The matricellular protein CCN5 induces apoptosis in myofibroblasts through SMAD7-mediated inhibition of NFκB.

We previously showed that the matricellular protein CCN5 reverses established cardiac fibrosis (CF) through inducing apoptosis in myofibroblasts (MyoFBs) but not in cardiomyocytes or fibroblasts (FBs). In this study, we set out to elucidate the molecular mechanisms underlying CCN5-mediated selective apoptosis of MyoFBs. We first observed that the apoptotic protein p53 and the anti-apoptotic protein NFκB are simultaneously induced in MyoFBs. When the expression level of p53 was suppressed using a siRNA, CCN5 did not induce apoptosis in MyoFBs. By contrast, when NFκB signaling was inhibited using IKK VII, an IκB inhibitor, MyoFBs underwent apoptosis even in the absence of CCN5. SMAD7 is one of the downstream targets of CCN5 and it was previously shown to potentiate apoptosis in epithelial cells through inhibition of NFκB. In accordance with these reports, when the expression of SMAD7 was suppressed using a siRNA, NFκB signaling was enhanced, and CCN5 did not induce apoptosis. Lastly, we used a luciferase reporter construct to show that CCN5 positively regulated SMAD7 expression at the transcriptional level. Collectively, our data suggest that a delicate balance between the two mutually antagonistic proteins p53 and NFκB is maintained for MyoFBs to survive, and CCN5 tips the balance in favor of the apoptotic protein p53. This study provides insight into the anti-fibrotic activity of CCN5 during the regression of CF.

Production of human spinal-cord organoids recapitulating neural-tube morphogenesis.

Human spinal-cord-like tissues induced from human pluripotent stem cells are typically insufficiently mature and do not mimic the morphological features of neurulation. Here, we report a three-dimensional culture system and protocol for the production of human spinal-cord-like organoids (hSCOs) recapitulating the neurulation-like tube-forming morphogenesis of the early spinal cord. The hSCOs exhibited neurulation-like tube-forming morphogenesis, cellular differentiation into the major types of spinal-cord neurons as well as glial cells, and mature synaptic functional activities, among other features of the development of the spinal cord. We used the hSCOs to screen for antiepileptic drugs that can cause neural-tube defects. hSCOs may also facilitate the study of the development of the human spinal cord and the modelling of diseases associated with neural-tube defects.

Modulation of Cellular NAD+ Attenuates Cancer-Associated Hypercoagulability and Thrombosis via the Inhibition of Tissue Factor and Formation of Neutrophil Extracellular Traps.

Cancer-associated thrombosis is the second-leading cause of mortality in patients with cancer and presents a poor prognosis, with a lack of effective treatment strategies. NAD(P)H quinone oxidoreductase 1 (NQO1) increases the cellular nicotinamide adenine dinucleotide (NAD+) levels by accelerating the oxidation of NADH to NAD+, thus playing important roles in cellular homeostasis, energy metabolism, and inflammatory responses. Using a murine orthotopic 4T1 breast cancer model, in which multiple thrombi are generated in the lungs at the late stage of cancer development, we investigated the effects of regulating the cellular NAD+ levels on cancer-associated thrombosis. In this study, we show that dunnione (a strong substrate of NQO1) attenuates the prothrombotic state and lung thrombosis in tumor-bearing mice by inhibiting the expression of tissue factor and formation of neutrophil extracellular traps (NETs). Dunnione increases the cellular NAD+ levels in lung tissues of tumor-bearing mice to restore the declining sirtuin 1 (SIRT1) activity, thus deacetylating nuclear factor-kappa B (NF-κB) and preventing the overexpression of tissue factor in bronchial epithelial and vascular endothelial cells. In addition, we demonstrated that dunnione abolishes the ability of neutrophils to generate NETs by suppressing histone acetylation and NADPH oxidase (NOX) activity. Overall, our results reveal that the regulation of cellular NAD+ levels by pharmacological agents may inhibit pulmonary embolism in tumor-bearing mice, which may potentially be used as a viable therapeutic approach for the treatment of cancer-associated thrombosis.

The matricellular protein CCN5 prevents adverse atrial structural and electrical remodelling.

