Pulmonary Metabolism Research Articles

Pulmonary Metabolism of Substrates for Key Drug-Metabolizing Enzymes by Human Alveolar Type II Cells, Human and Rat Lung Microsomes, and the Isolated Perfused Rat Lung Model.

Significant pulmonary metabolism of inhaled drugs could have drug safety implications or influence pharmacological effectiveness. To study this in vitro, lung microsomes or S9 are often employed. Here, we have determined if rat and human lung microsomes are fit for purpose or whether it is better to use specific cells where drug-metabolizing enzymes are concentrated, such as alveolar type II (ATII) cells. Activities for major hepatic and pulmonary human drug-metabolizing enzymes are assessed and the data contextualized towards an in vivo setting using an ex vivo isolated perfused rat lung model. Very low rates of metabolism are observed in incubations with human ATII cells when compared to isolated hepatocytes and fewer of the substrates are found to be metabolized when compared to human lung microsomal incubations. Reactions selective for flavin-containing monooxygenases (FMOs), CYP1B1, CYP2C9, CYP2J2, and CYP3A4 all show significant rates in human lung microsomal incubations, but all activities are higher when rat lung microsomes are used. The work also demonstrates that a lung microsomal intrinsic clearance value towards the lower limit of detection for this parameter (3 µL/min/mg protein) results in a very low level of pulmonary metabolic clearance during the absorption period, for a drug dosed into the lung in vivo.

Less burn, more fat: electronic cigarettes and pulmonary lipid homeostasis.

Electronic nicotine delivery systems (ENDS) are rapidly increasing in popularity due to the perception that they may represent a safe alternative to conventional cigarettes. However, a growing body of evidence indicates that ENDS exposure can disrupt maintenance of pulmonary immune homeostasis and antimicrobial immunity. In this issue of the JCI, Madison et al. demonstrate that in mice, chronic ENDS exposure induces profound alterations in lipid homeostasis. ENDS-exposed mice showed irregularities in the surfactant-secreting lamellar bodies within type 2 alveolar cells and increased intracellular phospholipid accumulation within alveolar macrophages. Moreover, ENDS-exposed mice displayed greater inflammation and tissue damage in response to influenza A, which may be due to downregulated expression of a viral pattern-recognition receptor in alveolar macrophages. Collectively, the results of this study identify previously unrecognized adverse effects of ENDS exposure on pulmonary lipid metabolism, although the implication of these effects on long-term respiratory health requires future exploration.

Pulmonary capillary surface area in supine exercising humans: demonstration of vascular recruitment.

In exercising humans, cardiac output (CO) increases, with minor increases in pulmonary artery pressure (PAP). It is unknown if the CO is accommodated via distention of already perfused capillaries or via recruitment of nonconcomitantly perfused pulmonary capillaries. Ten subjects (9 female) performed symptom-limited exercise. Six had resting mean PAP (PAPm) <20 mmHg, and four had PAPm between 21 and 24 mmHg. The first-pass pulmonary circulatory metabolism of [3H]benzoyl-Phe-Ala-Pro (BPAP) was measured at rest and at peak exercise, and functional capillary surface area (FCSA) was calculated. Data are means ± SD. Mean pulmonary arterial pressure rose from 18.8 ± 3.3 SD mmHg to 28.5 ± 4.6 SD mmHg, CO from 6.4 ± 1.6 to 13.4 ± 2.9 L/min, and pulmonary artery wedge pressure from 14 ± 3.3 to 19.5 ± 5 mmHg (all P ≤ 0.001). Percent BPAP metabolism fell from 74.7 ± 0.1% to 67.1 ± 0.1%, and FCSA/body surface area (BSA) rose from 2,939 ± 640 to 5,018 ± 1,032 mL·min-1·m-2 (all P < 0.001). In nine subjects, the FCSA/BSA-to-CO relationship suggested principally capillary recruitment and not distention. In subject 10, a marathon runner, resting CO and FCSA/BSA were high, and increases with exercise suggested distention. Exercising humans demonstrate pulmonary capillary recruitment and distention. At moderate resting CO, increasing blood flow causes principally recruitment while, based on one subject, when exercise begins at high CO, further increases appear to cause distention. Our findings clarify an important physiologic question. The technique may provide a means for further understanding exercise physiology, its limitation in pulmonary hypertension, and responses to therapy.

