Diagnostic Values of sVEGFR-1 and Endostatin in Malignant Pleural Effusions in Patients with Lung Cancer

BACKGROUND

The diagnosis of malignant pleural effusion (MPE) remains a common clinical challenge because of the sensitivity of conventional cytology for the detection is insufficient. Thus, a sensitive clinical marker for diagnosis is required. The aim of this study was to assess the role of two anti-angiogenic cytokines, soluble vascular endothelial growth factor receptor-1 (sVEGFR-1) and endostatin, in diagnosing MPE.

METHODS

Effusion samples from 44 patients with MPE caused by lung cancer and from 36 patients with benign pleural effusion (BPE) were collected. The concentrations of sVEGFR-1 and endostatin in pleural fluid were determined by an enzyme-linked immunosorbent assay (ELISA). The diagnostic performance was measured by receiver operating characteristic curves (ROCs).

RESULTS

The levels of sVEGFR-1 and endostatin in MPE due to lung cancer were significantly higher than those in BPE (p < 0.05). The sensitivity and specificity of endostatin were 52.27% and 86.11%, respectively, while for sVEGFR-1, the sensitivity was 88.64% and the specificity was 58.33%. Interestingly, the combination of sVEGFR1 and endostatin produced better sensitivity and specificity of 72.73% and 83.33%, respectively. In addition, the levels of sVEGFR-1 and endostatin were significantly related to each other (p < 0.05), and the levels of endostatin in bloody effusions were significantly higher than those in non-bloody effusions (p < 0.05).

CONCLUSIONS

Our study indicated that the levels of sVEGFR-1 and endostatin were significantly elevated in MPE. The combined detection of sVEGFR-1 and endostatin may be useful in the diagnosis of MPE.

[Age-related changes of the content of angiomatin and endostatin in human skin]

Human skin structures stained positively for angiomotin or endostatin were studied by indirect immunohistochemical method. Skin specimens from frontal surface of the lower part of the neck (from upper corner of standard autopsy skin incision) from human fetuses died antenatally from 20 to 40 weeks of pregnancy, humans who died from different causes from 1 day to 85 years of life were obtained at autopsy. Positive staining for angiomotin or endostatin in the skin was found in epidermal cells, fibroblasts, sweat and sebaceous glands, blood vessels of the dermis. Blood vessels stained positively for angiomotin were detected in skin samples in all ages. Age-dependent decrease in the content of angiomotin in blood vessels of the dermis was detected. Most prominent decrease in angiomotin content in dermal blood vessels was found in 61-85 years age-group. Endostatin positive blood vessels were also detected in skin samples of all ages. However, the intensity of staining for endostatin in dermal blood vessels was increased during aging. It can be proposed that changes in the content of angiomotin and endostatin yield a negative impact on angiogenesis in human skin during aging.

Chronic alcohol consumption stimulates VEGF expression, Tumor angiogenesis and progression of melanoma in mice

The mechanisms of alcohol-induced cancer in humans are unclear. We used the immunocompetent mice implanted with B16F10 cells to evaluate the effects of physiologically relevant EtOH intake on tumor growth and angiogenesis of melanoma. Six-wk-old male mice (C57BL/6J) were given 1% EtOH in drinking water for 12-hrs during the night which was then replaced with regular water during the remaining 12-hrs each day for 4 wks (n = 10). The control mice received regular drinking water only. In the second week, all mice were inoculated subcutaneously on the right proximal dorsal with 5 x 10(5) B16F10 cells. In the end, the tumors were isolated for measuring tumor size, average microvascular density (AMVD) using CD31 immunohistochemistry, and the expression of VEGF and its receptor (Flt-1) using Northern blot, ELISA, and immunohistochemistry. EtOH intake caused a 2.16-fold increase in tumor weight over the control (4.81 +/- 0.39 vs. 2.23 +/- 0.48 g; n = 10; p = 0.003), a 2.02-fold increase in AMVD (60.63 +/- 5.56 vs. 30.01 +/- 7.41/mm(2); p = 0.0014), and a significant increase in VEGF mRNA and protein expression plus Flt-1 protein levels in melanoma compared to the control group (p < 0.01). These results suggest that progression of melanoma growth and angiogenesis may be mediated by upregulation of VEGF and Flt-1, especially under the influence of EtOH.

