Hypoxia-inducible factor 1 alpha expression correlates with angiogenesis and unfavorable prognosis in bladder cancer

INTRODUCTION AND OBJECTIVES: Hypoxia-inducible factor 1 alpha (HIF-1 alpha) is a critical regulatory protein of cellular response to hypoxia and is closely related to the triggering of the angiogenic process. We examined the relationship between hypoxia and angiogenesis, as well as their prognostic impact in patients with urothelial bladder cancer. METHODS: The immunohistochemical expression of HIF-1 alpha was evaluated in 93 formalin-fixed paraffin-embedded primary transitional cell carcinoma tissue samples. HIF-1 alpha was recognized through nuclear staining of positive cells. The angiogenic profile was individually assessed immunohistochemically using a monoclonal antibody to vascular endothelial growth factor (VEGF) and microvessel density (MVD) was calculated with immunohistochemical staining of the adhesion molecule CD31 of the endothelial cells. RESULTS: A significant positive association between HIF-1 alpha immunoreactivity and histological grade (p=0.009) was found. VEGF and MVD were closely related to tumor grade (p=0.06 and p<0.001) and clinical stage (p=0.04 and p<0.01, respectively). HIF-1 alpha was significantly correlated with VEGF expression (p=0.01) and MVD (p<0.001). Patients characterized by HIF-1 alpha overexpression had significantly worse overall (p=0.009) and disease-free survival (p=0.03). When HIF-1 alpha, histologic grade and stage were included in multivariate Cox regression analysis, HIF-1 alpha emerged as an independent prognostic factor (p=0.02) along with grade and stage, but lost its independent prognostic value after the inclusion of angiogenic factors in the multivariate model. In the subgroup of patients with T1 disease, HIF-1 alpha emerged as a significant negative predictor of the time to first recurrence. CONCLUSIONS: HIF-1 alpha and angiogenesis markers may play an important predictive and prognostic role in patients with bladder cancer. HIF-1 alpha may be of biologic and clinical value as its overexpression is related to up-regulation of VEGF, the stimulation of angiogenesis and worse prognosis.     

Ang2,HIF-1α及VEGF对肝癌血管形成的影响

摘要：目的:探讨促血管生成素2（Ang2）、缺氧诱导因子1α（HIF-1α）及血管内皮生长因子（VEGF）与肝细胞癌血管形成的关系。方法:检测52例肝癌组织中Ang2，HIF-1α及VEGF mRNA及蛋白的表达，对共表达的肝癌组织进行微血管计数。结果:RT-PCR 显示,52例肝癌组织中有38例共表达Ang2mRNA，HIF-1αmRNA 和VEGF mRNA，且两两之间呈明显正相关(分别为r=0.783，P<0.01；r=0.427，P<0.05；r=0.433，P<0.05)；免疫组化发现,52例肝癌组织36例共表达Ang2，HIF-1α和VEGF蛋白。共表达Ang2 mRNA，HIF-αmRNA 和VEGF蛋白的38例肝癌组织中,平均微血管数［(45.4±8.90) 个/HP］,明显高于非共表达组［(13.6±3.30)个/HP］（P<0.05)。结论:Ang2，HIF-1α和VEGF与肝癌的新生血管形成有关；肿瘤组织缺氧可能是其始动因素。     

Expression of hypoxia-inducible angiogenic proteins (hypoxia-inducible factor-1alpha, vascular endothelial growth factor, and E26 transformation-specific-1) and plaque hemorrhage in human carotid atherosclerosis

OBJECT: Plaque hemorrhage in carotid atherosclerosis promotes plaque progression, resulting in cerebrovascular disease. Hypoxia inducible factor-1alpha (HIF-1alpha) induces angiogenesis via the expression of vascular endothelial growth factor (VEGF) and E26 transformation-specific-1 (Ets-1). The authors investigated human carotid plaques to determine whether these hypoxia-inducible angiogenic proteins play a major role in intraplaque angiogenesis and hemorrhage. METHODS: The expression of HIF-1alpha, VEGF, and Ets-1 was analyzed using immunohistochemistry and Western blotting in 29 human carotid plaques obtained at carotid endarterectomy. The authors investigated the relationship between plaque characteristics and clinical symptoms. RESULTS: A higher incidence of plaque hemorrhage was observed in plaques associated with symptoms than in those without symptoms (p = 0.03). Hypoxia-inducible factor-1alpha, VEGF, and Ets-1 coexisted in the deep layer of plaque, where angiogenesis was remarkably developed; the expression levels of HIF-1alpha, VEGF, and Ets-1 were significantly enhanced in the main lesion of the plaque (p < 0.01). Symptomatic plaques showed higher expression of VEGF (p = 0.04) than asymptomatic plaques. Plaques with hemorrhage showed a higher incidence of plaque ulcer (p = 0.001) and higher expression of Ets-1 (p = 0.03) than those without hemorrhage. Moreover, significantly increased expressions of VEGF (p = 0.01) and Ets-1 (p = 0.006) were observed in plaques with not only hemorrhages but also ulcers and severe stenosis. CONCLUSIONS: The findings in this study suggest that hypoxia-inducible angiogenic proteins in human carotid atherosclerosis promote intraplaque angiogenesis, which can induce plaque hemorrhage and progression.     

