Simvastatin combined with nifedipine enhances endothelial cell protection by inhibiting ROS generation and activating Akt phosphorylation

Glutathione Peroxidase 1 Promotes NSCLC Resistance to Cisplatin via ROS-Induced Activation of PI3K/AKT Pathway

Purpose

Reactive oxygen species (ROS)-induced cytotoxicity is an important mechanism by which cisplatin kills tumor cells. Glutathione peroxidase family (GPXs) is an important member of antioxidant system which metabolizes intracellular ROS and maintains homeostasis of cells. Altered expressions of GPXs enzymes, especially GPX1, have been described in a variety of human cancers. However, their functional roles in cisplatin-based chemoresistance in human malignancies including non-small cell lung cancer have never been explored.

Methods

A panel of NSCLC cell lines were selected for this study. GPX1 expression was detected using quantitative RT-PCR and Western blot. Cisplatin-induced cell killing was analyzed by CCK8 assay. Intracellular ROS levels were detected by fluorescence-based flow cytometry analysis. In vitro overexpression and knockdown of GPX1 expression were performed using GPX1 expression vector and siRNA approaches. Protein levels of PTEN, NF-κB, BCL2, Bax, and phosphorylated AKT were detected with western blot analysis using specific antibodies.

Results

GPX1 expression was upregulated in a subset of NSCLC cell lines resistant to cisplatin treatment. Expression vector-mediated forced overexpression of GPX1 significantly increased cisplatin resistance in NSCLC cell lines, whereas RNA inference-mediated downregulation of GPX1 could restore sensitivity to cisplatin. Overexpression of GPX1 significantly suppressed elevation of intracellular ROS and activation of AKT pathway when NSCLC cell lines were exposed to different concentrations of cisplatin. Activation of the AKT pathway inhibited proapoptotic cascade and subsequently led to cisplatin resistance in NSCLC cells. Inhibition of NF-κB by its chemical inhibitor BAY can significantly downregulate GPX1 expression and restore the cisplatin sensitivity of the cell lines resistant to cisplatin.

Conclusions

Our findings suggested that overexpression of GPX1 is a novel molecular mechanism for cisplatin-based chemoresistance in NSCLC. GPX1 overexpression blocks cisplatin-induced ROS intracellular accumulation, activates PI3K-AKT pathway by increased AKT phosphorylation, and further leads to cisplatin resistance in NSCLC cells. Inhibition of NF-κB signaling may be an alternative approach for restoring cisplatin sensitivity for NSCLC cells resistant to cisplatin-based chemotherapy.

Co-Amorphous Simvastatin-Nifedipine with Enhanced Solubility for Possible Use in Combination Therapy of Hypertension and Hypercholesterolemia

The high index of simultaneous incidence of hypertension and hypercholesterolemia in the population of many countries demands the preparation of more efficient drugs. Therefore, there is a significant area of opportunity to provide as many alternatives as possible to treat these illnesses. Taking advantage of the solubility enhancement that can be achieved when an active pharmaceutical ingredient (API) is obtained and stabilized in its amorphous state, in the present work, new drug-drug co-amorphous formulations (Simvastatin SIM- Nifedipine NIF) with enhanced solubility and stability were prepared and characterized. Results show that the co-amorphous system (molar ratio 1:1) is more soluble than the pure commercial APIs studied separately. Aqueous dissolution profiles showed increments of solubility of 3.7 and 1.7 times for SIM and NIF, correspondingly, in the co-amorphous system. The new co-amorphous formulations, monitored in time, (molar fractions 0.3, 0.5 and 0.7 of SIM) remained stable in the amorphous state for more than one year when stored at room temperature and did not show any signs of crystallization when re-heating. Inspection on the remainder of a sample after six hours of dissolution showed no recrystallization, confirming the stability of co-amorphous system. The enhanced solubility of the co-amorphous formulations makes them promising for simultaneously targeting of hypertension and hypercholesterolemia through combination therapy.

Nifedipine Prevents Apoptosis of Alcohol-Exposed First-Trimester Trophoblast Cells

BACKGROUND

Maternal alcohol abuse leading to fetal alcohol spectrum disorder (FASD) includes fetal growth restriction (FGR). Ethanol (EtOH) induces apoptosis of human placental trophoblast cells, possibly disrupting placentation and contributing to FGR in FASD. EtOH facilitates apoptosis in several embryonic tissues, including human trophoblasts, by raising intracellular Ca²⁺ . We previously found that acute EtOH exposure increases trophoblast apoptosis due to signaling from both intracellular and extracellular Ca²⁺ . Therefore, nifedipine, a Ca²⁺ channel blocker that is commonly administered to treat preeclampsia and preterm labor, was evaluated for cytoprotective properties in trophoblast cells exposed to alcohol.

