Novel application assigned to toluquinol: inhibition of lymphangiogenesis by interfering with VEGF-C/VEGFR-3 signaling pathway.

BACKGROUND AND PURPOSE: Lymphangiogenesis is an important biological process associated with the pathogenesis of several diseases, including metastatic dissemination, graft rejection, lymphedema and other inflammatory disorders. The development of new drugs blocking lymphangiogenesis has become a promising therapeutic strategy. In this study, we aim at investigating the ability of toluquinol, a 2-methyl-hydroquinone isolated from the culture broth of the marine fungus Penicillium sp. HL-85-ALS5-R004, to inhibit lymphangiogenesis in vitro, ex vivo and in vivo. EXPERIMENTAL APPROACH: We used human lymphatic endothelial cells (LEC) to analyze the effect of toluquinol in 2D and 3D in vitro cultures, and in the ex vivo mouse lymphatic ring assay. For in vivo approaches, the transgenic Fli1:eGFPy1 zebrafish, the mouse ear sponges and cornea models were used. Western-blotting and apoptosis analyses were carried out to search for drug targets. KEY RESULTS: Toluquinol inhibited LEC proliferation, migration, tubulogenesis and sprouting of new lymphatic vessels. Furthermore, toluquinol induced LEC apoptosis after 14 h of treatment in vitro, blocked the thoracic duct development in zebrafish, and reduced the VEGF-C-induced lymphatic vessel formation and corneal neovascularization in mice. Mechanistically, we are providing evidence that this drug abrogates the VEGF-C-induced VEGFR-3 phosphorylation in a dose-dependent manner, and represses Akt and ERK1/2 phosphorylations. CONCLUSIONS AND IMPLICATIONS: Based on these findings, we propose toluquinol as a new candidate with pharmacological potential for the treatment of lymphangiogenesis-related pathologies. Notably, its ability to suppress corneal neovascularization paves the way for applications in vascular ocular pathologies. This article is protected by copyright. All rights reserved.