The angiogenic pathway "vascular endothelial growth factor/flk-1(KDR)-receptor" in rheumatoid arthritis and osteoarthritis

Active angiogenesis, together with an up-regulation of angiogenic factors, is evident in the synovium of both rheumatoid arthritis (RA) and osteoarthritis (OA). The present study assessed, by immunohistochemistry, the microvessel density in the synovium of these arthritides and in normal controls, in relation to the expression of the angiogenic factors vascular endothelial growth factor (VEGF) and platelet-derived endothelial cell growth factor (PD-ECGF) and the apoptosis-related proteins bcl-2 and p53. More importantly, using the novel 11B5 MAb, the activated "VEGF/flk-1(KDR)-receptor" microvessel density was assessed. VEGF expression in fibroblasts was diffuse in both RA and OA. Diffuse PD-ECGF expression of fibroblasts was noted in all cases of RA, while fibroblast reactivity was focal in the OA material. The standard microvessel density (sMVD), as assessed with the anti-CD31 monoclonal antibody (MAb), was higher in RA (64+/-12) and in OA (65+/-16) than in normal tissues (52+/-8; p=0.008 and 0.0004, respectively). The activated microvessel density (aMVD), assessed with the 11B5 MAb, was significantly higher in RA (29+/-10) than in OA (17+/-4; p<0.0001) and than in normal tissues (14+/-2; p<0.0001). The "activation ratio" (aMVD/sMVD) was statistically higher in RA (0.46+/-0.17) than in OA and normal synovial tissues, the latter two having a similar ratio (0.28+/-0.08 and 0.26+/-0.03, respectively). Cytoplasmic bcl-2 expression was frequent in the synovial cells of OA, but rare in RA. Nuclear p53 protein accumulation was never observed. It is suggested that the angiogenic pathway VEGF/flk-1(KDR) may play an important role in the pathogenesis of RA and OA. Thus, failure of VEGF/flk-1(KDR) activation, in the presence of increased VEGF expression, may indicate a synovium with an impaired capacity to establish a viable vasculature, consistent with the degenerative nature of OA. On the other hand, the activated angiogenesis in RA shows a functional, still pathologically up-regulated VEGF/flk-1(KDR) pathway. Whether restoration of an impaired VEGF/flk-1(KDR) pathway in OA, or inhibition of this in RA, would prove of therapeutic importance requires further investigation.     

Non-endothelial KDR/flk-1 expression is associated with increased survival of patients with urothelial bladder carcinomas

AIMS: To investigate the immunohistochemical expression of KDR/flk-1 in a series of 114 urothelial bladder carcinomas in relation to clinicopathological parameters, Ki67, p53 and Bcl-2 protein expression and patient survival. KDR/flk-1 is a high-affinity tyrosine kinase receptor for vascular endothelial growth factor (VEGF), on vascular endothelium. However, there is increasing evidence that KDR/flk-1 is also expressed by normal non-endothelial and tumour cells. METHODS AND RESULTS: Immunohistochemistry was performed on paraffin sections using monoclonal and polyclonal antibodies. Statistical analysis was univariate (chi2 log rank test) and multivariate (Cox's model). KDR/flk-1 expression was observed in the cytoplasm of cancerous cells in 68.4% of cases. No statistically significant associations were observed between KDR/flk-1 expression and grade or stage of urothelial carcinomas, Ki67, p53 or Bcl-2 expression. In contrast, widespread KDR/flk-1 expression in more than 50% of cancerous cells was associated with increased survival, on univariate and multivariate analysis (P = 0.0119 and P = 0.042, respectively). CONCLUSIONS: Although the biological significance of non-endothelial KDR/flk-1 expression has not yet been elucidated, its association with better patient survival may be related to the failure of non-endothelial KDR/flk-1 to mediate angiogenic and mitogenic effects.     