METHODS

Human first-trimester chorionic villous explants and the human trophoblast cell line HTR-8/SVneo (HTR) were pretreated with 12.5 to 50 nM of the Ca²⁺ channel blocker nifedipine for 1 hour before exposure to 50 mM EtOH for an additional hour. Intracellular Ca²⁺ concentrations were monitored in real time by epifluorescence microscopy, using fluo-4-AM. Apoptosis was assessed by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL), accumulation of cytoplasmic cytochrome c, and cleavage rates of caspase 3 and caspase 9.

RESULTS

The increase in intracellular Ca²⁺ upon exposure to EtOH in both villous explants and HTR cells was completely blocked (p < 0.05) when pretreated with nifedipine, accompanied by inhibition of EtOH-induced release of cytochrome c, caspase activities, and TUNEL.

CONCLUSIONS

This study indicates that nifedipine can interrupt the apoptotic pathway downstream of EtOH exposure and could provide a novel strategy for future interventions in women with fetuses at risk for FASD.

Antioxidant therapy for management of oxidative stress induced hypertension

Hypertension is considered as the most common risk factor for cardiovascular diseases, also is regarded as a leading cause of the mortality and morbidity worldwide. The mechanisms underlying the pathological process of hypertension are not completely explained. However, there is growing evidence that increased oxidative stress plays an important role in the pathophysiology of hypertension. Several preclinical studies and clinical trials have indicated that antioxidant therapy is important for management of hypertension, using antioxidants compounds such as alpha tocopherol (Vit E) and ascorbic acid (Vit C), polyphenols with others and some antihypertensive drugs that are now in clinical use (e.g. ACEIs, ARBs, novel B-blockers, dihydropyridine CCBs) which have antioxidative pleiotropic effects. The purpose of this review is to highlight the importance of antioxidant therapy for management of oxidative stress induced hypertension. Furthermore, we review the current knowledge in the oxidative stress and its significance in hypertension.

Nifedipine attenuation of abdominal aortic aneurysm in hypertensive and non-hypertensive mice: Mechanisms and implications

Rupture of abdominal aortic aneurysm (AAA) is a lethal event. No oral medicine has been available to prevent or treat AAA. We have recently identified a novel mechanism of eNOS uncoupling by which AAA develops, in angiotensin II (Ang II) infused hyperphenylalaninemia 1 (hph-1) mice. Using this unique model we investigated effects on AAA formation of the L-type calcium channel blocker nifedipine, in view of the unclear relationship between hypertension and AAA, and unclear mechanisms of aneurysm protective effects of some blood pressure lowering drugs. Six-month old hph-1 mice were infused with Ang II (0.7 mg/kg/day) for 2 weeks, and fed nifedipine chow at two different doses (5 and 20 mg/kg/day). While the high dose of nifedipine reduced blood pressure, the lower dose had no effect. Interestingly, the incidence rate of AAA dropped from 71% to 7 and 12.5% for low and high dose nifedipine, respectively. Expansion of abdominal aorta, determined by ultrasound imaging, was abolished by both doses of nifedipine, which recoupled eNOS completely to improve NO bioavailability. Both also abrogated aortic superoxide production. Of note, Ang II activation of NADPH oxidase in vascular smooth muscle cells and endothelial cells, known to uncouple eNOS, was also attenuated by nifedipine. Although low dose was a sub-pressor while the high dose reduced blood pressure via inhibition of calcium channels, both doses were highly effective in preventing AAA by preserving eNOS coupling activity to eliminate sustained oxidative stress from uncoupled eNOS. These data demonstrate that oral treatment of nifedipine is highly effective in preserving eNOS function to attenuate AAA formation. Nifedipine may be used for AAA prevention either at low dose in AAA risk group, or at high dose in patients with co-existing hypertension.

