All-trans retinoic acid suppresses the angiopoietin-Tie2 pathway and inhibits angiogenesis and metastasis in esophageal squamous cell carcinoma.

Esophageal squamous cell carcinoma (ESCC) is the second common cancer in Henan province and is well-known for aggressiveness and dismal prognosis. Adjuvant therapies, chemotherapy, radiotherapy and endoscopic treatment have not improved survival rates in patients with late stage esophageal carcinoma. All-trans retinoic acid (ATRA) is the active ingredient of Vitamin A and affects a wide spectrum of biological processes including development, growth, neural function, immune function, reproduction, and vision. It is one of the most potent therapeutic agents used for treating cancers, especially lung adenocarcinomas. ATRA inhibits metastatic potential and angiogenesis in several tumor models. We investigated the effects of ATRA on the expression of angiopoietin 1 (Ang-1), angiopoietin 2 (Ang-2) and receptor Tie-2 in EC1 cells in vitro. We also assessed the growth and migration of EC1 cells in vitro. ATRA treatment caused 29.5% and 40.3% reduction of the growth of EC1 cells after 24 hours and 48 hours, relative to the control. ATRA plus fluorouracil treatment reduced the viability more strongly than either drug alone, indicating an additive effect. Moreover, ATRA decreased EC1 migration by 87%. Furthermore, ATRA treatment led to a marked decrease of the transcript levels of Ang-1, Ang-2, Tie-2, VEGF, and VEGF receptors, as assessed by real-time RT-PCR. Importantly, the protein levels of Ang-1, Ang-2 and Tie-2 were reduced by ATRA treatment. In vivo, we found ATRA treatment suppressed the tumor growth and improved the cachexia of mice. Importantly, ATRA treatment decreased the expression of CD31, Ang-1, Ang-2 and Tie-2 in subcutaneous tumors of EC1 cells. Collectively, our findings demonstrate that ATRA exhibits a dose- and temporal-dependent effect on the metastatic behavior, suppresses the angiopoietin-Tie2 pathway and inhibits angiogenesis and the progression of xenograft tumors of EC1 cells.

Single-dose local simvastatin injection improves implant fixation via increased angiogenesis and bone formation in an ovariectomized rat model.

BACKGROUND: Statins have been reported to promote bone formation. However, taken orally, their bioavailability is low to the bones. Implant therapies require a local repair response, topical application of osteoinductive agents, or biomaterials that promote implant fixation. MATERIAL/METHODS: The present study evaluated the effect of a single local injection of simvastatin on screw fixation in an ovariectomized rat model of osteoporosis. RESULTS: Dual-energy X-ray absorptiometry, micro-computed tomography, histology, and biomechanical tests revealed that 5 and 10 mg simvastatin significantly improved bone mineral density by 18.2% and 22.4%, respectively (P<0.05); increased bone volume fraction by 51.0% and 57.9%, trabecular thickness by 16.4% and 18.9%, trabeculae number by 112.0% and 107.1%, and percentage of osseointegration by 115.7% and 126.3%; and decreased trabeculae separation by 34.1% and 36.6%, respectively (all P<0.01). Bone mineral apposition rate was significantly increased (P<0.01). Furthermore, implant fixation was significantly increased (P<0.05), and bone morphogenetic protein 2 (BMP2) expression was markedly increased. Local injection of a single dose of simvastatin also promoted angiogenesis. Vessel number, volume, thickness, surface area, and vascular volume per tissue volume were significantly increased (all P<0.01). Vascular endothelial growth factor (VEGF), VEGF receptor-2, von Willebrand factor, and platelet endothelial cell adhesion molecule-1 expression were enhanced. CONCLUSIONS: A single local injection of simvastatin significantly increased bone formation, promoted osseointegration, and enhanced implant fixation in ovariectomized rats. The underlying mechanism appears to involve enhanced BMP2 expression and angiogenesis in the target bone.

Epigalloccatechin-3-gallate inhibits ocular neovascularization and vascular permeability in human retinal pigment epithelial and human retinal microvascular endothelial cells via suppression of MMP-9 and VEGF activation.