Normal ranges of angiogenesis regulatory proteins in human platelets

Platelets sequester angiogenesis regulatory proteins early in tumor growth, which suggests a new avenue for monitoring disease. To date, there are no clinically relevant reference ranges for markers of early angiogenesis. We introduce a new ELISA-based method for accurate and reproducible measurement of vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF), platelet factor 4 (PF4), thrombospondin-1 (TSP-1), fibroblast growth factor, basic (bFGF), and endostatin in platelets. To facilitate clinical applicability, the platelet levels in isolated samples were determined utilizing a new actin ELISA method. Platelets from healthy donors at single and repetitive time points were used for the assessment of normal ranges of these proteins. The physiological levels in platelets were: VEGF (0.74 +/- 0.37 pg/10(6) platelets); PDGF (23 +/- 6 pg/10(6)); PF4 (12 +/- 5 ng/10(6)); TSP-1 (31 +/- 12 ng/10(6)); bFGF (0.44 +/- 0.15 pg/10(6)); and endostatin (5.6 +/- 3.0 pg/10(6)). There was an excellent correlation (R(2) = 0.7) between the platelet levels calculated with the actin ELISA and complete blood count. The levels of the platelets were higher than those in platelet-poor plasma by factors of: VEGF (215-fold); PDGF (914-fold); PF-4 (516-fold); TSP-1 (813-fold); and bFGF (17-fold). The endostatin levels were nearly equivalent. The biovariability of the platelet proteins in eight healthy subjects over a 5-week period was found to be minimal. We describe accurate and direct measurements of the concentrations of VEGF, bFGF, PDGF, TSP-1, endostatin, and PF4 in platelets of healthy human subjects. In contrast to the highly variable levels in plasma and serum, the platelet-derived measurements were accurate and reproducible with minimal biovariability.

Characterization of a monoPEG20000-Endostar

In this study, we investigated the PEG attachment site of mono-PEGylated Endostar, a modified recombinant human endostatin approved in China for lung cancer. N-terminal site-directed mono-PEGylation of Endostar was accomplished using mPEG-propionaldehyde derivatives (Mw=20 kDa) under slightly acidic pH conditions (pH 5.5). One-step cation exchange chromatography was used to purify the mono-PEGylated Endostar. Following tryptic digestion, the peptide fragment containing PEG was separated by SDS-PAGE. Barium iodide staining and Western blotting were used to detect the PEG moiety and the N-terminus of Endostar, respectively. The peptide fragment stained by barium iodide showed a positive response to anti-(His) 6 mAb, demonstrating that PEG was located at the N-terminus of Endostar. LC/MS was applied to verify the occurrence of mono-PEGylation at the N-terminus of Endostar.

Diagnostic value of vascular endothelial growth factor and endostatin in malignant pleural effusions

OBJECTIVE

To assess the value of vascular endothelial growth factor (VEGF) and endostatin in the differential diagnosis of malignant and tuberculous pleural effusions (PE).

METHODS

Effusion samples were collected from 62 patients with malignant PE caused by lung cancer and from 64 patients with tuberculous pleurisy. Concentrations of pleural fluid VEGF and endostatin were measured simultaneously using enzyme-linked immunosorbent assay (ELISA) and enzyme immunoassay, respectively. The sensitivity, specificity and accuracy were calculated.

RESULTS

PE levels of VEGF and endostatin were found to be significantly elevated in effusions with malignancy rather than in those of tuberculous origin (both P < 0.01). For VEGF, the sensitivity, specificity and accuracy in diagnosing malignant pleural effusions were respectively 71%, 61% and 66%, while for endostatin the values were respectively 69%, 83% and 76%. A combination of VEGF and endostatin can increase these to respectively 81%, 97% and 89%.

CONCLUSIONS

Elevated levels of VEGF and endostatin in pleural effusions may be helpful in diagnosing malignant pleural effusions, while a combination of VEGF and endostatin can increase the sensitivity, specificity and accuracy of differentiating malignant from tuberculous pleural effusions.

[Effects of electroacupuncture on expression of angiogenic growth factors and antiangiogenic growth factors in the brain tissue of the rat after focal cerebral ischemia reperfusion]

OBJECTIVE

To explore the mechanism of electroacupuncture (EA) in improving ischemic stroke.

METHODS

A Wistar rat model of focal cerebral ischemia reperfusion was made by filament occlusion. The rats were randomly divided into a normal group, a model group, an EA group. EA was given at bilateral "Hegu" (LI 4) in the EA group. Vascular endothelial growth factor (VEGF) mRNA was detected with in situ hybridization and expression of angiogenin-1 (Ang-1) and endostatin proteins with immunohistochemical method.

RESULTS

The expressions of angiogenic growth factors including VEGF and Ang-1 in the EA group were significantly increased, while the expressions of endostatin was significantly decreased as compared with those in the model group (both P<0.05).

CONCLUSION

EA improving ischemic stroke is carried out possibly through up-regulating the expression of angiogenic growth factors and down-regulating the expression of antiangiogenic growth factors.

