Expression of angiopoietin 1, 2 and their common receptor Tie2 in human gastric carcinoma: implication for angiogenesis

Vagus innervation in the gastrointestinal tumor: Current understanding and challenges

The vagus nerve (VN) is the main parasympathetic nerve of the autonomic nervous system. It is widely distributed in the gastrointestinal tract and maintains gastrointestinal homeostasis with the sympathetic nerve under physiological conditions. The VN communicates with various components of the tumor microenvironment to positively and dynamically affect the progression of gastrointestinal tumors (GITs). The intervention in vagus innervation delays GIT progression. Developments in adeno-associated virus vectors, nanotechnology, and in vivo neurobiological techniques have enabled the creation of precisely regulated "tumor neurotherapies". Furthermore, the combination of neurobiological techniques and single cell sequencing may reveal more insights into VN and GIT. The present review aimed to summarize the mechanisms of communication between the VN and the gastrointestinal TME and to explore the potential and challenges of VN-based tumor neurotherapy in GITs.

Adaptor Protein ShcD/SHC4 Interacts with Tie2 Receptor to Synergistically Promote Glioma Cell Invasion

Gliomas are characterized by diffuse infiltration of tumor cells into surrounding brain tissue, and this highly invasive nature contributes to disease recurrence and poor patient outcomes. The molecular mechanisms underlying glioma cell invasion remain incompletely understood, limiting development of new targeted therapies. Here, we have identified phosphotyrosine adaptor protein ShcD as upregulated in malignant glioma and shown that it associates with receptor tyrosine kinase Tie2 to facilitate invasion. In human glioma cells, we find that expression of ShcD and Tie2 increases invasion, and this significant synergistic effect is disrupted with a ShcD mutant that cannot bind Tie2 or hyperphosphorylate the receptor. Expression of ShcD and/or Tie2 further increases invadopodia formation and matrix degradation in U87 glioma cells. In a coculture model, we show that U87-derived tumor spheroids expressing both ShcD and Tie2 display enhanced infiltration into cerebral organoids. Mechanistically, we identify changes in focal adhesion kinase phosphorylation in the presence of ShcD and/or Tie2 in U87 cells upon Tie2 activation. Finally, we identify a strong correlation between transcript levels of ShcD and Tie2 signaling components as well as N-cadherin in advanced gliomas and those with classical or mesenchymal subtypes, and we show that elevated expression of ShcD correlates with a significant reduction in patient survival in higher grade gliomas with mesenchymal signature. Altogether, our data highlight a novel Tie2-ShcD signaling axis in glioma cell invasion, which may be of clinical significance. IMPLICATIONS: ShcD cooperates with Tie2 to promote glioma cell invasion and its elevated expression correlates with poor patient outcome in advanced gliomas.

Angiopoietin 2 signal complexity in cardiovascular disease and cancer

The angiopoietin signal transduction system is a complex of vascular-specific kinase pathways that plays a crucial role in angiogenesis and maintenance of vascular homeostasis. Angiopoietin1 (Ang1) and 2 (Ang2), the ligand proteins of the pathway, belong to a family of glycoproteins that signal primarily through the transmembrane Tyrosine-kinase-2 receptor. Despite a considerable sequence homology, Ang1 and Ang2 manifest antagonistic effects in pathophysiological conditions. While Ang1 promotes the activation of survival pathways and the stabilization of the normal mature vessels, Ang2 can either favor vessel destabilization and leakage or promote abnormal EC proliferation in a context-dependent manner. Altered Ang1/Ang2 balance has been reported in various pathological conditions in association with inflammation and deregulated angiogenesis. In particular, increased Ang2 levels have been documented in human cancer and cardiovascular disease (CVD), including ischemic myocardial injury, heart failure and other cardiovascular complications secondary to diabetes, chronic renal damage and hypertension. Despite the obvious phenotypic differences, CVD and cancer share some common Ang2-dependent etiopathological mechanisms such as inflammation, epithelial (or endothelial) to mesenchymal transition, and adverse vascular network remodeling. Interestingly, both cancer and CVD are negatively affected by thyroid hormone dyshomeostasis. This review provides an overview of the complex Ang2-dependent signaling involved in CVD and cancer, as well as a survey of the related clinical literature. Moreover, on the basis of recent molecular acquisitions in an experimental model of post ischemic cardiac disease, the putative novel role of the thyroid hormone in the regulation of Ang1/Ang2 balance is also briefly discussed.