Epigalloccatechin-3-gallate (EGCG) is the main polyphenol component of green tea (leaves of Camellia sinensis). EGCG is known for its antioxidant, anti-inflammatory, antiviral, and anti-carcinogenic properties. Here, we identify EGCG as a new inhibitor of ocular angiogenesis and its vascular permeability. Matrix metalloproteinases (MMPs) and vascular endothelial growth factor (VEGF) play a key role in the processes of extracellular matrix (ECM) remodeling and microvascular permeability during angiogenesis. We investigated the inhibitory effects of EGCG on ocular neovascularization and vascular permeability using the retina oriented cells and animal models induced by VEGF and alkaline burn. EGCG treatment significantly decreased mRNA and protein expression levels of MMP-9 in the presence of 12-O-tetradecanoylphorbol-13-acetate (TPA) and tumor necrosis factor alpha (TNF-α) in human retinal pigment epithelial cells (HRPECs). EGCG also effectively protected ARPE-19 cells from cell death and attenuated mRNA expressions of key angiogenic factors (MMP-9, VEGF, VEGF Receptor-2) by inhibiting generation of reactive oxygen species (ROS). EGCG significantly inhibited proliferation, vascular permeability, and tube formation in VEGF-induced human retinal microvascular endothelial cells (HRMECs). Furthermore, EGCG significantly reduced vascular leakage and permeability by blood-retinal barrier breakdown in VEGF-induced animal models. In addition, EGCG effectively limited upregulation of MMP-9 and platelet endothelial cell adhesion molecule (PECAM/CD31) on corneal neovascularization (CNV) induced by alkaline burn. Our data suggest that MMP-9 and VEGF are key therapeutic targets of EGCG for treatment and prevention of ocular angiogenic diseases such as age-related macular degeneration, diabetic retinopathy, and corneal neovascularization.

Magnolol inhibits angiogenesis by regulating ROS-mediated apoptosis and the PI3K/AKT/mTOR signaling pathway in mES/EB-derived endothelial-like cells.

Magnolol, a neolignan from the traditional medicinal plant Magnolia obovata, has been shown to possess neuroprotective, anti-inflammatory, anticancer and anti-angiogenic activities. However, the precise mechanism of the anti-angiogenic activity of magnolol remains to be elucidated. In the present study, the anti-angiogenic effect of magnolol was evaluated in mouse embryonic stem (mES)/embryoid body (EB)-derived endothelial-like cells. The endothelial-like cells were obtained by differentiation from mES/EB cells. Magnolol (20 µM) significantly suppressed the transcriptional and translational expression of platelet endothelial cell adhesion molecule (PECAM), an endothelial biomarker, in mES/EB-derived endothelial-like cells. To further understand the molecular mechanism of the suppression of PECAM expression, signaling pathways were analyzed in the mES/EB-derived endothelial-like cells. Magnolol induced the generation of reactive oxygen species (ROS) by mitochondria, a process that was associated with the induction of apoptosis as determined by positive Annexin V staining and the activation of cleaved caspase-3. The involvement of ROS generation by magnolol was confirmed by treatment with an antioxidant, N-acetyl-cysteine (NAC). NAC inhibited the magnolol-mediated induction of ROS generation and suppression of PECAM expression. In addition, magnolol suppressed the activation of MAPKs (ERK, JNK and p38) and the PI3K/AKT/mTOR signaling pathway in mES/EB-derived endothelial-like cells. Taken together, these findings demonstrate for the first time that the anti-angiogenic activity of magnolol may be associated with ROS-mediated apoptosis and the suppression of the PI3K/AKT/mTOR signaling pathway in mES/EB-derived endothelial-like cells.

Increased endogenous H2S generation by CBS, CSE, and 3MST gene therapy improves ex vivo renovascular relaxation in hyperhomocysteinemia.

