The angiopoietins, tie2 and vascular endothelial growth factor are differentially expressed in the transformation of normal lung to non-small cell lung carcinomas

Update Overview of the Role of Angiopoietins in Lung Cancer

Angiogenesis is a biological process that involves the formation of new blood vessels from the existing vasculature, and it plays a fundamental role in the development and progression of several types of cancer, including lung cancer. The angiopoietin/Tie2 ligand/receptor system orchestrates vascular integrity. In particular, Angiopoietin-1 activates the endothelial cell (EC)-specific receptor tyrosine kinase, Tie2, which is essential for preserving endothelial quiescence. On the other hand, Angiopoietin-2 acts as an inhibitor of the Angiopoietin-1/Tie2 signaling pathways, thus facilitating the destabilization of quiescent endothelium in cases of inflammation and cancer. Clinical studies have proven that high levels of Angiopoietin-2 indicate the development of non-small-cell lung carcinomas (NSCLC), while high levels of Angiopoietin-2 are strongly related to tumor angiogenesis, lymphangiogenesis, metastasis, and poor prognosis. Interestingly, the association of Angiopoietin-2 levels with the type of surgical approach makes Angiopoietin-2 a valuable factor in selecting the most suitable therapeutic strategy for lung cancer patients. The role of the Angiopoietin-1 and Angiopoietin-4 levels in NSCLC development requires further investigation. The present review focuses on the clinical impact of the Angiopoietin-1, Angiopoietin-2, and Angiopoietin-4 levels in patients diagnosed with NSCLC, emphasizing the interaction between them, and how they affect the development, progression, and metastasis of lung disease. Finally, it estimates the role of angiopoietins levels in the effective therapy of lung cancer patients.

Identification of significant genes as prognostic markers and potential tumor suppressors in lung adenocarcinoma via bioinformatical analysis

Background

Lung adenocarcinoma (LAC) is the predominant histologic subtype of lung cancer and has a complicated pathogenesis with high mortality. The purpose of this study was to identify differentially expressed genes (DEGs) with prognostic value and determine their underlying mechanisms.

Methods

Gene expression data of GSE27262 and GSE118370 were acquired from the Gene Expression Omnibus database, enrolling 31 LAC and 31 normal tissues. Common DEGs between LAC and normal tissues were identified using the GEO2R tool and Venn diagram software. Next, the Database for Annotation, Visualization, and Integrated Discovery (DAVID) was used to analyze the Gene Ontology and Kyoto Encyclopedia of Gene and Genome (KEGG) pathways. Then, protein-protein interaction (PPI) network of DEGs was visualized by Cytoscape with Search Tool for the Retrieval of Interacting Genes and central genes were identified via Molecular Complex Detection. Furthermore, the expression and prognostic information of central genes were validated via Gene Expression Profiling Interactive Analysis (GEPIA) and Kaplan-Meier analysis, respectively. Finally, DAVID, real-time PCR and immunohistochemistry were applied to re-analyze the identified genes, which were also further validated in two additional datasets from ArrayExpress database.

Results

First, 189 common DEGs were identified among the two datasets, including 162 downregulated and 27 upregulated genes. Next, Gene Ontology and KEGG pathway analysis of the DEGs were conducted through DAVID. Then, PPI network of DEGs was constructed and 17 downregulated central genes were identified. Furthermore, the 17 downregulated central genes were validated via GEPIA and datasets from ArrayExpress, and 12 of them showed a significantly better prognosis. Finally, six genes were identified significantly enriched in neuroactive ligand-receptor interactions (EDNRB, RXFP1, P2RY1, CALCRL) and Rap1 signaling pathway (TEK, P2RY1, ANGPT1) via DAVID, which were further validated to be weakly expressed in LAC tissues via RNA quantification and immunohistochemistry analysis.

Conclusions

The low expression pattern and relation to prognosis indicated that the six genes were potential tumor suppressor genes in LAC. In conclusion, we identified six significantly downregulated DEGs as prognostic markers and potential tumor suppressor genes in LAC based on integrated bioinformatics methods, which could act as potential molecular markers and therapeutic targets for LAC patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08308-3.

miR-19a-3p Facilitates Lung Adenocarcinoma Cell Phenotypes by Inhibiting TEK

Background: Both TEK and miR-19a-3p have been reported to regulate lung adenocarcinoma (LUAD) progression. However, the association between TEK and miR-19a-3p in LUAD remained unknown. This research aimed to investigate a novel miR-19a-3p/TEK interactome in LUAD cells. Methods: The mRNA expression and protein expression in the cell lines were determined using qPCR and Western blot assay, respectively. CCK-8 assay, EDU assay, flow cytometry cell apoptosis assay, scratch assay, and cell-to-extracellular matrix adhesion assay were performed to detect the proliferation, apoptosis, migration, and adhesion ability of A549 and H1975 cell lines. Results: Findings revealed that both mRNA and protein levels of TEK were downregulated in the LUAD tumor tissues and cell lines. It was also found that compared with the control group, the transfection of TEK overexpression plasmids into H1975 and A549 cell lines significantly inhibited cancerous phenotypes. However, experimental results indicated that by downregulating TEK, miR-19a-3p promoted LUAD cell phenotypes. Conclusion: This research demonstrated that an interactome existed between miR-19a-3p and TEK and that miR-19a-3p could suppress LUAD tumors by inhibiting TEK. This novel interactome could be used as a novel therapy target for LUAD.

ERK1/2 Signaling Induces Upregulation of ANGPT2 and CXCR4 to Mediate Liver Metastasis in Colon Cancer

Carcinoma development in colorectal cancer is driven by genetic alterations in numerous signaling pathways. Alterations in the RAS-ERK1/2 pathway are associated with the shortest overall survival for patients after diagnosis of colorectal cancer metastatic disease, yet how RAS-ERK signaling regulates colorectal cancer metastasis remains unknown. In this study, we used an unbiased screening approach based on selection of highly liver metastatic colorectal cancer cells in vivo to determine genes associated with metastasis. From this, an ERK1/2-controlled metastatic gene set (EMGS) was defined. EMGS was associated with increased recurrence and reduced survival in patients with colorectal cancer tumors. Higher levels of EMGS expression were detected in the colorectal cancer subsets consensus molecular subtype (CMS)1 and CMS4. ANGPT2 and CXCR4, two genes within the EMGS, were subjected to gain-of-function and loss-of-function studies in several colorectal cancer cell lines and then tested in clinical samples. The RAS-ERK1/2 axis controlled expression of the cytokine ANGPT2 and the cytokine receptor CXCR4 in colorectal cancer cells, which facilitated development of liver but not lung metastases, suggesting that ANGPT2 and CXCR4 are important for metastatic outgrowth in the liver. CXCR4 controlled the expression of cytokines IL10 and CXCL1, providing evidence for a causal role of IL10 in supporting liver colonization. In summary, these studies demonstrate that amplification of ERK1/2 signaling in KRAS-mutated colorectal cancer cells affects the cytokine milieu of the tumors, possibly affecting tumor-stroma interactions and favoring liver metastasis formation. SIGNIFICANCE: These findings identify amplified ERK1/2 signaling in KRAS-mutated colorectal cancer cells as a driver of tumor-stroma interactions that favor formation of metastases in the liver.

[Research Advances of Ang-2 in Non-small Cell Lung Cancer]

Non-small cell lung cancer (NSCLC) is one of the malignant tumors with highest mortality in the world, it is still a difficult problem in clinical field. Its occurrence and development are closely associated with tumor angiogenesis. Angiopoietin-2 (Ang-2) is an important angiogenesis factor that has involved in many researches and it has been confirmed that the expression of Ang-2 is significantly up-regulated in tissues and blood of NSCLC. Meanwhile, Ang-2 is related to malignant biological behavior of cancer cells, making it a potential biological marker for the diagnosis and prognosis of NSCLC. At present, researches on Ang-2 how to promote the progression of NSCLC around the world are focused on Ang-2 regulating the proliferation, invasion, and metastasis of NSCLC. This paper summarized and estimated the studies and literature reports of regulatory mechanisms of Ang-2 in NSCLC, hopefully it could help looking for targeted drug treatment of Ang-2 in the future.
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Angiogenesis in NSCLC: is vessel co-option the trunk that sustains the branches?

