Lymphatic endothelium and Kaposi's sarcoma spindle cells detected by antibodies against the vascular endothelial growth factor receptor-3.

Lymphatic vessels have been difficult to study in detail in normal and tumor tissues because of the lack of molecular markers. Here, monoclonal antibodies against the extracellular domain of the vascular endothelial growth factor-C receptor that we have named VEGFR-3 were found to specifically stain endothelial cells of lymphatic vessels and vessels around tumors such as lymphoma and in situ breast carcinoma. Interestingly, the spindle cells of several cutaneous nodular AIDS-associated Kaposi's sarcomas and the endothelium around the nodules were also VEGFR-3 positive. The first specific molecular marker for the lymphatic endothelium should provide a useful tool for the analysis of lymphatic vessels in malignant tumors and their metastases and the cellular origin and differentiation of Kaposi's sarcomas.

Vascular endothelial growth factor receptor-3 (VEGFR-3): a marker of vascular tumors with presumed lymphatic differentiation, including Kaposi's sarcoma, kaposiform and Dabska-type hemangioendotheliomas, and a subset of angiosarcomas.

Recently, a novel monoclonal antibody to vascular endothelial growth factor receptor 3 (VEGFR-3), a tyrosine kinase receptor expressed almost exclusively by lymphatic endothelium in the adult, has been shown to react with a small number of cases of Kaposi's sarcoma (KS) and cutaneous lymphangiomas. We sought to extend these studies to a large number of well-characterized vascular neoplasms to evaluate diagnostic uses of this antibody and to determine whether it defines them in a thematic fashion. Formalin-fixed, paraffin-embedded sections from 70 vascular tumors were immunostained with antibodies to VEGFR-3 von Willebrand factor (vWF), and CD31. Anti-VEGFR-3 was positive in 23 of 24 KS, 8 of 16 angiosarcomas (AS), 6 of 6 kaposiform hemangioendotheliomas, 4 of 4 Dabska tumors, and 2 of 13 hemangiomas. Positively staining angiosarcomas were characterized either by a prominent lymphocytic component, a hobnail endothelial cell similar to that encountered in the Dabska tumor, or spindled areas resembling KS. No VEGFR-3 expression was noted in any cases of epithelioid hemangioendothelioma, pyogenic granuloma, littoral angioma, or stasis dermatitis. vWF expression was seen in 10 of 13 KS; 13 of 14 AS; 4 of 5 kaposiform hemangioendotheliomas; and all Dabska tumors, hemangiomas, lymphangiomas, epithelioid hemangioendotheliomas, vascular malformations, stasis dermatitis, and splenic littoral angiomas. CD31 expression was present in 12 of 13 KS, 13 of 14 AS, and in all other cases. Expression of VEGFR-3 is a very sensitive marker of KS, kaposiform, and Dabska-type hemangioendotheliomas, suggesting that all show at least partial lymphatic endothelial differentiation. Expression of VEGFR-3 does not reliably discriminate KS from AS. However, the expression of VEGFR-3 by certain AS having Kaposi-like areas, a prominent lymphocytic infiltrate, or hobnail endothelium may define subset(s) having phenotypic, if not pathogenetic and biologic, differences.

Angiogenesis and lymphangiogenesis in stage 1 germ cell tumours of the testis.

OBJECTIVE: To determine whether angiogenesis can be used as an additional prognostic indicator in patients with stage 1 germ cell tumours of the testis. PATIENTS AND METHODS: Paraffin sections were assessed immunohistochemically from 51 patients with clinical stage 1 germ cell tumours of the testis (28 seminoma, 23 teratoma) treated by orchidectomy and surveillance only. Sections were analysed for microvascular density (MVD), and expression of the angiogenic factors vascular endothelial growth factor (VEGF) and thymidine phosphorylase (TP). In addition, in the seminoma cases the presence of mRNA for the lymphangiogenic factor VEGF-C was examined by in situ hybridization, and its corresponding receptor VEGFR-3 by immunohistochemistry. RESULTS: Teratoma specimens had a significantly higher mean (range) MVD (85, 26-163; P < 0.01) than both seminoma (37, 16-91) and four normal specimens (26, 18-30). Teratoma specimens also had significantly higher VEGF expression than both seminoma and normal specimens (P < 0.01). Despite these differences between groups, and indeed individual tumours, there was no significant correlation between MVD and VEGF, or between either MVD or VEGF and relapse-free survival. TP expression was significantly greater in tumours than in normal specimens (P < 0.02) but with very little inter-tumour variation. VEGF-C mRNA and VEGFR-3 protein were detected in a third to a half of cases, with expression mostly around endothelial vessels. CONCLUSIONS: The marked differences between normal testis and tumours implicate angiogenesis in the biology of germ cell tumours of the testis. In addition, the detection of factors involved in lymphangiogenesis in some seminomas, tumours which initially metastasize primarily to lymph nodes, indicate that although not prognostic in this study, further studies are warranted in both these areas in the search for further prognostic indicators and therapeutic targets.

VEGFR-3 and its ligand VEGF-C are associated with angiogenesis in breast cancer.

Recently, monoclonal antibodies against the human vascular endothelial growth factor receptor VEGFR-3 were shown to provide a specific antigenic marker for lymphatic endothelium in various normal tissues. In this study we have investigated the expression of VEGFR-3 and its ligand VEGF-C in normal breast tissue and in breast tumors by immunohistochemistry. VEGFR-3 was weakly expressed in capillaries of normal breast tissue and in fibroadenomas. In intraductal breast carcinomas, VEGFR-3 was prominent in the "necklace" vessels adjacent to the basal lamina of the tumor-filled ducts. VEGF receptor 1 and 2 as well as blood vessel endothelial and basal lamina markers were colocalized with VEGFR-3 in many of these vessels. Antibodies against smooth muscle alpha-actin gave a weak staining of the necklace vessels, suggesting that they were incompletely covered by pericytes/smooth muscle cells. A highly elevated number of VEGFR-3 positive vessels was found in invasive breast cancer in comparison with histologically normal breast tissue (P < 0.0001, the Mann-Whitney test). VEGF-C was located in the cytoplasm of intraductal and invasive cancer cells. The results demonstrate that the expression of VEGFR-3 becomes up-regulated in the endothelium of angiogenic blood vessels in breast cancer. The results also suggest that VEGF-C secreted by the intraductal carcinoma cells acts predominantly as an angiogenic growth factor for blood vessels, although this paracrine signaling network between the cancer cells and the endothelium may also be involved in modifying the permeabilities of both blood and lymphatic vessels and metastasis formation.

Prognosis of breast-carcinoma lymphagenesis evaluated by immunohistochemical investigation of vascular-endothelial-growth-factor receptor 3.

Very few studies have yet addressed the question of the existence and role of lymphagenesis in tumor growth; it is generally overshadowed by the greater emphasis placed on the blood vascular system. Monoclonal antibodies against vascular endothelial-growth-factor receptor 3 (VEGFR3) have been shown to provide a specific antigenic marker for lymphatic endothelium. By comparison with the microvascular count (MVC), we investigated the prognostic value of the microlymphatic count (MLC) in a series of 60 cases of 2-cm-diameter breast carcinomas. The mean value of MVC was 72.5 and of MLC, 40.5. There was no quantitative correlation between these 2 parameters. The MVC but not the MLC had a prognostic value in overall survival. Neither the MLC nor the MVC had any correlation with axillary-lymph-node invasion.