Hydrogen sulfide (H(2)S) has recently been identified as a regulator of various physiological events, including vasodilation, angiogenesis, antiapoptotic, and cellular signaling. Endogenously, H(2)S is produced as a metabolite of homocysteine (Hcy) by cystathionine ß-synthase (CBS), cystathionine γ-lyase (CSE), and 3-mercaptopyruvate sulfurtransferase (3MST). Although Hcy is recognized as vascular risk factor at an elevated level [hyperhomocysteinemia (HHcy)] and contributes to vascular injury leading to renovascular dysfunction, the exact mechanism is unclear. The goal of the current study was to investigate whether conversion of Hcy to H(2)S improves renovascular function. Ex vivo renal artery culture with CBS, CSE, and 3MST triple gene therapy generated more H(2)S in the presence of Hcy, and these arteries were more responsive to endothelial-dependent vasodilation compared with nontransfected arteries treated with high Hcy. Cross section of triple gene-delivered renal arteries immunostaining suggested increased expression of CD31 and VEGF and diminished expression of the antiangiogenic factor endostatin. In vitro endothelial cell culture demonstrated increased mitophagy during high levels of Hcy and was mitigated by triple gene delivery. Also, dephosphorylated Akt and phosphorylated FoxO3 in HHcy were reversed by H(2)S or triple gene delivery. Upregulated matrix metalloproteinases-13 and downregulated tissue inhibitor of metalloproteinase-1 in HHcy were normalized by overexpression of triple genes. Together, these results suggest that H(2)S plays a key role in renovasculopathy during HHcy and is mediated through Akt/FoxO3 pathways. We conclude that conversion of Hcy to H(2)S by CBS, CSE, or 3MST triple gene therapy improves renovascular function in HHcy.

Scutellarin promotes in vitro angiogenesis in human umbilical vein endothelial cells.

Angiogenesis is critical to a wide range of physiological and pathological processes. Scutellarin, a major flavonoid of a Chinese herbal medicine Erigeron breviscapus (Vant.) Hand. Mazz. has been shown to offer beneficial effects on cardiovascular and cerebrovascular functions. However, scutellarin's effects on angiogenesis and underlying mechanisms are not fully elucidated. Here, we studied angiogenic effects of scutellarin on human umbilical vein endothelial cells (HUVECs) in vitro. Scutellarin was found by MTT assay to induce proliferation of HUVECs. In scutellarin-treated HUVECs, a dramatic increase in migration was measured by wound healing assay; Transwell chamber assay found significantly more invading cells in scutellarin-treated groups. Scutellarin also promoted capillary-like tube formation in HUVECs on Matrigel, and significantly upregulated platelet endothelial cell adhesion molecule-1 at both mRNA and protein levels. Scutellarin's angiogenic mechanism was investigated in vitro by measuring expression of angiogenic factors associated with cell migration and invasion. Scutellarin strongly induced MMP-2 activation and mRNA expression in cultured HUVECs in a concentration-dependent manner. Taken together, these results suggest that scutellarin promotes angiogenesis and may form a basis for angiogenic therapy.

Hyperbaric oxygen treatment induces platelet aggregation and protein release, without altering expression of activation molecules.

OBJECTIVES: To investigate the effect of hyperbaric oxygen (HBO) on platelet physiology. DESIGN AND METHODS: Human platelets were exposed to HBO (97.7% O(2), balance CO(2) at 2.2 ata) or control (CON; 5% CO(2), balance air at 1 ata) for 90 min, and analyzed for aggregation, protein release, ()NO production, and activation. RESULTS: HBO induced 29.8+/-3.0% of platelets to aggregate compared with CON (5.5+/-0.9%). Proteins observed to be released in greater abundance from HBO- compared with CON-treated platelets included 14-3-3 zeta and alpha-2-macroglobulin. Release of ()NO by platelets was unaffected following exposure to HBO, as was platelet activation as measured by surface expression of PECAM-1, CD62P and the activated form of alpha(IIB)beta(IIIa). CONCLUSIONS: Exposure to HBO induces both platelet aggregation and protein release. Further study will better define the precise mechanisms and effects of HBO on platelet activation.

Effect of rapamycin alone and in combination with sorafenib in an orthotopic model of human hepatocellular carcinoma.

