Mitochondrial reactive oxygen species mediates nicotine-induced hypoxia-inducible factor-1α expression in human non-small cell lung cancer cells

Dexpanthenol protects against nicotine-induced kidney injury by reducing oxidative stress and apoptosis through activation of the AKT/Nrf2/HO-1 pathway

Dexpanthenol (DEX), a subtype of vitamin B5, plays an important role in anabolic reactions, cellular energy and regeneration in the body. Nicotine has been shown to induce kidney damage through the mechanisms of oxidative stress and apoptosis. The purpose of this study was to investigate the potential protective effects of DEX against nicotine-induced kidney damage through modulation of the AKT/Nrf2/HO-1 signaling pathway. Male rats were intraperitoneally administered with 0.5 mg/kg/day nicotine and/or 500 mg/kg/day DEX for 8 weeks. Following administration, renal function tests were conducted on serum samples, and histopathological examinations and analysis of oxidative stress markers and antioxidant enzymes were performed on tissue samples. Protein levels of Akt, Nrf-2, HO-1, Bcl-xL, and Caspase-9 were also evaluated. Nicotine administration resulted in decreased protein levels of p-Akt, Nrf-2, HO-1, and Bcl-xL and increased Caspase-9 protein levels. In addition, nicotine administration caused an increase in MDA, TOS, and OSI levels and a decrease in GSH, GSH-Px, GST, CAT, SOD, and TAS levels. Additionally, BUN and Creatinine levels increased after nicotine administration. DEX administration positively regulated these parameters and brought them closer to control levels. Nicotine-induced kidney injury caused apoptosis and oxidative stress through Caspase-9 activation. DEX effectively prevented nicotine-induced kidney damage by increasing intracellular antioxidant levels and regulating apoptosis through Bcl-xL activation. These findings suggest that DEX has potential as a protective agent against nicotine-induced kidney damage.

Nicotinic receptors in airway disease

With continued smoking of tobacco products and expanded use of nicotine delivery devices worldwide, understanding the impact of smoking and vaping on respiratory health remains a major global unmet need. Although multiple studies have shown a strong association between smoking and asthma, there is a relative paucity of mechanistic understanding of how elements in cigarette smoke impact the airway. Recognizing that nicotine is a major component in both smoking and vaping products, it is critical to understand the mechanisms by which nicotine impacts airways and promotes lung diseases such as asthma. There is now increasing evidence that α7 nicotinic acetylcholine receptors (α7nAChRs) are critical players in nicotine effects on airways, but the mechanisms by which α7nAChR influences different airway cell types have not been widely explored. In this review, we highlight and integrate the current state of knowledge regarding nicotine and α7nAChR in the context of asthma and identify potential approaches to alleviate the impact of smoking and vaping on the lungs.

Nicotine promotes renal interstitial fibrosis via upregulation of XIAP in an alpha7-nAChR-dependent manner

Renal fibrosis, characterized by excessive accumulation of the extracellular matrix in the renal tubulointerstitium, can lead to chronic kidney disease (CKD), resulting in a heavy burden on families and society. Clinical studies have shown that smoking is closely associated with CKD deterioration in patients with diabetes, hypertension, polycystic kidney disease, and kidney transplantation. However, the mechanism of action of nicotine in renal fibrosis pathogenesis remains largely unknown. X-linked inhibitor of apoptosis (XIAP), a member of the inhibitor of apoptosis protein (IAP) family, is involved in apoptosis, necroptosis, autophagy, and immune response. Here, the upregulated expression of XIAP and α7 nicotine acetylcholine receptor (α7-nAChR) was determined in the kidneys of the CKD smoking group in human and animal studies. A significant positive correlation between XIAP and cotinine was observed. In addition, the nuclear translocation and transcriptional activity of SP1 were promoted when nicotine bound to α7-nAChR, resulting in XIAP overexpression and renal interstitial fibrosis progression. This phenotype can be reversed by the nicotine receptor subtype α7-nAChR antagonists methyllycaconitine. Our results revealed the complex underlying mechanism of nicotine in promoting renal fibrosis by altering SP1 nucleocytoplasmic translocation and regulating XIAP expression. These results provide novel insights into the pathogenesis and treatment of CKD.