Oncogenic function of angiopoietin-2 in vitro and its modulation of tumor progression in colorectal carcinoma

Angiopoietin-2 (Ang-2) has been investigated in cancer primarily in terms of its angiogenic function, and its role as an oncogene has yet to be elucidated. The current study hypothesized that Ang-2 may be an oncogene and have a function in tumor progression. An investigation of the function of Ang-2 in the LoVo colorectal cancer (CRC) cell line in vitro, which expresses a high level of Ang-2, was performed by knocking down endogenous expression with a targeted short hairpin RNA. The aggressive phenotypic effects of Ang-2 on experimental and control group cells were assessed using cell proliferation, migration and invasion assays. The association between Ang-2 expression levels and clinicopathological factors was evaluated in 415 CRC tissues using immunohistochemistry. Suppressing Ang-2 expression decreased cellular proliferation, invasion and migration in an in vitro study. Ang-2 overexpression was observed in 46% of patients with CRC and was significantly associated with pT (P=0.048), pN (P<0.001), venous invasion (P=0.023), lymphatic invasion (P<0.001) and tumor-node-metastasis stage (P=0.022). Furthermore, Ang-2 overexpression was an independent prognostic factor in pN stages 1 and 2. These results reveal that Ang-2 may be an oncogene in colorectal carcinogenesis and its expression may exert aggressive phenotypic effects during tumor progression. In addition, Ang-2 expression may serve as a prognostic marker and a potential drug target.

A new angiogenesis prognostic index with VEGFA, PlGF, and angiopoietin1 predicts survival in patients with advanced gastric cancer

BACKGROUND/AIM

The role of angiogenic factors in gastric cancer is not clear. We aimed to assess the role of vascular endothelial growth factor A (VEGFA), angiopoietin 1 (Ang-1), and placental growth factor (PlGF) in the prognosis of patients with advanced gastric cancer.

MATERIALS AND METHODS

Thirty consecutive patients treated with a modified DCF (docetaxel, cisplatin, and fluorouracil) regimen were included in the study. The plasma VEGFA, Ang-1, and PlGF levels of the patients before treatment and following two cycles of chemotherapy were measured and evaluated as prognostic factors.

RESULTS

Poor performance status and lower Ang-1 levels were correlated with poor overall survival (OS). No significant correlation between VEGFA or PlGF and OS was found. An angiogenesis prognostic index (API) based on the levels of VEGFA, Ang-1, and PlGF was found to be highly correlated with OS. Performance status and API were found as independent prognostic factors for OS. Furthermore, a decrease in VEGFA by 25% from the pretreatment level was also found as a prognostic factor for OS independent of response to DCF regimen.

CONCLUSION

Our results support the use of the new API including VEGFA, Ang-1, and PlGF levels in patients with advanced gastric cancer as a predictor of survival.

The anti-angiogenic effect of dexamethasone in a murine hepatocellular carcinoma model by augmentation of gluconeogenesis pathway in malignant cells

PURPOSE

Angiogenesis is a long-term complex process involving various protein factors in hepatocellular carcinoma (HCC). Dexamethasone (Dex), considered as a synthetic glucocorticoid drug in clinical therapy, has been reported to have the therapeutic efficacy against liver cancer by intervention of abnormal glycolysis. In this study, we investigated the anti-angiogenic effect of Dex in murine liver cancer and attempted to demonstrate the potential mechanism.