Black lungs in the general population: a new look at an old dispute.

Almost from the time that autopsies were first routinely carried out, darkening of lungs with increasing age was described. Different explanations for the origin of the accumulating black pigment arose and by the early nineteenth century three hypotheses had emerged: 1) soot inhaled into the lungs from the air; 2) carbon accumulating in the lungs from abnormal pulmonary carbon dioxide metabolism; and, 3) pigment derived from the blood. In 1813 the English physician and chemist George Pearson published a paper in which he described the recovery of the black pigment from lungs and its chemical analysis. Pearson declared the black pigment to be airborne carbon/soot from the burning of coal and wood. He described these particles depositing in 'black spots' in the terminal airways and accumulating in the peribronchial lymph nodes, forming 'black glands'. Despite Pearson's prescient account, debate continued and the true explanation, given in that paper, was not fully accepted until the late nineteenth century.

Alleviation of paraquat-induced oxidative lung injury by betaine via regulation of sulfur-containing amino acid metabolism despite the lack of betaine-homocysteine methyltransferase (BHMT) in the lung.

Betaine is a methyl donor utilized in regeneration of methionine from homocysteine in a metabolic reaction catalyzed by betaine-homocysteine methyltransferase (BHMT), an enzyme mostly localized in the liver. However, we recently showed that the metabolism of sulfur-containing amino acids in the kidney was also influenced by betaine, which is attributable to elevation of renal methionine availability resulting from an increase in its supply through blood. In this study we investigated the change in pulmonary sulfur-containing amino acid metabolism by betaine and its potential beneficial effect on paraquat (PQ)-induced lung injury. Male rats were provided with betaine for 2 weeks prior to an intratracheal instillation of PQ (0.3 mg/500 μl kg-1). Two weeks after PQ exposure, histopathological assessment revealed severe fibrotic lesions accompanied with elevation of 4-hydroxyproline in the lung, which were all prevented effectively by betaine supplementation. PQ-induced DNA fragmentation in lymphocytes, reduction of oxidant scavenging capacity, expression of heme oxygenase 1 and inducible nitric oxide synthase in the lung, and elevation of serum transforming growth factor beta 1 were also inhibited. PQ instillation increased cysteine, but depleted glutathione in the lung. Betaine supplementation before PQ exposure suppressed the cysteine accumulation and increased the glutathione synthesis. The polyamine synthesis, which requires decarboxylated S-adenosylmethionine as a substrate, was also increased significantly. The results suggest that betaine may enhance pulmonary antioxidant capacity by modulating the metabolism of sulfur-containing amino acids and related substances despite the lack of BHMT in the lung.

Exhaled breath mass spectrometry in heart failure diagnostics

Heart failure (HF) affects almost all organs and systems, including general and local pulmonary metabolism, thus effecting on volatile organic compounds concentration in expired air. The aim of the present study is to evaluate the value of expired air analysis (proton mass spectrometry, PTR-MS) for the diagnosis of HF. The study population included 19 patients with stable chronic New York Heart Association (NYHA) functional classification class 2-3 and 16 sex and age matched controls without signs and symptoms of HF. Expired air analysis could provide facilities of early diagnosis and monitoring in HF patients. Most patients had ischemic aetiology of HF, and 31% of them had NYHA class 2 and 69% NYHA class 3 symptoms. Fasted expired air collected by special Tedlar bags was analysed by Compact PTR-MS. The composition of expired air was analysed by deviation of the content of certain substances against their concentration in neutral air. Analysis of samples from patients reveals 24 substances that differ in concentration from the neutral air. Six of them differ significantly in patients with and without HF. Namely, the concentrations of acetone, formaldehyde, propylene, acetic acid, xylene and benzoates were significantly elevated in HF patients (p > 0.05).