Immunohistochemical identification and localization of endogenous endostatin and its related peptides in murine tumors

Endostatin, a fragment of the C-terminal domain of mouse collagen XVIII, is a recently demonstrated endogenous inhibitor of tumor angiogenesis. Although endostatin can be detected in blood and urine of tumor-bearing as well as normal mice, the exact localization of the endogenous protein and its related peptides in tumor tissues is unknown. We used immunohistochemistry and immunoblotting to identify endostatin tissue location and staining patterns in tumor, as well as to determine the differences in the levels of endostatin expression between tumor cells (in vitro) and tumor tissues (in vivo). Using a specific polyclonal antibody against murine endostatin, we quantitatively determined the levels of endostatin in five murine mammary tumors and the KHT sarcoma by Western blotting. The staining patterns for this protein in tumor sections were examined histologically by immunohistochemistry. Our results show that: (1) Endogenous endostatin and its related peptides are widely distributed in all in vivo tumor types tested, but not in most of the cultured tumor cell lines. (2) Endogenous endostatin stained most tumor stromal components, including vessel walls, basement membranes, extracellular spaces, and tumor cells. (3) Staining patterns and localization of endostatin and thrombospondin-1 were similar in these tumor sections.

Endostatin peptide, an inhibitor of angiogenesis, prevents the progression of peritoneal sclerosis in a mouse experimental model

Peritoneal sclerosis is a major and serious complication in patients on long-term continuous ambulatory peritoneal dialysis (PD). The involvement of angiogenesis and proangiogenic factors such as vascular endothelial growth factor (VEGF)-A in progressing peritoneal sclerosis has been reported. We previously reported the therapeutic efficacy of endostatin peptide, a potent inhibitor of angiogenesis derived from type XVIII collagen, in a mouse diabetic nephropathy model. Here, we examined the therapeutic effect of endostatin peptide in preventing progression in a mouse peritoneal sclerosis model. Male ICR mice received intraperitoneal injections of chlorhexidine gluconate (CG) every other day to induce peritoneal sclerosis. Endostatin peptide (1 or 4 mg/kg/day) was administered via subcutaneously implanted osmotic minipumps. Peritoneal sclerosis (day 24) was significantly suppressed by endostatin peptide in a dose-dependent manner. Peritoneal accumulation of type III collagen was significantly suppressed by endostatin peptide. Increase in the number of CD31(+) blood vessels, F4/80(+) monocyte/macrophage accumulation, and 5-bromodeoxyuridine(+) proliferating cells was significantly inhibited by endostatin peptide. Increase in peritoneal expression of VEGF-A, profibrotic transforming growth factor-beta1, and alpha-smooth muscle actin was suppressed by endostatin peptide. Immunoreactivity for endogenous endostatin (whole molecule) and endostatin receptor alpha5beta1-integrin was increased and colocalized to CD31(+) blood vessels in the thickened peritonea of CG-injected mice. These results demonstrate the potential use of antiangiogenic endostatin peptide as a novel therapeutic agent in preventing peritoneal sclerosis, a severe complication in patients undergoing long-term PD.

Collagen XVIII modulation is altered during progression of oral dysplasia and carcinoma

BACKGROUND

Collagen XVIII is a ubiquitous basement membrane (BM) component and a precursor of endostatin.

METHODS

Using immunohistochemistry and in situ hybridization, we studied the expression and localization of collagen XVIII in different stages of normal oral wound healing, epithelial dysplasia and squamous cell carcinoma (SCC).

RESULTS

In mild epithelial dysplasias collagen XVIII appeared as a continuous signal in the BM, whereas in severe epithelial dysplasias and in the invasive areas of oral SCCs collagen XVIII was absent. In situ hybridization showed that collagen XVIII mRNA expression did not decrease in severe dysplasia or oral carcinoma samples when compared with the mild dysplasias.

CONCLUSIONS

The results indicate that the absence of collagen XVIII protein in severe oral dysplasias is related to the processing of the protein rather than to changes in mRNA expression.

Expression of endostatin in human choroidal neovascular membranes secondary to age-related macular degeneration

Endostatin is an endogenous angiogenesis inhibitor which requires E-selectin for its antiangiogenic activity. The aim of this study was to investigate the expression of endostatin in human choroidal neovascular membranes (CNV) secondary to age-related macular degeneration (AMD) with regard to vascularization and proliferative activity. An interventional case series of 36 patients who underwent removal of CNV were retrospectively investigated. Thirty-six CNV were analyzed by light microscopic immunohistochemistry for the expression of CD34 (endothelial cells, EC), CD105 (activated EC), Ki-67 (cell proliferation), Cytokeratin 18 (epithelial cells), VEGF (vascular endothelial growth factor), E-selectin and endostatin. Donor eyes (n=7) including one with AMD were used as controls. Endostatin immunoreactivity was present in choroidal vessels of five as well as in the retinal pigment epithelium (RPE)-Bruch's membrane complex of two donor eyes without AMD. In one eye with AMD, endostatin was detected in RPE, Bruch's membrane and choroidal vessels. Ninety-two percent (33/36) of CNV disclosed endostatin staining. RPE-Bruch's membrane complex, choroidal vessels and stroma were positive in 50% (18/36), 72% (26/36), and 78% (28/36) of the membranes, respectively. Both control eyes and CNV expressed all the investigated markers except E-selectin being positive only in membranes. Endostatin, an endogenous angiogenesis inhibitor, is expressed in CNV and its therapeutic up-regulation may be a new strategy in the treatment of neovascular AMD.

