Statins, HMG-CoA reductase inhibitors have been studied for their antiproliferative and proapototic effects. Recently, statin-induced apoptosis has been associated with down-regulation of survivin expression in cancer cells. However, the mechanism of deregulated survivin by simvastatin on lung cancer is still unclear. Herein, we demonstrated that simvastatin induced caspase-dependent apoptosis in A549 lung cancer cells. Simvastatin also resulted in a decrease in the expression of phosphorylated Akt. In addition, simvastatin effectively down-regulated survivin mRNA and protein, but not cIAP-1 and cIAP-2. The combination of simvastatin and 10 μM LY294002 (non-toxic dose) augmented apoptosis significantly, as evidenced by cleavage of PARP. The immunoreactive band of survivin was markedly decreased in cells treated with 50 μM LY294002 (toxic dose) as well as by the combination of simvastatin and 10 μM LY294002. Moreover, survivin down-regulation by RNA interference induced apoptosis accompanied by an increase in hypodiploid DNA content. Taken together, these data suggest that the anti-cancer effect of simvastatin via induction of apoptosis is related to Akt signaling dependent down-regulation of survivin in lung cancer A549 cells.

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The non-steroidal anti-inflammatory drugs (NSAIDs) celecoxib and sulindac have been reported to suppress lung cancer migration and invasion. The class III deacetylase sirtuin 1 (SIRT1) possesses both pro- and anticarcinogenic properties. However, its role in inhibition of lung cancer cell epithelial-mesenchymal transition (EMT) by NSAIDs is not clearly known. We attempted to investigate the potential use of NSAIDs as inhibitors of TGF-β1-induced EMT in A549 cells, and the underlying mechanisms of suppression of lung cancer migration and invasion by celecoxib and sulindac. We demonstrated that celecoxib and sulindac were effective in preventing TGF-β1-induced EMT, as indicated by upregulation of the epithelial marker, E-cadherin, and downregulation of mesenchymal markers and transcription factors. Moreover, celecoxib and sulindac could inhibit TGF-β1-enhanced migration and invasion of A549 cells. SIRT1 downregulation enhanced the reversal of TGF-β1-induced EMT by celecoxib or sulindac. In contrast, SIRT1 upregulation promoted TGF-β1-induced EMT. Taken together, these results indicate that celecoxib and sulindac can inhibit TGF-β1-induced EMT and suppress lung cancer cell migration and invasion via downregulation of SIRT1. Our findings implicate overexpressed SIRT1 as a potential therapeutic target to reverse TGF-β1-induced EMT and to prevent lung cancer cell migration and invasion.

Pemetrexed is a multitargeted antifolate used for the treatment of malignant mesothelioma and non-small cell lung cancer (NSCLC). However, the mechanism by which pemetrexed induces apoptosis remains unclear. In the present study, we investigated the involvement of reactive oxygen species (ROS) and sirtuin 1 (SIRT1) in pemetrexed-induced apoptosis in MSTO-211 malignant mesothelioma cells and A549 NSCLC cells. Pemetrexed enhanced caspase-dependent apoptosis, induced intracellular ROS generation, and downregulated SIRT1 in the MSTO-211 and A549 cells. Pemetrexed-induced apoptosis, which was prevented by pretreatment with N-acetyl-cysteine (NAC), was mediated by effects on the mitochondria, including mitochondrial membrane potential transition (MPT) and cytosolic release of cytochrome c, and also involved regulation of SIRT1 expression. Interference with SIRT1 expression using siRNA enhanced pemetrexed-induced apoptosis through mitochondrial dysfunction and ROS generation, whereas resveratrol, an activator of SIRT1, protected against pemetrexed-induced apoptosis. These results show that pemetrexed induces apoptosis in MSTO-211 mesothelioma cells and A549 NSCLC cells through mitochondrial dysfunction mediated by ROS accumulation and SIRT1 downregulation.

