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High endothelial venules (HEVs) are specialized vessels in lymphoid organs, supporting lymphocyte trafficking from the blood. As the presence of these vessels was described recently in tumors, it was proposed that they could facilitate the development of antitumor immune response, resulting in improved prognosis. The aim of our study was to analyze the correlation of the density of HEVs with that of the different immune cell types as well as with the clinicopathologic parameters and the disease outcomes in patients with cutaneous melanoma. Primary melanoma samples of 118 patients were analyzed retrospectively by immunohistochemical labeling and quantitation of vessels stained with the MECA-79 antibody, as well as a panel of eight different immune cell types (CD8 and CD45RO T cells, lymphocytes expressing the CD25, CD134, or CD137 activation markers, FOXP3 regulatory T cells, CD20 B cells, and DC-LAMP mature dendritic cells). Correlations of MECA-79 vessel density with that of the immune cells, as well as with clinicopathologic parameters and disease outcomes were evaluated. We showed that the number of MECA-79 vessels correlates strongly with the peritumoral density of B and T lymphocytes. Moreover, higher HEV numbers were detected in tumors hosting tertiary lymphoid structures as well as in those of axial location compared with the ones in the extremity and in men compared with women, whereas no association was found with patient age, tumor thickness, histologic type or ulceration, or with the survival of melanoma patients. The density of MECA-79 HEVs in primary melanomas shows a correlation with B and T-lymphocyte density and differences according to the presence of tertiary lymphoid structures, tumor site, and the sex of the patient. However, it has no prognostic value.

As previous studies suggested the expression of a 12-LOX enzyme in murine and human melanoma cell lines, the primary aim of this project was to genetically identify the 12-LOX enzyme (platelet-, leukocyte- or epithelial form). By using reverse transcriptase-polymerase chain reaction, sequencing and various immunological techniques we have demonstrated conclusively the expression of the platelet-type 12-LOX in human melanoma cells of different origin, in their transplanted xenografts and in fresh human skin tumors. Furthermore, we found that p12-LOX is able to provide a survival signal for melanoma cells since inhibition of the enzyme by general LOX or selective 12-LOX inhibitors induced apoptosis in vitro. p12-LOX of human melanoma has been shown to be involved in the control of the metastatic phenotype, since we have detected the upregulation of the 12-LOX protein expression in spontaneously metastasizing xenografts and in thick human skin tumors (> 3.0 mm) characterized by high risk for the development of metastasis. Co-expression of two megakaryocytic genes, p12-LOX and alphaIIb integrin chains, was found to be a frequent phenomenon in human melanoma (approximately 70%) suggesting a common regulatory defect in this tumor., (Copyright 2004 Lippincott Williams & Wilkins)

Intratumoral vessels are different both structurally and phenotypically, and this may have clinical significance. In this study we analysed the expression of an adhesion molecule--vascular adhesion protein-1 (VAP-1)--in melanoma-associated blood vessels in 28 primary skin melanoma cases using immunocytochemistry and immunoelectron microscopy. We have found that VAP-1 protein expression is significantly decreased in intratumoral vessels compared with peritumoral ones; this difference was independent of the tumour thickness. Loss of VAP-1 protein expression occurred in both endothelial and smooth muscle cell components. Unlike in other cancer types, the VAP-1 protein expression of intratumoral vessels did not correlate with the density of cytotoxic T-lymphocytes or dendritic cells. On the other hand, the 5-year survival of melanoma patients with low VAP-1 protein expression in intratumoral blood vessels (< or =25%) was lower (26.3%) than in patients whose VAP-1 expression was higher (42.6%, P=0.0632). These results support the idea that the phenotype of intratumoral blood vessels is important in the progression of malignant melanoma.