Endostatin/Collagen XVIII Accumulates in Patients with Traumatic Brain Injury

In patients with traumatic brain injury (TBI), hypoperfusion contributes to ongoing and expanding areas of neuronal damage long after the initial trauma has ceased. In order to evaluate whether the antiangiogenic protein endostatin may play a role in this process, we analyzed its spatial distribution in brains of 18 patients with TBI. We observed an increase of endostatin/collagen XVIII(+) macrophages/microglial cells but not astrocytes up to day 14 and a consequent decrease to day 16 post-TBI. In addition, paracellular endostatin/collagen XVIII deposits were detected. In vitro experiments revealed that microglial endostatin release is induced predominantly by hypoxia and, to a lesser extent, by reactive oxygen intermediates. Common NO synthase inhibitor pharmacotherapy with aminoguanidine and L-NAME completely abolished endostatin release from microglial cells, raising hopes of altering endostatin release in vivo.

Tissue Endostatin Correlates Inversely with Capillary Network in Rat Heart and Skeletal Muscles

The role of angiostatic factors, including endostatin, in regulating physiological angiogenesis is poorly understood. We used normal adult rats under physiological resting conditions to examine the relationship between tissue endostatin, VEGF, and capillary density (CD) in the heart (high metabolic activity) versus the skeletal muscle (relatively low metabolic activity). The heart (left ventricle, LV) and skeletal muscle (anterior tibialis, AT) were dissected from 12-week-old male Sprague-Dawley rats. Transverse cryosections of LV and AT were stained with FITC-conjugated GS-I-lectin. CD was determined by analysis of randomly acquired digital images of the cryosections using Optimas software. Tissue protein levels of endostatin and VEGF were determined by ELISA assays. Tissue endostatin levels were lower in the LV and higher in the AT (135 +/- 39 vs. 663 +/- 114 pg/mg) and VEGF levels were higher in the LV and lower in the AT (41 +/- 3 vs. 27 +/- 4 pg/mg), respectively (n = 7, P < 0.01). CD in LV and AT were 3632 +/- 428 and 437 +/- 44/mm2, respectively (P < 0.01). We demonstrated that an 8.3-fold greater capillary density is related to a 4.9-fold lower level of tissue endostatin and a 1.5-fold higher level of tissue VEGF in the heart (LV) versus the skeletal muscle (AT) of normal rats under physiological resting conditions. Also, exercise training increased capillary density, decreased tissue endostatin and increased tissue VEGF in the skeletal muscle (AT). These findings suggest that tissue endostatin content correlates inversely with capillary network in the muscle tissues with different metabolic activity, and that tissue endostatin may play a very important role in the metabolic control of angiogenesis under physiological conditions.

Angiogenic factors and angiogenesis inhibitors in exudative pleural effusions

The angiogenesis system has been implicated in inflammatory and neoplastic processes; nevertheless, it has been little studied in relation to the pleural space. Our aim is to analyze pleural and plasma levels of the activators--vascular endothelial growth factor, basic fibroblastic growth factor, and inhibitors--endostatin and thrombospondin-1 and to estimate the association between these factors and related biochemical markers. We analyzed pleural fluid from 105 patients with one of the following types of pleural effusion: empyema or complicated parapneumonic, non-complicated parapneumonic, tuberculous, neoplastic and transudative. Angiogenesis activators were higher in exudates than in transudates (p < 0.001) and in empyema than in non-complicated parapneumonic patients (p < 0.001). Endostatin showed no significant differences. Trombospondin-1 showed higher levels in exudates than in transudates and in empyema than in non-complicated parapneumonic effusions (p < 0.001). In pleural exudates there was a positive correlation of angiogenesis activators and trombospondin-1 with low glucose and pH and high LDH. There was no correlation between pleural and plasma levels of the angiogenesis factors. We conclude that exudative pleural effusions showed higher vascular endothelial growth factor, basic-fibroblastic growth factor and trombospondin-1 values than transudative effusions that associated to low glucose and pH, and high LDH. There was no correlation between pleural and plasma concentrations, suggesting a compartmentalized response.