The critical role of angiogenesis in tumor development makes its inhibition a valuable new approach in therapy, rapidly making anti-angiogenesis a major focus in research. While the VEGF/VEGFR pathway is the main target of the approved anti-angiogenic molecules in NSCLC treatment, the results obtained are still modest, especially due to resistance mechanisms. Accumulating scientific data show that vessel co-option is an alternative mechanism to angiogenesis during tumor development in well-vascularized organs such as the lungs, where tumor cells highjack the existing vasculature to obtain its blood supply in a non-angiogenic fashion. This can explain the low/lack of response to current anti-angiogenic strategies. The same principle applies to lung metastases of other primary tumors. The exact mechanisms of vessel co-option need to be further elucidated, but it is known that the co-opted vessels regress by the action of Angiopoietin-2 (Ang-2), a vessel destabilizing cytokine expressed by the endothelial cells of the pre-existing mature vessels. In the absence of VEGF, vessel regression leads to tumor cell loss and hypoxia, with a subsequent switch to a neoangiogenic phenotype by the remaining tumor cells. Unravelling the vessel co-option mechanisms and involved players may be fruitful for numerous reasons, and the particularities of this form of vascularization should be carefully considered when planning anti-angiogenic interventions or designing clinical trials for this purpose. In view of the current knowledge, rationale for therapeutic approaches of dual inhibition of Ang-2 and VEGF are swiftly gaining strength and may serve as a launchpad to more successful NSCLC anti-vascular treatments.

Expression Analysis of Angiogenesis-Related Genes in Bulgarian Patients with Early-Stage Non-Small Cell Lung Cancer

Aims and background

Angiogenesis is a key process in the early stages of tumor development. In this study we aimed to evaluate the expression of a panel of angiogenesis-related genes in a group of Bulgarian patients with early-stage non-small cell lung cancer (NSCLC).

Methods and study design

We analyzed the expression of 84 genes associated with the angiogenic process in 12 NSCLCs of two histological subtypes: 7 adenocarcinomas and 5 squamous cell carcinomas. Eight peripheral nontumorous tissues were used as controls. We performed real-time PCR on pathway-specific gene arrays (SABiosciences).

Results

Our pilot study identified upregulated genes in early-stage NSCLC including growth factors (TGFA and EFNA3), the adhesion molecule THBS2, cytokines and chemokines (MDK, CXCL9, CXCL10), and the serine protease PLAU. Several genes showed downregulation including one growth factor (FIGF), the receptors for growth factors TEK and S1PR1 as well as adhesion molecules (COL4A3 and CDH5), the cytokine IL6, the matrix protein LEP and the transcription factor NOTCH4. The study demonstrated deregulated genes specific for the two histological subtypes including the transcription factor HAND2, which was overexpressed in squamous cell carcinomas but not adenocarcinomas.

Conclusions

Despite the limited number of patients, our results demonstrated the potential of angiogenesis-related genes as biomarkers in the early stages of NSCLC development. Free full text available at www.tumorionline.it

The role of serum angiopoietin-2 levels in progression and prognosis of lung cancer: A meta-analysis

BACKGROUND

Angiogenesis is an essential process in the development and progression of malignant tumors including lung cancer, in which angiopoietin-2 (Ang-2) plays an important role. The objective of this study was to assess the prognostic value of serum Ang-2 levels in patients with lung cancer.

METHODS

A comprehensive systematic electronic search was performed in the Pubmed, Embase, Web of Science, china national knowledge infrastructure, and VIP databases update to October, 2016 (qikan.cqvip.com). Literatures examining the relevance of serum Ang-2 levels to progression and prognosis of lung cancer were eligible for our study. Standardized mean differences (SMD) with 95% confidence interval (95% CI) and a P value were applied to compare continuous variables, and hazard ratio (HR) with 95% CI as well as P value were applied for prognostic role.

RESULTS

Twenty studies with 1911 patients met the eligibility criteria. Among them, 7 studies with 575 patients with lung cancer assessed the association between expression of serum Ang-2 and prognosis. According to our results, higher levels of serum Ang-2 were associated with the later stage of tumor. Serum Ang-2 levels were significantly lower in stage I than in stage II (SMD: -0.51; 95% CI: -0.75 to -0.27; P < .001), in stage II than in stage III (SMD: -0.52; 95% CI: -0.80 to -0.24; P < .001), in stage III than in stage IV (SMD: -0.58; 95% CI: -0.93 to -0.23; P = .001). In addition, serum Ang-2 levels were higher in patients with lymph node metastasis (SMD: 1.06; 95% CI, 0.57-1.56; P < .001). Meanwhile, patients with lung cancer with higher levels of serum Ang-2 were associated with a significant poorer prognosis when compared to those with lower serum Ang-2 levels (HR: 1.64; 95% CI: 1.20-2.25; P = .002), and this role was further detected when stratified by ethnicity and histological type.

CONCLUSIONS

This systematic review and meta-analysis suggested that serum Ang-2 levels might be a potential predictor for staging, and were associated with prognosis of lung cancer.

Elevated Serum Level of Angiopoietin-2 as a Potential Marker for Poor Prognosis in Small Cell Lung Cancer

Small cell lung cancer (SCLC) is a fast-growing cancer with poor prognosis. Patients with extensive-stage SCLC are generally treated with chemotherapy. Thus, it is essential to identify a predictor of efficacy and prognosis for SCLC. Angiopoietin-2 promotes vascular remodeling and angiogenesis. Increasing evidence reveals that angiopoietin-2 is preferentially expressed in cancer cells, and elevated angiopoietin-2 expression is related to invasive and metastatic phenotypes in various cancers. However, serum angiopoietin-2 level and its prognostic potential in SCLC have not been investigated. The aim of this study was to determine the usefulness of angiopoietin-2 level as a predictor of efficacy and prognosis for SCLC. This study consisted of sixty patients with SCLC. Each patient received four cycles of cisplatin-etoposide chemotherapy, and was followed for 36 months. Serum angiopoietin-2 levels were measured by Enzyme-linked immunosorbent assays. The angiopoietin-2 levels were significantly higher in SCLC patients than those in healthy subjects (P < 0.001). The patients were divided into high-level group (32 patients, 2,923.9 ± 294.7 pg/ml) and low-level group (28 patients, 1,789.5 ± 355.1 pg/ml) according to the mean value of the angiopoietin-2 level (2,400 pg/ml). Compared with the patients in the high-level group, the patients in the low-level group showed remarkably survival advantage (P = 0.002). During chemotherapy, the patients in the low-level group showed better treatment response than the patients in the high-level group (P < 0.05). Therefore, angiopoietin-2 might be useful as a prognostic factor for SCLC and for predicting SCLC response to chemotherapy.

Serum angiopoietin is associated with lung function in patients with asthma: a retrospective cohort study

Background

Angiopoietin-1 (Ang-1) is an essential mediator of angiogenesis that establishes vascular integrity, and angiopoietin-2 (Ang-2) acts as its natural inhibitor. We considered that angiopoietin might be important in bronchial asthma.

Methods

In total, 35 patients with asthma and 20 healthy subjects were studied.

Results

The serum Ang-1 levels were significantly elevated in patients with asthma compared to control subjects (293.9 ± 13.8 pg/mL vs. 248.3 ± 16.2 pg/mL, respectively, p = 0.04). The serum Ang-2 levels were not different between the two groups. The areas under the curve (AUC) for serum angiopoietins revealed that the serum level of Ang-1 (0.68) was more sensitive and specific than the serum Ang-2 level (0.55) for differentiating between patients with asthma and control subjects. The serum Ang-1/Ang-2 ratio was correlated with the FEV1/FVC ratio (r = -0.312, p = 0.02), while serum Ang-2 was correlated with body mass index.

Conclusions

Our results indicate that the serum Ang-1 levels were higher in asthma patients compared with healthy subjects. As the Ang-1/Ang-2 ratio was related to lung function, the data suggest that serum angiopoietin is associated with lung function in patients with asthma.