METHODS

The malignant cells H22 were treated with Dex. Western blotting was used to explore the expression of PEPCK and G6Pase which were the two key enzymes that regulated gluconeogenesis. The supernatants from cultured H22 treated by Dex were collected and co-cultured with HUVECs. In vitro, migration assay, transwell assay and tube formation assay were performed to assess for migration, proliferation and tube formation abilities of HUVECs, respectively. In situ murine hepatoma model with green fluorescent protein markers (HepG2-GFP) was constructed to determine angiogenesis after treatment by Dex.

RESULTS

PEPCK and G6Pase were almost deficient in H22 compared with normal liver cells NCTC-1469 (P < 0.01). After treated by Dex, the gluconeogenesis could be restored significantly (P < 0.01) in H22 cells. The supernatant of H22 treated by Dex inhibited the migration, tube formation and endothelial permeability in HUVECs (P < 0.05). In mouse tissue, PEPCK and G6Pase were highly expressed in Dex group than control groups (P < 0.01). 11β-HSDs abnormally expressed in tumor also could be restored by Dex. Meanwhile, the density and total length of microvessels in Dex-treated group were less than those in HCC groups (P < 0.05).

CONCLUSIONS

This study explored the therapeutic efficacy of Dex in murine HCC. Dex might inhibit tumor growth and angiogenesis by augmenting the gluconeogenesis pathway.

Angiopoietins promote ovarian cancer progression by establishing a procancer microenvironment

Despite decades of research, the survival rate of ovarian cancer patients is largely unchanged. Current chemotherapeutic drugs are effective only transiently because patients with advanced disease eventually develop resistance. Thus, there is a pressing need for identifying novel therapeutic targets in ovarian cancer. Mounting evidence suggests that angiopoietins (Angpts) may play an essential role in cancer progression; however, the expression profiles and biological effects of Angpts on ovarian cancer remain largely unknown. Here, we show that, compared with their normal counterparts, expressions of Angpt1, Angpt2, and Angpt4 are increased in ovarian cancer cells and tissues and that human ovarian cancer cells also express the Angpt receptor Tie-2-receptor tyrosine kinase. We show that increased expression of Angpt1, Angpt2, or Angpt4 promotes intraperitoneal growth of ovarian cancers and shortens survival of the experimental mice. We further show, for the first time, that Angpts promote accumulation of cancer-associated fibroblasts and tumor angiogenesis in the ovarian cancer microenvironment, as well as enhance ovarian cancer cell proliferation and invasion in vivo. In addition, we establish a novel function of Angpts in promoting proliferation and invasion and inducing Tie-2 and extracellular signal-regulated kinase 1/2 activation in ovarian cancer-associated fibroblasts. Taken together, these data suggest that the Angpt-Tie-2 functional axis is an important player in ovarian cancer progression and an attractive target for ovarian cancer therapy.

Angiogenic and growth factors in gastric cancer

BACKGROUND

Antiangiogenic treatment is at the horizon in the palliative treatment of gastric cancer (GC), but data on proangiogenic biomarkers are still limited. The aim of this study was to analyze five proteins with a function in tumor angiogenesis: vascular endothelial growth factor (VEGF), angiopoietin-2 (Ang-2), follistatin, leptin, and platelet endothelial cell adhesion molecule 1 (CD31) in peripheral blood and corresponding tumor tissue.

MATERIAL AND METHODS

From 2008-2010, tumor tissue (n = 76) and corresponding preoperative serum (n = 69) of patients with localized GC were collected; 45 had perioperative chemotherapy. Protein serum or tumor lysate levels of these factors were measured by an angiogenesis multiplex immunoassay and correlated with response and survival.