胰岛素对牛胸主动脉内皮细胞血管内皮生长因子及其受体表达的影响

目的:评价胰岛素对培养的牛胸主动脉内皮细胞血管内皮生长因子(VEGF)及其受体表达的影响。方法: 取新生的小牛胸主动脉,做血管内皮细胞原代及传代培养,取4-6代培养细胞分组,应用不同浓度的胰岛素(30 mU/L、300 mU/L、3 000 mU/L)干预培养过程,48 h后应用免疫组化法测定内皮细胞VEGF及其受体(flt-1、flk-1/KDR)的表达水平。结果: 低浓度胰岛素组(30 mU/L、300 mU/L)内皮细胞VEGF表达明显高于不用胰岛素组(P<0.01);高浓度组(3 000 mU/L)内皮细胞VEGF表达明显低于不用胰岛素组(P＜0.05);各组内皮细胞VEGF受体(flt-1及flk-1/KDR)的表达无明显差异(P＞0.05)。结论: 低浓度胰岛素促进小牛主动脉血管内皮细胞VEGF表达;高浓度胰岛素可抑制血管内皮细胞VEGF表达;胰岛素对小牛主动脉血管内皮细胞VEGF受体(flt-1、flk-1/KDR)的表达无直接影响。     

Phosphorylated KDR expression in endometrial cancer cells relates to HIF1alpha/VEGF pathway and unfavourable prognosis.

Vascular endothelial growth factor (VEGF) is a potent angiogenic factor for many malignant neoplasms exerting its function through activation of specific membrane receptors, that is, KDR/flk-1, residing in endothelial cells. Several recent reports indicate that VEGF receptors are also expressed in cancer cells, suggesting that specific VEGF-originated cancer cell reactions may parallel the endothelial response. Using a novel monoclonal antibody, recognizing the activated (phosphorylated) form of the KDR receptor (pKDR), we assessed the expression of pKDR in normal and malignant endometrium. A strong and consistent cytoplasmic and nuclear pKDR expression was noted in the normally cycling endometrium, including epithelial, stromal and endothelial cells, suggesting a role in the normal menstrual cycle. Approximately, one-third of the 70 stage I endometrioid adenocarcinomas analysed exhibited an intense cytoplasmic and nuclear pKDR expression in both cancer cells and peritumoral vessels. It was noted that such pKDR reactivity in cancer cells was related directly to VEGF, VEGF/KDR complexes and HIF1alpha (hypoxia inducible factor 1alpha) expression. Furthermore, pKDR expression was significantly associated with poor prognosis. It is concluded that the VEGF/KDR pathway is activated in both normally cycling and malignant endometrium, suggestive of an important role in the biology of this tissue. The unfavourable prognosis that VEGF confers to endometrial adenocarcinomas could be attributed to its angiogenic activity, but also to a direct effect on cancer cells through an autocrine VEGF/KDR loop.     

Systemic activation of the vascular endothelial growth factor receptor KDR/flk-1 selectively triggers endothelial cells with an angiogenic phenotype.

The hypothesis that tumor growth is angiogenesis dependent has been documented by a considerable body of direct and indirect experimental data. A prerequisite for the development of novel anti-angiogenic agents is the design of drugs that would be active only on those endothelial cells with an angiogenic phenotype. We took advantage of the anti-idiotypic strategy to obtain circulating agonists specific for the vascular endothelial growth factor receptor KDR/flk-1 (J-IgG). They induced in the absence of VEGF cell proliferation in vitro and angiogenesis in the corneal pocket assay either through local or systemic delivery. Intraperitoneal injections of J-IgG in nude mice grafted with a prostatic adenocarcinoma led to tumor enlargement associated with an increase in both tumor vascularization and proliferation. In contrast KDR/flk-1 overstimulation had no detectable effect on normal tissues. These data underline that KDR/flk-1 is a functional marker of the angiogenic phenotype of endothelial cells.     

Analysis of Vascular Endothelial Growth Factor (VEGF) and a receptor subtype (KDR/flk-1) in the liver of rats exposed to riddelliine: a potential role in the development of hemangiosarcoma