Abstract. Pemetrexed is a multitarget antifolate currently used for the treatment of malignant mesothelioma and non-small cell lung cancer (NSCLC). Statins, 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors used primarily for hyperlidpidemia, have been studied for their antiproliferative and pro-apoptotic effects. However, the effects of simvastatin on pemetrexed-induced apoptosis have not been investigated. In this study, we investigated whether combination treatment with pemetrexed and simvastatin potentiates the apoptotic activity above that is seen with either drug alone in malignant mesothelioma and NSCLC cells. We found that the combination of pemetrexed and simvastatin induced more extensive caspase-dependent apoptosis than either drug alone in malignant mesothelioma cells (MSTO-211) or NSCLC cells (A549). In addition, reactive oxygen species (ROS) generation in cells treated with both pemetrexed and simvastatin was markedly increased compared to cells treated with either pemetrexed or simvastatin alone. Combination treatment also increased the loss of mitochondrial membrane potential, increased cytosolic release of cytochrome c, and altered expression of inhibitor of apoptosis proteins (IAP) and B-cell lymphoma-2 (Bcl-2) families of apoptosis related proteins. On the other hand, pretreatment with N-acetylcysteine (NAC) prevented apoptosis and mitochondrial dysfunction by pemetrexed and simvastatin. In addition, Bim siRNA conferred protection against apoptosis induced by pemetrexed and simvastatin. These results suggest that combination of pemetrexed and simvastatin potentiates their apoptotic activity beyond that of either drug alone in malignant mesothelioma and lung cancer cells. This activity is mediated through ROS-dependent mitochondrial dysfunction and Bim induction.

Our results identified that HNRNPA1 is the best diagnostic marker among the SFs and conventional markers given its excellent diagnostic efficacy for cervical carcinoma, and it has a p16-comparable diagnostic value. We suggest that HNRNPA1 is an additional effective target protein for developing cervical cancer detection tools.

Prevention of lung cancer is more feasible and holds greater promise when different agents are used in combination to target multiple processes during carcinogenesis. The mechanisms by which non-steroidal anti-inflammatory drugs and statins inhibit cancer cell growth and induce apoptosis are not fully understood. This study was designed to investigate lung cancer chemoprevention through a mechanism-based approach using sulindac at low doses in combination with simvastatin. We found that sulindac-induced cytotoxicity was significantly enhanced in the presence of simvastatin. The combination of sulindac and simvastatin induced more extensive caspase-dependent apoptosis in A549 cells compared to that induced with either drug alone. The combination of sulindac and simvastatin also increased the loss of mitochondrial transmembrane potential (∆Ψm) and the cytosolic release of cytochrome c. In addition, ROS generation in cells treated with both sulindac and simvastatin was markedly increased compared to cells treated with either sulindac or simvastatin alone. The enhancement of ROS generation by sulindac and simvastatin was abrogated by pretreatment with NAC, which also prevented apoptosis and mitochondrial dysfunction induced by sulindac and simvastatin. These results suggest that sulindac and simvastatin-induced ROS generation in A549 lung cancer cells causes their accumulation in mitochondria, triggering the release of apoptogenic molecules from the mitochondria to the cytosol, and thus leading to caspase activation and cell death.

The expression levels of Prx1 are frequently elevated in several human cancers, including lung cancer and may confer increased resistance to treatment. In this study, we investigated the role of Prx1 in docetaxel-induced apoptosis in A549 lung cancer cells. To test whether Prx1 knockdown affected the sensitivity of A549 cells to docetaxel treatment, we generated short hairpin RNA (shRNA) constructs targeting Prx1 and analyzed the effect of Prx1 knockdown on growth and apoptosis. Tumor growth was evaluated in scrambled shRNA- or shPrx1-infected A549 cell tumors receiving docetaxel treatment. In addition, mechanistic information was gathered by western blot analysis from cell lysates of scrambled- and shPrx1-infected A549 cells pretreated with or without LY294002 and subsequently treated with docetaxel. We found that Prx1 knockdown resulted in enhanced docetaxel-induced cytotoxicity in a dose-dependent manner. In vivo, the growth rate of shPrx1-infected A549 tumors was significantly reduced compared to that of scrambled shRNA-infected A549 tumors. Prx1 knockdown also augmented the inhibitory effects of docetaxel on tumor growth. Prx1 knockdown increased the apoptotic potential through activation of the caspase cascade and suppressed docetaxel-induced phosphorylation of Akt and its substrate forkhead box O1 (FOXO1). Moreover, treatment with the phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002 reduced the phosphorylation of FOXO1 and increased the cytotoxicity of docetaxel in A549 cells. Our findings suggest that Prx1 may modulate the chemosensitivity of lung cancer to docetaxel through suppression of FOXO1-induced apoptosis.