Dynamics of pulmonary endothelial barrier function in acute inflammation: mechanisms and therapeutic perspectives

The lungs provide a large inner surface to guarantee respiration. In lung alveoli, a delicate membrane formed by endo- and epithelial cells with their fused basal lamina ensures rapid and effective gas exchange between alveolar and vascular compartments while concurrently forming a robust barrier against inhaled particles and microbes. However, upon infectious or sterile inflammatory stimulation, tightly regulated endothelial barrier leakiness is required for leukocyte transmigration. Further, endothelial barrier disruption may result in uncontrolled extravasation of protein-rich fluids. This brief review summarizes some important mechanisms of pulmonary endothelial barrier regulation and disruption, focusing on the role of specific cell populations, coagulation and complement cascades and mediators including angiopoietins, specific sphingolipids, adrenomedullin and reactive oxygen and nitrogen species for the regulation of pulmonary endothelial barrier function. Further, current therapeutic perspectives against development of lung injury are discussed.

Suppression of angiogenesis and tumor growth in vitro and in vivo using an anti-angiopoietin-2 single-chain antibody

Hepatocellular carcinomas (HCCs) are tumors with a highly developed vascular architecture. HCC cells require access to blood vessels for growth and metastasis; therefore, the inhibition of angiogenesis represents a potential therapeutic target for HCC that may reduce the mortality and morbidity from HCC. Various attempts to develop an anti-angiogenic therapy have been made in past decades; however, modest results have been achieved in clinical trials and the challenge of HCC treatment remains. Single-chain antibodies (scFv) are characterized by low molecular weight, low immunogenicity, high penetration and a short half-life, and are easy to produce on a large scale by genetic engineering. Accordingly, an scFv against a specific angiogenic regulator, such as angiopoietin (Ang), may be a promising anti-angiogenic therapy for HCC. Our previous study indicated that an imbalanced expression of angiopoietin-2 (Ang-2) vs. angiopoietin-1 (Ang-1) in HCCs contributes to initiation of neovascularization and promotes the angiogenesis and progression of HCCs. Therefore, we suggest that specific Ang-2-targeting interventions may be valuable in the treatment of HCC via remodeling the neovascular network and changing the tumor microenvironment. In this study, a prokaryotic expression vector of Ang-2 was constructed and purified human Ang-2 protein was isolated. An scFv against human Ang-2 (scFv-Ang2) was identified and purified via phage display technology, and the effects of scFv-Ang2 in vitro and in vivo on HCC in nude mice were evaluated. The results show that scFv-Ang2 inhibits vascular endothelial growth factor (VEGF) and Ang-2 induces the proliferation, migration and tubule formation of human umbilical vein endothelial cells (HUVECs) in vitro. In the in vivo assay, statistical indices, including tumor weight and volume, metastases to lungs, CD31 expression and the microvessel density (MVD) count in the scFv-Ang2-treated group of mice were significantly lower than those in the control group (P<0.05). In conclusion, the successfully generated scFv-Ang2 showed significant inhibitory effects on the angiogenesis and tumor growth of human HCC in vitro and in vivo.

Expression of angiopoietin-TIE system components in angiosarcoma

Angiosarcoma is an aggressive malignancy of endothelial differentiation. Potential roles of the endothelial angiopoietin-tunica interna endothelial cell kinase (ANGPT-TIE) system in angiosarcoma diagnosis, pathogenesis, prognosis and treatment are undefined. To examine the expression and prognostic significance of angiopoietin-1, angiopoietin-2, TIE1 and TEK (TIE2) proteins in angiosarcoma, we immunohistochemically evaluated clinically annotated human angiosarcoma samples. Correlations of protein expression with overall survival and pathological features were explored. The cohort included 51 patients diagnosed with angiosarcoma at the age of 30-86 years (median 67). The 5-year overall survival was 45% with a median of 26 months. Moderate to strong expression of angiopoietin-1, TIE1 and TEK (TIE2) was identified in the majority of angiosarcomas and moderate to strong expression of angiopoietin-2 was observed in 42% of angiosarcomas. Increased angiopoietin-1 expression correlated with improved survival. Non-significant trends toward longer survival were also observed with increased TIE1 and TEK (TIE2) expression. Increased expression of angiopoietin-2, TIE1 and TEK (TIE2) was associated with vasoformative architecture. No differences in expression of these proteins were observed when patients were segregated by age, gender, presence or absence of metastases at diagnosis, primary tumor location, radiation association or the presence of necrosis. We conclude that components of the ANGPT-TIE system are commonly expressed in angiosarcomas. Reduced expression of these proteins is associated with non-vasoformative and clinically more aggressive lesions.

Novel targets for VEGF-independent anti-angiogenic drugs

INTRODUCTION

In the last decades, the active research in the field of tumor angiogenesis led to the development of a class of agents providing an effective inhibition of neovessels formation through the blockade of VEGF-related pathways. More recently, the identification of several non-VEGF factors such as PDGF, FGF, HGF, angiopoietins, ALK1/endoglin, endothelis and ephrins involved in tumor angiogenesis have emphasized the need to develop agents targeting multiple pro-angiogenic pathways.

AREAS COVERED

This review aimed at summarizing the role of non-VEGF molecular pathways in targeting tumor angiogenesis. Preclinical and clinical data for investigational agents against non-VEGF targets have been reviewed emphasizing the role of combined inhibition strategies.

EXPERT OPINION

Besides the successful development of drugs providing a specific VEGF blockade, novel agents targeting alternative angiogenesis-related pathways are being tested. Although it seems that the potential clinical usefulness of these novel compounds have been not yet fully investigated, sunitinib, sorafenib, pazopanib and other multikinase inhibitors have certainly displayed encouraging results. A more in-depth clarification of anti-angiogenic agents is still needed, in order to design the best clinical setting and schedule for target-based agents and possibly anticipate potential tools to overcome the emerging issue of anti-angiogenic drug resistance.

Importance of serum levels of angiopoietin-2 and survivin biomarkers in non-small cell lung cancer

BACKGROUND

Angiogenesis is an essential process in cancer growth maintenance, and metastasis. Angiopoietin-2 promotes tumor angiogenesis by priming the vasculature and potentiating the effects of cytokines at the front of active neovascularization. Enhanced expression of angiopoietin-2 has been reported in lung cancer tissue. Survivin is one of the inhibitors of apoptosis protein that has been shown to play a key role in cancer progression, and in tumor angiogenesis. Also plays a key role in tumor cell resistance to anticancer agents and ionizing radiation.

AIM

To measure the serum levels of angiopoietin-2 and survivin as possible angiogenic factors in lung cancer patients with the assessment of their interrelationships and clinical significance.

PATIENTS AND METHODS

Patients with lung cancer as NSCLC (n=70) and healthy volunteers (n=10) were enrolled. Serum angiopoietin-2 and survivin concentrations were measured using enzyme-linked immunosorbent assay (ELIZA).

RESULTS

Median serum angiopoietin-2 levels with lung cancer (2730pg/mL) ranged from 1171 to 6541pg/mL was higher than the median of the control group (1795pg/mL) ranged from 1076 to 2730/mL, p<0.001. Median serum survivin levels were also higher in patients with lung cancer (53.0pg/mL) ranged from 39.3 to 96.3pg/mL than the median of the control group (48.8pg/mL) ranged from 38.0 to 74.6pg/mL, but did not reach statistical significance p=0.206. In all patients with lung cancer, serum angiopoietin-2 was not significantly correlated with survivin (r=0.073, p=0.657). Neither serum angiopoietin-2 nor survivin showed significant relation with the serum angiopoietin-2 or survivin levels depending on the cell types, stage progression, and metastasis among the patients with NSCLC.

CONCLUSIONS

Our study suggests that serum angiopoietin-2 is a useful marker for the diagnosis of NSCLC by ELIZA technique.

Clinical value of assaying tumor supplied group of factor/tumor specific growth factor in patients with solitary pulmonary nodule

OBJECTIVE

This pilot study was designed to evaluate the clinical value of assaying tumor supplied group of factor/tumor specific growth factor (TSGF) in solitary pulmonary nodule (SPN).

PATIENTS AND METHODS

The study was conducted from March 2007 to September 2010 and included 33 patients with SPN and 28 healthy volunteers. TSGF was assayed in preoperative serum, intraoperative pleural lavage fluid (IPLF), and postoperative serum.