Riddelliine alters hepatocellular and endothelial cell kinetics and function including stimulating an increase in hepatocytic vascular endothelial growth factor (VEGF) in the absence of increased serological levels of VEGF (Nyska etal. 2002). The objective of this study was to further assess hepatic VEGF and KDR/flk-1 synthesis and expression by hepatic cells under riddelliine treatment conditions. Forty-two male F344/N rats were dosed by gavage with riddelliine (0, 1.0, and 2.5 mg/kg/day) for 6 weeks. Seven animals/group were sacrificed after 8 consecutive daily doses; remaining rats were terminated after 30 daily doses, excluding weekends. Hepatic tissues were evaluated by immunohistochemistry and in situ hybridization. The results showed that VEGF mRNA expression was observed in control and treated animals; however, qualitative differences were noted. Treated animals exhibited VEGF mRNA in clustered, focal hepatocytes and bile duct epithelium, whereas VEGF mRNA in hepatocytes from vehicle control rats was distributed evenly across all hepatocytes. Results evaluating the distribution of the VEGF cognate receptor, KDR/flk-1 showed that randomly distributed, rare sinusoidal endothelium, including those demonstrating karyomegaly and cytomegaly expressed KDR/flk-1. Phosphorylation of KDR/flk-1 at pTyr996 and pTyr1054/1059, but not pTyr951, was also detected, evidence that endothelial cell KDR/flk-1 was activated. These results suggest that both hepatocytes and endothelial cells are targets of riddelliine-induced injury. We speculate that damage to both populations of cells may lead to dysregulated VEGF synthesis by hepatocytes and activation of KDR/flk-1 by endothelium leading to the induction of sustained endothelial cell proliferation, culminating in the development of hepatic hemangiosarcoma.     

Angiogenic co-operation of VEGF and stromal cell TP in endometrial carcinomas

Vascular endothelial growth factor (VEGF) and thymidine phosphorylase (TP) are important angiogenic enzymes, inducing new blood vessel formation in many human malignancies. In this study, the immunohistochemical expression of the two molecules was analysed in a series of 121 endometrial carcinomas. VEGF was expressed exclusively in cancer cells, while TP expression was shown in cancer cells (TPcc) and in stromal cells (TPsc) of both fibroblastic and myometrial origin. In all cases, enzymatic detection was particularly evident at the invading tumour front. At this site, TPsc, but not VEGF, expression was associated with non-endometrioid-type carcinomas, high tumour grade, deep myometrial invasion, and advanced stage. VEGF, but not TP, expression was related to increased angiogenesis (p=0.01). Double stratification of the two factors, however, marked VEGF/TPsc co-expression as the most potent angiogenic phenotype (p=0.008), suggesting a synergistic function. Survival analysis revealed that VEGF and TPsc, whether expressed alone or in combination, define poor prognosis. In multivariate analysis, however, stage of disease (p<0.0001, t-ratio 4.4) and VEGF expression (p=0.01, t-ratio 2.4) were the most important prognostic variables. Furthermore, VEGF expression emerged as the only independent prognostic variable in stage I endometrial carcinomas (p=0.04, t-ratio 1.9). This was not shown for TP, probably because of its close association with histopathological parameters. In conclusion, VEGF is a major angiogenic factor in endometrial carcinomas and an independent prognostic factor in stage I endometrial disease. TP is not an effective contributor to the angiogenic process, but is associated with aggressive histological features. The two factors, when co-expressed, play a co-operative role in the induction of angiogenesis.     

Expression of vascular endothelial growth factor and its receptors correlates closely with formation of the plexiform lesion in human pulmonary hypertension

The pulmonary vasculature exhibits various morphological changes in patients with pulmonary hypertension (PH). Among them, the plexiform lesion is one of the most characteristic vascular lesions, although nothing is known about the molecular mechanisms of its formation. In the present study, the expression of vascular endothelial growth factor (VEGF), an endothelial cell-specific angiogenic mitogen, and its receptors, fms-like tyrosine kinase (Flt-1) and kinase insert domain-containing receptor (KDR), in the lungs of five cases with PH, were examined. By in situ hybridization, VEGF expression was found in modified smooth muscle cells inside the plexiform lesions as well as in medial smooth muscle cells of the arteries adjacent to the lesions. The expression of Flt-1 mRNA was observed in endothelial cells of the arteries adjacent to the plexiform lesions, while KDR mRNA was expressed in the endothelial cells inside the plexiform lesions. VEGF was immunolocalized to the endothelial cells expressing its receptors as well as the modified smooth muscle cells producing VEGF. These results demonstrate that VEGF and its receptors are upregulated with a close correlation to the plexiform lesions, and suggest that VEGF expressed by smooth muscle cells may activate the endothelial cells to form the plexiform lesions.     