A Significant Increasing Risk Association between Cigarette Smoking and XPA and XPC Genes Polymorphisms

Cigarette smoking (CS) is a major cause of various serious diseases due to tobacco chemicals. There is evidence suggesting that CS has been linked with the DNA damage repair system, as it can affect genomic stability, inducing genetic changes in the genes involved in the repair system, specifically the nucleotide excision repair (NER) pathway, affecting the function and/or regulation of these genes. Single nucleotide polymorphism (SNP), along with CS, can affect the work of the NER pathway and, therefore, could lead to different diseases. This study explored the association of four SNPs in both XPA and XPC genes with CS in the Saudi population. The Taq Man genotyping assay was used for 220 healthy non-smokers (control) and 201 healthy smokers to evaluate four SNPs in the XPA gene named rs10817938, rs1800975, rs3176751, and rs3176752 and four SNPs in the XPC gene called rs1870134, rs2228000, rs2228001, and rs2607775. In the XPA gene, SNP rs3176751 showed a high-risk association with CS-induced diseases with all clinical parameters, including CS duration, CS intensity, gender, and age of smokers. On the other hand, SNP rs1800975 showed a statistically significant low-risk association with all clinical parameters. In addition, rs10817938 showed a high-risk association only with long-term smokers and a low-risk association only with younger smokers. A low-risk association was found in SNP rs3176752 with older smokers. In the XPC gene, SNP rs2228001 showed a low-risk association only with female smokers. SNP rs2607775 revealed a statistically significant low-risk association with CS-induced diseases, concerning all parameters, except for male smokers. However, SNP rs2228000 and rs1870134 showed no association with CS. Overall, the study results demonstrated possible significant associations (effector/and protector) between CS and SNPs polymorphisms in DNA repair genes, such as XPA and XPC, except for rs2228000 and rs1870134 polymorphisms.

Nicotine activates HIF-1α and regulates acid extruders through the nicotinic acetylcholine receptor to promote the Warburg effect in non-small cell lung cancer cells

Cigarette smoking is the greatest risk factor for lung cancer, accounting for approximately 90% of all lung cancer-related deaths. Moreover, nicotine is associated with lung cancer onset and progression. Hypoxia-inducible factor 1α (HIF-1α) is involved in the metabolic reprogramming of cancer cells and accelerates cancer progression via regulation of pH and acid-base homeostasis. Previous studies have reported that nicotine upregulates HIF-1α expression. Therefore, we hypothesized that nicotine-mediated activation of HIF-1α regulates metabolic reprogramming and pH homeostasis in non-small cell lung cancer A549 cells and could potentially play a role in the progression of lung cancer. We examined the effects of nicotine on metabolic reprogramming and intracellular pH (pH_i) homeostasis, which are critical for cancer progression. A549 cells were exposed to nicotine in the absence and presence of the nicotinic acetylcholine receptor antagonist, mecamylamine (MEC). We then analyzed glycolytic stress and the activity and expression of acid-extruder proteins, including the Na⁺-H⁺ exchanger 1 (NHE1) and monocarboxylate cotransporters 1 & 4 (MCT1 and MCT4, respectively). Nicotine promoted the Warburg effect, which is associated with accelerated migration of A549 cells through the activation of nicotinic acetylcholine receptors. Furthermore, nicotine upregulated the activities and expression of acid-extruder proteins, namely NHE1 and MCT4, and facilitated glycolysis. To the best of our knowledge, this is the first study to demonstrate that nicotine plays a pivotal regulatory role in metabolic reprogramming as well as regulation of pH_i homeostasis in A549 cells via activation of nicotinic acetylcholine receptors and can therefore aggravate lung cancer progression.