RESULTS

At operation, 20 patients were diagnosed with malignancy and 13 patients were diagnosed with nonmalignancy and placed in group A and group B, respectively. In group A, pathologic staging demonstrated 8 patients (group A1) with stage T1N0M0, 7 patients (group A2) with stage T1N1M0 and 53 patients (group A) with stage T1N2M0 disease. In group B, 8 patients were diagnosed with tuberculoma (group B1) and 5 patients were diagnosed with inflammatory pseudotumor (group B2). Before operation, levels of TSGF in peripheral blood were significantly higher in group A compared with group B and the control group (98.8 ± 29.9 vs. 62.1 ± 24.9 and 50.1 ± 17.9, Student-Newman-Keuls test; P < .05). The percentage of patients with positive serum TSGF results was significantly higher in group A than in group B or the control group (90.0% vs. 30.8% and 17.9%, χ(2) test; P < .05). With respect to the diagnostic value of serum TSGF in malignant SPN, we found sensitivity to be 90%, specificity to be 69.2%, positive forecast rate to be 74.5%, negative forecast rate to be 87.4%, and accurate diagnosed rate to be 79.5%. The TSGF level in IPLF in group A was significantly higher than that in group B (132.2 ± 51.9 vs. 84.6 ± 12.6, Student t test, P < .05). Additionally, TSGF in group A2 and group A3 was significantly higher compared with group A1 (162.2 ± 52.3 and 176.4 ± 17.8 vs. 100.2 ± 35.8, Student-Newman-Keuls test; P < .05). Postoperative serum TSGF in the patients diagnosed with lung cancer decreased significantly after operation. TSGF returned to a normal threshold level (71 U/mL) in the sixth month postoperatively. In addition, there was no appreciable change in the patients in group B.

CONCLUSION

Serum TSGF is conducive to discriminating between benign and malignant features of SPN. Additionally, investigation of IPLF TSGF can potentially offer a new approach to predict the existence of lymph node metastases.

Prognostic impacts of angiopoietins in NSCLC tumor cells and stroma: VEGF-A impact is strongly associated with Ang-2

Introduction

Angiopoietins and their receptor Tie-2 are, in concert with VEGF-A, key mediators in angiogenesis. This study evaluates the prognostic impact of all known human angiopoietins (Ang-1, Ang-2 and Ang-4) and their receptor Tie-2, as well as their relation to the prognostic expression of VEGF-A.

Methods

335 unselected stage I-IIIA NSCLC-patients were included and tissue samples of respective tumor cells and stroma were collected in tissue microarrays (TMAs). Immunohistochemistry (IHC) was used to semiquantitatively evaluate the expression of markers in duplicate tumor and stroma cores.

Principal Findings

In univariate analyses, low tumor cell expression of Ang-4 (P = 0.046) and low stromal expressions of Ang-4 (P = 0.009) and Ang-2 (P = 0.017) were individually associated with a poor survival. In the multivariate analysis, low stromal Ang-2 (HR 1.88; CI 95% 1.15-3.08) and Ang-4 (HR 1.47, CI 95% 1.02–2.11, P = 0.04) expressions were independently associated with a poor prognosis. In patients with high tumor cell expression of Ang-2, a concomitantly high tumor VEGF-A expression mediated a dramatic survival reduction (P<0.001). In the multivariate analysis of patients with high Ang-2 expression, high tumor VEGF-A expression appeared an independent poor prognosticator (HR 6.43; CI 95% 2.46–16.8; P<0.001).

Conclusions

In tumor cells, only Ang-4 expression has prognostic impact in NSCLC. In tumor stroma, Ang-4 and Ang-2 are independently associated with survival. The prognostic impact of tumor cell VEGF-A in NSCLC appears strongly associated with a concomitantly high tumor cell expression of Ang-2.

Targeting the ANGPT-TIE2 pathway in malignancy

Angiopoietins (ANGPTs) are ligands of the endothelial cell receptor TIE2 and have crucial roles in the tumour angiogenic switch. Increased expression of ANGPT2 relative to ANGPT1 in tumours correlates with poor prognosis. The biological effects of the ANGPT-TIE system are context dependent, which brings into question what the best strategy is to target this pathway. This Review presents an encompassing picture of what we know about this important axis in tumour biology. The various options for therapeutic intervention are discussed to identify the best path forwards.

The interaction of soluble Tie2 with angiopoietins and pulmonary vascular permeability in septic and nonseptic critically ill patients

Circulating angiopoietin (Ang) 1 may inhibit and Ang-2 may enhance pulmonary vascular permeability in septic and nonseptic patients with or at risk for acute lung injury or acute respiratory distress syndrome. We hypothesized that the soluble form of the Ang-binding Tie2 receptor (sTie2), whose shedding may be induced by vascular endothelial growth factor (VEGF) levels, may bind circulating Angs and thereby inhibit their effects on pulmonary vascular permeability. In 24 septic and 40 nonseptic mechanically ventilated patients, sTie2, Ang-1, Ang-2, and VEGF plasma levels were measured together with the pulmonary leak index (PLI) for (67)Gallium-labeled transferrin as a measure of pulmonary vascular permeability. Soluble Tie2 and VEGF levels correlated (r = 0.53, P = 0.001). Soluble Tie2 was higher in septic than in nonseptic patients (7.43 [6.57 - 8.40] vs. 5.03 [4.57 - 5.54] ng/mL; P < 0.001). Soluble Tie2 was associated with the PLI (standardized regression coefficient [beta] = 0.26; P = 0.006) but lost its association with the PLI when the Angs were included in a multivariate model. Soluble Tie2 did not affect the association between Ang-1 or Ang-2 and the PLI (beta = -0.39, P < 0.001; beta = 0.52, P < 0.001, respectively), independently of underlying disease. Although limited to correlations and associations, the clinical data support in vivo shedding of sTie2 through VEGF signaling upon pulmonary vascular injury. However, this shedding may not prevent a direct role of Angs in pulmonary vascular permeability.

Serum levels of angiopoietin-1, angiopoietin-2, and their receptor tie-2 in patients with nonsmall cell lung cancer during chemotherapy

This pilot study was conducted to investigate the prognostic role and the effects of chemotherapy on serum angiogenic factors enzyme-linked immunosorbent assay consisting of Angiopoietin-1 and 2 (Ang-1, Ang-2) and their receptor Tie-2 in patients with advanced stage nonsmall cell lung cancer (NSCLC). Concentration of Ang-2 was higher in NSCLC (n= 40) than in healthy people (n= 15), whereas Ang-1 and Tie-2 were comparable. In our opinion determination of Ang-1, Ang-2, and Tie-2 concentrations have no clinical significance in the prognosis of the survival time in lung cancer and can not be used as a predictor of response to the chemotherapy.

Serum angiopoietin-1 as a prognostic marker in resected early stage lung cancer

PURPOSE

We evaluated the clinical significance of angiopoietins and vascular endothelial growth factor (VEGF) in patients with resected early stage lung cancer.

PATIENTS AND METHODS

The study enrolled 101 patients with completely resected non-small cell lung cancer (NSCLC) of stage I or II, along with 70 healthy volunteers. Serum concentrations of angiopoietin-1, angiopoietin-2, and VEGF were measured with an ELISA. Immunohistochemical expression of angiopoietin-1 was compared with the microvessel density on the lung cancer tissues.

RESULTS

The patients had lower serum angiopoietin-1 (32.1+/-9.9 ng/mL vs. 39.0+/-10.8 ng/mL, p<0.001), higher angiopoietin-2 (1949.2+/-1099.4 pg/mL vs. 1498.6+/-650.0 pg/mL, p<0.01), and higher VEGF (565.1+/-406.3 pg/mL vs. 404.6+/-254.8 pg/mL, p<0.01) levels than the controls. The angiopoietin-2 level was higher in stage II than in stage I patients (p<0.05). The levels of angiopoietin-1 (r=0.28) and angiopoietin-2 (r=0.36) each correlated with the VEGF level. Patients with a higher level of angiopoietin-1 (> or =31.2 ng/mL) had better disease-specific and relapse-free survival than those with a lower angiopoietin-1 level (<31.2 ng/mL). Angiopoietin-1 expression negatively correlated with the microvessel density.

CONCLUSION

Serum angiopoietin-1 is a potential marker for predicting postoperative survival and recurrence in patients with early stage NSCLC.

