cilag: Consultancy, Honoraria; Sanofi-Aventis: Honoraria. Richardson:Oncopeptides, Celgene and Takeda: Membership on an entity's Board of Directors or advisory committees.

K20E, an oxidative-coupling compound of methyl caffeate, exhibits anti-angiogenic activities through down-regulations of VEGF and VEGF receptor-2

Anti-angiogenesis is one of the most popular clinical interventions for cancer chemotherapy. A series of synthesized derivative of methyl caffeate were used to evaluate the anti-angiogenic activity and to investigate possible pharmacological mechanisms in the present study. The most potent anti-angiogenic compound was evaluated in the experiments of murine allograft tumor model and Matrigel plug assay as well as cell models in the human umbilical vascular endothelial cells (HUVECs) and the LLC1 lung cancer cells. Our results suggested that K20E suppressed the tumor growth in the allograft tumor model and exhibited anti-angiogenic activity in Matrigel plug assay. Besides, HUVEC viability was found to be significantly reduced by arresting cell cycle at G2/M phase and apoptosis. Cell migration, invasion, and tube formation of the HUVECs were also markedly suppressed by K20E treatment. K20E largely down-regulated the intracellular and secreted vascular endothelial growth factor (VEGF) in the LLC1 cancer cells. Besides, VEGF receptor-2 (VEGFR-2) and its downstream signaling cascades (AKT-mTOR and MEK1/2-ERK1/2) as well as gelatinases were all evidently reduced in the HUVECs treated with K20E. Inversely, K20E can up-regulate the expression levels of p53 and p21 proteins in the HUVECs. Based on these results, our study suggested that K20E possessed inhibiting angiogenesis through regulation of VEGF/VEGFR-2 and its downstream signaling cascades in the vascular endothelial cells (VECs).

The Brominated Compound Aeroplysinin-1 Inhibits Proliferation and the Expression of Key Pro- Inflammatory Molecules in Human Endothelial and Monocyte Cells

Aeroplysinin-1 is a brominated antibiotic used by some sponges for defense against bacterial pathogen invasion. Aeroplysinin-1 has a wide spectrum of anti-tumoral action and behaves as a potent anti-angiogenic compound for bovine aortic endothelial cells. In this study, we demonstrate anti-angiogenic effects of aeroplysinin-1 on human endothelial cells. Furthermore, the response of angiogenesis related genes to aeroplysinin-1 treatment was studied in human endothelial cells by using gene arrays. The major changes were observed in thrombospondin 1 (TSP-1) and monocyte chemoattractant protein-1 (MCP-1), both of which were down-regulated. These inhibitory effects of aeroplysinin-1 were confirmed by using independent experimental approaches. To have a deeper insight on the anti-inflammatory effects of aeroplysinin-1 in endothelial cells, cytokine arrays were also used. This experimental approach confirmed effects on MCP-1 and TSP-1 and showed down-regulation of several other cytokines. Western blotting experiments confirmed down-regulation of ELTD1 (EGF, latrophilin and seven transmembrane domain-containing protein 1), interleukin 1α and matrix metalloproteinase 1 (MMP-1). These results along with our observation of a dramatic inhibitory effect of aeroplysinin-1 on cyclooxygenase-2 protein expression levels in endothelial cells and a human monocyte cell line suggest that aeroplysinin-1 could be a novel anti-inflammatory compound with potential pharmacological interest.

Vixapatin (VP12), a c-type lectin-protein from Vipera xantina palestinae venom: characterization as a novel anti-angiogenic compound.

A C-type lectin-like protein (CTL), originally identified as VP12 and lately named Vixapatin, was isolated and characterized from Israeli viper Vipera xantina palestinae snake venom. This CTL was characterized as a selective α2β1 integrin inhibitor with anti-melanoma metastatic activity. The major aim of the present study was to prove the possibility that this protein is also a potent novel anti-angiogenic compound. Using an adhesion assay, we demonstrated that Vixapatin selectively and potently inhibited the α2 mediated adhesion of K562 over-expressing cells, with IC50 of 3 nM. 3 nM Vixapatin blocked proliferation of human dermal microvascular endothelial cells (HDMEC); 25 nM inhibited collagen I induced migration of human fibrosarcoma HT-1080 cells; and 50 nM rat C6 glioma and human breast carcinoma MDA-MB-231 cells. 1 µM Vixapatin reduced HDMEC tube formation by 75% in a Matrigel assay. Furthermore, 1 µM Vixapatin decreased by 70% bFGF-induced physiological angiogenesis, and by 94% C6 glioma-induced pathological angiogenesis, in shell-less embryonic quail chorioallantoic membrane assay. Vixapatin’s ability to inhibit all steps of the angiogenesis process suggest that it is a novel pharmacological tool for studying α2β1 integrin mediated angiogenesis and a lead compound for the development of a novel anti-angiogenic/angiostatic/anti-cancer drug.