Antiangiogenic endostatin peptide ameliorates renal alterations in the early stage of a type 1 diabetic nephropathy model

Diabetic nephropathy is one of the major microvascular complications in diabetes and is the leading cause of end-stage renal disease worldwide. Among various factors, angiogenesis-associated factors such as vascular endothelial growth factor (VEGF)-A and angiopoietin (Ang)-2 are involved in the development of diabetic nephropathy. We previously reported the therapeutic efficacy of antiangiogenic tumstatin peptide in the early diabetic nephropathy model. Here, we examine the effect of endostatin peptide, a potent inhibitor of angiogenesis derived from type XVIII collagen, in preventing progression in the type 1 diabetic nephropathy mouse model. Endostatin peptide did not affect hyperglycemia induced by streptozotocin (STZ). Glomerular hypertrophy, hyperfiltration, and albuminuria were significantly suppressed by endostatin peptide (5 mg/kg) in STZ-induced diabetic mice. Glomerular mesangial matrix expansion, the increase of glomerular type IV collagen, endothelial area (CD31(+)), and F4/80(+) monocyte/macrophage accumulation were significantly inhibited by endostatin peptide. Increase in the renal expression of VEGF-A, flk-1, Ang-2, an antagonist of angiopoietin-1, transforming growth factor-beta1, interleukin-6, and monocyte chemoattractant protein-1 was inhibited by endostatin peptide in diabetic mice. Decrease of nephrin mRNA and protein in diabetic mice was suppressed by treatment with endostatin peptide. The level of endostatin in the renal cortex and sera was increased in diabetic mice. Endogenous renal levels of endostatin were decreased in endostatin peptide-treated groups in parallel with VEGF-A. Although serum levels of endostatin were decreased in the low-dose endostatin-peptide group, high-dose administration resulted in elevated serum levels of endostatin. These results demonstrate the potential use of antiangiogenic endostatin peptide as a novel therapeutic agent in diabetic nephropathy.

Endostatin binds biglycan and LDL and interferes with LDL retention to the subendothelial matrix during atherosclerosis

Retention of lipoproteins to proteoglycans in the subendothelial matrix (SEM) is an early event in atherosclerosis. We recently reported that collagen XVIII and its proteolytically released fragment endostatin (ES) are differentially depleted in blood vessels affected by atherosclerosis. Loss of collagen XVIII/ES in atherosclerosis-prone mice enhanced plaque neovascularization and increased the vascular permeability to lipids by distinct mechanisms. Impaired endothelial barrier function increased the influx of lipoproteins across the endothelium; however, we hypothesized that enhanced retention might be a second mechanism leading to the increased lipid content in atheromas lacking collagen XVIII. We now demonstrate a novel property of ES that binds both the matrix proteoglycan biglycan and LDL and interferes with LDL retention to biglycan and to SEM. A peptide encompassing the alpha coil in the ES crystal structure mediates the major blocking effect of ES on LDL retention. ES inhibits the macrophage uptake of biglycan-associated LDL indirectly by interfering with LDL retention to biglycan, but it has no direct effect on the macrophage uptake of native or modified lipoproteins. Thus, loss of ES in advanced atheromas enhances lipoprotein retention in SEM. Our data reveal a third protective role of this vascular basement membrane component during atherosclerosis.

Expression of collagen XVIII mRNA and protein in human umbilical vein and placenta

Endostatin is a potent angiogenic inhibitor that is derived from collagen XVIII by proteolytic cleavage. Localization of collagen XVIII has been reported in the basement membrane of blood vessels. To examine the involvement of collagen XVIII/endostatin during pregnancy, the distribution of collagen XVIII/endostatin protein in human umbilical vein was evaluated by immunohistochemistry. The expression of collagen XVIII/endostatin in cultured human umbilical vein endothelial cells (HUVEC) was also examined by immunocytochemistry and Northern blot analysis. To examine the release of endostatin in vivo and in vitro, concentrations of endostatin in umbilical venous blood and in HUVEC culture medium were determined using an enzyme-linked immunosorbent assay. Collagen XVIII/endostatin protein was localized to endothelial cells and their basement membrane in the umbilical vein. The expression of collagen XVIII mRNA and protein was detected in HUVEC. However, endostatin was not detected in umbilical venous blood or in HUVEC culture medium. The absence of endostatin release and the presence of its parental protein, collagen XVIII, suggest that the cleavage mechanisms of endostatin might be strongly inhibited under the physiological conditions present during pregnancy. It is therefore considered that vasculature in the feto-placental unit is highly angiogenic, even at the time of parturition.