The positive correlation between gene expression of the two angiogenic factors: VEGF and BMP-2 in lung cancer patients

Lung cancer is a particular challenge in oncology. More than 1 million new cases occur worldwide every year and despite many clinical trials and modern diagnostic techniques, long-term survival rate has only marginally improved. The aim of the current research is to explore new molecular prognostic factors and identify new targets for anticancer therapy. Current evidence shows that angiogenesis is controlled by several angiogenic factors including VEGF and BMP-2. It has been also demonstrated that VEGF plays a key role in this process that is essential in carcinogenesis. Our study has shown that the expressions of the VEGF, BMP-2 and BMP-4 mRNAs were significantly higher (7.1-fold, 25.6-fold and 2.3-fold, respectively) in lung cancer samples than in adjacent normal lung tissues (real-time RT-PCR). Analysis based on the Pearson's correlation coefficient indicated the positive correlation between VEGF and BMP-2 gene expression, whereas no significant correlation between VEGF and BMP-4 gene expression was found. The mean+/-standard deviation serum level of VEGF was 423+/-136 pg/ml. Significant differences in the serum levels of VEGF between patients with T1 tumors and patients with T2, T3 or T4 tumors were observed. Patients with T2, T3 and T4 tumors, respectively, had 1.6-fold, 1.8-fold and 2.3-fold greater serum levels of VEGF than their peers with T1 tumors. In current study patients homozygous for the 936T allele of the +936C/T VEGF gene polymorphism had 12-fold lower VEGF gene expression and 1.3-fold lower VEGF serum level than patients homozygous for the 936C allele. In conclusion, our findings underline the importance of the two angiogenic factors namely VEGF and BMP-2 as well as +936C/T VEGF gene polymorphism in the evaluation of lung cancer patients.

The angiopoietin-Tie2 system as a therapeutic target in sepsis and acute lung injury

BACKGROUND

Sepsis and acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) are life-threatening syndromes characterised by inflammation and increased vascular permeability. Amongst other factors, the angiopoietin-tyrosine kinase with immunoglobulin-like and EGF-like domains 2 (Tie2) system is involved.

OBJECTIVE

To explore whether the angiopoietin-Tie2 system provides suitable targets for the treatment of sepsis and ALI/ARDS.

METHODS

Original experimental and patient studies on angiopoietins and sepsis/endotoxemia, inflammation, lung injury, hyperpermeability, apoptosis, organ functions and vital outcomes were reviewed.

RESULTS/CONCLUSION

The angiopoietin-Tie2 system controls the responsiveness of the endothelium to inflammatory, hyperpermeability, apoptosis and vasoreactive stimuli. Angiopoietin-2 provokes inflammation and vascular hyperpermeability, while angiopoietin-1 has a protective effect. Targeted angiopoietin-2 inhibition with RNA aptamers or blocking antibodies is a potential anti-inflammatory and anti-vascular hyperpermeability strategy in the treatment of sepsis and ALI/ARDS.

Pharmacophore modeling studies of type I and type II kinase inhibitors of Tie2

In this study, chemical feature based pharmacophore models of type I and type II kinase inhibitors of Tie2 have been developed with the aid of HipHop and HypoRefine modules within Catalyst program package. The best HipHop pharmacophore model Hypo1_I for type I kinase inhibitors contains one hydrogen-bond acceptor, one hydrogen-bond donor, one general hydrophobic, one hydrophobic aromatic, and one ring aromatic feature. And the best HypoRefine model Hypo1_II for type II kinase inhibitors, which was characterized by the best correlation coefficient (0.976032) and the lowest RMSD (0.74204), consists of two hydrogen-bond donors, one hydrophobic aromatic, and two general hydrophobic features, as well as two excluded volumes. These pharmacophore models have been validated by using either or both test set and cross validation methods, which shows that both the Hypo1_I and Hypo1_II have a good predictive ability. The space arrangements of the pharmacophore features in Hypo1_II are consistent with the locations of the three portions making up a typical type II kinase inhibitor, namely, the portion occupying the ATP binding region (ATP-binding-region portion, AP), that occupying the hydrophobic region (hydrophobic-region portion, HP), and that linking AP and HP (bridge portion, BP). Our study also reveals that the ATP-binding-region portion of the type II kinase inhibitors plays an important role to the bioactivity of the type II kinase inhibitors. Structural modifications on this portion should be helpful to further improve the inhibitory potency of type II kinase inhibitors.

Angiogenic molecule Tie-2 and VEGF in the pathogenesis of pleural effusions

BACKGROUND

The role of angiogenesis in the pathogenesis of pleural effusion (PE) has not been determined. The expression of angiogenic factors may represent useful markers for the diagnosis and prediction of disease outcome. To measure the pleural fluid (PF) and serum levels of vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF) and Tie receptor tyrosine kinase (Tie-2) in order to investigate their role in the pathogenesis of PEs.

METHODS

Sixty-seven, 17 with transudative PEs due to heart failure and 50 with exudative PEs (malignant, 22; inflammatory, 15; undiagnosed, 13) were included in the study. PF and serum levels of the growth factors (VEGF, bFGF and Tie-2) were measured using enzyme-linked immunosorbent assays.

RESULTS

PF and serum VEGF levels but not bFGF and Tie-2 levels were higher (p<0.005) in exudates than in transudates. PF VEGF levels were significantly higher in malignant than inflammatory and undiagnosed PEs (p=0.03). In addition, PF Tie-2 levels were not found different in malignant or in parapneumonic PEs.

CONCLUSION

Our results showed that VEGF is one of the main mediators in exudative PEs, but this effect is not mediated through the angiogenetic pathway Ang-1/Tie-2. However, the role of angiogenesis and its pathways in the pathogenesis of exudative PEs needs further exploration.

Expression of choline kinase alpha to predict outcome in patients with early-stage non-small-cell lung cancer: a retrospective study

BACKGROUND

Adequate prognostic markers to predict outcome of patients with lung cancer are still needed. The aim of this study was to assess whether choline kinase alpha (ChoKalpha) gene expression could identify patients with different prognoses. ChoKalpha is an enzyme involved in cell metabolism and proliferation and has a role in oncogene-mediated transformation in several human tumours, including lung cancer.

METHODS

60 patients with non-small-cell lung cancer (NSCLC) who had undergone surgical resection in a single centre were enrolled into the study as the training group. We used real-time reverse-transcriptase PCR (RT-PCR) to measure ChoKalpha gene expression and analyse the association between ChoKalpha expression and survival in evaluable patients. Additionally, a second group of 120 patients with NSCLC from a different hospital were enrolled into the study as the validation group. We did an overall analysis of all 167 patients who had available tissue to confirm the cut-off point for future studies. The primary endpoints were lung-cancer-specific survival and relapse-free survival.

FINDINGS

Seven of the 60 patients in the training group were not evaluable due to insufficient tissue. In the 53 evaluable patients, the cut-off for those with ChoKalpha overexpression was defined by receiver operator under the curve (ROC) methodology. 4-year lung-cancer-specific survival was 54.43% (95% CI 28.24-80.61) for 25 patients with ChoKalpha expression above the ROC-defined cut-off compared with 88.27% (75.79-100) for 28 patients with concentrations of the enzyme below this cut-off (hazard ratio [HR] 3.14 [0.83-11.88], p=0.07). In the validation group, six of the 120 enrolled patients were not evaluable due to insufficient tissue. For the other 114 patients, 4-year lung-cancer-specific survival was 46.66% (32.67-59.65) for those with ChoKalpha expression above the ROC-defined cut-off compared with 67.01% (50.92-81.11) for patients with concentrations of ChoKalpha below the cut-off (HR 1.87 [1.01-3.46], p=0.04). A global analysis of all 167 patients further confirmed the association between ChoKalpha overexpression and worse clinical outcome of patients with NSCLC: 4-year lung-cancer-specific survival for ChoKalpha expression above the ROC-defined cut-off was 49.00% (36.61-60.38) compared with 70.52% (59.80-76.75) for those with concentrations of ChoKalpha below the cut-off (HR 1.98 [1.14-3.45], p=0.01). The overall analysis confirmed the cut-off for ChoKalpha expression should be 1.91-times higher than concentrations noted in healthy tissues when ChoKalpha is used as an independent predictive factor of relapse-free and lung-cancer-specific survival in patients with early-stage NSCLC.

INTERPRETATION

ChoKalpha expression is a new prognostic factor that could be used to help identify patients with early-stage NSCLC who might be at high risk of recurrence, and to identify patients with favourable prognosis who could receive less aggressive treatment options or avoid adjuvant systemic treatment. New treatments that inhibit ChoKalpha expression or activity in patients with lung cancer should be studied further.