Atrial structural remodelling including atrial hypertrophy and fibrosis is a key mediator of atrial fibrillation (AF). We previously demonstrated that the matricellular protein CCN5 elicits anti-fibrotic and anti-hypertrophic effects in left ventricles under pressure overload. We here determined the utility of CCN5 in ameliorating adverse atrial remodelling and arrhythmias in a murine model of angiotensin II (AngII) infusion. Advanced atrial structural remodelling was induced by AngII infusion in control mice and mice overexpressing CCN5 either through transgenesis (CCN5 Tg) or AAV9-mediated gene transfer (AAV9-CCN5). The mRNA levels of pro-fibrotic and pro-inflammatory genes were markedly up-regulated by AngII infusion, which was significantly normalized by CCN5 overexpression. In vitro studies in isolated atrial fibroblasts demonstrated a marked reduction in AngII-induced fibroblast trans-differentiation in CCN5-treated atria. Moreover, while AngII increased the expression of phosphorylated CaMKII and ryanodine receptor 2 levels in HL-1 cells, these molecular features of AF were prevented by CCN5. Electrophysiological studies in ex vivo perfused hearts revealed a blunted susceptibility of the AAV9-CCN5-treated hearts to rapid atrial pacing-induced arrhythmias and concomitant reversal in AngII-induced atrial action potential prolongation. These data demonstrate the utility of a gene transfer approach targeting CCN5 for reversal of adverse atrial structural and electrophysiological remodelling.

Role of SIRT1 in Modulating Acetylation of the Sarco-Endoplasmic Reticulum Ca2+-ATPase in Heart Failure.

RATIONALE: SERCA2a, sarco-endoplasmic reticulum Ca2+-ATPase, is a critical determinant of cardiac function. Reduced level and activity of SERCA2a are major features of heart failure. Accordingly, intensive efforts have been made to develop efficient modalities for SERCA2a activation. We showed that the activity of SERCA2a is enhanced by post-translational modification with SUMO1 (small ubiquitin-like modifier 1). However, the roles of other post-translational modifications on SERCA2a are still unknown. OBJECTIVE: In this study, we aim to assess the role of lysine acetylation on SERCA2a function and determine whether inhibition of lysine acetylation can improve cardiac function in the setting of heart failure. METHODS AND RESULTS: The acetylation of SERCA2a was significantly increased in failing hearts of humans, mice, and pigs, which is associated with the reduced level of SIRT1 (sirtuin 1), a class III histone deacetylase. Downregulation of SIRT1 increased the SERCA2a acetylation, which in turn led to SERCA2a dysfunction and cardiac defects at baseline. In contrast, pharmacological activation of SIRT1 reduced the SERCA2a acetylation, which was accompanied by recovery of SERCA2a function and cardiac defects in failing hearts. Lysine 492 (K492) was of critical importance for the regulation of SERCA2a activity via acetylation. Acetylation at K492 significantly reduced the SERCA2a activity, presumably through interfering with the binding of ATP to SERCA2a. In failing hearts, acetylation at K492 appeared to be mediated by p300 (histone acetyltransferase p300), a histone acetyltransferase. CONCLUSIONS: These results indicate that acetylation/deacetylation at K492, which is regulated by SIRT1 and p300, is critical for the regulation of SERCA2a activity in hearts. Pharmacological activation of SIRT1 can restore SERCA2a activity through deacetylation at K492. These findings might provide a novel strategy for the treatment of heart failure.

CCN5 knockout mice exhibit lipotoxic cardiomyopathy with mild obesity and diabetes.

Obesity is associated with various human disorders, such as type 2 diabetes, cardiovascular diseases, hypertension, and cancers. In this study, we observed that knockout (KO) of CCN5, which encodes a matricellular protein, caused mild obesity in mice. The CCN5 KO mice also exhibited mild diabetes characterized by high fasting glucose levels and impaired insulin and glucose tolerances. Cardiac hypertrophy, ectopic lipid accumulation, and impaired lipid metabolism in hearts were observed in the CCN5 KO mice, as determined using histology, quantitative RT-PCR, and western blotting. Fibrosis was significantly greater in hearts from the CCN5 KO mice both in interstitial and perivascular regions, which was accompanied by higher expression of pro-fibrotic and pro-inflammatory genes. Both systolic and diastolic functions were significantly impaired in hearts from the CCN5 KO mice, as assessed using echocardiography. Taken together, these results indicate that CCN5 KO leads to lipotoxic cardiomyopathy with mild obesity and diabetes in mice.