肝细胞癌中血管内皮生长因子和cNOS与血管生成及细胞增殖的关系

目的　观察血管内皮生长因子 (VEGF)及含激酶插入区受体 (KDR)在原发性肝癌中的表达情况及其与cNOS表达的相关性 ,探讨它们在肝癌肿瘤性血管生成、肿瘤细胞增殖和转移过程中的作用。　方法　收集手术切除的 80例原发性肝癌、4 0例肝硬化、2 0例正常肝组织标本 ,应用免疫组织化学和原位杂交的方法观察VEGF及其KDR、cNOS在肝细胞癌中的表达情况 ,分析VEGF及其受体KDR、cNOS与微血管密度 (MVD)、肿瘤细胞增殖指数和转移的关系。　结果　肝癌组织中癌细胞VEGF的表达与MVD、细胞增殖指数明显相关 (P <0 0 1和P <0 0 5 ) ,与肝癌内皮细胞中cNOSmRNA的表达之间也有相关性 (Pearson列联系数 =0 2 984 ,P <0 0 5 )。内皮细胞中cNOSmRNA与VEGF均阳性者微血管密度、细胞增殖指数均明显高于cNOSmRNA阴性和VEGF阳性者 (P <0 0 1) ,也明显高于两者均阴性者 (P <0 0 1)。　结论　肝细胞癌中癌细胞VEGF的表达与血管生成、细胞增殖和肝癌转移密切相关 ,且内皮细胞cNOSmRNA的表达可能参与VEGF的促血管生成作用。     

HER2 is unlikely to be involved in directly regulating angiogenesis in human breast cancer.

Angiogenesis is a fundamental component of oncogenesis. Angiogenic factors such as vascular endothelial growth factor (VEGF) and platelet derived-endothelial cell growth factor/thymidine phosphorylase (PD-ECGF/TP) are generated from tumor cells to provide tumor growth and are thought to be regulated via the HER2 oncogene, whose amplification is the most common genetic alteration in breast cancer. The present study aimed to evaluate the immunoreactivity of angiogenic factors (VEGF, PD-ECGF/TP) and microvessel density (MVD) via epidermal growth factor receptor (EGFR) and HER2, and to correlate their expression with clinicopathologic features. Two hundred one invasive human breast cancer specimens were tested immunohistochemically for the expression of these proteins. In addition, MVD was examined using computerized image analysis. VEGF could be an additional interesting prognostic variable, as it was significantly associated with tumor grade (P=0.002), stage (P=0.018), and negative estrogen receptor status (P=0.011). EGFR was significantly related to invasive ductal carcinoma (P=0.030), tumor grade (P=0.009), VEGF expression (P=0.013), PD-ECGF/TP expression (P=0.024), and MVD (P=0.050). The finding that VEGF is not correlated to MVD does not rule out a crucial role of VEGF as a key factor in angiogenesis. HER2 could not be correlated to MVD, VEGF expression, or PD-ECGF/TP expression, indicating that this factor is unlikely to be involved in directly regulating angiogenesis, whereas the significant correlations between EGFR and histologic tumor type, tumor grade, the angiogenic factors VEGF and PD-ECGF/TP, and MVD point out that EGF is the major modulating growth factor for angiogenesis in breast cancer.     

sEPCR、VEGF、MVD、KDR在早发型子痫前期胎盘中的表达

目的 研究sEPCR、VEGF、MVD、KDR在早发型子痫前期胎盘中的表达情况.方法 选取2016年3月至2017年4月我院收治的早发型子痫前期患者50例为研究对象,以同期入院体检的50例健康产妇为对照组,测定入组对象胎盘组织中可溶性血管内皮细胞蛋白C受体(sEPCR)、血管内皮生长因子(VEGF)、胎盘微血管密度(MVD)、含有激酶插入区的受体(KDR)及可溶性血管内皮生长因子受体(sFlt-1)水平,同时比较子痫前期病情轻度、中重度患者上述指标,分析PE患者sEPCR、VEGF、MVD、KDR及sFlt-1的相关性,评价上述指标联合诊断PE的效能.结果 早发型组胎盘组织VEGF(30.25 ±1.87)％、MVD(37.11 ±1.54)条低于对照组(P＜0.05),而其sEPCR(156.34±1.25) ng/mL、KDR(70.34±1.38)％、sFlt-1 (80.32±1.67)％较对照组升高(P＜0.05);重度子痫前期患者VEGF(30.18±1.30)％、MVD(36.20±1.31)条与轻度组比较明显降低,而sEPCR(154.22±1.05)％、KDR(71.20±1.66)％、sFlt-1 (81.11±1.56)升高(P＜0.05);sEPCR、VEGF、MVD、KDR联合诊断早发型PE患者灵敏度为98.05％,特异性为93.11％,准确度为96.20％,均高于上述指标单项诊断;相关分析显示子痫前期患者胎盘组织中VEGF、MVD与sFlt-1呈负相关(P＜0.05).结论 sEPCR、VEGF、MVD、KDR在早发型子痫前期胎盘中呈异常表达,随病情加重VEGF、MVD表达降低,sEPCR、KDR表达增多,其中VEGF、MVD表达水平与sFlt-1高表达有关.     