Inhibition of osteopontin would suppress angiogenesis in gastric cancer

Osteopontin (OPN) plays an important role in tumorigenesis, tumor invasion, and metastasis in many types of cancers, including gastric cancer. Recently, much interest has been focused on the role of OPN in tumor angiogenesis. Our previous studies have shown that OPN is overexpressed, and associated with mean microvessel density in, the tissue samples of patients with gastric cancer. In the present study, we aimed to further determine and provide evidence for the role of OPN in gastric-cancer-associated angiogenesis by diminishing OPN expression in gastric cancer cells using the small interference RNA method, and then evaluate the effects of OPN on gastric cancer-associated angiogenesis by in vivo and in vitro assays. Our results revealed that reduced OPN production by gastric cancer cells would reduce the proliferation, migration, and tube formation of human umbilical vein endothelial cells, and lead to a lower microvessel density, i.e., angiogenesis, in transplanted tumors of mice. These data confirm the positive role of OPN in gastric-cancer-associated angiogenesis.

Serum Angiopoietin-2 as a Clinical Marker for Lung Cancer

BACKGROUND

Angiopoietins play a critical role in the angiogenesis related to tumor growth in concert with vascular endothelial growth factor (VEGF), and enhanced expression of angiopoietin-2 has been reported in lung cancer tissue.

METHODS

Patients with lung cancer (n = 136) and healthy volunteers (n = 40) were enrolled. Serum angiopoietin-2 and VEGF concentrations were measured using enzyme-linked immunosorbent assay.

RESULTS

Patients with lung cancer had higher serum angiopoietin-2 (2,046.3 +/- 1,171.3 pg/mL vs 1,269.8 +/- 494.1 pg/mL, p < 0.001) and VEGF (542.9 +/- 445.8 pg/mL vs 364.7 +/- 185.9 pg/mL, p < 0.05) [mean +/- SD] levels than the control group. Serum angiopoietin-2 and VEGF levels correlated with each other in patients with lung cancer (Spearman r = 0.30, p < 0.001), specifically in non-small cell lung cancer (NSCLC) [n = 110; r = 0.34; p < 0.001] but not in small cell lung cancer (n = 26). With stage progression in NSCLC, serum angiopoietin-2 levels increased, and patients with distant metastasis had higher levels than those without metastasis (p < 0.005). By contrast, serum VEGF level did not increase with stage progression, and only had a trend toward elevation in distant metastasis (p = 0.05). In NSCLC, the low angiopoietin-2 group (< 1,605.5 pg/mL) had a better overall survival compared to the high angiopoietin-2 group (> or = 1,605.5 pg/mL; p < 0.05), although this survival benefit was not maintained after controlling for stage in a multivariate analysis. The angiopoietin-2 levels were higher in NSCLC patients with postoperative recurrence than in those without.

CONCLUSIONS

Our study suggests that serum angiopoietin-2 is a useful clinical marker for detecting NSCLC with distant metastasis and is of potential prognostic value.

Angiopoietins in malignancy

BACKGROUND

Tumour growth is dependant upon the development of an adequate blood supply. This, in turn, is thought to depend upon a switch by the tumour, from a dormant to angiogenic state. Recent data suggest that this switch may occur when the balance of pro- and anti-angiogenic agents alters to promote angiogenesis. Angiopoietins may be involved in this balance.

METHODS

An electronic literature search was performed with respect to angiopoietins from 1996 to the present. Published data from in-vitro and in-vivo studies were critically analysed. A specific focus was made of studies relating to tumour growth and vasculature.

RESULTS

Since angiopoietin-1 was first described in 1996, three more angiopoietins have been described. All family members bind to the Tie-2 receptor. There is now a considerable accumulation of data that suggests they play a pivotal role in the development and stabilisation of tumour vasculature. angiopoietin-2 appears to be pro-angiogenic whilst angiopoietin-1 appears to be a stabilising factor.

CONCLUSIONS

Recent trials of anti-angiogenic agents show promise in the treatment of solid human cancers. The angiopoietins are a new family of proteins that appear to be influential in the development of the tumour vasculature. Manipulation of the angiopoietin balance may provide a potential therapeutic target in human cancer.

A phase I/randomized phase II, non-comparative, multicenter, open label trial of CP-547,632 in combination with paclitaxel and carboplatin or paclitaxel and carboplatin alone as first-line treatment for advanced non-small cell lung cancer (NSCLC)

PURPOSE

To evaluate the toxicity profile and pharmacological properties of oral CP-547,632 alone and in combination with paclitaxel and carboplatin administered every 3 weeks, and to assess efficacy as measured by the objective response and progressive disease rates of oral CP-547,632 administered in combination with paclitaxel and carboplatin.

PATIENTS AND METHODS

Patients with stage IIIB/IV or recurrent non-small cell lung cancer receiving first-line chemotherapy were treated with oral daily CP-547,632 in combination with paclitaxel 225 mg/m(2) and carboplatin AUC = 6 every 3 weeks. Pharmacokinetics parameters for CP-547,632 and paclitaxel were determined independently and during co-administration.

RESULTS

Seventy patients were enrolled and 68 patients were treated, 37 in phase 1 and 31 in phase 2 (14 with the combination and 17 with chemotherapy alone). Dose-limiting toxicity of CP-547,632 250 mg by mouth daily in combination with paclitaxel and carboplatin was grade 3 rash and grade 3 diarrhea despite medical intervention. CP-547,632 did not significantly affect the pharmacologic profiles of paclitaxel and carboplatin. No subject had CR. In phase I, seven subjects (22.6%) had a confirmed partial response. In phase II, four subjects (28.6%) receiving CP-547,632 plus chemotherapy had a confirmed partial response. In the phase II chemotherapy alone group, four subjects (25%) had a confirmed partial response.

CONCLUSION

The combination of CP-547,632 and paclitaxel and carboplatin was well-tolerated at doses up to 200 mg by mouth daily. Dose-limiting toxicity of CP-547,632 at 250 mg consisted of diarrhea and rash. CP-547,632 did not increase the objective response rate to chemotherapy alone in patients with advanced non-small cell lung cancer.

Celecoxib could reverse the hypoxia-induced Angiopoietin-2 upregulation in gastric cancer

We investigated the potential effect of Cyclooxygenase-2 (Cox-2) on hypoxia-induced Angiopoietin-2 (Ang-2) expression in gastric cancer cells. Our results revealed that hypoxia augmented Cox-2 and Ang-2 expressions. Also, the hypoxia-induced Ang-2 could be mimicked by CoCl(2) treatment while genestein treatment could partially counteract the hypoxia-induced Ang-2 expression. Celecoxib but not Cox-1 inhibitor sc-560 reversed the hypoxia-induced Ang-2 expression, while this effect could be partially restored by addition of exogenous PGE2. Our findings suggest that the hypoxia-elevated Ang-2 expression in gastric cancer cells may be mediated by both Cox-2-derived PGE2 and HIF-1alpha pathways, while celecoxib could counteract the hypoxia-induced Ang-2 expression.

Expression of angiopoietins, Tie2 and vascular endothelial growth factor in angiogenesis and progression of hepatocellular carcinoma

AIM: To investigate the significance of angiopoietins, Tie2 and vascular endothelial growth factor (VEGF) expression in the angiogenesis and progress of hepatocellular carcinoma (HCC).

METHODS: Fresh surgically resected specimens of HCC and noncancerous liver (NCL) tissue from 38 patients with HCC were obtained, and expression of angiopoietin-1 (Ang-1), angiopoietin-2 (Ang-2), Tie2, and VEGF messenger RNA (mRNA) was examined by real-time quantitative reverse transcription-polymerase chain reaction (RT-PCR). Expression pattern of each gene in HCC and NCL tissue specimens was compared and the potential role and interaction in angiogenesis of HCC were analyzed. Genes’ expression level and its relationship with tumor’s clinicopathological parameters were also investigated. Immunohistochemical staining of CD34 was performed to determine the microvessel density (MVD) and Ang-2/Ang-1 ratio was calculated. Relationships between Ang-2/Ang-1 ratio, VEGF and MVD and clinicopathological features were also tested so as to evaluate their significance in the progression of HCC.

RESULTS: Ang-2 and VEGF mRNAs in HCC were significantly higher than those in NCL tissue (P < 0.05), whereas the Ang-1 and Tie2 mRNAs showed no statistical significance (P > 0.05), though slightly lower level of Ang-1 mRNA in HCC was observed. Ang-2/Ang-1 ratio and VEGF were both positively correlated to MVD. The Ang-2/ Ang-1 ratio, Ang-2 and VEGF were all associated with tumor’s clinicopathological parameters (P < 0.05) except for histological grades (P > 0.05). Ang-1 and Tie2 levels in different clinicopathological groups were not significantly different (P > 0.05).