PURPOSE: Novel therapeutic strategies are needed to prevent the tumor recurrence or metastasis after liver transplantation for hepatocellular carcinoma (HCC). This study was to investigate the effect of rapamycin, alone and in combination with sorafenib, on HCC in vivo. EXPERIMENTAL DESIGN: Xenograft of a highly metastatic human HCC tumor (LCI-D20) was used to evaluate primary tumor growth and lung metastasis after treatment with rapamycin alone or in combination with sorafenib. Tumor cell proliferation was determined by Ki-67 immunostaining. To detect tumor cell apoptosis, the terminal deoxynucleotidyl-transferase-mediated dUTP nick-end labeling assay was used. Tumor angiogenesis was investigated by using a monoclonal anti-CD31 antibody. A vascular endothelial growth factor ELISA kit was used to measure vascular endothelial growth factor protein levels in the mice serum. RESULTS: Rapamycin, alone and in combination with sorafenib, strongly inhibited primary tumor growth and lung metastases in LCI-D20 model. Furthermore, the combination therapy significantly enhanced the effect of antitumor on primary tumor growth compared with single treatment with either rapamycin (P < 0.001) or sorafenib (P < 0.001). Rapamycin alone inhibited HCC cell proliferation, induced apoptosis, and decreased tumor angiogenesis. Nevertheless, the combination therapy showed a significant inhibition of tumor cell proliferation (P < 0.05). Additionally, the combination therapy also further enhanced suppression of tumor cell angiogenesis compared with rapamycin treatment (P < 0.01). However, the induction of apoptosis in combination therapy group was not significantly higher than in the rapamycin-treated group (P > 0.05). CONCLUSIONS: The combination therapy of rapamycin and sorafenib could be a new and promising therapeutic approach to the treatment of HCC and prevention of HCC recurrence after liver transplantation.

Improved therapeutic effectiveness by combining liposomal honokiol with cisplatin in lung cancer model.

BACKGROUND: Honokiol is a major bioactive compound extracted from Magnolia. The present study was designed to determine whether liposomal honokiol has the antitumor activity against human lung cancer as well as potentiates the antitumor activity of cisplatin in A549 lung cancer xenograft model, if so, to examine the possible mechanism in the phenomenon. METHODS: human A549 lung cancer-bearing nude mice were treated with liposomal honokiol, liposomal honokiol plus DDP or with control groups. Apoptotic cells and vessels were evaluated by fluorescent in situ TUNEL assay and by immunohistochemistry with an antibody reactive to CD31 respectively. RESULTS: The present study showed that liposomal honokiol alone resulted in effective suppression of the tumor growth, and that the combined treatment with honokiol plus DDP had the enhanced inhibition of the tumor growth and resulted in a significant increase in life span. The more apparent apoptotic cells in the tumors treated with honokiol plus DDP was found in fluorescent in situ TUNEL assay, compared with the treatment with control groups. In addition, the combination of honokiol and DDP apparently reduced the number of vessels by immunolabeling of CD31 in the tissue sections, compared with control groups. CONCLUSION: In summary, our data suggest that honokiol alone had the antitumor activity against human lung cancer in A549 lung cancer xenograft model, and that the combination of honokiol with DDP can enhance the antitumor activity, and that the enhanced antitumor efficacy in vivo may in part result from the increased induction of the apoptosis and the enhanced inhibition of angiogenesis in the combined treatment. The present findings may be of importance to the further exploration of the potential application of the honokiol alone or the combined approach in the treatment of lung carcinoma.

Combination therapy of human pancreatic cancer implanted in nude mice by oral fluoropyrimidine anticancer agent (S-1) with interferon-alpha.