Fluvastatin attenuated the effect of expression of β1 integrin in PAN-treated podocytes by inhibiting reactive oxygen species

It is well accepted that β1 integrin plays a key role in maintaining normal podocytes form and functions; however, its mechanism of the potential protective effect remains unclear. Furthermore, the investigation and understanding of the non-lipid-dependent renal protection of Statins in addition to well-known lipid-lowering effect may provide the therapeutic utility and ultimately improve clinical outcome for patients with renal diseases. In the present study, we investigated the effect and mechanism of fluvastatin (FLV) on the expression of β1 integrin in puromycin aminonucleoside (PAN)-treated podocytes in vitro. Cultured human podocytes were treated with PAN, and/or different concentrations of FLV (1 × 10(-8)-1 × 10(-5 )mol/l), superoxide dismutase (SOD), or H2O2, respectively. The expression of β1 integrin and reactive oxygen species (ROS) in human podocytes under each experimental condition was evaluated by western blot, RT-PCR, and 2'7'-dichlorofluorescein 3'6'-diacetate, respectively. The viability of podocytes was also assessed by MTT colorimetry in the present study. The expression of β1 integrin was significantly decreased, and the synthesis of ROS was significantly increased in podocytes following either PAN or H2O2 treatment (p < 0.05). The up-regulation of β1 integrin and down-regulation of ROS were also observed in PAN-treated podocytes following lower concentrations of FLV or SOD treatment (p < 0.05, respectively). The cytotoxicity data derived from MTT assay revealed that lower podocyte viability was found in the presence of higher concentrations of FLV, PAN, or H2O2. Lower concentration of FLV or SOD can protect podocytes from being impaired by PAN treatment. FLV attenuated the podocyte injury induced by PAN and increased the production of β1 integrin in human podocytes in vitro. This underlying mechanism of FLV may be through inhibiting the activity of ROS in human podocytes.

Calcium channel blockers prevent endothelial cell activation in response to necrotic trophoblast debris: possible relevance to pre-eclampsia

AIMS

Pre-eclampsia is characterized by endothelial activation, which is triggered by placental factor(s). One such factor may be trophoblastic debris that is shed into the maternal blood to become trapped against the maternal pulmonary endothelium. Phagocytosis of necrotic trophoblastic debris (NTD) induces endothelial cell activation with increased secretion of interleukin-6 (IL-6) and transforming growth factor β1 (TGFβ1), which may induce systemic endothelial cell activation. In addition to its effects on vascular smooth muscle, evidence suggests that nifedipine may also affect the endothelium, contributing to the therapeutic benefits of the drug. We investigated whether nifedipine could reverse the endothelial cell activation induced by NTD.

METHODS AND RESULTS

Trophoblastic debris was collected from placental explants and exposed to endothelial cells with or without nifedipine, verapamil, or a nitric oxide (NO) donor for 24 h. Endothelial cell activation was measured by cell-surface intracellular adhesion molecule-1 and E-selectin, as well as monocyte adhesion. The activation of endothelial cells exposed to NTD or sera from pre-eclamptic women was significantly reduced by nifedipine or verapamil. In addition, the increases in the levels of IL-6 or TGFβ1 in conditioned media from endothelial cells following phagocytosis of NTD were significantly reduced by nifedipine. These actions of nifedipine were reversed by the NO synthetase inhibitor l-NAME and mimicked by a NO donor.

CONCLUSION

Our results suggest that calcium channel blockers may have a direct effect upon endothelial cells, reducing the endothelial cell activation that is a key pathogenic feature of pre-eclampsia. This action may be mediated, in part, by NO.

Statins Enhance Expression of Growth Factors and Activate the PI3K/Akt-mediated Signaling Pathway after Experimental Intracerebral Hemorrhage

Previous studies have demonstrates that statins improve neurological outcome and promote neurovascular recovery after ICH. This study is designed to examine whether simvastatin and atorvastatin affect levels of growth factors and activate the Akt signaling pathway during the recovery phase after intracerebral hemorrhage (ICH) in rats. Sixty (60) male Wistar rats were subjected to ICH by stereotactic injection of 100 μL of autologous blood into the striatum and were treated with or without simvastatin or atorvastatin. Neurological functional outcome was evaluated by behavioral tests (mNSS and corner turn test) at different time points after ICH. Brain extracts were utilized for Enzyme-linked immunosorbent assay (ELISA) analyses to measure vascular endothelial growth factor (VEGF); brain-derived neurotrophin factor (BDNF) expression, and nerve growth factor (NGF). Western blot was used to measure the changes in the Akt-mediated signaling pathway. Both the simvastatin- and atorvastatin-treated animals had significant neurological improvement at 2 weeks post-ICH. Simvastatin and atorvastatin treatment increased the expression of BDNF, VEGF and NGF in both low- and high-dose groups at 7 days after ICH (p < 0.05). Phosphorylation of Akt, glycogen synthase kinase-3β (GSK-3β), and cAMP response element-binding proteins (CREB) were also increased at 7 days after statin treatment. These results suggest that the therapeutic effects of statins after experimental ICH may be mediated by the transient induction of BDNF, VEGF and NGF expression and the activation of the Akt-mediated signaling pathway.