CONCLUSION: Dominant Ang-2 expression against Ang-1 through Tie2 receptor in the presence of VEGF plays a critical role in initiating early neovascularization and transformation of noncancerous liver to hepatocellular carcinoma. Its consequently constant operation in formed HCC induces further angiogenesis and progression of HCC.

Antisense angiopoietin-1 inhibits tumorigenesis and angiogenesis of gastric cancer

AIM: To investigate the effect of angiopoietin-1 (Ang-1) on biological behaviors in vitro and tumorigenesis and angiogenesis in vitro of human gastric cancer cells.

METHODS: Human full-length Ang-1 gene was cloned from human placental tissues by RT-PCR method. Recombinant human Ang-1 antisense eukaryotic expression vector was constructed by directional cloning, and transfected by lipofectin method into human gastric cancer line SGC7901 with high Ang-1 expression level. Inhibition efficiency was confirmed by semi- quantitive PCR and Western blot method. Cell growth curve and cell cycle were observed with MTT assays and flow cytometry, respectively. Nude mice tumorigenicity test was employed to compare in vitro tumorigenesis of cells with Ang-1 suppression. Microvessel density (MVD) of implanted tumor tissues was analyzed by immunohistochemistry for factor VIII staining.

RESULTS: Full-length Ang-1 gene was successfully cloned and stable transfectants were established, namely 7Ang1- for antisense，and 7901P for empty vector transfected. 7Ang1- cells showed down-regulated Ang-1 expression, while its in vitro proliferation and cell cycle distribution were not significantly changed. In contrast, xenograft of 7Ang1- cells in nude mice had lower volume and weight than those of 7901P after 30 days’ implantation (P < 0.01, 293.00 ± 95.54 mg vs. 624.00 ± 77.78 mg) accompanied with less vessel formation with MVD 6.00±1.73 compared to 7901P group 8.44±1.33 (P < 0.01).

CONCLUSION: Ang-1 may play an important role in tumorigenesis and angiogenesis of gastric cancer, and targeting its expression may be beneficial for the therapy of gastric cancer.

Role of angiopoietin-1 in experimental and human pulmonary arterial hypertension

INTRODUCTION

The pulmonary microvasculature, consisting mainly of an endothelial cell (EC) monolayer and scant matrix support, is incompletely muscularized. Thus, the distal pulmonary arterioles may be predisposed to regression on exposure to environmental stresses (ie, hypoxia) and may be dependent on EC survival factors, like angiopoietin (Ang) 1, to attenuate the development of pulmonary arterial hypertension (PAH). In order to clarify the link between Ang1 expression and the development of PAH in patients, we also studied messenger RNA and protein expression in lung samples from healthy control subjects and patients with idiopathic PAH (IPAH) or PAH associated with other diseases (APAH).

METHODS

Ang/Tie2 gene expression was assessed in rats that had been exposed to hypoxia (ie, 10% O2) for 1, 3, or 7 days. In a separate experiment, the cell-based gene transfer of Ang1/Ang2 was performed, and the effects were evaluated in rats with hypoxia-induced PAH.

RESULTS

Hypoxia induced significant early increases in right ventricular systolic pressure (RVSP) and right ventricle/left ventricle-plus-septum mass ratio (RV/[LV + S]), with a significant decrease in Tie2 expression. Hypoxic rats receiving Ang1 demonstrated significant improvements in RVSP and RV/(LV + S), with a partial normalization in Tie2 protein levels. Robust Ang1 expression was observed in healthy human lungs. Furthermore, there were no significant changes in the levels of Ang1 or Ang2 in IPAH or APAH samples vs those in control subjects.

CONCLUSIONS

Decreased activity of the Tie2 pathway with hypoxia may contribute to PAH, possibly by loss of EC survival signaling, which can be overcome by Ang1 gene transfer.

Expressions and clinical significances of angiopoietin-1, -2 and Tie2 in human gastric cancer

The roles of angiopoietins in gastric cancer progression are still not fully understood. In this study the expressions of angiopoietin-1 (Ang-1), -2 (Ang-2) were compared by immunohistochemistry in 53 gastric cancer and 23 normal gastric mucosa samples. Results revealed that Ang-2 expression was significantly increased in gastric cancer tissues (74%) and was correlated with higher TNM stage, lymph node metastasis as well as distance metastasis. The expression of Ang-1 was also elevated in cancerous tissues (66%) and significantly associated with differentiation degree. In addition, Ang-2 as well as its receptor Tie2 expressions were higher in 12 pairs of gastric cancer tissue samples than those in corresponding adjacent samples by Western blot, while Ang-1 expression showed great heterogeneity. Furthermore, the expressions of Ang-1 and Ang-2 were almost positive in eight gastric cancer cell lines. Among them, AGS expressed both Ang-2 and a relatively moderate amount of Ang-2(443), a novel splice form of Ang-2, while others showed only Ang-2 mRNA expression.

Surfactant Protein A Gene Deletion and Prognostics for Patients with Stage I Non–Small Cell Lung Cancer

PURPOSE

The present study was conducted to determine clinical relevance of surfactant protein A (SP-A) genetic aberrations in early-stage non-small cell lung cancer (NSCLC).

EXPERIMENTAL DESIGN

To determine whether SP-A aberrations are lung cancer-specific and indicate smoking-related damage, tricolor fluorescence in situ hybridization with SP-A and PTEN probes was done on touch imprints from the lung tumors obtained prospectively from 28 patients with primary NSCLC. To further define the clinical relevance of SP-A aberrations, fluorescence in situ hybridization was done on both tumor cells and adjacent bronchial tissue cells from paraffin-embedded tissue blocks from 130 patients NSCLC for whom we had follow-up information.

RESULTS

SP-A was deleted from 89% of cancer tissues and the deletion was related to the smoking status of patients (P < 0.001). PTEN was deleted from 16% in the cancer tissues and the deletion was not related to the smoking status of patients (P > 0.05). In the cells isolated from paraffin-embedded tissue blocks, SP-A was deleted from 87% of the carcinoma tissues and 32% of the adjacent normal-appearing bronchial tissues. SP-A deletions in tumors and adjacent normal-appearing bronchial tissues were associated with increases in the risk of disease relapse (P = 0.0035 and P < 0.001, respectively). SP-A deletions in the bronchial epithelium were the strongest prognostic indicators of disease-specific survival (P = 0.025).

CONCLUSIONS

Deletions of the SP-A gene are specific genomic aberrations in bronchial epithelial cells adjacent to and within NSCLC, and are associated with tumor progression and a history of smoking. SP-A deletions might be a useful biomarker to identify poor prognoses in patients with NSCLC who might therefore benefit from adjuvant treatment.

Angiopoietin 2 expression is related to histological grade, vascular density, metastases, and outcome in prostate cancer

BACKGROUND

In several malignant tissues, the angiopoietins are principal regulators of vascular growth and regression, but in normal prostate and prostate tumors the role of the angiopoietins is unknown.

METHODS

Angiopoietin (ang) 1 and 2 were immunolocalized in TUR-diagnosed prostate tumors with long follow-up and the expression was related to vascular density and clinicopathological variables.

RESULTS

Ang 1 was strongly expressed in the basal epithelial cell layer in non-malignant tissue, whereas tumors had lower levels localized to the epithelial cells. A weak ang 2 immunoreaction was observed in non-malignant tissue and in low to intermediate Gleason score (GS) tumors, with a similar expression pattern. However, most high GS tumors showed an intense ang 2 staining. Ang 2 was significantly correlated to GS, density of endoglin stained blood vessels, metastases, and to cancer specific survival.

CONCLUSIONS

We conclude that ang 2 probably is an important regulator of angiogenesis in prostate cancer.

Expression of angiopoietin-1 and -2, and its clinical significance in human bladder cancer

OBJECTIVE

To investigate the relationship between angiopoietin-1 and -2 expression and the clinicopathological variables and clinical outcome in patients with bladder cancer treated by surgical resection, as both have been recently identified as antagonistic angiogenic factors which regulate tumour growth.