Mitigation of nicotine-induced developmental effects by 24-epibrassinolide in zebrafish

Nicotine is a highly addictive substance that can cause teratogenic impacts in the embryo through redox-dependent pathways. As antioxidants, naturally occurring chemicals can protect cells from redox imbalance. The purpose of this study was to evaluate the effectiveness of 24-epibrassinolide (24-EPI), a natural brassinosteroid with well-known antioxidant properties, in protecting zebrafish embryos against nicotine's teratogenic effects. For 96 h, embryos (2 h post-fertilization - hpf) were exposed to 100 μM nicotine, co-exposed with 24-EPI (0.01, 0.1, and 1 μM), and 24-EPI alone (1 μM). Lethal and sublethal developmental characteristics were evaluated during exposure. Biochemical tests were performed at the conclusion of the exposure, and distinct behavioural paradigms were analysed 24 h later. Nicotine exposure resulted in a higher proportion of larvae with deformities, which were decreased following co-exposure to 24-EPI. Nicotine exposure also caused an increase in oxidative stress as observed by the increased activity of superoxide dismutase and catalase accompanied by an increase in the malondialdehyde levels. Besides, metabolic changes were noticed as observed by the increased lactate dehydrogenase activity that were hypothesised to be associated to nicotine-induced hypoxia which may be responsible for the increased oxidative damage. In addition, locomotor deficits were observed as well as a decrease in the acetylcholinesterase activity denoting nicotine-induced cognitive dysfunction. However, co-exposure to 24-EPI alleviated behavioural deficits and improved nicotine-induced emotional states. Overall, and although further studies are required to clarify these effects, 24-EPI showed promising ameliorative properties against the teratogenic effects induced by nicotine.

Guishaozichuan granules can attenuate asthma in rats via the MUC5AC/EGFR signaling pathway

Background: Guishaozichuan (GSZC) granules are a traditional Chinese medicine formulation created by Professor Li (Chinese-Japanese Friendship Hospital, Beijing, China) we studied the effect of GSZC granules in rats suffering from asthma. Methods: Specific pathogen-free Sprague-Dawley rats were divided randomly into seven groups. Ovalbumin (OVA) and Al (OH)3 gel were used to create an asthma model. On day 1, rats were injected with OVA (10 mg) and an Al(OH)3 gel suspension (100 mg). One week later, rats were sensitized again. On day 15, rats were given aerosolized OVA (1%) for 30 min/day for 10 days. Gastric administration of OVA was 1 h before nebulization. At 24 h after the last stimulation, changes in airway resistance (RI) and dynamic compliance (Cdyn) in rat lungs were measured after challenge with methacholine at increasing concentrations. The contents of immunoglobulin (Ig)E, interleukin (IL)-4, IL-5, IL-13, and IL-17 in serum were measured by enzyme-linked immunosorbent assays. The percentage of eosinophils (EOS) and the white blood cell (WBC) count in bronchoalveolar lavage fluid (BALF) were counted under an optical microscope. Pathologic alterations in lung tissue were evaluated by optical microscopy, and lung injury score calculated. Expression of mucin 5AC, oligomeric mucus/gel-forming (MUC5AC) and epidermal growth factor receptor (EGFR) in lung tissue was measured by immunohistochemistry. mRNA expression of MUC5AC and EGFR in lung tissue was measured by real-time reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Results: GSZC granules reduced RI markedly and improved Cdyn, decreased serum levels of IgE, IL-4, IL-5, IL-13, IL-17, %EOS and the WBC count in BALF. GSZC granules alleviated lung-tissue damage, diminished the Inflammation Score, and reduced mRNA and protein expression of MUC5AC and EGFR in lung tissue. Conclusion: GSZC granules could improve bronchial hyperresponsiveness, bronchial inflammation, and histopathologic damage in the lungs of rats suffering from asthma. This phenomenon may be related to its regulation of cytokine levels and the MUC5AC/EGFR signaling pathway.

Brain Energy Metabolism in Ischemic Stroke: Effects of Smoking and Diabetes

Proper regulation of energy metabolism in the brain is crucial for maintaining brain activity in physiological and different pathophysiological conditions. Ischemic stroke has a complex pathophysiology which includes perturbations in the brain energy metabolism processes which can contribute to worsening of brain injury and stroke outcome. Smoking and diabetes are common risk factors and comorbid conditions for ischemic stroke which have also been associated with disruptions in brain energy metabolism. Simultaneous presence of these conditions may further alter energy metabolism in the brain leading to a poor clinical prognosis after an ischemic stroke event. In this review, we discuss the possible effects of smoking and/or diabetes on brain glucose utilization and mitochondrial energy metabolism which, when present concurrently, may exacerbate energy metabolism in the ischemic brain. More research is needed to investigate brain glucose utilization and mitochondrial oxidative metabolism in ischemic stroke in the presence of smoking and/or diabetes, which would provide further insights on the pathophysiology of these comorbid conditions and facilitate the development of therapeutic interventions.

