Microvessel density, vascular endothelial growth factor and its receptors Flt-1 and Flk-1/KDR in hepatocellular carcinoma.

Assessment of angiogenesis may yield important information for an effective antiangiogenic treatment for hepatocellular carcinoma (HCC) because HCC is characteristically hypervascular We examined the relationship of microvessel density (MVD), vascular endothelial growth factor (VEGF), and VEGF receptors Flt-1 and Flk-1/KDR in 50 patients with HCC and in 3 hepatoma cell lines. VEGF messenger RNA (mRNA) was overexpressed in 26 tumors (52%), and the 3 VEGF isoforms (121, 165, and 189) were present in high frequencies. Flt-1 mRNA was overexpressed in 34 tumors (68%), with levels significantly increased in HCCs compared with the nontumorous livers. Tumor Flt-1 mRNA significantly correlated with tumor VEGF mRNA levels. Within the group of tumors 8.5 cm or less in diameter, tumors with intrahepatic metastasis in the form of tumor microsatellite formation had significantly higher VEGF mRNA levels. MVD assessed by immunohistochemical analysis with CD34 antibody was inversely related to tumor size. Angiogenesis as assessed by MVD and tumor VEGF expression seems to have a more important role in tumor growth and intrahepatic metastasis in smaller HCCs. The differential up-regulation of Flt-1 suggests that it may have an important role in angiogenesis in HCC.

Ng IO ，Poon RT ，Lee JM ，Fan ST ，Ng M ，Tso WK ... -  《AMERICAN JOURNAL OF CLINICAL PATHOLOGY》

Clinical significance of microvessel density and vascular endothelial growth factor expression in hepatocellular carcinoma and surrounding liver: possible involvement of vascular endothelial growth factor in the angiogenesis of cirrhotic liver.

As in other tumors, the assessment of microvessel density (MVD) in hepatocellular carcinoma (HCC) may be essential to perform an effective anti-angiogenic therapy for this tumor. The relationship between vascular endothelial growth factor (VEGF) and MVD of HCC as well as the surrounding liver remains to be elucidated. In 71 patients who had undergone curative hepatic resection for HCC, MVD and VEGF expressions were evaluated for HCC and the liver by quantitative reverse-transcription polymerase chain reaction (RT-PCR) and/or immunostaining. The intensity and extent of VEGF immunoreactivity were evaluated using a computer image analyzer-cell analysis system (CAS). Angiographic data were re-evaluated and compared with MVD in 50 tumors. Tumoral MVD was significantly correlated with tumor capsule formation (t test, P = .0016). Small HCCs (< or = 2 cm) had a significantly lower MVD compared with moderate-sized HCCs (2-5 cm) (t test, P = .016), and the MVD of large HCCs was relatively lower than that of moderate tumors. Tumor vascularity on angiography was not correlated with the MVD. Neither VEGF mRNA levels nor protein expression in HCC were correlated with the tumoral MVD or any histopathological features of the tumor. However, cirrhotic livers had significantly higher MVD and VEGF expressions compared with noncirrhotic livers (t test, P = .0015 and P = .047, respectively). Only the MVD of tumor was significantly correlated with intrahepatic recurrence (t test, P = .0048) and disease-free survival (DFS) rates (log rank test, P = .0035). Moreover, the MVD was an independent predictor for DFS by multivariate analysis (chi2 test, P = .03). In conclusion, the MVD in HCC may be involved in the dismal prognosis of this tumor, and VEGF may be associated with the angiogenic process of the cirrhotic liver, but not with the angiogenesis of HCC.

El-Assal ON ，Yamanoi A ，Soda Y ，Yamaguchi M ，Igarashi M ，Yamamoto A ，Nabika T ，Nagasue N ... -  《HEPATOLOGY》

Gene expression of vascular endothelial growth factor and its receptors and angiogenesis in bronchial asthma.

