Fulvene-5 potently inhibits NADPH oxidase 4 and blocks the growth of endothelial tumors in mice

Abstract

Hemangiomas are the most common type of tumor in infants. As they are endothelial cell-derived neoplasias, their growth can be regulated by the autocrine-acting Tie2 ligand angiopoietin 2 (Ang2). Using an experimental model of human hemangiomas, in which polyoma middle T-transformed brain endothelial (bEnd) cells are grafted subcutaneously into nude mice, we compared hemangioma growth originating from bEnd cells derived from wild-type, Ang2 +/-, and Ang2 -/-mice. Surprisingly, Ang2-deficient bEnd cells formed endothelial tumors that grew rapidly and were devoid of the typical cavernous architecture of slow-growing Ang2-expressing hemangiomas, while Ang2 +/-cells were greatly impaired in their in vivo growth. Gene array analysis identified a strong downregulation of NADPH oxidase 4 (Nox4) in Ang2 +/-cells. Correspondingly, lentiviral silencing of Nox4 in an Ang2-sufficient bEnd cell line decreased Ang2 mRNA levels and greatly impaired hemangioma growth in vivo. Using a structure-based approach, we identified fulvenes as what we believe to be a novel class of Nox inhibitors. We therefore produced and began the initial characterization of fulvenes as potential Nox inhibitors, finding that fulvene-5 efficiently inhibited Nox activity in vitro and potently inhibited hemangioma growth in vivo. In conclusion, the present study establishes Nox4 as a critical regulator of hemangioma growth and identifies fulvenes as a potential class of candidate inhibitor to therapeutically interfere with Nox function.

NADPH Oxidase 4 Induces Cardiac Arrhythmic Phenotype in Zebrafish

“…3 and 5A and Table 1). Fulvene-5 inhibits NOX4 activity to 40% at 5 M in cells (30). In our treatments, we found that fulvene-5 at 10 M starting before 24 hpf significantly abolished NOX4-induced ROS production and arrhythmic phenotype (Figs.…”

NADPH oxidase 4 is a critical mediator in Ataxia telangiectasia disease

“…ATM-deficient mice fed with antioxidants lived longer, exhibited a reduced incidence of lymphoma and showed mitigated loss of hematopoietic stem cells compared with controls (15,16). We show here that Atm-null mice also exhibit a reduced incidence of lymphoma when given fulvene-5, a known inhibitor of NOX4 (17). Thus, down-regulation of NOX4 ameliorates the detrimental effects of ATM loss in both human cells and in mice.…”

Malignant cell-derived PlGF promotes normalization and remodeling of the tumor vasculature

“…This PlGF-induced vascular remodeling effect resembles activation of the Dll-4-Notch signaling pathways, which define the arteriole identity and restrict vascular sprouting (40,(42)(43)(44)(45)53). Consequently, inhibition of Notch ligands and receptors resulted in generation of a disorganized tumor vasculature that remain poorly perfused and functionally non-productive 40,[42][43][44]54).…”