Alterations of Mitochondrial Network by Cigarette Smoking and E-Cigarette Vaping

Toxins present in cigarette and e-cigarette smoke constitute a significant cause of illnesses and are known to have fatal health impacts. Specific mechanisms by which toxins present in smoke impair cell repair are still being researched and are of prime interest for developing more effective treatments. Current literature suggests toxins present in cigarette smoke and aerosolized e-vapor trigger abnormal intercellular responses, damage mitochondrial function, and consequently disrupt the homeostasis of the organelle's biochemical processes by increasing reactive oxidative species. Increased oxidative stress sets off a cascade of molecular events, disrupting optimal mitochondrial morphology and homeostasis. Furthermore, smoking-induced oxidative stress may also amalgamate with other health factors to contribute to various pathophysiological processes. An increasing number of studies show that toxins may affect mitochondria even through exposure to secondhand or thirdhand smoke. This review assesses the impact of toxins present in tobacco smoke and e-vapor on mitochondrial health, networking, and critical structural processes, including mitochondria fission, fusion, hyper-fusion, fragmentation, and mitophagy. The efforts are focused on discussing current evidence linking toxins present in first, second, and thirdhand smoke to mitochondrial dysfunction.

Quantifying the contribution of transcription factor activity, mutations and microRNAs to CD274 expression in cancer patients

Immune checkpoint inhibitors targeting the programmed cell death protein 1 (PD-1)/programmed cell death protein ligand 1 (PD-L1) axis have been remarkably successful in inducing tumor remissions in several human cancers, yet a substantial number of patients do not respond to treatment. Because this may be partially due to the mechanisms giving rise to high PD-L1 expression within a patient, it is highly relevant to fully understand these mechanisms. In this study, we conduct a bioinformatic analysis to quantify the relative importance of transcription factor (TF) activity, microRNAs (miRNAs) and mutations in determining PD-L1 (CD274) expression at mRNA level based on data from the Cancer Genome Atlas. To predict individual CD274 levels based on TF activity, we developed multiple linear regression models by taking the expression of target genes of the TFs known to directly target PD-L1 as independent variables. This analysis showed that IRF1, STAT1, NFKB and BRD4 are the most important regulators of CD274 expression, explaining its mRNA levels in 90–98% of the patients. Because the remaining patients had high CD274 levels independent of these TFs, we next investigated whether mutations associated with increased CD274 mRNA levels, and low levels of miRNAs associated with negative regulation of CD274 expression could cause high CD274 levels in these patients. We found that mutations or miRNAs offered an explanation for high CD274 levels in 81–100% of the underpredicted patients. Thus, CD274 expression is largely explained by TF activity, and the remaining unexplained cases can largely be explained by mutations or low miRNA abundance.

Iron-Regulated Reactive Oxygen Species Production and Programmed Cell Death in Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is characterized by persistent respiratory symptoms and airflow limitation. However, the pathogenesis of COPD remains unclear. Currently, it is known to involve the loss of alveolar surface area (emphysema) and airway inflammation (bronchitis), primarily due to exposure to cigarette smoke (CS). CS causes epithelial cell death, resulting in pulmonary emphysema. Moreover, CS induces iron accumulation in the mitochondria and cytosol, resulting in programmed cell death. Although apoptosis has long been investigated as the sole form of programmed cell death in COPD, accumulating evidence indicates that a regulated form of necrosis, called necroptosis, and a unique iron-dependent form of non-apoptotic cell death, called ferroptosis, is implicated in the pathogenesis of COPD. Iron metabolism plays a key role in producing reactive oxygen species (ROS), including mitochondrial ROS and lipid peroxidation end-products, and activating both necroptosis and ferroptosis. This review outlines recent studies exploring CS-mediated iron metabolism and ROS production, along with the regulation of programmed cell death in COPD. Elucidating the mechanisms of these pathways may provide novel therapeutic targets for COPD.