PURPOSE: We evaluated the antitumor and antiangiogenic activities of human natural interferon-alpha (IFN-alpha) alone or in combination with S-1 against human pancreatic cancer cells. METHODS: Three days after the subcutaneous (s.c.) implantation of tumor cells, mice (n = 12) were received s.c. injection with IFN-alpha alone (10,000 U six times a week), oral administration with S-1 alone (8 mg/kg six times a week), or both with IFN-alpha and S-1 (8, 10, 12 mg/kg six times a week). RESULTS: Administration of IFN-alpha in combination with S-1 significantly decreased progressive growth and angiogenesis of human pancreatic cancer cells. The combination therapy produced more significant inhibition in expression of the representative proangiogenic molecules, vascular endothelial growth factor and basic fibroblast growth factor than individual treatment either IFN-alpha or S-1 alone did. These treatments also decreased the staining of proliferating cell nuclear antigen, induced apoptosis and decreased microvessel density. In order to better understand the precise molecular mechanisms by which IFN-alpha and S-1 exert its effects, we have utilized cDNA microarray including 124 known genes to determine the gene expression profile altered by IFN-alpha and S-1 treatment. We found a total of seven genes which showed a twofold change after IFN-alpha and S-1 treatment in addition to VEGF, bFGF, CD31, MMP-2, MMP-7 and MMP-9. Among these genes, we found down-regulation of six genes and up-regulation of one gene, which are related to angiogenesis, tumor cell invasion and metastasis. CONCLUSIONS: These data suggest that administration of IFN-alpha in combination with S-1 may provide a novel and effective approach to the treatment of human pancreatic cancer.

Platelet endothelial cell adhesion molecule deficiency or blockade significantly reduces leukocyte emigration in a majority of mouse strains.

PECAM is a molecule used specifically during the diapedesis step when neutrophils and monocytes leave the blood compartment. Anti-PECAM reagents, such as Abs and soluble fusion proteins, block diapedesis both in vivo and in vitro. However, the PECAM knockout mouse in C57BL/6 strain has no serious defects in most models of inflammation. We show in this study that the same PECAM knockout backcrossed into the FVB/n strain clearly has reduced leukocyte emigration in two models of inflammation. Furthermore, we show that anti-PECAM reagents can block leukocyte emigration in several other wild-type strains of mice like FVB/n, SJL, and the outbred strain Swiss Webster. This clearly shows that the C57BL/6 strain is uniquely able to compensate for the loss of PECAM function. Murine models of inflammatory disease that have been studied using C57BL/6 mice should be re-evaluated using FVB/n or other mouse strains to determine whether PECAM plays a role in those models.

Effects of TCMP-1 on the changes of platelet endothelial cell adhesion molecule-1 expression in acute edematous pancreatitis.

BACKGROUND: Traditional Chinese medicine is a potent agent in the management of clinical and experimental acute pancreatitis (AP), but the molecular mechanism of its therapeutic action is unclear. Numerous experimental and clinical studies have shown that platelet endothelial cell adhesion molecule-1 (PECAM-1) is pivotal to leukocyte recruitment, which results in microcirculatory injury during inflammation, but its role in acute pancreatitis is poorly understood. We investigated the effects of a compound of traditional Chinese medicine pancreatitis-1 (TCMP-1) on the changes of platelet endothelial cell adhesion molecule-1 (PECAM-1) expression on polymorphonuclear leukocytes (PMNs) in acute edematous pancreatitis (AEP). METHODS: The model of acute pancreatitis was established by subcutaneous injection of caerulein, and TCMP-1 treated groups were given TCMP-1 by catheterization from mouth to stomach (20 ml/kg) immediately after first time subcutaneous injection of caerulein. The changes of expression of PECAM-1 on leukocytes from the blood of the splenic vein and inferior vena cava were determined by flow cytometry. RESULTS: In the AEP group, expression of PECAM-1 on PMNs was not significantly different between pancreatic microcirculation and systemic circulation at AEP2h and AEP4h time point. Then from AEP4h time point to AEP8h time point, expression of PECAM-1 was up-regulated in systemic circulation while it was down-regulated in pancreatic microcirculation and was significantly different between pancreatic microcirculation and systemic circulation at AEP8h time point (P<0.05). In the TCMP-1 treated group, compared with the AEP group, expression of PECAM-1 on PMNs decreased in different levels between pancreatic microcirculation and systemic circulation and was of significant difference at AEP8h time point (P<0.05). CONCLUSION: Inhibition of PECAM-1 expression on PMNs may prevent PMNs from transmigration through the endothelium and may be one of the treatment mechanisms of TCMP-1 decoction on AEP.

A simple quantitative method for evaluation of angiogenesis activity.