Acute resistance exercise increases skeletal muscle angiogenic growth factor expression

AIMS: Both aerobic and resistance exercise training promote skeletal muscle angiogenesis. Acute aerobic exercise increases several pro-angiogenic pathways, the best characterized being increases in vascular endothelial growth factor (VEGF). We hypothesized that acute resistance exercise also increases skeletal muscle angiogenic growth factor [VEGF and angiopoietin (Ang)] expression. METHODS: Seven young, sedentary individuals had vastus lateralis muscle biopsies and blood drawn prior to and at 0, 2 and 4 h post-resistance exercise for the measurement of VEGF; VEGF receptor [KDR, Flt-1 and neuropilin 1 (Nrp1)]; Ang1 and Ang2; and the angiopoietin receptor--Tie2 expression. Resistance exercise consisted of progressive knee extensor (KE) exercise to determine one repetition maximum (1-RM) followed by three sets of 10 repetitions (3 x 10) of KE exercise at 60-80% of 1-RM. RESULTS: Resistance exercise significantly increased skeletal muscle VEGF mRNA and protein and plasma VEGF protein at 2 and 4 h. Resistance exercise increased KDR mRNA and Tie2 mRNA at 4 h and Nrp1 mRNA at 2 and 4 h. Skeletal muscle Flt-1, Ang1, Ang2 and Ang2/Ang1 ratio mRNA were not altered by resistance exercise. CONCLUSIONS: These findings suggest that acute resistance exercise increases skeletal muscle VEGF, VEGF receptor and angiopoietin receptor expression. The increases in muscle angiogenic growth factor expression in response to acute resistance exercise are similar in timing and magnitude with responses to acute aerobic exercise and are consistent with resistance exercise promoting muscle angiogenesis.     

Angiogenic potential of ductal carcinoma in situ (DCIS) of human breast

AIMS: Comedo carcinoma is generally regarded as the subtype of ductal carcinoma in situ (DCIS) most likely to progress to invasive carcinoma. Increased angiogenesis could be associated with an enhanced risk of progression and might therefore be a marker of poor prognosis, as can be demonstrated for invasive breast tumours. Therefore, the present study investigates the correlations between the expression of oncoproteins (HER2, HER1/EGFR), angiogenic growth factors (VEGF and PD-ECGF/TP) and microvessel density (MVD) in DCIS. METHODS AND RESULTS: Forty-six breast cancer specimens of DCIS were tested immunohistochemically for the expression of angiogenic factors and oncoproteins. Different vascular distribution patterns of DCIS were examined semiquantitatively. Our results showed a significantly inverse correlation between HER1/EGFR and comedo-type DCIS (P = 0.048), but HER1/EGFR expression seemed to be independent of HER2 overexpression. VEGF expression was significantly associated with endoglin expression (P = 0.031) and the cuffing phenomenon (P = 0.017). CONCLUSIONS: The significantly inverse correlation between HER1/EGFR and comedo-type DCIS and the observation that VEGF and the other angiogenic factors tested are independent of HER2 overexpression, suggest that progression of comedo-type DCIS and angiogenesis in breast carcinoma are not regulated via the HER1/EGFR or HER2 pathway.     