The Antiangiogenic Compound Aeroplysinin-1 Induces Apoptosis in Endothelial Cells by Activating the Mitochondrial Pathway

Aeroplysinin-1 is a brominated metabolite extracted from the marine sponge Aplysina aerophoba that has been previously characterized by our group as a potent antiangiogenic compound in vitro and in vivo. In this work, we provide evidence of a selective induction of apoptosis by aeroplysinin-1 in endothelial cells. Studies on the nuclear morphology of treated cells revealed that aeroplysinin-1 induces chromatin condensation and nuclear fragmentation, and it increases the percentage of cells with sub-diploid DNA content in endothelial, but not in HCT-116, human colon carcinoma and HT-1080 human fibrosarcoma cells. Treatment of endothelial cells with aeroplysinin-1 induces activation of caspases-2, -3, -8 and -9, as well as the cleavage of apoptotic substrates, such as poly (ADP-ribose) polymerase and lamin-A in a caspase-dependent mechanism. Our data indicate a relevant role of the mitochondria in the apoptogenic activity of this compound. The observation that aeroplysinin-1 prevents the phosphorylation of Bad relates to the mitochondria-mediated induction of apoptosis by this compound.

Synthetic 2-Methoxyestradiol Derivatives: Structure-Activity Relationships

2-Methoxyestradiol (2ME2), a natural metabolite of estradiol which has no estrogenic activity, is a potent antitumor and anti-angiogenic compound, currently undergoing clinical trials for treatment of a variety of cancers. In the last two decades, an ever increasing number of synthetic 2-methoxyestradiol analogues have been reported. Structural changes include A/B/C/D-rings modification, homologation, aromatization, and introduction of various substituents on C-2 position along with substitution of alkyl and ethynyl groups for the 17-hydroxy function. In this review, an attempt has been made to compile the structure-activity relationships of various synthesized 2-methoxyestradiol analogues.

Fumagillin and Structurally Related Molecules as Source of New Drugs

Cancer is one of the most prolific causes of death all around the world. Currently there is a huge focus around the globe on the identification of effective drugs against this disease. One important target is the development of new anti-angiogenic compounds. Fumagillin and other structurally related molecules are some of the most potent anti-angiogenic compounds reported to date with several currently being investigated in clinical studies. Fumagillin has been used for more than 50 years against microsporidial parasites in animals, however, angiogenesis inhibition constitutes a new activity and an important research topic, this is the reason why nowadays some teams are working to achieve an effective way to obtain fumagillin analogues with more potent anti-angiogenic activity. Here we present an overview on fumagillin and fumagillin analogues as leads products; we summarize the key structural features for antiangiogenic activity and discuss the total synthesis and synthesis of analogues and their biological activity.

A novel angiopoietin‐derived peptide displays anti‐angiogenic activity and inhibits tumour‐induced and retinal neovascularization

Pathological angiogenesis is associated with various human diseases, such as cancer, autoimmune diseases and retinopathy. The angiopoietin (Ang)-Tie2 system plays critical roles in several steps of angiogenic remodelling. Here, we have investigated the anti-angiogenic effect of a novel angiopoietin-derived peptide. Using computational methods, we identified peptides from helical segments within angiopoietins, which were predicted to inhibit their activity. These peptides were tested using biochemical methods and models of angiogenesis. The peptide with best efficacy, A11, was selected for further characterization as an anti-angiogenic compound. The potent anti-angiogenic activity of A11 was demonstrated in a multicellular assay of angiogenesis and in the chorioallantoic membrane model. A11 bound to angiopoietins and reduced the binding of Ang-2 to Tie2. A11 was also significantly reduced vascular density in a model of tumour-induced angiogenesis. Its ability to inhibit Ang-2 but not Ang-1-induced endothelial cell migration, and to down-regulate Tie2 levels in tumour microvessels, suggests that A11 targets the Ang-Tie2 pathway. In a rat model of oxygen-induced retinopathy, A11 strongly inhibited retinal angiogenesis. Moreover, combination of A11 with an anti-VEGF antibody showed a trend for further inhibition of angiogenesis, suggesting an additive effect. Our results indicate that A11 is a potent anti-angiogenic compound, through modulation of the Ang-Tie2 system, underlining its potential as a therapeutic agent for the treatment of ocular and tumour neovascularization, as well as other pathological conditions that are dependent on angiogenesis.