Contributions of Disulfide Bonds in a Nested Pattern to the Structure, Stability, and Biological Functions of Endostatin

Endostatin can inhibit the proliferation and migration of endothelial cells. It contains two pairs of disulfide bonds in a nested pattern. We constructed three mutants, C33A/C173A, C135A/C165A, and all-Ala, to evaluate the contributions of individual disulfide bonds to the structure, stability, and biological functions of endostatin. Both tryptophan emission fluorescence spectrum and 1H nuclear magnetic resonance spectrum show that C135A/C165A and all-Ala, the two mutants lacking disulfide bond Cys135-Cys165, lost nearly their entire tertiary structure. Although C33A/C173A appears to retain some native-like structures, it is less stable and has a higher helical content, which confirms our earlier hypothesis that the polypeptide backbone of endostatin has a high helical propensity. C135A/C165A and all-Ala mutants lost most of their inhibitory activities both on the migration and proliferation of human microvascular endothelial cells, whereas C33A/C173A is partially active. The mutants without disulfide bond Cys135-Cys165 can hardly be internalized and localized to cytoskeleton and nucleus in the cell, which probably contributes to their loss of inhibition on the migration and proliferation of endothelial cells. Our studies provide a structural basis for the two disulfide bonds on the biological functions of endostatin.

Inhibition of tumor growth in xenografted nude mice with adenovirus-mediated endostatin gene comparison with recombinant endostatin protein

BACKGROUND

Inhibition of tumor growth by endostatin has been shown to be an effective strategy in cancer therapy in mice. However, its widespread application has been hampered by difficulties in a large-scale production of the recombinant endostatin protein, rapid loss bioactivity of the protein, and the cumbersome daily administration. These limitations could be resolved by in vivo delivery and expression of the endostatin gene. In this study, we observed the effect and advantage of endostatin gene therapy mediated by a recombinant adenoviral vector (Ad/hEndo) on the growth of hepatocellular carcinoma BEL-7402 xenografted tumors, comparison with recombinant endostatin protein.

METHODS

Hepatocellular carcinoma BEL-7402 cells were inoculated subcutaneously in the flank of Balb/c nude mice. Nine days after tumor cell inoculation, animals were given a cycle of four courses of intra-tumoral injections of Ad/hEndo of 5 x 10(8) pfu (low-dose group) and 1 x 10(9) pfu (high-dose group) at intervals of six days, respectively. Recombinant human endostatin protein (rhEndo) was administrated daily subcutaneously at a dose of 10 mg.kg(-1).d(-1) at a site nearby the tumor for ten days. The expression of endostatin mRNA in tumor tissue was analyzed by reverse transcription-polymerase chain reaction (RT-PCR) after Ad/hEndo injection. Dynamic changes of concentration of endostatin protein in tumor tissue were quantitated by enzyme-linked immunosorbent assay (ELISA).

RESULTS

After 4 courses of treatment, the tumor growth rates of high-dose treated group with 1 x 10(9) pfu of Ad/hEndo were inhibited by 42.26% compared with the Ad/LacZ control group (P = 0.001) and by 46.26% compared with the NIH buffer control group (P = 0.003), respectively. However, in this study, Ad/hEndo at low dose of 5 x 10(8) pfu failed to demonstrate significant inhibition of tumor growth, compared with control groups. After daily administration of recombinant human endostatin protein (rhEndo) for 9 days, the ratio of T/C (rhEndo group versus PBS group) was less than 47%. However, two days after rhEndo treatment ceased, the ratio of T/C was more than 50%. The peak of expression of endostatin mRNA in tumor tissue was at 2 or 3 days after administration intratumorally with Ad/hEndo of 1 x 10(9) pfu and gradually dropped undetectable by day 7. Dynamic analysis of endostatin concentration in tumor tissue showed that the highest level of mRNA is up at the third day after injection, and dropped to basal level three weeks later.

CONCLUSIONS

Endostatin gene therapy mediated by a recombinant adenoviral vector had significantly inhibited the growth of hepatocellular carcinoma BEL-7402 xenografted tumors at a high dose of 1 x 10(9) pfu compared with other groups. The analysis of dynamic expression of endostatin in vivo indicated that Ad/hEndo had acquired a high-level, relatively long-term expression in vivo and bioactivity capability.

Circulating angiogenic factor levels correlate with extent of disease and risk of recurrence in patients with soft tissue sarcoma

BACKGROUND

Tumor angiogenesis, or new blood vessel formation, is regulated by a balance between pro-angiogenic factors such as vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF), and anti-angiogenic factors such as endostatin.

PATIENTS AND METHODS

To investigate this angiogenic balance in soft tissue sarcomas (STS), blood samples were collected from 76 STS patients and 15 healthy controls, and analyzed for VEGF, bFGF and endostatin using quantitative enzyme-linked immunosorbent assays (ELISA).

