Bando 06_09

Lymphangiogenesis plays an important role in several normal and pathological conditions, such as wound healing, pathogen infection, inflammation or the metastasis formation of endothelial malignancies. Vascular endothelial growth factor-C (VEGF-C) and VEGF-D are important and specific regulatory factors for lymphatic endothelial proliferation and lymphangiogenesis. Both growth factors mediate their biological activity mainly by VEGF receptor-3 (VEGFR-3, Flt-4). In this study, we measured intratumoral levels of VEGF-C and VEGFR-3 through enzyme-linked immunosorbent assay (ELISA) in 193 primary breast cancer tissues and examined their prognostic values. A significant correlation was found between the VEGF-C and VEGFR-3 protein levels. High VEGF-C levels were associated with low-grade tumors and a smaller size. Univariate analysis showed that high VEGF-C was significantly associated with a favourable prognosis for disease-free survival (DFS) and overall survival (OS). No significant prognostic value of VEGFR-3 was detected. Multivariate analysis confirmed the independent prognostic value of VEGF-C. The intratumoral VEGF-C level is a significant prognostic indicator of primary breast cancer. An investigation of the mechanisms of VEGF-C protein processing in human cancer tissue should be carried out in the future. Introduction Lymphangiogenesis is the growth of lymphatic vessels which occurs after tissue injury, obstruction or damage to lymphatic vessels (1). The lymphatic system reduces increased tissue pressure associated with edema and inflammation (2). In the last 5-7 years, it has emerged that the receptor tyrosine kinase VEGFR-3 (Flt-4) and its ligands are key players in the molecular regulation of lymphangiogenesis (3). The two ligands, VEGF-C and VEGF-D, induce the phosphorylation of VEGFR-3 and regulate the growth and differentiation of lymphatic endothelium alone or in combination with other growth factors (4,5). Both ligands are members of the PDGF/ VEGF growth factor super-family and are virtually identical in their molecular properties. They are produced as precursor molecules and are then progressively processed during biosynthesis to remove their Nand C-terminal ends (6). This processing increases the affinity of VEGF-C and VEGF-D for VEGFR-3, but fully processed forms of both ligands also activate VEGFR-2 (7). Although they are less potent activators of VEGFR-2 than of VEGFR-3, they contribute to normal angiogenesis (5,7,8). However, after binding to VEGF-C and VEGF-D, VEGFR-3 is capable of transducing signals that trigger the proliferation of VEGFR-3 expressing cells in vitro and in vivo (9-11). Blocking VEGFR-3 activation inhibits the formation of lymphatic vessels in the developing embryo (10). VEGFR-3 and its ligands may play an important role in several pathological conditions where lymphangiogenesis occurs or lymphatic is involved. More recent studies suggest that patients with mutations in the VEGFR-3 gene develop lymph-edema (12,13). However, several normal tissues, such as the heart and lung, also express high levels of the VEGF-C gene. This suggests that VEGF-C is necessary for tissue homeostasis, but its exact physiological role is unknown (14,15). Recently, indirect ELISA was performed to measure VEGF-C protein in cancer patient plasma samples (16). In this assay, it was not possible to use purified VEGF-C standards and, for that reason, only indirect statements can be made about the amount and distribution of VEGF-C in the plasma. ONCOLOGY REPORTS 15: 653-659, 2006 653 The association between vascular endothelial growth factor-C, its corresponding receptor, VEGFR-3, and prognosis in primary breast cancer: A study with 193 cases HIROKO BANDO1,4, HERBERT A. WEICH5, SHINICHIRO HORIGUCHI2, NOBUAKI FUNATA2, TAEKO OGAWA1 and MASAKAZU TOI1,3 Departments of 1Surgery, 2Pathology and 3Clinical Trials and Research, Tokyo Metropolitan Komagome Hospital, Tokyo Metropolitan Cancer and Infectious Disease Center, 3-18-22 Honkomagome Bunkyo-ku, Tokyo 113-8677; 4Department of Surgery, Institute of Clinical Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba-shi, Ibaraki, Japan; 5Department of Gene Regulation and Differentiation; National Research Centre for Biotechnology, Braunschweig, Germany Received September 6, 2005; Accepted October 28, 2005 _________________________________________ Correspondence to: Dr Masakazu Toi, Metropolitan Komagome Hospital, Tokyo Metropolitan Center for Cancer and Infectious Disease, 3-18-22 Honkomagome Bunkyo-ku, Tokyo 113-8677, Japan E-mail: [email protected] Abbreviations: VEGF, vascular endothelial growth factor; VEGF-C, vascular endothelial growth factor-C; VEGFR-3, vascular endothelial growth factor receptor-3; ELISA, enzyme-linked immunosorbent assay; DFS, disease-free survival; OS, overall survival