Abstract 15844: WWOX Contributes to the Cancer-Like Microenvironment in Pulmonary Hypertension

Background:Pulmonary vascular remodeling is a hallmark of pulmonary arterial hypertension (PAH), involving exaggerated proliferation and resistance to apoptosis of pulmonary artery smooth muscle cells (PASMCs). WW domain containing oxidoreductase (WWOX) is a tumor suppressor and loss of WWOX affects cell proliferation, motility, attachment and deregulates expression of genes involved in cell cycle, motility and DNA damage. We hypothesized that loss of WWOX expression contributes to pulmonary vascular remodeling in PAH.Methods:mRNA, and protein levels of WWOX were measured in PASMCs from patients with PAH and in the lungs of rodent models of pulmonary hypertension. Tamoxifen inducible SMC-specific Wwox knockout mice were generated by crossing Wwoxflox/floxmice with myosin heavy chain Cre+mice (WWOX-SMC KO). The effects of hPASMC WWOX expression on proliferation, migration, cell cycle regulation and survival were tested.Results:PASMCs from PAH patients showed decreased WWOX mRNA and protein levels after 6 and 24 hours of hypoxia (3% O2) exposure. Compared to control, WWOX levels in lungs from rat models of pulmonary hypertension (Sugen plus hypoxia and monocrotaline) were reduced by 40% (P= 0.0187) and 60% (P=0.0023), respectively. A similar pattern was found in mice exposed to 4-weeks 10%-hypoxia, especially after 28 days, where WWOX expression in hypoxia was 80% lower than in normoxia (P=0.0038). Tamoxifen-induced SMC-WWOX KO mice developed more severe hypoxia induced-PH evidenced by higher right ventricular systolic pressure (P=0.002) and worse right ventricular hypertrophy (P=0.0031), in comparison to vehicle treated animals. hPASMCs incubated under hypoxia (3% O2) showed a time-dependent decrease in WWOX mRNA (P=0.0076) and protein expression (P=0.034). WWOX-silencing stimulated hPASMCs proliferation (P=0.0031) and migration (P<0.001), modulated cell cycle progression and HIF1? protein expression (P= 0.0190) and, increased the mRNA expression of GLUT1 (P=0.0012).Conclusion:PASMCs WWOX loss promotes cell proliferation and migration through perturbation in cell cycle regulatory and metabolic pathways and induces pulmonary vascular remodeling in vivo. Together, these data suggest that WWOX is mechanistic target in PAH.