Overexpression of Human Catalase Inhibits Proliferation and Promotes Apoptosis in Vascular Smooth Muscle Cells

Abstract

The role of reactive oxygen species, such as superoxide anions (O 2) and hydrogen peroxide (H 2 O 2), in modulating vascular smooth muscle cell proliferation and viability is controversial. To investigate the role of endogenously produced H 2 O 2 , rat aortic smooth muscle cells were infected with adenoviral vectors containing cDNA for human catalase (AdCat) or a control gene,-galactosidase (AdLacZ). Infection with AdCat resulted in dose-dependent increases in intracellular catalase protein, which was predominantly localized to peroxisomes. After infection with 100 multiplicity of infection (MOI) of AdCat, cellular catalase activity was increased by 50-to 100-fold, and intracellular H 2 O 2 concentration was reduced, as compared with control. Infection with AdCat reduced [ 3 H]thymidine uptake, an index of DNA synthesis, in cells maintained in medium supplemented with 2% serum (0.370.09 disintegrations per minute per cell [AdLacZ] versus 0.220.08 disintegrations per minute per cell [AdCat], P0.05). Five days after infection with 100 MOI of AdCat, cell numbers were reduced as compared with noninfected or AdLacZ-infected cells (157 7808413 [AdCat], P0.05 versus 233 7003032 [noninfected] or 222 4105332 [AdLacZ]). Furthermore, the number of apoptotic cells was increased 5-fold after infection with 100 MOI of AdCat as compared with control. Infection with AdCat resulted in induction of cyclooxygenase (COX)-2, and treatment with a COX-2 inhibitor overcame the AdCat-induced reduction in cell numbers. These findings indicate that overexpression of catalase inhibited smooth muscle proliferation while increasing the rate of apoptosis, possibly through a COX-2-dependent mechanism. Our results suggest that endogenously produced H 2 O 2 importantly modulates survival and proliferation of vascular smooth muscle cells. (Circ Res. 1999;85:524-533.) Key Words: catalase apoptosis vascular smooth muscle cell cell proliferation hydrogen peroxide P roliferation of vascular smooth muscle cells is an important contributing factor in the pathophysiology of hyper-tension and atherosclerosis, as well as in coronary artery restenosis after angioplasty and stent placement. 1,2 However, the factors that induce proliferation of vascular smooth muscle cells, which normally exist in the arterial wall in a state of quiescence, are unknown. 3 Recently, it has been reported that reactive oxygen species, such as superoxide anions (O 2) and hydrogen peroxide (H 2 O 2), are capable of stimulating vascular smooth muscle cell proliferation. 4,5 These oxidants were shown to be rapidly produced by smooth muscle cells after exposure to platelet-derived growth factor or angiotensin II, factors that stimulate smooth muscle cell growth. 5,6 In addition, the production of reactive oxygen species in the blood vessel wall is enhanced in experimental models of hypercholesterolemia, hypertension, diabetes, and balloon injury to the coronary arteries. 7-10 Moreover, in angiotensin II-induced hypertension, excess free radical production was predominantly localized...

Mechanisms of H2O2-induced oxidative stress in endothelial cells

“…The highest rates of growth of cardiovascular disease diagnosis are in poorer nations where the prevalence of disease is significantly higher in young age brackets, compared to higher prevalence in older age brackets in industrialized nations. (Brown et al 1999;Rhee 1999;Griendling et al 2000c;Patel et al 2000a). At higher concentrations, ROS and RNS participate in the alteration of cellular phenotype from a basal state to an activated state resulting in increased inflammatory signaling and in increased ROS and RNS formation.…”

“…In addition, O 2 ·-participates in cell proliferation, migration, and apoptosis regulation through its ability to form H 2 O 2 (Brown et al 1999;Rhee 1999;Wolin et al 2002). To reduce O 2 ·-, it is converted to H 2 O 2 by superoxide dismutase (SOD), discussed in section 2.4.3, and through O 2 ·-self-interaction.…”

“…(Brown et al 1999), proliferation (Brown et al 1999), and modulation of intracellular Ca 2+ levels (Dreher et al 1995). It also upregulates eNOS gene expression and activity, and increases NO production .…”

“…Endogenous H 2 O 2 has been shown to be an important signaling molecule leading to increased DNA replication and proliferation in smooth muscle cells and endothelial cells (Brown et al 1999). Also, endogenous H 2 O 2 has been demonstrated to regulate vascular smooth muscle cell tone in several species and experimental models (Rabelo et al 2003;Yada et al 2003).…”

A redox cycle within the cell cycle: ring in the old with the new

“…Catalase overexpression in vascular smooth muscle cells inhibits proliferation and increases the apoptotic rate, indicating H 2 O 2 not only regulates proliferation but also survival (Brown et al, 1999). We have shown overexpression of GPx4 (PhGPx) inhibits progression from G 1 to S, suggesting the possible involvement of lipid peroxidation-mediated signaling in cell cycle progression .…”