Augmentation of NAD+ levels by enzymatic action of NAD(P)H quinone oxidoreductase 1 attenuates adriamycin-induced cardiac dysfunction in mice.

BACKGROUND: Adriamycin (ADR) is a powerful chemotherapeutic agent extensively used to treat various human neoplasms. However, its clinical utility is hampered due to severe adverse side effects i.e. cardiotoxicity and heart failure. ADR-induced cardiomyopathy (AIC) has been reported to be caused by myocardial damage and dysfunction through oxidative stress, DNA damage, and inflammatory responses. Nonetheless, the remedies for AIC are even not established. Therefore, we illustrate the role of NAD+/NADH modulation by NAD(P)H quinone oxidoreductase 1 (NQO1) enzymatic action on AIC. METHODS AND RESULTS: AIC was established by intraperitoneal injection of ADR in C57BL/6 wild-type (WT) and NQO1 knockout (NQO1-/-) mice. All Mice were orally administered dunnione (named NQO1 substrate) before and after exposure to ADR. Cardiac biomarker levels in the plasma, cardiac dysfunction, oxidative biomarkers, and mRNA and protein levels of pro-inflammatory mediators were determined compared the cardiac toxicity of each experimental group. All biomarkers of Cardiac damage and oxidative stress, and mRNA levels of pro-inflammatory cytokines including cardiac dysfunction were increased in ADR-treated both WT and NQO1-/- mice. However, this increase was significantly reduced by dunnione in WT, but not in NQO1-/- mice. In addition, a decrease in SIRT1 activity due to a reduction in the NAD+/NADH ratio by PARP-1 hyperactivation was associated with AIC through increased nuclear factor (NF)-κB p65 and p53 acetylation in both WT and NQO1-/- mice. While an elevation in NAD+/NADH ratio via NQO1 enzymatic action using dunnione recovered SIRT1 activity and subsequently deacetylated NF-κB p65 and p53, however not in NQO1-/- mice, thereby attenuating AIC. CONCLUSION: Thus, modulation of NAD+/NADH by NQO1 may be a novel therapeutic approach to prevent chemotherapy-associated heart failure, including AIC.

NAD+ augmentation ameliorates acute pancreatitis through regulation of inflammasome signalling.

Acute pancreatitis (AP) is a complicated disease without specific drug therapy. The cofactor nicotinamide adenine dinucleotide (NAD+) is an important regulator of cellular metabolism and homeostasis. However, it remains unclear whether modulation of NAD+ levels has an impact on caerulein-induced AP. Therefore, in this study, we investigated the effect of increased cellular NAD+ levels on caerulein-induced AP. We demonstrated for the first time that the activities and expression of SIRT1 were suppressed by reduction of intracellular NAD+ levels and the p53-microRNA-34a pathway in caerulein-induced AP. Moreover, we confirmed that the increase of cellular NAD+ by NQO1 enzymatic action using the substrate ß-Lapachone suppressed caerulein-induced AP with down-regulating TLR4-mediated inflammasome signalling, and thereby reducing the inflammatory responses and pancreatic cell death. These results suggest that pharmacological stimulation of NQO1 could be a promising therapeutic strategy to protect against pathological tissue damage in AP.

Novel Therapeutic Transplantation of Induced Neural Stem Cells for Stroke.

Somatic cells can be directly converted into induced neural stem cells (iNSCs) by defined transcription factors. However, the therapeutic effect of undifferentiated iNSCs on ischemic stroke has not been demonstrated. In this study, we used a mouse model of transient middle cerebral artery occlusion (tMCAO). iNSCs (5 × 105) were injected directly into the ipsilateral striatum and cortex 24 h after tMCAO. Histological analysis was performed at 7 days, 28 days, and 8 months after tMCAO. We found that iNSC transplantation successfully improved the survival rate of stroke model mice with significant functional recovery from the stroke. The fate of engrafted iNSCs was that the majority of iNSCs had differentiated into astroglial cells but not into neural cells in both the sham-operated brain and the poststroke brain without forming a tumor up to 8 months after tMCAO. Our data suggest that the directly converted iNSCs can be regarded as a candidate of safe cell resource for transplantation therapy in patients suffering from ischemic stroke.

Generation of Integration-free Induced Neural Stem Cells from Mouse Fibroblasts.