RESULTS

Serum Ang-2 had prognostic relevance in the whole study population (P = 0.027). In subgroup analysis, serum VEGF and Ang-2 had prognostic relevance in primarily resected patients (P = 0.028; P = 0.048) but no association was found in neoadjuvantly treated patients. Follistatin concentration in the tumor tissue was associated with prognosis in all patients (P = 0.019). Tumor VEGF concentrations were correlated with histopathologic response (P = 0.011), with patients showing >50% remaining tumor having higher VEGF concentrations. The tissue Ang-2/VEGF ratio was significantly correlated with both clinical and histopathologic response (P = 0.029, P = 0.009). Additionally, the level of leptin in the tissue was associated with clinical response: nonresponding patients had higher leptin levels than those of responding patients (P = 0.032).

CONCLUSIONS

Our results show the importance of angiogenetic factors in serum and tumor tissue in GC for prognosis and treatment response. Further trials in larger patient populations are warranted for a further evaluation of proangiogenetic factors as biomarkers in gastrointestinal cancer.

Immunohistochemical Expression of Angiogenic Factors by Neoplastic Epithelial Cells Is Associated With Canine Prostatic Carcinogenesis

The dog is the only species, other than humans, in which spontaneous prostatic cancer occurs; therefore, dogs are a valuable model for the study of factors that regulate tumor progression. Angiogenesis is important in the development and spread of a variety of cancers, including prostate cancer. To better define the role of cancer epithelial cells in prostate cancer neovascularization, immunohistochemical staining for angiogenic factors (vascular endothelial growth factor [VEGF], platelet endothelial cell adhesion molecule–1 [PECAM-1], Tie-2, and fibroblast growth factor–2 [FGF-2]) was performed on formalin-fixed, paraffin-embedded tissues from 10 normal prostates, 15 hyperplastic prostates, and 11 prostatic carcinomas from dogs. Normal and hyperplastic epithelial cells were negative for PECAM-1, VEGF, and Tie-2, while the same markers were expressed with a variable intensity of cytoplasmic staining by neoplastic cells. Mild to moderate FGF-2 staining was detected in all normal prostates with less than 10% of positive cells, mainly distributed in the basal layer. The percentage of FGF-2–positive hyperplastic cells was variable, with both basal and secretory cells exhibiting a perinuclear to diffuse cytoplasmic staining. The mean number of positive cells and the intensity of staining were higher in prostatic carcinomas than normal and hyperplastic prostates. Moreover, microvessel density analyzed on PECAM-1–stained slides was increased in prostate cancer compared with normal and hyperplastic prostates. Therefore, prostatic neoplastic cells are capable of simultaneous expression of various angiogenic factors and may increase tumor proliferation and angiogenesis in a paracrine and autocrine fashion.

Angiogenesis-related biomarkers in patients with alcoholic liver disease: their association with liver disease complications and outcome

Angiogenesis is believed to be implicated in the pathogenesis of alcoholic liver disease (ALD). We aimed to explore the usefulness and accuracy of plasma angiogenic biomarkers for noninvasive evaluation of the severity of liver failure and ALD outcome. One hundred and forty-seven patients with ALD were prospectively enrolled and assessed based on their (1) gender, (2) age, (3) severity of liver dysfunction according to the Child-Turcotte-Pugh and MELD scores, and (4) the presence of ALD complications. Plasma levels of vascular endothelial growth factor (VEGF-A) and angiopoietins 1 and 2 (Ang1 and Ang2) were investigated using ELISAs. Multivariable logistic regression was applied in order to select independent predictors of advanced liver dysfunction and the disease complications. Significantly higher concentrations of Ang2 and VEGF-A in ALD patients as compared to controls were found. There was no difference in Ang1 levels in both groups. A positive correlation of Ang2 levels with INR (Rho 0.66; P < 0.0001) and its inverse correlation with plasma albumin levels (Rho –0.62; P < 0.0001) were found. High Ang2 concentrations turned out to be an independent predictor of severe liver dysfunction, as well as hepatic encephalopathy and renal impairment. Ang2 possessed the highest diagnostic and prognostic potential among three studied angiogenesis-related molecules.