Current therapeutic strategies to mitigate the eNOS dysfunction in ischaemic stroke

Impairment of endothelial nitric oxide synthase (eNOS) activity is implicated in the pathogenesis of endothelial dysfunction in many diseases including ischaemic stroke. The modulation of eNOS during and/or following ischaemic injury often represents a futile compensatory mechanism due to a significant decrease in nitric oxide (NO) bioavailability coupled with dramatic increases in the levels of reactive oxygen species that further neutralise NO. However, applications of a number of therapeutic agents alone or in combination have been shown to augment eNOS activity under a variety of pathological conditions by potentiating the expression and/or activity of Akt/eNOS/NO pathway components. The list of these therapeutic agents include NO donors, statins, angiotensin-converting enzyme inhibitors, calcium channel blockers, phosphodiesterase-3 inhibitors, aspirin, dipyridamole and ellagic acid. While most of these compounds exhibit anti-platelet properties and are able to up-regulate eNOS expression in endothelial cells and platelets, others suppress eNOS uncoupling and tetrahydrobiopterin (an eNOS stabiliser) oxidation. As the number of therapeutic molecules that modulate the expression and activity of eNOS increases, further detailed research is required to reveal their mode of action in preventing and/or reversing the endothelial dysfunction.

Synergism between melatonin and atorvastatin against endothelial cell damage induced by lipopolysaccharide

The beneficial effects of atorvastatin are based on both cholesterol-dependent and independent mechanisms. The latter probably include the ability of the estatin to enhance the expression of endothelial nitric oxide synthase (eNOS) and to cause a vasodilatation. In turn, the antioxidant and anti-inflammatory actions of melatonin are related to its vascular protection. In the present study, we investigated the efficacy of the combination of melatonin plus atorvastatin against endothelial cell damage induced by inflammation and oxidative stress injury. Human umbilical vein endothelial cells (HUVEC) were cultured with bacterial lipopolysaccharide (LPS) in the presence or absence of melatonin and/or atorvastatin. LPS inhibited eNOS mRNA and protein expression, which was reversed by atorvastatin and, to a lesser extent, by melatonin. Together, melatonin + atorvastatin induced higher eNOS protein expression than either compound alone. Melatonin, but not atorvastatin, reduced free radical generation, lipid peroxidation, and interleukin-6 levels induced by LPS. In the presence of atorvastatin, the effects of melatonin were maintained or even improved. These data suggest that melatonin improves the beneficial effects of atorvastatin and reduces its side effects in endothelial cells during inflammation and under conditions of oxidative stress.

Recent development in pleiotropic effects of statins on cardiovascular disease through regulation of transforming growth factor-beta superfamily

BACKGROUND

3-Hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors, also known as statins, are a drug class that reduce the level of cholesterol in the blood. As a result, statins are used to suppress the progression of cardiovascular disease. Evidence points to another component of statins involving the non-lipid effects of the drug class in preventing cardiovascular disease. One specific mediator of this action is the transforming growth factor β (TGF-β) superfamily. The TGF-β superfamily consists of proteins that include TGF-β and bone morphogenetic proteins (BMPs). These proteins regulate cellular pathways to mediate effects including immunomodulation, cell cycling, and angiogenesis. One pathway that mediates these effects is Ras. Moreover, within this pathway, different functions are possible depending on the activation of the specific receptor subtype. This review discusses the recent development of the non-lipid effects of statins in preventing cardiovascular disease progression by regulating Ras pathway of the TGF-β superfamily, especially RhoA/ROCK pathway.

METHODS

A systematic PubMed database search of all English-language articles up to 2011 was conducted using the following terms: statin, TGF-β, Ras, ROCK, GGPP, inducible nitric oxide synthase, endothelial nitric oxide synthase, actin filament formation, PPARγ, MMP-2, and human trials.

CONCLUSION

With better understanding of the pathway, various mediators were identified; some of these mediators are important biomarkers producing more specific and accurate assessment of the pleiotropic effects of statins. The review of human trials also highlights that more specific biomarkers are employed in recent studies, and the non-lipid effects on human subjects are more accurately documented. Confirmation of the accuracy of these biomarkers by further large-scale studies and further development of new biomarkers may prove an important path leading to better patient selection for treatment, and thus better cost-effectiveness may be achieved.