The viral vector-mediated overexpression of the defined transcription factors, Brn4/Pou3f4, Sox2, Klf4, and c-Myc (BSKM), could induce the direct conversion of somatic fibroblasts into induced neural stem cells (iNSCs). However, viral vectors may be randomly integrated into the host genome thereby increasing the risk for undesired genotoxicity, mutagenesis, and tumor formation. Here we describe the generation of integration-free iNSCs from mouse fibroblasts by non-viral episomal vectors containing BSKM. The episomal vector-derived iNSCs (e-iNSCs) closely resemble control NSCs, and iNSCs generated by retrovirus (r-iNSCs) in morphology, gene expression profile, epigenetic status, and self-renewal capacity. The e-iNSCs are functionally mature, as they could differentiate into all the neuronal cell types both in vitro and in vivo Our study provides a novel concept for generating functional iNSCs using a non-viral, non-integrating, plasmid-based system that could facilitate their biomedical applicability.

Matricellular Protein CCN5 Reverses Established Cardiac Fibrosis.

BACKGROUND: Cardiac fibrosis (CF) is associated with increased ventricular stiffness and diastolic dysfunction and is an independent predictor of long-term clinical outcomes of patients with heart failure (HF). We previously showed that the matricellular CCN5 protein is cardioprotective via its ability to inhibit CF and preserve cardiac contractility. OBJECTIVES: This study examined the role of CCN5 in human heart failure and tested whether CCN5 can reverse established CF in an experimental model of HF induced by pressure overload. METHODS: Human hearts were obtained from patients with end-stage heart failure. Extensive CF was induced by applying transverse aortic constriction for 8 weeks, which was followed by adeno-associated virus-mediated transfer of CCN5 to the heart. Eight weeks following gene transfer, cellular and molecular effects were examined. RESULTS: Expression of CCN5 was significantly decreased in failing hearts from patients with end-stage heart failure compared to nonfailing hearts. Trichrome staining and myofibroblast content measurements revealed that the established CF had been reversed by CCN5 gene transfer. Anti-CF effects of CCN5 were associated with inhibition of the transforming growth factor beta signaling pathway. CCN5 significantly inhibited endothelial-mesenchymal transition and fibroblast-to-myofibroblast transdifferentiation, which are 2 critical processes for CF progression, both in vivo and in vitro. In addition, CCN5 induced apoptosis in myofibroblasts, but not in cardiomyocytes or fibroblasts, both in vivo and in vitro. CCN5 provoked the intrinsic apoptotic pathway specifically in myofibroblasts, which may have been due the ability of CCN5 to inhibit the activity of NFκB, an antiapoptotic molecule. CONCLUSIONS: CCN5 can reverse established CF by inhibiting the generation of and enhancing apoptosis of myofibroblasts in the myocardium. CCN5 may provide a novel platform for the development of targeted anti-CF therapies.

New Therapeutic Concept of NAD Redox Balance for Cisplatin Nephrotoxicity.

Cisplatin is a widely used chemotherapeutic agent for the treatment of various tumors. In addition to its antitumor activity, cisplatin affects normal cells and may induce adverse effects such as ototoxicity, nephrotoxicity, and peripheral neuropathy. Various mechanisms such as DNA adduct formation, mitochondrial dysfunction, oxidative stress, and inflammatory responses are closely associated with cisplatin-induced nephrotoxicity; however, the precise mechanism remains unclear. The cofactor nicotinamide adenine dinucleotide (NAD(+)) has emerged as a key regulator of cellular energy metabolism and homeostasis. Recent studies have demonstrated associations between disturbance in intracellular NAD(+) levels and clinical progression of various diseases through the production of reactive oxygen species and inflammation. Furthermore, we demonstrated that reduction of the intracellular NAD(+)/NADH ratio is critically involved in cisplatin-induced kidney damage through inflammation and oxidative stress and that increase of the cellular NAD(+)/NADH ratio suppresses cisplatin-induced kidney damage by modulation of potential damage mediators such as oxidative stress and inflammatory responses. In this review, we describe the role of NAD(+) metabolism in cisplatin-induced nephrotoxicity and discuss a potential strategy for the prevention or treatment of cisplatin-induced adverse effects with a particular focus on NAD(+)-dependent cellular pathways.

Dunnione ameliorates cisplatin ototoxicity through modulation of NAD(+) metabolism.