Phase II randomized, double-blind, placebo-controlled study of AMG 386 (trebananib) in combination with cisplatin and capecitabine in patients with metastatic gastro-oesophageal cancer

BACKGROUND

We evaluated AMG 386, an investigational peptibody that neutralizes the interaction between angiopoietins-1 and -2 and the Tie2 receptor, combined with cisplatin/capecitabine (CX) as first-line treatment for metastatic gastro-oesophageal cancer.

PATIENTS AND METHODS

Patients with metastatic gastric, gastro-oesophageal junction, or distal oesophageal adenocarcinoma were randomized 1:1:1 to CX (cisplatin 80 mg/m(2) IV Q3W; capecitabine 1000 mg/m(2) P.O. BID for 14 days Q3W) plus intravenous AMG 386 10 mg/kg QW (Arm A) or 3 mg/kg QW (Arm B), or placebo QW (Arm C). The primary end point was estimated progression-free survival (PFS).

RESULTS

A total of 171 patients were enrolled. Median estimated PFS in Arms A, B, and C was 4.2, 4.9, and 5.2 months, respectively (hazard ratio for Arms A+B combined versus Arm C, 0.98; 95% CI 0.67-1.43; P = 0.92). Objective response rates were 27% (Arm A), 43% (Arm B), and 35% (Arm C). Incidence of grade ≥3 adverse events was 80% in Arm A, 84% in Arm B, and 75% in Arm C. There was no evidence of pharmacokinetic interactions.

CONCLUSIONS

In this study, PFS and ORR were estimated to be similar with AMG 386 plus CX and placebo plus CX treatment. Compared with placebo, toxicity of AMG 386 plus CX was greater but manageable.

PREVIOUS PRESENTATION

The results of this study have not been previously published or submitted for publication elsewhere. The results were presented in part at the Gastrointestinal Cancers Symposium, San Francisco, CA, January 20-22, 2011.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov registration number: NCT00583674.

The complex role of angiopoietin-2 in the angiopoietin-tie signaling pathway

The angiopoietin-Tie signaling system is a vascular-specific receptor tyrosine kinase pathway that is essential for normal vascular development. Although the basic functioning of the pathway is understood, many uncertainties remain about the role of certain members of the pathway, particularly angiopoietin-2 (Ang2), in pathological vascular remodeling and angiogenesis. We summarize the components of the angiopoietin-Tie pathway and then focus on studies that highlight the role of Ang2 in disease settings, including cancer and inflammation. The expression of Ang2 is elevated in many cancers and types of inflammation, which prompted the development of specific reagents to block its interaction with the Tie2 receptor. The application of these reagents in preclinical models of inflammation and cancer has begun to elucidate the role of Ang2 in vascular remodeling and disease pathogenesis and has led to emerging clinical tests of Ang2 inhibitors.

The effects of designed angiopoietin-1 variant on lipid droplet diameter, vascular endothelial cell density and metabolic parameters in diabetic db/db mice

Metabolic syndrome consists of metabolic abnormality with central obesity, hypertriglyceridemia, insulin resistance and hypertension. Adipose tissue has been known as a primary site of insulin resistance and its adipocyte size may be correlated with the degree of insulin resistance. A designed angiopoietin-1, COMP-Angiopoietin-1 (COMP-Ang1), mitigated high-fat diet-induced insulin resistance in skeletal muscle. In this study, we examined effects of COMP-Ang1 on adipocyte droplet size, vascular endothelial cell density in adipose tissue and metabolic parameters in db/db mice by administering COMP-Ang1 or LacZ (as a control) adenovirus. Administration of COMP-Ang1 decreased fat droplet diameter in epididymal and abdominal visceral adipocyte and visceral fat content in db/db mice. The density of vascular endothelial cell in adipose tissue was increased in db/db mice after treatment with COMP-Ang1. Serum resistin and tumor necrosis factor-α level was lower after treatment with COMP-Ang1 in db/db mice. COMP-Ang1 caused a restoration of fasting glycemic control in db/db mice and decreased serum insulin level and insulin resistance measured by HOMA index. These findings indicate that COMP-Ang1 regulates adipocyte fat droplet diameter, vascular endothelial cell density and metabolic parameters in db/db mice.