Experimental varicocele induces hypoxia inducible factor-1alpha, vascular endothelial growth factor expression and angiogenesis in the rat testis

PURPOSE: In this study we investigated hypoxia inducible factor-1alpha (HIF-1alpha) and vascular endothelial growth factor (VEGF) expression, and angiogenesis in an experimental model of varicocele in the rat testis. MATERIALS AND METHODS: A total of 30 adult male Sprague-Dawley rats were investigated in 3 groups, namely varicocele group 1 (13), sham operated group 2 (9) and control group 3 (8). At 30 days after surgery was completed in groups 1 and 2 orchiectomy was performed in all rats. Histological findings in the left testicles of rats from each group were compared. HIF-1alpha and VEGF expression was immunohistochemically studied and CD31 panendothelial antigen was used to identify the number of microvessels, that is microvessel density (MVD), in paraffin embedded sections of testis tissue. Data were analyzed using the chi-square test, Fisher's exact test, 1-way ANOVA and the Tukey HSD test for post hoc comparison. RESULTS: HIF-1alpha expression was detected in 12 specimens (92.3%) in group 1, 4 (44.4%) in group 2 and 2 (25%) in group 3. The frequency of HIF-1alpha positivity in group 1 was significantly higher than the rates in groups 2 (p = 0.023) and 3 (p = 0.003). VEGF expression was detected in 8 specimens (61.5%) in group 1 but none of the group 2 or 3 specimens were VEGF positive. The frequency of VEGF positivity in group 1 was significantly higher than that in groups 2 (p = 0.006) and 3 (p = 0.007). Mean MVD +/- SD in group 1 was 7.53 +/- 1.50 (range 6 to 12), and findings in groups 2 and 3 were 5.88+/-1.45 (range 4 to 8) and 5.12 +/-1.12 (range 4 to 7), respectively. Mean MVD in group 2 was higher than in group 3 but this difference was not significant (p = 0.509). Mean MVD in group 1 was significantly higher than the mean values in groups 2 (p = 0.030) and 3 (p = 0.002). CONCLUSIONS: Previous study of experimental varicocele models in rats documented HIF-1alpha and VEGF expression combined with angiogenesis in the testis. The results of this study show that varicocele can lead to tissue hypoxia and related pathophysiological events, such as angiogenesis.     

Expression of hypoxia inducible factor-1 alpha and correlation with preoperative embolization of meningiomas

OBJECT: Vascular endothelial growth factor (VEGF) has been implicated in meningioma tumorigenesis and growth. The production of VEGF is regulated by hypoxia inducible factor-1alpha (HIF-1alpha), especially under conditions of hypoxia. In this study, the authors examine the expression of HIF-1alpha and VEGF in meningiomas, with a special emphasis on conditions of hypoxia, such as preoperative embolization, and on in vitro studies in cultured cells. METHODS: Meningiomas obtained in 142 patients were studied using immunohistochemical methods to detect HIF-1alpha and the results were correlated with the extent or lack of preoperative embolization and expression of VEGF. Primary meningioma cell cultures were established and cell culture experiments were performed using a hypoxia chamber to stimulate HIF-1alpha and VEGF production. Expression of HIF-1alpha in primary meningioma cell cultures was measured using immunoblot assays. The VEGF secretion was measured using enzyme-linked immunosorbent assay. Half of the meningiomas studied were positive for HIF-1alpha, with a strong correlation between complete embolization and HIF-1alpha expression. Most of the meningiomas studied expressed VEGF protein, and VEGF expression did not correlate with the degree of embolization. A strong correlation was found between VEGF and HIF-1alpha expression in immunohistochemical studies. Secretion of VEGF is increased by hypoxia and growth factor stimulation. In meningiomas, growth factors stimulate HIF-1alpha expression. The role of hypoxia is less clear. CONCLUSIONS: The expression of HIF-1alpha is increased by complete preoperative embolization of meningiomas. The expression of HIF-1alpha also correlates with VEGF secretion in meningiomas. Growth factor and hypoxic stimulation both contribute to VEGF control, but which is most important (or whether both are equally important) will require further studies.     

