Statin-triggered cell death in primary human lung mesenchymal cells involves p53-PUMA and release of Smac and Omi but not cytochrome c

Abstract

Statins inhibit 3-hydroxy-3-methyl-glutarylcoenzyme CoA (HMG-CoA) reductase, the proximal enzyme for cholesterol biosynthesis. They exhibit pleiotropic effects and are linked to health benefits for diseases including cancer and lung disease. Understanding their mechanism of action could point to new therapies, thus we investigated the response of primary cultured human airway mesenchymal cells, which play an effector role in asthma and chronic obstructive lung disease (COPD), to simvastatin exposure. Simvastatin induced apoptosis involving caspase-9, -3 and -7, but not caspase-8 in airway smooth muscle cells and fibroblasts. HMG-CoA inhibition did not alter cellular cholesterol content but did abrogate de novo cholesterol synthesis. Pro-apoptotic effects were prevented by exogenous mevalonate, geranylgeranyl pyrophosphate and farnesyl pyrophosphate, downstream products of HMG-CoA. Simvastatin increased expression of Bax, oligomerization of Bax and Bak, and expression of BH3-only p53-dependent genes, PUMA and NOXA. Inhibition of p53 and silencing of p53 unregulated modulator of apoptosis (PUMA) expression partly counteracted simvastatin-induced cell death, suggesting a role for p53-independent mechanisms. Simvastatin did not induce mitochondrial release of cytochrome c, but did promote release of inhibitor of apoptosis (IAP) proteins, Smac and Omi. Simvastatin also inhibited mitochondrial fission with the loss of mitochondrial Drp1, an essential component of mitochondrial fission machinery. Thus, simvastatin activates novel apoptosis pathways in lung mesenchymal cells involving p53, IAP inhibitor release, and disruption of mitochondrial fission.

Antimitogenic effect of bitter taste receptor agonists on airway smooth muscle cells

“…ASM cells undergo apoptosis under various conditions, and a decreased rate of apoptosis has been reported to contribute to excessive ASM mass in asthma (21). Recent studies demonstrated that statins inhibit ASM growth by inducing apoptosis of ASM cells (17). Effects of TAS2R agonists on ASM mass could also be the result of cytotoxicity or necrosis.…”

β-Dystroglycan binds caveolin-1 in smooth muscle: a functional role in caveolae distribution and Ca2+ release

“…12663). The plasmid was transfected into HEK293T cells using a Ca 2+ -phosphate three-plasmid transfection VSVG (envelope vector), 8.2vpr (packaging vector) and expression vector for -dystroglycan to generate lentivirus by counting the puromycin-resistant colonies, as previously described (Ghavami et al, 2010;Kung et al, 2000). A non-coding -dystroglycan refractory shRNA (shRNAi noncode) was used as a transduction control.…”

“…Cytosolic and membrane fractions were generated using a subcellular fractionation technique at 4°C as previously described (Ghavami et al, 2010). Cells were scraped in ice-cold buffer (10 mM Tris-HCl, pH 7.5, 0.1 mM EDTA, 0.1 mM EGTA, 1 mM dithiothreitol, and protease inhibitor cocktail), sonicated on ice three times for 5 seconds, and then the homogenate was separated into cytoplasmic and membrane fractions by ultra-centrifugation (100,000 g for 35 minutes).…”

p53 Mediates Colistin-Induced Autophagy and Apoptosis in PC-12 Cells

“…For example, treatment of cells with pemetrexed and simvastatin promoted autophagy and inhibited apoptosis (16), while oridonin phosphate induced autophagy and enhanced apoptotic cell death (17). However, the precise mechanisms that determine autophagy, apoptosis, and their interaction remain to be elucidated.A number of studies in tumor cells (e.g., hepatocellular carcinoma and OVCAR-3 cancer cells) have shown that the p53 tumor suppressor protein, which is an important cellular stress sensor, can trigger cell cycle arrest and apoptosis and also regulate autophagy (18)(19)(20). Activation of p53 in response to a death stimulus leads to the transcription of genes involved in apoptosis, including PUMA (p53 upregulated modulator of apoptosis), AMPK (AMPactivated protein kinase), and Bax in the nucleus.…”