Mitochondrial metabolism in pulmonary hypertension: beyond mountains there are mountains.

Pulmonary hypertension (PH) is a heterogeneous and fatal disease of the lung vasculature, where metabolic and mitochondrial dysfunction may drive pathogenesis. Similar to the Warburg effect in cancer, a shift from mitochondrial oxidation to glycolysis occurs in diseased pulmonary vessels and the right ventricle. However, appreciation of metabolic events in PH beyond the Warburg effect is only just emerging. This Review discusses molecular, translational, and clinical concepts centered on the mitochondria and highlights promising, controversial, and challenging areas of investigation. If we can move beyond the "mountains" of obstacles in this field and elucidate these fundamental tenets of pulmonary vascular metabolism, such work has the potential to usher in much-needed diagnostic and therapeutic approaches for the mitochondrial and metabolic management of PH.

Inhaled Therapy in Respiratory Disease: The Complex Interplay of Pulmonary Kinetic Processes.

The inhalation route is frequently used to administer drugs for the management of respiratory diseases such as asthma or chronic obstructive pulmonary disease. Compared with other routes of administration, inhalation offers a number of advantages in the treatment of these diseases. For example, via inhalation, a drug is directly delivered to the target organ, conferring high pulmonary drug concentrations and low systemic drug concentrations. Therefore, drug inhalation is typically associated with high pulmonary efficacy and minimal systemic side effects. The lung, as a target, represents an organ with a complex structure and multiple pulmonary-specific pharmacokinetic processes, including (1) drug particle/droplet deposition; (2) pulmonary drug dissolution; (3) mucociliary and macrophage clearance; (4) absorption to lung tissue; (5) pulmonary tissue retention and tissue metabolism; and (6) absorptive drug clearance to the systemic perfusion. In this review, we describe these pharmacokinetic processes and explain how they may be influenced by drug-, formulation- and device-, and patient-related factors. Furthermore, we highlight the complex interplay between these processes and describe, using the examples of inhaled albuterol, fluticasone propionate, budesonide, and olodaterol, how various sequential or parallel pulmonary processes should be considered in order to comprehend the pulmonary fate of inhaled drugs.

Lung Metabolism and Inflammation during Mechanical Ventilation; An Imaging Approach

Acute respiratory distress syndrome (ARDS) is a major cause of mortality in critically ill patients. Patients are currently managed by protective ventilation and alveolar recruitment using positive-end expiratory pressure (PEEP). However, the PEEP’s effect on both pulmonary metabolism and regional inflammation is poorly understood. Here, we demonstrate the effect of PEEP on pulmonary anaerobic metabolism in mechanically ventilated injured rats, using hyperpolarized carbon-13 imaging. Pulmonary lactate-to-pyruvate ratio was measured in 21 rats; 14 rats received intratracheal instillation of hydrochloric-acid, while 7 rats received sham saline. 1 hour after acid/saline instillation, PEEP was lowered to 0 cmH2O in 7 injured rats (ZEEP group) and in all sham rats; PEEP was continued in the remaining 7 injured rats (PEEP group). Pulmonary compliance, oxygen saturation, histological injury scores, ICAM-1 expression and myeloperoxidase expression were measured. Lactate-to-pyruvate ratio progressively increased in the dependent lung during mechanical ventilation at ZEEP (p < 0.001), but remained unchanged in PEEP and sham rats. Lactate-to-pyruvate ratio was correlated with hyaline membrane deposition (r = 0.612), edema severity (r = 0.663), ICAM-1 (r = 0.782) and myeloperoxidase expressions (r = 0.817). Anaerobic pulmonary metabolism increases during lung injury progression and is contained by PEEP. Pulmonary lactate-to-pyruvate ratio may indicate in-vivo neutrophil activity due to atelectasis.