121 Identification, validation and mechanisms of action of novel therapeutic compounds modulating angiogenesis

Abnormal angiogenesis is a signature feature in over 70 health conditions and is critical for tumour growth and metastasis. Therefore, discovering novel therapeutic compounds, that stimulate or abrogate this biological process would be, potentially, clinically invaluable. The zebrafish has emerged as an important model for studying vascular development and angiogenesis. Advantages over other models include rapid embryonic development and optical clarity of the embryos. The small body size of the zebrafish embryo and accessibility of embryonic developmental structures within water make zebrafish embryos suitable for high through-put drug screens. We performed an angiogenesis chemical genetic screen with two compound libraries (LOPAC and Spectrum Collection) using Flk1:EGFP (fluorescently labelled endothelial cells) transgenic zebrafish embryos. The compound bioactivity was measured by numbers of the zebrafish trunk intersegmental vessel (ISV) number. The screens were performed in 96 well plates and a total of ten antiangiogenic compounds and three proangiogenic compounds were identified. A CFI-funded high throughput screening facility will be use for identification of more lead compounds. The goal of the current study was to validate the potential therapeutic efficacy of selected compounds and investigate their molecular mechanisms. Retinoic acid p-hydroxyanilide (4HPR; Fenretinide) was identified as a pro-angiogenic compound. At 4 μM, 4HPR promoted ISV development with increased ISV numbers (ISV = 32.82 ± 0.98; control ISV = 27.58 ± 0.76; P < 0.05). In HUVEC cell proliferation assay, 4HPR stimulated human endothelial cell proliferation at low molar concentrations (0.06-0.12 μM). The effects of this compound on physiological angiogenesis are currently being tested on larvae and adult zebrafish fin regeneration models. Indirubin-3-oxime (IO) was identified as a very potent antiangiogenic compound, which inhibited zebrafish ISV development in a dose-dependent manner (Fig. 1). At 16 μM, IO almost completely inhibited ISV development. In tissue regeneration models, IO inhibited larval and adult zebrafish fin regeneration. The efficacy of IO in cancer therapy will be further studied in a zebrafish cancer metastasis model. Possible molecular mechanisms responsible for IO and 4HPR action such as VEGF and notch signaling will be studied. Using the zebrafish chemical genetic screen, we demonstrated that indirubin-3-oxime is a potent angiogenic inhibitor which inhibits zebrafish angiogenesis and fin regeneration. IO may prove to be effective as an anti-cancer drug. Retinoic acid p-hydroxyanilide was identified as a pro-angiogenic effector, which may be clinically effective in promoting tissue regeneration and in treatment of myocardial infarction.

Coupling In vitro and In vivo Paradigm Reveals a Dose Dependent Inhibition of Angiogenesis Followed by Initiation of Autophagy by C6-Ceramide

The activity of N-hexanoyl-D-erythro-sphingosine, a C6-ceramide against angiogenesis was tested in vitro and in vivo. The effect of ceramide in inhibiting MCF-7 cancer cells was also determined. The aim of this study was to potentiate the effect of ceramide as anti-angiogenic compound that can regulate tumor induced angiogenesis.C6-ceramide inhibited vascular endothelial growth factor (VEGF)-induced human umbilical vein endothelial cells (HUVEC) tube formation in a dose-dependent manner within 24 hours. Ceramide at concentrations between 12.5 and 25 μM inhibited the viability of MCF-7 cells and reduced VEGF-induced cell migration in 24 hours. At 50 μM, ceramide induced MCF-7 cell death via autophagy as demonstrated by accumulation of MDC in ceramide-treated MCF-7 vacuoles. The expression of VEGF was reduced and the levels of cathepsin D in MCF-7 increased. In vivo, 50 μM ceramide caused a 40% reduction of new vessel formation in the CAM assay within 24 hours. Zebrafish exposed to 100 - 400 μM ceramide had a distinct disruption of blood vessel development at 48 hours post-fertilization. Ceramide-exposed embryos also had primary motoneurons exhibiting abnormal axonal trajectories and ectopic branching. Ceramide induced cell-death was not detected in the zebrafish assay. Collectively, these data indicate that ceramide is a potent anti-angiogenic compound and that the mechanism underlying its anti-angiogenic capabilities does not rely upon the induction of apoptosis.

Novel pyrazole derivatives: Synthesis and evaluation of anti-angiogenic activity

The synthesis of a series of novel trisubstituted pyrazole derivatives and their PIFA-mediated conversion to molecules bearing the fused pyrazolo[4,3- c]quinoline ring system is reported. The anti-angiogenic activity of these compounds was evaluated by using in vitro assays for endothelial cell proliferation and migration, and in the chicken chorioallantoic membrane (CAM) assay. Compounds containing the fused pyrazolo[4,3- c]quinoline motifs emerged as potent anti-angiogenic compounds, which also had the ability to inhibit the growth of human breast (MCF-7) and cervical (Hela) carcinoma cells in vitro.