Angiogenesis plays a major role in many physiological and pathological processes. Pathological development of diseased conditions like growth and metastasis of solid tumors and psoriasis is associated with angiogenesis. Assays developed, thus far, for evaluation of angiogenesis activity are qualitative or semiquantitative. In vivo angiogenesis assays are more physiologically relevant than in vitro models and, however, time-consuming, labor-intensive, and expensive. The ex vivo rat aorta tube formation model has been demonstrated to correlate well to the physiological conditions. The present study established a reproducible and quantitative assay for evaluating angiogenesis with rat aorta ring cultures. Rat thoracic aortas were harvested, cross-sectioned into rings of 1-mm thickness using a set of aligned blades, and cultured in a three-dimensional extracellular matrix. Endothelial cells outgrow consistently from the aorta rings cultured in endothelial cell growth medium. Angiogenic activity was quantified by a colorimetric 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2H-tetrazolium/phenazine methosulfate method. The colorimetric assay was reproducible, and its results were compared in parallel with that of the imaging analysis method. IC(50) values of several known antiangiogenics, SU5416, suramin, paclitaxel, and 2-methoxyestradiol, were determined and were comparable to those obtained using the imaging analysis method. We have established a simple, reproducible, and quantitative assay for evaluation of angiogenesis activity with the cultured rat aorta ring, which can be used to screen for angiogenics and angiostatics.

Transplantation of motoneuron-enriched neural cells derived from mouse embryonic stem cells improves motor function of hemiplegic mice.

Embryonic stem (ES) cells are expected to be a potential donor source for neural transplantation. We have obtained motoneuron-enriched neural progenitor cells by culturing mouse ES cells with retinoic acid (RA). The cells also expressed mRNA of a neurotrophic factor, neurotrophin-3 (NT-3). The left motor cortex area of mice was damaged by cryogenic brain injury, and the neural cells were transplanted underneath the injured motor cortex, neighboring to the paraventricular region. We found that the cells expressing neuronal phenotypes not only remained close to the implantation site, but also exhibited substantial migration penetrating into the damaged lesion, in a seemingly directed manner up to cortical region. We found that some of the neural cells differentiated into Islet1-positive motoneurons. It seems likely that the ability of the ES cell-derived neural progenitor cells to respond in vivo to guidance cues and signals that can direct their migration and differentiation may contribute to functional recovery of the recipient mice. We found that an "island of the mature neuronal cells" of recipient origin emerged in the damaged motor cortex. This may be associated with the neuroprotective effects of the ES cell-derived neural cells. The ES cells differentiated into CD31+ vasculoendothelial cells with the RA treatment in vitro. Furthermore, the grafted cells may provide sufficient neurotrophic factors such as NT-3 for neuroprotection and regeneration. The grafted neural cells that migrated into residual cortex and differentiated into neurons had purposefully elongated axons that were stained with anti-neurofilament middle chain (NFM) antibody. Our study suggests that motoneurons can be induced from ES cells, and ES cells become virtually an unlimited source of cells for experimental and clinical neural cell transplantation.

Loss of Bmp7 and Fgf8 signaling in Hoxa13-mutant mice causes hypospadia.

In humans and mice, mutations in Hoxa13 cause malformation of limb and genitourinary (GU) regions. In males, one of the most common GU malformations associated with loss of Hoxa13 function is hypospadia, a condition defined by the poor growth and closure of the urethra and glans penis. By examining early signaling in the developing mouse genital tubercle, we show that Hoxa13 is essential for normal expression of Fgf8 and Bmp7 in the urethral plate epithelium. In Hoxa13(GFP)-mutant mice, hypospadias occur as a result of the combined loss of Fgf8 and Bmp7 expression in the urethral plate epithelium, as well as the ectopic expression of noggin (Nog) in the flanking mesenchyme. In vitro supplementation with Fgf8 restored proliferation in homozygous mutants to wild-type levels, suggesting that Fgf8 is sufficient to direct early proliferation of the developing genital tubercle. However, the closure defects of the distal urethra and glans can be attributed to a loss of apoptosis in the urethra, which is consistent with reduced Bmp7 expression in this region. Mice mutant for Hoxa13 also exhibit changes in androgen receptor expression, providing a developmental link between Hoxa13-associated hypospadias and those produced by antagonists to androgen signaling. Finally, a novel role for Hoxa13 in the vascularization of the glans penis is also identified.