RESPIRATORY DISTRESS SYNDROME IN ACUTE PANCREATITIS (EXPERIMENTAL STUDY)

Aim. To assess the role of lipid metabolism disorders and coagulation-lytic changes of lung tissue structures in the pathogenesis of respiratory distress syndrome in acute pancreatitis. Material and Methods. The study is based on experiments on adult mongrel dogs. The model is acute pancreatitis by V.M. Buyanov et al. (1989). In target dates blood sample, bronchoalveolar lavage and biopsy of lung tissue were analyzed. We investigated free-radical processes, phospholipase and protease activity, qualitative and quantitative composition of lipids, coagulation-lytic state of tissues, functional state of surfactant and transcapillary fluid exchange. Results. It was found that acute pancreatitis is associated with significant disorders of transcapillary exchange of fluid in lungs, function and composition of surfactant, that led to respiratory impairment. Lipid metabolism disorders and coagulation-lytic changes in lungs are main pathogenetic mechanisms of respiratory distress syndrome. Metabolic changes in lungs are associated with endogenous intoxication. Conclusion. Pulmonary lipid metabolism changes and tissue coagulation-lytic system modification occur in acute pancreatitis due to endogenous intoxication, increased phospholipase and proteolytic activity, intensification of lipid peroxidation. These disorders leads to violation of transcapillary fluid exchange, functional state of surfactant followed by respiratory distress syndrome development.excessive intensification of lipid peroxidation, increased activity of phospholipases and proteases.

Presence and inter-individual variability of carboxylesterases (CES1 and CES2) in human lung

Lungs are pharmacologically active organs and the pulmonary drug metabolism is of interest for inhaled drugs design. Carboxylesterases (CESs) are enzymes catalyzing the hydrolysis of many structurally different ester, amide and carbamate chemicals, including prodrugs. For the first time, the presence, kinetics, inhibition and inter-individual variations of the major liver CES isozymes (CES1 and CES2) were investigated in cytosol and microsomes of human lungs from 20 individuals using 4-nitrophenyl acetate (pNPA), 4-methylumbelliferyl acetate (4-MUA), and fluorescein diacetate (FD) as substrates the rates of hydrolysis (Vmax) for pNPA and 4-MUA, unlike FD, were double in microsomes than in cytosol. In these cellular fractions, the Vmax of pNPA, as CES1 marker, were much greater (30–50-fold) than those of FD, as a specific CES2 marker. Conversely, the Km values were comparable suggesting the involvement of the same enzymes. Inhibition studies revealed that the FD hydrolysis was inhibited by bis-p-nitrophenylphosphate, phenylmethanesulfonyl fluoride, and loperamide (specific for CES2), whereas the pNPA and 4-MUA hydrolysis inhibition was limited. Inhibitors selective for other esterases missed having any effect on above-mentioned activities. In cytosol and microsomes of 20 lung samples, inter-individual variations were found for the hydrolysis of pNPA (2.5–5-fold), FD or 4-MUA (8–15-fold). Similar variations were also observed in CES1 and CES2 gene expression, although determined in a small number (n = 9) of lung samples. The identification of CES1 and CES2 and their variability in human lungs are important for drug metabolism and design of prodrugs which need to be activated in this organ.

ОЦЕНКА СТЕПЕНИ ВЫРАЖЕННОСТИ И ТИПИЗАЦИЯ СТРЕСС-РЕАКЦИЙ ЛЕГОЧНОЙ ТКАНИ ПО СОСТОЯНИЮ СУРФАКТАНТА И СВОБОДНОРАДИКАЛЬНЫХ ПРОЦЕССОВ, "Российский физиологический журнал им. И.М. Сеченова"

На моделях острого стресса проведен анализ изменений поверхностно-активных свойств и перекисного окисления липидов в легочной ткани белых крыс. В условиях действия температурных (холод разной интенсивности, гипертермия), эмоционально-болевых (иммобилизация, электрокожное раздражение), химического (острое отравление этанолом в разных дозах) воздействий, гипобарической гипоксии и гипербарической гипероксии выявлены разнонаправленные изменения изучаемых параметров легочного метаболизма, которые зависят от модальности и интенсивности действующих стимулов. Полученные данные обобщаются в виде типизации реакций легочной ткани в ответ на стресс-индуцирующие воздействия по состоянию поверхностной активности, стабильности альвеолярного выстилающего комплекса и свободнорадикальных процессов.