Ototoxicity is an important issue in patients receiving cisplatin chemotherapy. Numerous studies have demonstrated that cisplatin-induced ototoxicity is related to oxidative stress and DNA damage. However, the precise mechanism underlying cisplatin-associated ototoxicity is still unclear. The cofactor nicotinamide adenine dinucleotide (NAD(+)) has emerged as an important regulator of energy metabolism and cellular homeostasis. Here, we demonstrate that the levels and activities of sirtuin-1 (SIRT1) are suppressed by the reduction of intracellular NAD(+) levels in cisplatin-mediated ototoxicity. We provide evidence that the decreases in SIRT1 activity and expression facilitated by increasing poly(ADP-ribose) polymerase-1 (PARP-1) activation and microRNA-34a levels through cisplatin-mediated p53 activation aggravate the associated ototoxicity. Furthermore, we show that the induction of cellular NAD(+) levels using dunnione, which targets intracellular NQO1, prevents the toxic effects of cisplatin through the regulation of PARP-1 and SIRT1 activity. These results suggest that direct modulation of cellular NAD(+) levels by pharmacological agents could be a promising therapeutic approach for protection from cisplatin-induced ototoxicity.

Dunnione ameliorates cisplatin-induced small intestinal damage by modulating NAD(+) metabolism.

Although cisplatin is a widely used anticancer drug for the treatment of a variety of tumors, its use is critically limited because of adverse effects such as ototoxicity, nephrotoxicity, neuropathy, and gastrointestinal damage. Cisplatin treatment increases oxidative stress biomarkers in the small intestine, which may induce apoptosis of epithelial cells and thereby elicit damage to the small intestine. Nicotinamide adenine dinucleotide (NAD(+)) is a cofactor for various enzymes associated with cellular homeostasis. In the present study, we demonstrated that the hyper-activation of poly(ADP-ribose) polymerase-1 (PARP-1) is closely associated with the depletion of NAD(+) in the small intestine after cisplatin treatment, which results in downregulation of sirtuin1 (SIRT1) activity. Furthermore, a decrease in SIRT1 activity was found to play an important role in cisplatin-mediated small intestinal damage through nuclear factor (NF)-κB p65 activation, facilitated by its acetylation increase. However, use of dunnione as a strong substrate for the NADH:quinone oxidoreductase 1 (NQO1) enzyme led to an increase in intracellular NAD(+) levels and prevented the cisplatin-induced small intestinal damage correlating with the modulation of PARP-1, SIRT1, and NF-κB. These results suggest that direct modulation of cellular NAD(+) levels by pharmacological NQO1 substrates could be a promising therapeutic approach for protecting against cisplatin-induced small intestinal damage.

A Dunnione Compound MB12662 Improves Cisplatin-Induced Tissue Injury and Emesis.

The present study was aimed to investigate the effects of MB12662, a synthetic dunnione compound, on cisplatin-induced vomiting reflexes and intestinal, renal, immune system, and hematopoietic toxicities in ferrets and mice, respectively. Male ICR mice were orally administered MB12662 (5, 10, 25 or 50 mg/kg) for 10 days, during which intraperitoneally challenged with cisplatin (3.5 mg/kg) from day 4 to 7, and sacrificed on day 10 for the pathological examination. Male ferrets were orally administered MB12662 (25, 50 or 100 mg/kg) for 7 days, subcutaneously challenged with cisplatin (5 mg/kg), and monitored for vomiting reflexes and survival of the animals. Four-day injection of cisplatin (3.5 mg/kg) to mice caused body weight loss and degeneration and atrophy of intestinal villi, reducing villi/crypt ratio to a half level of control animals. Cisplatin also induced renal and hepatic toxicities, and depletion of splenocytes and bone marrow progenitor cells. The systemic toxicities including decreased villi/crypt ratio, immune system atrophy, splenocyte depletion, and decreased cellularity in bone marrow were improved by MB12662. Cisplatin (5 mg/kg) induced retching and emetic responses of ferrets, which were remarkably attenuated by MB12662 in a dose-dependent manner. All the ferrets pretreated with MB12662 survived the challenge of cisplatin, in comparison with 40% mortality in vehicle-treated animals, and blood parameters of nephrotoxicity and hepatotoxicity were markedly recovered. It is expected that MB12662 could be a candidate for the body protection against burden, including emesis, of chemotherapeutic agents.