Antibody drug-conjugates targeting the tumor vasculature: Current and future developments

Reducing the blood supply of tumors is one modality to combat cancer. Monoclonal antibodies are now established as a key therapeutic approach for a range of diseases. Owing to the ability of antibodies to selectively target endothelial cells within the tumor vasculature, vascular targeting programs have become a mainstay in oncology drug development. However, the antitumor activity of single agent administration of conventional anti-angiogenic compounds is limited and the improvements in patient survival are most prominent in combinations with chemotherapy. Furthermore, prolonged treatment with conventional anti-angiogenic drugs is associated with toxicity and drug resistance. These circumstances provide a strong rationale for novel approaches to enhance the efficacy of mAbs targeting tumor vasculature such as antibody-drug conjugates (ADCs).Here, we review trends in the development of ADCs targeting tumor vasculature with the aim of informing future research and development of this class of therapeutics.

Eukaryotic expression of extracellular ligand binding domains of murine Tie-2 and its anti-angiogenesis effect in SGC-7901 cell lines

BACKGROUND AND AIMS

Researches about blocking angiogenesis to treat tumor have become one of the most promising and active fields in anticancer research. This study aimed to investigate the eukaryotic expression of extracellular ligand binding domains of murine Tie-2 and its anti-angiogenesis effect.

METHODS

A eukaryotic expression vector pcDNA3.1(+) integrating with a DNA fragment which encode extracellular ligand binding domains of murine Tie-2 was transfected into SGC-7901 gastric cancer cell line. The protein expression was detected by western blot analysis and immunocytochemistry staining. Following the construction of nude mouse tumor xenograft model with and without transfected cells, tumor microvessel density was determined by counting per high power field in the sections stained with an antibody to CD31 to test its inhibition of angiogenesis.

RESULTS

The extracellular ligand binding domains of murine Tie-2 receptor was highly expressed in SGC-7901 gastric cancer cells with plasmid transfection. The mean tumor sizes of groups with and without transfection were 1.27 +/- 0.35 and 1.75 +/- 0.17 cm(3), respectively (P = 0.025). The mean inhibitory rate of tumor was 27.18 +/- 19.93%. The comparison between highest microvessel density of group with transfection (14.00 +/- 3.80) and that of group without transfection (22.30 +/- 5.91) was statistically significant at P = 0.030.

CONCLUSION

The protein of extracellular ligand binding domains of murine Tie-2 can be expressed at high level in the eukaryotic expression system, and the expressed protein may have the anti-angiogenesis effect.

Effects of angiopoietin-1 on attachment and metastasis of human gastric cancer cell line BGC-823

AIM: To evaluate the effects of angiopoietin-1 (Ang-1) on adhesion of gastric cancer cell line BGC-823 and expression of integrin β1, CD44V6, urokinase-type plasminogen activator (uPA) and matrix metalloproteinase-2 (MMP-2).

METHODS: BGC-823 cells were transfected transiently with adenovirus-Ang-1 (Ad-Ang-1). Cells transfected transiently with adenovirus-green fluorescent protein (Ad-GFP) and untransfected cells were used as a negative and blank control group, respectively. The cell adhesion rate between cell and extracellular matrix (ECM) was determined by cell adhesion assay. To investigate whether Ang-1 could reinforce gastric carcinoma metastasis, we performed migration and invasion assays in BGC-823 cells. The mRNA and protein expression of integrin β1, CD44V6, uPA and MMP-2 were detected by reverse transcription polymerase chain reaction and Western blotting, respectively. The expression of integrin β1 and CD44V6 was measured by immunohistochemistry.