RESULTS

Forty-one patients (54%) had primary tumors, 20 (26%) had local recurrences and 15 (20%) had metastatic disease with or without local disease. Levels of all three angiogenic factors were highly variable in STS patients. Mean levels of VEGF and bFGF were 12 and 14 times higher, respectively, in patients compared with controls (P<0.0001). VEGF levels correlated with size of tumor, with the highest levels found in tumors >10 cm in size. Patients with metastases had endostatin levels 45% lower than patients without metastases (P=0.047). In 54 patients who underwent resection of primary disease or local recurrence, low pre-operative bFGF level was associated with a higher risk of subsequent recurrence (P=0.044).

CONCLUSIONS

STS secrete widely variable levels of angiogenic factors, and levels of specific factors may correlate with extent of disease, predict risk of recurrence and possibly guide the use of anti-angiogenic agents.

The effects of surgery, with or without rhGM-CSF, on the angiogenic profile of patients treated for colorectal carcinoma

Wound healing is a process with immunological and angiogenic aspects. rhGM-CSF is known to stimulate the immune system and angiogenesis via multiple pathways. In this study we investigated the combined effects of surgery, with or without rhGM-CSF, on angiogenic parameters in patients with a colorectal carcinoma. In this phase II randomized, placebo-controlled trial, 16 patients were assigned to perioperative rhGM-CSF (2.8 microg/kg body weight) treatment or saline. Patients received subcutaneous injections from three days before surgery until four days after. IL-6, VEGF, endostatin and angiostatin levels were measured perioperatively. rhGM-CSF enhanced the production of IL-6 and VEGF, but had no effect on the antiangiogenic agents endostatin and angiostatin. Surgery induced a transient decrease of endostatin. Two types of angiostatin (kringle 1-3 and kringle 1-4) became visible postoperatively. We conclude that this study demonstrated the immediate initiation of angiogenesis postoperatively, reflected by the increase of VEGF and a transient decrease of endostatin, followed by the appearance of two angiostatin bands, which confirms physiological wound healing in these cancer patients.

Structurally altered basement membranes and hydrocephalus in a type XVIII collagen deficient mouse line

Type XVIII collagen/endostatin is known to be crucial for the eye, as witnessed by severe eye defects in Knobloch syndrome patients with mutations in this collagen and in Col18a1(-/-) mice. We show here that in a specific C57BL background, 20% of the Col18a1(-/-) mice developed hydrocephalus, and dilation of the brain ventricles was observed by MRI in all of the mutant mice. Significant broadening was observed in the epithelial basement membrane (BM) of the choroid plexuses (CP), its width being 86.4+/-10.52 nm, compared with 61.4+/-6.05 nm in wild-type mice. The CP epithelial cell morphology was balloon-shaped rather than cuboidal, and the microvilli of the apical surface of the CP epithelium contained more vacuoles in the null mice than in the wild-type, as also did the CP epithelial cells, which is suggestive of alterations in cerebrospinal fluid production. Analysis of BMs elsewhere in the body revealed a broadened epidermal BM in the Col18a1(-/-) mice, but this did not result in any apparent functional deficiencies. Moreover, markedly broadened BMs were found in the atrioventricular valves of the heart and in the kidney tubules, whereas the glomerular mesangial matrix of the kidneys was expanded in the mutant mice and serum creatinine levels were elevated, indicating alterations in kidney filtration capacity. We thus suggest that type XVIII collagen is a structurally important constituent of BMs, and that its absence can result in a variety of phenotypic alterations.

Detection and characterization of an acid-induced folding intermediate of endostatin

Endostatin, an important angiogenesis inhibitor, is very acid resistant. We are particularly interested in knowing that whether or not endostatin can form a folding intermediate during acid titration. 1H-NMR, CD spectrum, and ANS binding assay show that endostatin at pH 2.0 contains little tertiary structure, but retains substantial secondary structure with strong ANS binding, and Na2SO4 or TFE is found to strongly stabilize endostatin at pH 2.0. All these observations are consistent with the formation of a folding intermediate at pH 2.0. Kinetics studies show that sulfate anions significantly slow down the process for endostatin to reach its equilibrium state at pH 2.0. A regular increase in the amount of alpha-helix content of the intermediate of endostatin at pH 2.0 is found when the concentration of TFE is increased in the range of 0-40%, suggesting that endostatin has an intrinsic alpha-helical propensity.