Nicotinamide adenine dinucleotide: An essential factor in preserving hearing in cisplatin-induced ototoxicity.

Ototoxicity is an important issue in patients receiving cisplatin chemotherapy. Numerous studies have demonstrated that several mechanisms, including oxidative stress, DNA damage, and inflammatory responses, are closely associated with cisplatin-induced ototoxicity. Although much attention has been directed at identifying ways to protect the inner ear from cisplatin-induced damage, the precise underlying mechanisms have not yet been elucidated. The cofactor nicotinamide adenine dinucleotide (NAD(+)) has emerged as an important regulator of cellular energy metabolism and homeostasis. NAD(+) acts as a cofactor for various enzymes including sirtuins (SIRTs) and poly(ADP-ribose) polymerases (PARPs), and therefore, maintaining adequate NAD(+) levels has therapeutic benefits because of its effect on NAD(+)-dependent enzymes. Recent studies demonstrated that disturbance in intracellular NAD(+) levels is critically involved in cisplatin-induced cochlear damage associated with oxidative stress, DNA damage, and inflammatory responses. In this review, we describe the importance of NAD(+) in cisplatin-induced ototoxicity and discuss potential strategies for the prevention or treatment of cisplatin-induced ototoxicity with a particular focus on NAD(+)-dependent cellular pathways.

Enhanced activation of NAD(P)H: quinone oxidoreductase 1 attenuates spontaneous hypertension by improvement of endothelial nitric oxide synthase coupling via tumor suppressor kinase liver kinase B1/adenosine 5'-monophosphate-activated protein kinase-mediated guanosine 5'-triphosphate cyclohydrolase 1 preservation.

AIMS: Guanosine 5'-triphosphate cyclohydrolase-1 (GTPCH-1) is a rate-limiting enzyme in de-novo synthesis of tetrahydrobiopterin (BH4), an essential cofactor for endothelial nitric oxide synthase (eNOS) coupling. Adenosine 5'-monophosphate-activated protein kinase (AMPK) is crucial for GTPCH-1 preservation, and tumor suppressor kinase liver kinase B1 (LKB1), an upstream kinase of AMPK, is activated by NAD-dependent class III histone deacetylase sirtuin 1 (SIRT1)-mediated deacetylation. ß-Lapachone has been shown to increase cellular NAD/NADH ratio via NAD(P)H: quinone oxidoreductase 1 (NQO1) activation. In this study, we have evaluated whether ß-lapachone-induced NQO1 activation modulates blood pressure (BP) through preservation of GTPCH-1 in a hypertensive animal model. METHODS AND RESULTS: Spontaneously hypertensive rats (SHRs), primary aortic endothelial cells, and endothelial cell line were used to investigate the hypotensive effect of ß-lapachone and its action mechanism. ß-Lapachone treatment dramatically lowered BP and vascular tension in SHRs and induced eNOS activation in endothelial cells. Consistent with these effects, ß-lapachone treatment also elevated levels of both aortic cGMP and plasma nitric oxide in SHRs. Meanwhile, ß-lapachone-treated SHRs showed significantly increased levels of aortic NAD, LKB1 deacetylation, and AMPK Thr phosphorylation followed by increased GTPCH-1 and tetrahydrobiopterin/dihydrobiopterin ratio. In-vitro study revealed that AMPK inhibition by overexpression of dominant-negative AMPK nearly abolished GTPCH-1 protein conservation. Enhanced LKB1 deacetylation and AMPK activation were also elicited by ß-lapachone in endothelial cells. However, inhibition of LKB1 deacetylation by blocking of NQO1 or SIRT1 blunted AMPK activation by ß-lapachone. CONCLUSION: This is the first study demonstrating that eNOS coupling can be regulated by NQO1 activation via LKB1/AMPK/GTPCH-1 modulation, which is possibly correlated with relieving hypertension. These findings provide strong evidence to suggest that NQO1 might be a new therapeutic target for hypertension.

ß-Lapachone alleviates alcoholic fatty liver disease in rats.