MATERIALS AND METHODS

The expression of angiopoietin-1 and -2 were assessed by immunohistochemistry in tissue sections from 52 transitional cell carcinomas of the bladder (33 grade 1, 15 grade 2, four grade 3, including two associated with carcinoma in situ; 22 were stage Ta, 19 T1 and 11 T2 tumours). Normal bladder specimens were also resected during each operation as controls. The expression angiopoietins were related to the clinicopathological variables of the tumours.

RESULTS

Positive immunostaining was detected in 18 samples (35%) for angiopoietin-1 and in 23 (44) for angiopoietin-2. There was no significant difference in survival according to tumour angiopoietin-1 status in the patients, but in contrast the overall survival of patients with angiopoietin-2-positive tumours was significantly lower than for those with angiopoietin-2-negative tumours (P < 0.05). Positive angiopoietin-2 expression was significantly correlated with histological grade (P = 0.026), histological stage (P = 0.009) and poor prognosis (P < 0.05). On multivariate analysis, positive angiopoietin-2 expression was an independent negative predictor for survival (P = 0.042).

CONCLUSIONS

These results suggest that angiopoietin-2 overexpression is associated with tumour progression, thereby indicating a poor prognosis for some patients treated by surgical resection for bladder carcinoma.

Expression and purification of recombinant human angiopoietin-2 produced in Chinese hamster ovary cells

Angiopoietin-2 (Ang2) is a complex regulator of vascular remodeling that plays a role in both blood vessel sprouting and blood vessel regression through its receptor Tie2. Recombinant Chinese hamster ovary (rCHO) cell lines expressing a high level (20 microg/mL) of recombinant human Ang2 protein (rhAng2) with an amino-terminal FLAG-tag was constructed by transfecting the expression vectors into dihydrofolate reductase (dhfr)-deficient CHO cells and the subsequent gene amplification in medium containing stepwise increments in methotrexate level such as 0.02, 0.08, and 0.32 microM. The rhAng2 secreted from rCHO cells was purified at a purification yield of 53.6% from the cultured medium using an anti-FLAG M2 agarose affinity gel. SDS-PAGE and Western blot analyses showed that rCHO cells secret rhAng2 as a homodimeric glycoprotein form. Furthermore, rhAng2 binds to the Tie2 receptor and phosphorylates Tie2 in a concentration-dependent manner. Therefore, our rhAng2 could be useful for clarifying biological effect of exogenous Ang2 in the future.

Overexpression of S100A2 protein as a prognostic marker for patients with stage I non small cell lung cancer

S100A2, a calcium-binding protein, recently became of major interest because of its differential expression during transformation and metastasis in various tumors. The purpose of this study was to investigate the prognostic significance of S100A2 expression in the early-stage non small lung cancer (NSCLC). Immunohistochemical analysis to determine the percentage of cells staining positive for S100A2 was performed on 11 NSCLC tissue microarray slides containing samples from 113 patients with pathologic stage I NSCLC who had undergone curative surgery. S100A2 was expressed in samples from 79 patients (69.9%). Kaplan-Meier analysis showed that patients whose tumors had positive S100A2 expression had a significantly lower overall survival and disease-specific survival rate at 5 years after surgery than did patients with negative S100A2 expression (p < 0.001 and p < 0.001, respectively). Age at diagnosis, histologic type of cancer, degree of differentiation and smoking history did not have a statistically significant effect on survival. Multivariate analysis confirmed that S100A2 expression is a better predictor for disease-specific survival than were other clinical and histologic variables tested. Our results suggested that the expression of the S100A2 protein in stage I NSCLC indicates poor prognosis and may be used to identify patients with early-stage NSCLC who might benefit from adjuvant treatment.

Tumor necrosis factor-related apoptosis-inducing ligand can induce apoptosis in subsets of premalignant cells

During the transformation from a normal to a malignant cell, several mutations are required to bypass the pathways responsible for controlling proliferation. Premalignant cells have acquired some, but not all of these mutations and consequently have not yet attained a malignant phenotype characterized by tumor formation in vivo. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) can induce apoptosis in malignant cells while sparing normal ones and is currently being considered as adjuvant therapy for various human malignancies. Whether TRAIL is effective in inducing apoptosis in premalignant cells is unclear, however. We studied the effect of TRAIL on two human premalignant cell lines the SV7tert and HA1E cells. Both cell lines had been immortalized by the addition of simian virus 40 large T antigen and the telomerase subunit hTERT, but had not been transformed into malignant cells. TRAIL initiated apoptosis by activating both the mitochondrial-independent and -dependent apoptotic pathways in both cell lines at relatively low doses whereas it had no effect on normal human pulmonary artery smooth muscle cells even at high doses. These results suggest that TRAIL can induce apoptosis in premalignant cells and suggests a novel therapy for the treatment of premalignant lesions in vivo.

Not just angiogenesis--wider roles for the angiopoietins

Since the discovery of the angiopoietins, much interest has been focused on their biological actions and their potential use as therapeutic targets. It is generally accepted that the angiopoietins play an important role in angiogenesis and hence are described as angiogenic factors. However, it is becoming increasingly clear that this is not their only role and it is likely that the angiopoietins have important roles in a wider range of biological and pathological functions.

Hepatic expression of ANG2 RNA in metastatic colorectal cancer

We examined the RNA content of the gene encoding angiopoietin (Ang)-2, a modifier of angiogenesis, in hepatic metastases of colorectal cancer (CRC) to explore the role of this protein in neovascularization of metastatic foci. Metastatic CRC exhibited notable blood flow and tumor vessel formation at tumor frontiers. Reverse-transcription polymerase chain reaction assays indicated that the ANG2 RNA content was greater in metastatic CRC than in primary CRC. Investigation of metastatic foci using laser capture microdissection revealed that the RNA content of ANG2, but not ANG1, increased from the bordering liver region to the periphery of the metastatic disease, and also from the periphery to the intermediate portion of the metastatic lesion; immunohistochemical analysis confirmed that there was a corresponding gradual increase in Ang-2 protein expression. Tie-2, a receptor for angiopoietins, was preferentially expressed in the bordering liver region rather than in metastatic CRC. Vascular endothelial growth factor (VEGF) also exhibited an expression pattern similar to that of Ang-2, and there was a significant correlation between the RNA content of ANG2 and that of VEGF in dissected samples (P =.002). Western blot analysis suggested that expression of Ang-1, Ang-2, Tie-2, and VEGF may be regulated at a transcriptional level. The increase in ANG2 RNA content from the peripheral portion of the tumor to the intermediate portion, coinciding with the decrease in recruitment of periendothelial supporting cells around the vascular endothelial cells, suggests that Ang-2 may play a role in the immaturity of tumor vessels. In conclusion, the current study suggests that Ang-2 and VEGF may cooperate to enhance the formation of new blood vessels in metastases of CRC to the liver.

Angioarrestin mRNA expression in early-stage lung cancers

AIMS

Angioarrestin is a recently isolated gene, which has a novel function as an angiogenesis inhibitor. Angiogenesis plays an important role in tumorigenesis. It has been reported that the angioarrestin expression was decreased in lung cancer. We attempted to determine the influence of angioarrestin expression on clinicopathological features in patients with lung cancer who had undergone surgery.

METHODS

Expression of angioarrestin messenger RNA was evaluated by a quantitative reverse transcription-polymerase chain reaction (RT-PCR) in 93 lung carcinomas and adjacent histological normal lung samples using LightCycler.

RESULTS

Angioarrestin/GAPDH mRNA expression was significantly decreased in the tumor of lung cancer tissue (86.676+/-123.505) than in the normal lung tissue (1154.218+/-2003.508, p<0.0001), although only four lung cancer tissues had more than one tumor/normal ratio of angioarrestin/GAPDH mRNA expression. There was no relationship between angioarrestin gene expression and age, gender or T-status. However, decreased angioarrestin/GAPDH expression was especially seen at stage I lung cancer (54.156+/-62.783) when compared to stage II-IV lung cancer (110.315+/-151.359, p=0.0316). Decreased angioarrestin/GAPDH expression was especially seen at N0 lung cancer (56.396+/-69.941) when compared to N2 lung cancer (137.522+/-180.489, p=0.0362).

CONCLUSIONS

The decreased expression of angioarrestin mRNA was the early phase phenomena for tumor progression from lung cancer. Alternatively, loss of antianiogenesis might play a role in oncogenesis for lung cancer.