In vivo tumor imaging in mice with near-infrared labeled endostatin

Endostatin is a potent inhibitor of angiogenesis currently in phase I clinical trials. Imaging technologies that use near-infrared fluorescent probes are well suited to the laboratory setting. The goal of this study was to determine whether endostatin labeled with a near-infrared probe (Cy5.5) could be detected in an animal and whether it would selectively localize to a tumor. Endostatin was conjugated to Cy5.5 monofunctional dye and injected into mice bearing Lewis lung carcinoma tumors (350 mm2). Mice were imaged at various time points while under sedation using a lightproof box affixed to a fluorescent microscope mounted with a filter in the near-infrared bandwidth consistent with Cy5.5 fluorescence. After i.p. injection, endostatin-Cy5.5 was absorbed producing a near-infrared fluorescent image within the tumors at 18 h reaching a maximum at 42 h after injection. No signal was emitted from mice injected with unlabeled endostatin or Cy5.5 dye alone or those that received no injection. Further results show that a dose response exists with injection of endostatin-Cy5.5. Mimicking the clinical route of administration, an i.v. injection had a peak signal emission at 3 h but also persisted to 72 h. Finally, to determine the intratumoral binding site for endostatin, we performed immunofluorescence on tumor specimens and demonstrated that endostatin binds to tumor vasculature and colocalizes with platelet/endothelial cell adhesion molecule 1 expression. This study demonstrates that endostatin covalently bound to Cy5.5 will migrate from a distant i.p. injection site to a tumor. These data indicate that endostatin-Cy5.5 is appropriate for selectively imaging tumors in uninjured experimental animals.

[Expression of vascular endothelial growth factor and endostatin in peritoneal fluid of patients with endometriosis]

OBJECTIVE

To investigate the relationship of vascular endothelial growth factor (VEGF) and endostatin with endometriosis.

METHODS

The levels of vascular endothelial growth factor and endostatin were measured using ELISA in 50 women with endometriosis (stage I-II26 cases and stage III-IV 24 cases) in comparison with 42 women without endometriosis.

RESULTS

The VEGF, endostatin concentrations and VEGF/endostatin ratio in endometriosis group were significantly higher than the mean value in the control group (P<0.01). The VEGF and endostatin levels in stages III and IV were both significantly higher than those in stages I and II(397+/-81 pg/ml vs 315+/-64 pg/ml, 125+/-62 ng/ml vs 66+/-40 ng/ml, P<0.01). However, the VEGF/endostatin ratio was lower in the advanced stages. There was no significant difference between follicular phase and luteal phase except that the VEGF level in follicular phase was higher than that in luteal phases.

CONCLUSIONS

Both VEGF and endostatin may play a role in the regulation of angiogenesis of endometriosis, and the balance of angiogenic stimulators and inhibitors may be critical to the development of endometriosis.

[Inhibition of tongue cancer development in nude mice transfected with adenovirus carrying human endostatin gene]

BACKGROUND & OBJECTIVE

The squamous cell carcinoma of tongue is one of the most common malignant tumors of oral cavity. Surgical therapy is now the mainstay of combined treatment for tongue squamous cell Carcinoma with chemotherapy and radiotherapy. The overall 5-year survival rate was about 50%. The antiangiogenesis therapy has become a new approach of the treatment of tongue carcinoma. This paper was designed to study the characteristics of endostatin expression in tongue cancer cell line (Tca8113), human embryonic epithelial cell line (ECV) and the inhibition of carcinogenesis in nude mice, xenografted with Tca8113, after transfected with recombined adenovirus (Ad/hEnd) which was cloned with human endostatin gene in EI mutated region.

METHODS

(1) To determine the expression and distribution of endostatin in Tca and ECV cells transfected with Ad/hEnd using immunohistochemistry. To determine the endostatin in supernatants of Tca cells transfected with Ad/hEnd using ELISA method. To examine the characteristics of endostatin gene expression in Tca8113 and ECV cells by Western blot analysis. (2) To determine the inhibition rate of proliferation and apoptosis rate of ECV cells by WST-1 test and flow cytometry (FCM), respectively.(3) To observe the inhibition of tumor growth in xenografted nude mice with Tca8113 cells by Ad/hEnd administration.

RESULTS

(1) Immunohistochemistry detection indicated that the endostatin was expressed in cytoplasm of Tca8113 cells and ECV cells transfected with Ad/hEnd. Endostatin expression in the supernatant was dose-dependent with the highest to 597 ng/ml. The expression of endostatin in Tca cells was detectable from 1 day to 7 day. Ad/hEnd inhibited ECV cell growth in dose-dependent manner. (2) FCM showed that Ad/hEnd arrested ECV cells in S and G(2) phase and induced apoptosis.(3) The tumor growth curve showed that Ad/hEnd significantly repressed xenograft tumor growth with Tca cell in nude mice; the inhibition rate on Ad/hEnd administrated groups was 45.8% in the 3rd week.

CONCLUSION

Ad/hEnd expressed efficiently in Tca8113 and ECV cells. Ad/hEnd can change the cell cycle distribution of ECV cells and induce apoptosis and inhibit proliferation of ECV cells. Ad/hEnd could inhibit the growth of tongue carcinoma in xenograft nude mice.