Toxic effects of silica nanoparticles on human pulmonary cell metabolism

Toxic effects of silica nanoparticles on human pulmonary cell metabolism

Assessment of the pulmonary CYP1A1 metabolism of mavoglurant (AFQ056) in rat

1. AFQ056 phenotyping results indicate that CYP1A1 is responsible for the formation of the oxidative metabolite, M3. In line with the predominant assumption that CYP1A1 is mainly expressed in extrahepatic tissues, only traces of M3 were detected in hepatic systems. The aim of this study was to investigate the pulmonary CYP1A1 mediated metabolism of AFQ056 in rat.2. Western blot analysis confirmed that CYP1A1 is expressed in rat lung albeit at low levels. M3 formation was clearly observed in recombinant rat CYP1A1, lung microsomes and lung tissue slices and was strongly inhibited by ketoconazole in the incubations. As CYP3A4 and CYP2C9 metabolites were only observed at trace levels, we concluded that the reduced M3 formation was due to CYP1A1 inhibition.3. AFQ056 lung clearance (CLlung) as estimated from in vitro data was predicted to be negligible (<1% pulmonary blood flow). This was confirmed by in vivo experiments where intravenous and intra-arterial dosing to rats failed to show significant pulmonary extraction.4. While rat lung may make a contribution to the formation of M3, it is unlikely to be the only organ involved in this process and further experiments are required to investigate the potential metabolic elimination routes for AFQ056.

Cytokine filtration modulates pulmonary metabolism and edema formation during ex vivo lung perfusion

Ex vivo lung perfusion (EVLP) has improved the process of donor lung management. Cytokine accumulation during EVLP has been shown to correlate with worse outcome after lung transplantation. Our objective in this study was to test the safety and efficacy of cytokine filtration during EVLP in a large animal model. Pig donor lungs were preserved for 24 hours at 4°C, followed by 12 hours of EVLP, according to the Toronto protocol. The perfusate was continuously run through an absorbent device (CytoSorb) via a veno-venous shunt from the reservoir in the filter group. EVLP was performed according to the standard protocol in the control group (n = 5 each). EVLP physiology, lung X-ray, perfusate biochemistry, inflammatory response and microscopic injury were assessed. Cytokine filtration significantly improved airway pressure and dynamic compliance during the 12-hour perfusion period. Lung X-rays acquired at the end of perfusion showed increased consolidation in the control group. Electrolyte imbalance, determined by increased hydrogen, potassium and calcium ion concentrations in the perfusate, was markedly worsened in the control group. Glucose consumption and lactate production were markedly reduced, along with the lactate/pyruvate ratio in the filter group. Cytokine expression profile, tissue myeloperoxidase activity and microscopic lung injury were significantly reduced in the filter group. Continuous perfusate filtration through sorbent beads is effective and safe during prolonged EVLP. Cytokine removal decreased the development of pulmonary edema and electrolyte imbalance through the suppression of anaerobic glycolysis and neutrophil activation in this setting. Further studies are needed to test the beneficial effect of cytokine filtration on post-transplant lung function.

ABCG1 regulates pulmonary surfactant metabolism in mice and men

Idiopathic pulmonary alveolar proteinosis (PAP) is a rare lung disease characterized by accumulation of surfactant. Surfactant synthesis and secretion are restricted to epithelial type 2 (T2) pneumocytes (also called T2 cells). Clearance of surfactant is dependent upon T2 cells and macrophages. ABCG1 is highly expressed in both T2 cells and macrophages. ABCG1-deficient mice accumulate surfactant, lamellar body-loaded T2 cells, lipid-loaded macrophages, B-1 lymphocytes, and immunoglobulins, clearly demonstrating that ABCG1 has a critical role in pulmonary homeostasis. We identify a variant in the ABCG1 promoter in patients with PAP that results in impaired activation of ABCG1 by the liver X receptor α, suggesting that ABCG1 basal expression and/or induction in response to sterol/lipid loading is essential for normal lung function. We generated mice lacking ABCG1 specifically in either T2 cells or macrophages to determine the relative contribution of these cell types on surfactant lipid homeostasis. These results establish a critical role for T2 cell ABCG1 in controlling surfactant and overall lipid homeostasis in the lung and in the pathogenesis of human lung disease.