UNLABELLED: Alcohol-induced liver injury is the most common liver disease in which fatty acid metabolism is altered. It is thought that altered NAD(+)/NADH redox potential by alcohol in the liver causes fatty liver by inhibiting fatty acid oxidation and the activity of tricarboxylic acid cycle reactions. ß-Lapachone (ßL), a naturally occurring quinone, has been shown to stimulate fatty acid oxidation in an obese mouse model by activating adenosine monophosphate-activated protein kinase (AMPK). In this report, we clearly show that ßL reduced alcohol-induced hepatic steatosis and induced fatty acid oxidizing capacity in ethanol-fed rats. ßL treatment markedly decreased hepatic lipids while serum levels of lipids and lipoproteins were increased in rats fed ethanol-containing liquid diets with ßL administration. Furthermore, inhibition of lipolysis, enhancement of lipid mobilization to mitochondria and upregulation of mitochondrial ß-oxidation activity in the soleus muscle were observed in ethanol/ßL-treated animals compared to the ethanol-fed rats. In addition, the activity of alcohol dehydrogenase, but not aldehyde dehydrogenase, was significantly increased in rats fed ßL diets. ßL-mediated modulation of NAD(+)/NADH ratio led to the activation of AMPK signaling in these animals. CONCLUSION: Our results suggest that improvement of fatty liver by ßL administration is mediated by the upregulation of apoB100 synthesis and lipid mobilization from the liver as well as the direct involvement of ßL on NAD(+)/NADH ratio changes, resulting in the activation of AMPK signaling and PPARα-mediated ß-oxidation. Therefore, ßL-mediated alteration of NAD(+)/NADH redox potential may be of potential therapeutic benefit in the clinical setting.

Pharmacological activation of NQO1 increases NAD⁺ levels and attenuates cisplatin-mediated acute kidney injury in mice.

Cisplatin is a widely used chemotherapeutic agent for the treatment of various tumors. In addition to its antitumor activity, cisplatin affects normal cells and may induce adverse effects, such as ototoxicity, nephrotoxicity, and neuropathy. Various mechanisms, such as DNA adduct formation, mitochondrial dysfunction, oxidative stress, and inflammatory responses, are critically involved in cisplatin-induced adverse effects. As NAD(+) is a cofactor for various enzymes associated with cellular homeostasis, we studied the effects of increased NAD(+) levels by means of NAD(P)H: quinone oxidoreductase 1 (NQO1) activation using a known pharmacological activator (ß-lapachone) in wild-type and NQO1(-/-) mice on cisplatin-induced renal dysfunction in vivo. The intracellular NAD(+)/NADH ratio in renal tissues was significantly increased in wild-type mice co-treated with cisplatin and ß-lapachone compared with the ratio in mice treated with cisplatin alone. Inflammatory cytokines and biochemical markers for renal damage were significantly attenuated by ß-lapachone co-treatment compared with those in the cisplatin alone group. Notably, the protective effects of ß-lapachone in wild-type mice were completely abrogated in NQO1(-/-) mice. Moreover, ß-lapachone enhanced the tumoricidal action of cisplatin in a xenograft tumor model. Thus, intracellular regulation of NAD(+) levels through NQO1 activation might be a promising therapeutic target for the protection of cisplatin-induced acute kidney injury.

Effects of ß-lapachone, a new anticancer candidate, on cytochrome P450-mediated drug metabolism.

PURPOSE: This study aimed to assess the potential inhibitory effects of ß-lapachone, a new anticancer candidate, on the activities of the cytochrome P450 (CYP450) enzymes in vitro. METHODS: Different concentrations of ß-lapachone were incubated with human liver microsomes in the presence of CYP isozyme-specific substrates and NADPH, and the formation of the marker metabolites was measured using liquid chromatography-tandem mass spectrometry. In addition, time-dependent inhibition was examined to characterize the mode of the inhibition. RESULTS: ß-Lapachone showed concentration-dependent inhibitory effects on all CYP isozymes tested (CYP1A2, CYP2A6, CYP2C8, CYP2C9, CYPC19, CYP2D6, and CYP3A4), and its half-maximal inhibitory concentration (IC50) values ranged from 2.6 to 9.7 µM. However, ß-lapachone did not appear to modulate CYP450 activities as a mechanism-based inactivator. CONCLUSIONS: These results suggest that pharmacological drug-drug interactions might occur between ß-lapachone and drugs co-administered with it, which are extensively metabolized by CYP450 enzymes, and thus, careful observation is required in clinical pharmacokinetic studies.