Macrophage infiltration is associated with VEGF and EGFR expression in breast cancer

Angiogenesis is esential for tumour growth and metastasis. Vascular endothelial growth factor (VEGF) is a potent endothelial cell mitogen and is an important component of the angiogenic stimulus in a range of human neoplasias. In addition to its mitogenic activities, VEGF has also been found to stimulate migration in macrophages via the flt-1 VEGF receptor. It has previously been shown that increased focal tumour macrophage infiltration is associated with increased angiogenesis and worsened relapse-free and overall survival in breast cancer. Macrophages are able to stimulate angiogenesis by their production of a range of factors including VEGF, tumour necrosis factor-alpha (TNF-alpha), and thymidine phosphorylase (TP). Thus, in breast cancer, VEGF could have a dual role in the regulation of angiogenesis, by direct mitogenic stimulation of endothelial cells, and also indirectly by attracting macrophages into avascular tumours. The purpose of this study was to localize VEGF protein in a series of 96 consecutive primary breast carcinomas and to determine its relationship to focal macrophage infiltration (macrophage index). These two variables were also compared with the pathological features of the tumours, as well as oestrogen receptor (ER), epidermal growth factor receptor (EGFR), microvessel density, macrophage index, and survival. An inverse relationship (p=0.0006) was noted between VEGF and EGFR, with high VEGF expression correlating with low EGFR levels. In the EGFR-negative group of cases (n=56), positive associations were observed between VEGF expression and macrophage index (p=0.005), ER (p=0.05), p53 (p=0. 006), tumour grade (p=0.02), and tumour necrosis (p=0.03). Macrophage counts were higher in EGFR-positive tumours (p=0.0006) and no associations were found between VEGF expression and increased microvessel density. These results show that in breast cancers there are two types of macrophage infiltrates, one associated with the presence of EGFR and low VEGF expression in tumours and the other with high VEGF expression in EGFR-negative tumours. VEGF expression may be an important factor in the recruitment of tumour-associated macrophages into breast carcinomas and may thus have an additional, indirect, pathway of angiogenic stimulation in this type of tumour.     

Vascular endothelial growth factor expression in the basal subtype of breast carcinoma

The recognition of subtypes of breast carcinomas based on their molecular features has brought new perspectives in breast cancer research. Some key regulators of angiogenesis and tumor infiltration were evaluated in breast carcinomas of basal phenotype (cytokeratin [CK]5+). Immunohistochemical analysis with 14 primary antibodies was performed in 100 formalin-fixed, paraffin-embedded samples of invasive ductal carcinomas. CK5 correlated with indicators of poor outcome, including precocious age, high histologic grade, lymph node positivity, advanced pathologic stage, negativity for hormonal receptors, and a high proliferative rate (Ki-67 labeling index). CK5 also correlated with vascular endothelial growth factor (VEGF) expression but not with the microvessel density. Considering that VEGF-overexpressing neoplastic mammary cells display increased proliferative activity in vitro regardless of the angiogenic effect of VEGF, the differential expression of VEGF might contribute to the more aggressive behavior of these neoplasms. CK5 correlated with tissue inhibitor of metalloproteinase (TIMP)-1, but not matrix metalloproteinase (MMP)-1, MMP-2, extracellular matrix metalloproteinase inducer, TIMP-2 or plasminogen activator inhibitor, indicating that antiproteolytic stimuli might be preponderant in these neoplasms.     

Retroviral vectors bearing IgG-binding motifs for antibody-mediated targeting of vascular endothelial growth factor receptors

Targeting retroviral vectors to tumor vasculature is an important goal of cancer gene therapy. In this study, we report a novel targeting approach wherein IgG-binding peptides were inserted into the Moloney murine leukemia virus (MuLV) envelope (env) protein. The modifications on the viral env included replacement of the entire receptor binding region of the viral env with protein A (or ZZ) domains. The truncated env incorporating IgG-binding motifs (known as proteins) provided the targeting function, while the co-expressed wild-type (WT) env protein enabled viral fusion and cell entry. An anti-human VEGF receptor (Flk-1/KDR) antibody served as a molecular bridge, directing the retroviral vector to the endothelial cell. Hence, the IgG-targeted vectors bound to the Flk-1/KDR antibody which in turn bound to VEGF receptors on Kaposi sarcoma, KSY1, endothelial cells. The net effect was increased viral fusion and infectivity of IgG-bound retroviral vectors when compared to non-targeted vectors bearing WT env alone. These data provide the proof of concept that IgG-binding vector/VEGF receptor antibody complexes may be used to enhance retroviral gene delivery to activated endothelial cells.