Abstract 172: Abcg1 Regulates Pulmonary Surfactant Metabolism in Mice and Men

Inflammation is a hallmark characteristic of many diseases, including atherosclerosis and respiratory distress, and it is also a stereotypical response of the innate immune system to pathogens. Given the central role both inflammation and lipid homeostasis play in disease progression, defining the immune and lipid signaling pathways is key in identifying new strategies for therapeutic intervention. The ATP Binding Cassette (ABC) transporter ABCG1 is highly expressed in pulmonary type 2 cells, alveolar macrophages and immune cells. We, and others, have demonstrated that loss of ABCG1 attenuates atherosclerotic lesion progression, and profoundly impacts B cell and natural antibody homeostasis. ABCG1-deficient mice accumulate pulmonary surfactant, lamellar-body loaded type 2 cells, lipid-loaded macrophages, B-1 lymphocytes and immunoglobulins, clearly demonstrating the ABCG1 has a critical role in pulmonary homeostasis. We have identified a variant in the ABCG1 promoter in patients with pulmonary alveolar proteinosis, that results in impaired activation of ABCG1 by the liver X receptor alpha. We have generated mice that lack ABCG1 specifically in either type 2 cells or macrophages, and show that loss of ABCG1 from both cell types has specific effects on pulmonary lipid and immune homeostasis. These results establish a critical role for type 2 cell ABCG1 in controlling surfactant and lipid homeostasis in the lung and in the pathogenesis of human lung disease.

Sulfur Dioxide Protects Against Collagen Accumulation in Pulmonary Artery in Association With Downregulation of the Transforming Growth Factor β1/Smad Pathway in Pulmonary Hypertensive Rats.

BackgroundWe aimed to explore the role of endogenous sulfur dioxide (SO 2) in pulmonary vascular collagen remodeling induced by monocrotaline and its mechanisms.Methods and ResultsA rat model of monocrotaline‐induced pulmonary vascular collagen remodeling was developed and administered with l‐aspartate‐β‐hydroxamate or SO 2 donor. The morphology of small pulmonary arteries and collagen metabolism were examined. Cultured pulmonary arterial fibroblasts stimulated by transforming growth factor β1 (TGF‐β1) were used to explore the mechanism. The results showed that in monocrotaline‐treated rats, mean pulmonary artery pressure increased markedly, small pulmonary arterial remodeling developed, and collagen deposition in lung tissue and pulmonary arteries increased significantly in association with elevated SO 2 content, aspartate aminotransferase (AAT) activity, and expression of AAT1 compared with control rats. Interestingly, l‐aspartate‐β‐hydroxamate, an inhibitor of SO 2 generation, further aggravated pulmonary vascular collagen remodeling in monocrotaline‐treated rats, and inhibition of SO 2 in pulmonary artery smooth muscle cells activated collagen accumulation in pulmonary arterial fibroblasts. SO 2 donor, however, alleviated pulmonary vascular collagen remodeling with inhibited collagen synthesis, augmented collagen degradation, and decreased TGF‐β1 expression of pulmonary arteries. Mechanistically, overexpression of AAT1, a key enzyme of SO 2 production, prevented the activation of the TGF‐β/type I TGF‐β receptor/Smad2/3 signaling pathway and abnormal collagen synthesis in pulmonary arterial fibroblasts. In contrast, knockdown of AAT1 exacerbated Smad2/3 phosphorylation and deposition of collagen types I and III in TGF‐β1–treated pulmonary arterial fibroblasts.ConclusionsEndogenous SO 2 plays a protective role in pulmonary artery collagen accumulation induced by monocrotaline via inhibition of the TGF‐β/type I TGF‐β receptor/Smad2/3 pathway.