Angiogenesis is a feature of airway remodeling in bronchial asthma. The mechanism responsible for this angiogenesis is unknown. Vascular endothelial growth factor (VEGF) is a potent inducer of endothelial cells, which may contribute to chronic inflammation and angiogenesis. We sought to investigate the molecular mechanisms underlying increased vascularity, and we examined the mRNA expression of VEGF and its receptors (flt-1 and flk-1) within bronchial biopsy specimens from asthmatic patients and normal control subjects. Endobronchial biopsy specimens were examined immunocytochemically by staining with anti-type IV collagen mAb to evaluate vessel density by using computer-assisted image analysis. Specimens were also analyzed for the presence of the mRNAs of VEGF and its receptors with in situ hybridization. The extent of airway vascularity was increased in asthmatic subjects compared with that in control subjects (P <.01). Asthmatic subjects exhibited a greater expression of VEGF, flt-1, and flk-1 mRNA(+) cells in the airway mucosa compared with that in control subjects (P <.001 for each comparison). The degree of vascularity was associated with the number of VEGF, flt-1, and flk-1 mRNA(+) cells. Numbers of cells expressing VEGF mRNA inversely correlated with airway caliber (r = -0.83, P <.01) and airway hyperresponsiveness (r = -0.97, P <.001). Colocalization studies showed that macrophages, eosinophils, and CD34(+) cells were the major sources of VEGF; CD34(+) cells, macrophages, and T cells expressed both flt-1 and flk-1. These findings provide evidence that VEGF may play an important role in angiogenesis and subsequent airway remodeling in bronchial asthma.

Hoshino M ，Nakamura Y ，Hamid QA 《JOURNAL OF ALLERGY AND CLINICAL IMMUNOLOGY》

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.

Giatromanolaki A ，Sivridis E ，Athanassou N ，Zois E ，Thorpe PE ，Brekken RA ，Gatter KC ，Harris AL ，Koukourakis IM ，Koukourakis MI ... -  《JOURNAL OF PATHOLOGY》

KDR/Flk-1 is a major regulator of vascular endothelial growth factor-induced tumor development and angiogenesis in murine hepatocellular carcinoma cells.

Vascular endothelial growth factor (VEGF), which is one of the most potent angiogenic factors, has been shown to play a pivotal role in tumor angiogenesis, including hepatocellular carcinoma (HCC). The effects of VEGF are mediated mainly through two distinct receptors, flt-1 and KDR/Flk-1. It has been suggested that KDR/Flk-1 plays an important role in tumor development. However, the role of KDR/Flk-1 in HCC has not been examined. We previously reported that VEGF tightly regulated murine HCC development, based on the results of a study using a retroviral tetracycline-regulated (Retro-Tet) gene expression system. This system allows VEGF gene expression to be manipulated in vivo by providing tetracycline in the drinking water. In the present study, we combined the KDR/Flk-1-specific neutralizing monoclonal antibody (KDR/Flk-1mAb) and the Retro-Tet system to elucidate the role of KDR/Flk-1 in VEGF-induced tumor development and angiogenesis in a murine HCC experimental model. In a xenograft study, tumor augmentation induced by VEGF overexpression was almost abolished by means of KDR/Flk-1mAb treatment, with accompanying inhibition of angiogenesis, KDR/Flk-1 autophosphorylation, but not interference of flt-1 activation. This inhibitory effect was achieved even on established tumors and regardless of whether the tumor size was small or large. On the contrary, KDR/Flk-1mAb treatment significantly increased the apoptosis in the tumor. With orthotopic transplantation, KDR/Flk-1mAb also inhibited HCC development in the liver. These results suggest that KDR/Flk-1 is a major regulator of VEGF-mediated HCC development and angiogenesis not only at the initial stage, but also after the tumor has fully developed.

Yoshiji H ，Kuriyama S ，Hicklin DJ ，Huber J ，Yoshii J ，Miyamoto Y ，Kawata M ，Ikenaka Y ，Nakatani T ，Tsujinoue H ，Fukui H ... -  《HEPATOLOGY》