3,4-dihydroxyacetophenone inhibits hypoxia-associated human pulmonary artery smooth muscle cell proliferation by reducing Ca2+ influx

Abstract

The present study aimed to assess the effects of 3,4-dihydroxyacetophenone (DHAP) on human pulmonary artery smooth muscle cells (HPASMCs). HPASMCs were divided into the normoxia group (NG), hypoxia group (HG), and hypoxia and 0.6×10-4 mol/L (HD1), 1.9×10-4 mol/L (HD2) and 6.0×10-4 mol/L (HD3) DHAP treatment groups. Cell cycle was analyzed by flow-cytometrically. HPASMC growth was examined by the proliferating cell nuclear antigen (PCNA) and MTT assays. Intracellular Ca2+ ([Ca2+]i) was measured by laser scanning confocal microscopy. Compared with the NG, the HG showed significantly increased HPASMC proliferation (P<0.05); meanwhile, cells treated with DHAP showed decreased proliferation compared with the HG (P<0.05). Hypoxia enhanced cell cycle progression and DHAP partly restored cell cycle distribution toward the status of NG cells. Furthermore, CDK2 levels were markedly increased in hypoxic cells (P<0.05), while DHAP treatment starkly decreased CDK2 levels in comparison with the HG (P<0.05). Moreover, hypoxia increased intracellular [Ca2+] levels compared with normoxia (P<0.05); meanwhile, DHAP treatment decreased [Ca2+]i compared with the HG (P<0.05). These findings suggested that DHAP inhibits hypoxiainduced proliferation of HPASMCs involving [Ca2+]i reduction. Therefore, DHAP should be considered an ideal candidate for the prevention and/or treatment of hypoxia-associated pulmonary hypertension and pulmonary vascular remodeling.