Pulmonary artery smooth muscle cell hyperproliferation and metabolic shift triggered by pulmonary overcirculation.

Vascular cell hyperproliferation and metabolic reprogramming contribute to the pathophysiology of pulmonary arterial hypertension (PAH). An important cause of PAH in children with congenital heart disease (CHD) is increased pulmonary blood flow (PBF). To better characterize this disease course we studied early changes in pulmonary artery smooth muscle cell (PASMC) proliferation and metabolism using a unique ovine model of pulmonary overcirculation. Consistent with PAH in adults, PASMCs derived from 4-wk-old lambs exposed to increased PBF (shunt) exhibited increased rates of proliferation. While shunt PASMCs also exhibited significant decreases in mitochondrial oxygen consumption, membrane potential, and tricarboxylic acid (TCA) cycle function, suggesting a switch to Warburg metabolism as observed in advanced PAH in adults, they unexpectedly demonstrated decreased glycolytic lactate production, likely due to enhanced flux through the pentose phosphate pathway (PPP). This may be a response to the marked increase in NADPH oxidase (Nox) activity and decreased NADPH/NADP+ ratios observed in shunt PASMCs. Consistent with these findings, pharmacological inhibition of Nox activity preferentially slowed the growth of shunt PASMCs in vitro. Our results therefore indicate that PASMC hyperproliferation is observed early in the setting of pulmonary overcirculation and is accompanied by a unique metabolic profile that is independent of HIF-1α, PDHK1, or increased glycolytic flux. Our results also suggest that Nox inhibition may help prevent pulmonary overcirculation-induced PAH in children born with CHD.

C-Myc targeted regulators of cell metabolism in a transgenic mouse model of papillary lung adenocarcinoma.

c-Myc's role in pulmonary cancer metabolism is uncertain. We therefore investigated c-Myc activity in papillary lung adenocarcinomas (PLAC). Genomics revealed 90 significantly regulated genes (> 3-fold) coding for cell growth, DNA metabolism, RNA processing and ribosomal biogenesis and bioinformatics defined c-Myc binding sites (TFBS) at > 95% of up-regulated genes. EMSA assays at 33 novel TFBS evidenced DNA binding activity and ChIP-seq data retrieved from public repositories confirmed these to be c-Myc bound. Dual-luciferase gene reporter assays developed for RNA-Terminal-Phosphate-Cyclase-Like-1(RCL1), Ribosomal-Protein-SA(RPSA), Nucleophosmin/Nucleoplasmin-3(NPM3) and Hexokinase-1(HK1) confirmed c-Myc functional relevance and ChIP assays with HEK293T cells over-expressing ectopic c-Myc demonstrated enriched c-Myc occupancy at predicted TFBS for RCL1, NPM3, HK1 and RPSA. Note, c-Myc recruitment on chromatin was comparable to the positive controls CCND2 and CDK4. Computational analyses defined master regulators (MR), i.e. heterogeneous nuclear ribonucleoprotein A1, nucleolin, the apurinic/apyrimidinic endonuclease 1, triosephosphate-isomerase 1, folate transporter (SLC19A1) and nucleophosmin to influence activity of up to 90% of PLAC-regulated genes. Their expression was induced by 3-, 3-, 6-, 3-, 11- and 7-fold, respectively. STRING analysis confirmed protein-protein-interactions of regulated genes and Western immunoblotting of fatty acid synthase, serine hydroxyl-methyltransferase 1, arginine 1 and hexokinase 2 showed tumor specific induction. Published knock down studies confirmed these proteins to induce apoptosis by disrupting neoplastic lipogenesis, by endorsing uracil accumulation and by suppressing arginine metabolism and glucose-derived ribonucleotide biosynthesis. Finally, translational research demonstrated high expression of MR and of 47 PLAC up-regulated genes to be associated with poor survival in lung adenocarcinoma patients (HR 3.2 p < 0.001) thus, providing a rationale for molecular targeted therapies in PLACs.