Hypoxia promotes rabbit pulmonary artery smooth muscle cells proliferation through a 15-LOX-2 product 15(S)-hydroxyeicosatetraenoic acid

The initial event of hypoxic pulmonary hypertension is acute hypoxic pulmonary vasoconstriction followed by remodeling of pulmonary arteries. Although 15(S)-hydroxyeicosatetraenoic acid [15(S)-HETE] is found to be able to induce hypoxic pulmonary vasoconstriction, role of 15(S)-HETE in pulmonary artery smooth muscle cells (PASMCs) proliferation has been studied less. We sought evidence for a role of 15(S)-HETE in the development of hypoxia-induced pulmonary hypertension. We found that hypoxia enhances 15-lipoxygenase-2 (15-LOX-2) expression and stimulates cultured rabbit PASMCs proliferation. 15(S)-HETE at concentration 0.1 μM stimulated proliferation of PASMCs and induced ERK 1/ERK 2 phosphorylation but had no effect on p38 kinase expression as assessed by Western blotting. 15(S)-HETE-stimulated PASMC proliferation was blocked by the MEK inhibitors PD-98059. Hypoxia (3% O2)-stimulated PASMC proliferation was blocked by U0126, a MEK inhibitor, as well as by NDGA and CDC, inhibitors of 15-LOX, but not by the p38 MAPK inhibitor SB-202190. We conclude that 15-LOX-2 and its product, 15(S)-HETE, are important intermediates in hypoxia-induced rabbit PASMC proliferation and may participate in hypoxia-induced pulmonary hypertension.