RESULTS: BGC-823 cells were transfected successfully. The adhesion rate increased significantly in the Ad-Ang-1 group (P < 0.05). The Ad-Ang-1-transfected group had a significant increase in migration and invasion compared with that of the mock-transfected and Ad-GFP groups. The mRNA and protein expression of integrin β1, CD44V6, uPA and MMP-2 in the Ad-Ang-1 group was higher than that in the Ad-GFP and blank control groups (P < 0.05). Compared with mock-transfected and Ad-GFP groups, integrin β1 and CD44V6 expression intensity greatly increased (P < 0.05).

CONCLUSION: Transfection of Ang-1 into human gastric cancer cell line BGC-823 can significantly increase expression of integrin β1 and CD44V6, by which cell adhesion and metastasis to the ECM are promoted.

Prognostic value of tumor-related molecular expression in gastric carcinoma

In order to identify reliable molecular markers for prognostic prediction in gastric carcinoma, we evaluated the expression of six molecular markers, namely bFGF, IGF-2, HGF, MMP-9, integrin beta3 and uPA in gastric cancer. There was a significant correlation between the expression of these markers and the depth of tumor invasion, vessel invasion, lymph node and distant metastasis, TNM stage and microvessel density. The average survival time and 5-year survival rate of patients with positive expression of molecular markers was higher than those with negative expression. Multivariate analysis showed that abnormal expression of bFGF, MMP-9 and uPA, as well as depth of invasion, lymph node and distant metastasis and TNM stage were independently related to poor prognosis of gastric cancer. MMP-9, bFGF and uPA are potential candidates for development as clinically applicable molecular prognostic markers for gastric carcinoma, and may be effective therapeutic targets for the disease in the future.

Relationship between human tumour angiogenic profile and combretastatin-induced vascular shutdown: an exploratory study

Combretastatin-A4-phosphate (CA4P) acts most effectively against immature tumour vasculature. We investigated whether histological angiogenic profile can explain the differential sensitivity of human tumours to CA4P, by correlating the kinetic changes demonstrated by dynamic MRI (DCE-MRI) in response to CA4P, with tumour immunohistochemical angiogenic markers. Tissue was received from 24 patients (mean age 59, range 32–73, 18 women, 6 men). An angiogenic profile was performed using standard immunohistochemical techniques. Dynamic MRI data were obtained for the same patients before and 4 h after CA4P. Three patients showed a statistically significant fall in K^trans following CA4P, and one a statistically significant fall in IAUGC₆₀. No statistically significant correlations were seen between the continuous or categorical variables and the DCE-MRI kinetic parameters other than between ang-2 and K^trans (P=0.044). In conclusion, we found no strong relationships between changes in DCE-MRI kinetic variables following CA4P and the immunohistochemical angiogenic profile.

Angiopoietin-1 targeted RNA interference suppresses angiogenesis and tumor growth of esophageal cancer

AIM: To determine the inhibitory effect of the adenovirus-based angiopoietin-1 (Ang-1) targeted small interfering RNA expression system (Ad/Ang-1si) on the expression of the Ang-1 gene, cell growth and apoptosis in human esophageal cancer cell line Eca109.

METHODS: siRNA-expressing adenovirus targeting Ang-1 gene was constructed using the Ad Easy System. Cultured Eca109 cells were transfected with Ad/Ang-1si (Eca109/Ang-1si), and Ad/si was used to infect Eca109 cells as control (Eca109/si). Ang-1 gene expression and concentration was determined with RT-PCR and ELISA, respectively. Human umbilical vein endothelial cell (HUVEC) migration and proliferation were analyzed. After s.c. injection into athymic nu/nu mice, the tumor growth, vessel density and apoptosis of each group was also determined.