过表达缺氧诱导因子1α影响前列腺癌血管生成的体内研究

目的:观察转染缺氧诱导因子1α(HIF-1α)在体内环境下对人前列腺癌血管形成的影响,并探讨其分子机制。方法:对构建的转染HIF-1α人前列腺癌LNCaP细胞(LNCaP/HIF-1α)复苏后培养,ELISA法检测转染前后培养液上清PSA水平;流式细胞术检测细胞周期;将转染前后的LNCaP细胞建立免疫裸鼠皮下肿瘤模型,观察肿瘤生长情况;收集肿瘤标本后针对肿瘤血管生成相关蛋白血管内皮生长因子(VEGF),诱导型一氧化氮合酶(iN-OS),促血管生成素2(Ang-2)行免疫组化染色。结果:与LNCaP细胞相比,转染HIF-1α的人前列腺癌LNCaP细胞培养液PSA水平明显降低(t=8.243,P<0.05);流式细胞术显示其更具有增殖活性。体内实验显示皮下肿瘤成瘤率提高,成瘤时间提前。LNCaP/HIF-1α免疫组化研究显示VEGF、iNOS、Ang-2表达较LNCaP组增强。结论:在体内环境下,HIF-1α过表达能够诱导人前列腺癌LNCaP细胞血管形成相关蛋白VEGF、iNOS表达上调,提高肿瘤血管形成能力。并通过诱导肿瘤血管形成来增强肿瘤的侵袭转移能力;体内外实验显示HIF-1α可能对人前列腺癌LNCaP细胞Ang-2表达不产生影响,而在体内环境下Ang-2表达受其他因素调控。     

Expression of VEGF isoforms by epiphyseal chondrocytes during low-oxygen tension is HIF-1 alpha dependent

OBJECTIVE: To establish the role of hypoxia and HIF-1 alpha for VEGF expression of murine epiphyseal chondrocytes. To analyze the effect of hypoxia on VEGF isoform expression. MATERIALS AND METHODS: VEGF mRNA and VEGF isoform expression was investigated in epiphyses of murine newborns by in situ hybridization and real-time PCR. Further, epiphyseal chondrocytes were isolated from newborn mice with homozygous flanking of the HIF-1 alpha gene with lox-P sites. HIF-1 alpha was deleted by infection with adenovirus containing cre-recombinase. After chondrocytes reached confluency they were exposed to 0.5% or 20% oxygen, respectively. Total VEGF and VEGF isoform mRNA expression levels were measured by real-time PCR. Secreted VEGF protein was determined by ELISA. RESULTS: VEGF mRNA signals were detected in the hypertrophic zone and in the center of the proliferative zone of the murine epiphysis, which is considered to be hypoxic. Real-time PCR revealed that VEGF(120)is the dominant isoform in vivo. In cultured epiphyseal chondrocytes strongly increased VEGF gene expression levels were detected after exposure to hypoxia. Furthermore, secretion of VEGF protein was significantly enhanced under 0.5% oxygen. Remarkably, functional inactivation of HIF-1 alpha abolished the hypoxic increase of VEGF expression in chondrocytes completely. Furthermore, the soluble isoforms VEGF(120)and VEGF(164)are the most abundantly expressed splice variants in chondrocytes exposed to low oxygen levels. CONCLUSIONS: The data presented here clearly indicate that hypoxia is able to induce the synthesis of soluble VEGF isoforms by epiphyseal chondrocytes, most likely through stabilization of HIF-1 alpha. Thus it can be speculated that HIF-1 alpha is an essential prerequisite for hypoxic VEGF synthesis in the epiphysis, thereby contributing to the formation and invasion of blood vessels in long bone development.     

缺氧诱导因子-1α及其相关基因在腹主动脉瘤中的表达及意义

目的研究缺氧诱导因子(HIF)-1α信号转导通路及其相关基因在腹主动脉瘤(AAA)中的表达,探讨AAA的发病机制。方法选取AAA标本22例,以5例腹主动脉(NA)标本作对照。采用Northern杂交、Western蛋白印迹及免疫组织化学方法检测HIF-1α的mRNA及蛋白产物表达,Western蛋白印迹或免疫组织化学方法检测血管内皮生长因子(VEGF)及半胱氨酸蛋白酶(caspase)-3的表达,免疫组织化学抗CD34染色法检测微血管密度(MVD)。结果 AAA组织中HIF-1α的mRNA及蛋白产物表达明显高于NA(P<0.01);caspase-3和VEGF表达亦明显增强(P<0.01),与HIF-1α表达呈显著正相关(r值分别为0.783和0.693,P<0.01)。HIF-1α表达主要分布在AAA中层血管平滑肌细胞及外膜处,与caspase-3和VEGF的分布部位基本一致。AAA中微血管密度明显增加(P<0.01))。结论HIF-1α在AAA疾病进展过程中可能发挥重要作用,其作用机制可能是通过调控VEGF或caspase-3的表达而实现的。