RESULTS: HUVEC migration induced by conditioned medium from Ang-1si-transfected Eca109 cells was significantly less than that induced by conditioned medium from Eca109 cells and control adenovirus-transfected Eca109 cells. Furthermore, after s.c. injection into athymic nu/nu mice, the tumor growth and cell apoptosis of Ad/Ang-1si -expressing Eca109 cells was significantly lower than that of parental or control adenovirus-transfected cells. Vessel density assessed by CD31 immunohistochemical analysis and Ang-1 expression by RT-PCR were also decreased.

CONCLUSION: The targeting Ang-1 may provide a therapeutic option for esophageal cancer.

Mapping the human proteome for non-redundant peptide islands

We describe immune-proteome structures using libraries of protein fragments that define a structural immunological alphabet. We propose and validate such an alphabet as i) composed of letters of five consecutive amino acids, pentapeptide units being sufficient minimal antigenic determinants in a protein, and ii) characterized by low-similarity to human proteins, so representing structures unknown to the host and potentially able to evoke an immune response. In this context, we have thoroughly sifted through the entire human proteome searching for non-redundant protein motifs. Here, for the first time, a complete sequence redundancy dissection of the human proteome has been conducted. The non-redundant peptide islands in the human proteome have been quantified and catalogued according to the amino acid length. The library of uniquely occurring n-peptide sequences that was obtained is characterized by a logarithmic decrease of the number of non-redundant peptides as a function of the peptide length. This library represents a highly specific catalogue of molecular protein signatures, the possible use of which in cancer/autoimmunity research is discussed, with a major focus on non-redundant dodecamer sequences.

Angiopoietins lack of prognostic significance in ductal mammary carcinoma

Angiopoietins (Ang) have been shown to regulate the process of vasculature and angiogenesis in tumour. Different angiopoietins have different roles during the angiogenic process. The current study sought to examine the levels of the expression of Ang-1, Ang-2, Ang-3 and their receptor Tie-2 in mammary ductal carcinoma and to assess their relevance to prognosis. Fresh frozen ductal carcinoma tissues (n = 90) and adjacent non-cancerous breast tissues (n = 32) were used. The expression of Ang-1, Ang-2 and Ang-3 transcripts in cancer and normal breast tissues were examined quantitatively using quantitative RT-PCR. The protein expression of Ang-1, Ang-2 and Tie-2 was assessed by immunohistochemistry on frozen sectioned tissues.

Ang-1, Ang-2 and Ang-3 were detected in mammary tissues. Ang-1 was seen in both normal epithelial cells, breast cancer cells as well as in endothelial cells. Ang-2 was seen at a higher level than Ang-1 and it is expressed in epithelial, endothelial as well as stromal cells to certain degree. Ang-1 and Ang-2 transcripts were detected almost equally in cancer and normal breast tissue, and Ang-3 was high in cancer tissue compared to normal breast but not significant (155 ± 123 & 24.1 ± 22.6, P > 0.05). No significant differences were seen between patients with different predicted prognosis (using the Nottingham Prognostic Index as a guide) (Ang-1 p = 0.34, Ang-2 p = 0.26 and Ang-3 p = 0.32, respectively). No significant correlation was seen between Ang-1, Ang-2 and Ang-3 with tumour grade. When the levels of the transcripts were compared against clinical outcome (disease free, developed recurrence and patients who died of breast cancer), levels of Ang-3 transcript was found to be high in breast cancer patient who had bone metastasis 33.8 ± 28.3, although the difference was not significant (p = 0.08). No significant difference was seen with levels of Ang-1 and Ang-2 transcripts and clinical outcomes. Furthermore, no significant trend was observed between Tie-2 receptor and clinical/pathological parameters in the cohort.

These data suggest that angiopoietins (Ang-1, Ang-2 and Ang-3) are expressed in mammary tissues, both in normal and tumour. These molecules have limited value in predicting the prognosis and clinical outcome in patients with mammary ductal carcinoma.