New Pathways for the Skin's Stress Response: The Cholinergic Neuropeptide SLURP-1 Can Activate Mast Cells and Alter Cytokine Production in Mice

Background: The alpha7 nicotinic acetylcholine receptor (Chrna7) plays an essential anti-inflammatory role in immune homeostasis and was recently found on mast cells (MC). Psychosocial stress can trigger MC hyperactivation and increases pro-inflammatory cytokines in target tissues such as the skin. If the cholinergic system (CS) and Chrna7 ligands play a role in these cascades is largely unknown.

Objective: To elucidate the role of the CS in the response to psychosocial stress using a mouse-model for stress-triggered cutaneous inflammatory circuits.

Methods: Key CS markers (ACh, Ch, SLURP-1, SLURP-2, Lynx1, Chrm3, Chrna7, Chrna9, ChAT, VAChT, Oct3, AChE, and BChE) in skin and its MC (sMC), MC activation, immune parameters (TNFα, IL1β, IL10, TGFβ, HIF1α, and STAT3) and oxidative stress were analyzed in skin from 24 h noise-stressed mice and in cultured MC (cMC) from C57BL/6 or Chrna7-Knockout mice.

Results: First, Chrna7 and SLURP-1 mRNA were exclusively upregulated in stressed skin. Second, histomorphometry located Chrna7 and SLURP-1 in nerves and sMC and demonstrated upregulated contacts and increased Chrna7+ sMC in stressed skin, while 5 ng/mL SLURP-1 degranulated cMC. Third, IL1β+ sMC were high in stressed skin, and while SLURP-1 alone had no significant effect on cMC cytokines, it upregulated IL1β in cMC from Chrna7-KO and in IL1β-treated wildtype cMC. In addition, HIF1α+ sMC were high in stressed skin and Chrna7-agonist AR-R 17779 induced ROS in cMC while SLURP-1 upregulated TNFα and IL1β in cMC when HIF1α was blocked.

Conclusions: These data infer that the CS plays a role in the regulation of stress-sensitive inflammatory responses but may have a surprising pro-inflammatory effect in healthy skin, driving IL1β expression if SLURP-1 is involved.

Riding the tiger - physiological and pathological effects of superoxide and hydrogen peroxide generated in the mitochondrial matrix

Elevated mitochondrial matrix superoxide and/or hydrogen peroxide concentrations drive a wide range of physiological responses and pathologies. Concentrations of superoxide and hydrogen peroxide in the mitochondrial matrix are set mainly by rates of production, the activities of superoxide dismutase-2 (SOD2) and peroxiredoxin-3 (PRDX3), and by diffusion of hydrogen peroxide to the cytosol. These considerations can be used to generate criteria for assessing whether changes in matrix superoxide or hydrogen peroxide are both necessary and sufficient to drive redox signaling and pathology: is a phenotype affected by suppressing superoxide and hydrogen peroxide production; by manipulating the levels of SOD2, PRDX3 or mitochondria-targeted catalase; and by adding mitochondria-targeted SOD/catalase mimetics or mitochondria-targeted antioxidants? Is the pathology associated with variants in SOD2 and PRDX3 genes? Filtering the large literature on mitochondrial redox signaling using these criteria highlights considerable evidence that mitochondrial superoxide and hydrogen peroxide drive physiological responses involved in cellular stress management, including apoptosis, autophagy, propagation of endoplasmic reticulum stress, cellular senescence, HIF1α signaling, and immune responses. They also affect cell proliferation, migration, differentiation, and the cell cycle. Filtering the huge literature on pathologies highlights strong experimental evidence that 30-40 pathologies may be driven by mitochondrial matrix superoxide or hydrogen peroxide. These can be grouped into overlapping and interacting categories: metabolic, cardiovascular, inflammatory, and neurological diseases; cancer; ischemia/reperfusion injury; aging and its diseases; external insults, and genetic diseases. Understanding the involvement of mitochondrial matrix superoxide and hydrogen peroxide concentrations in these diseases can facilitate the rational development of appropriate therapies.

Lactate-induced MRP1 expression contributes to metabolism-based etoposide resistance in non-small cell lung cancer cells

BACKGROUND

Metabolic reprogramming contributes significantly to tumor development and is tightly linked to drug resistance. The chemotherapeutic agent etoposide (VP-16) has been used clinically in the treatment of lung cancer but possess different sensitivity and efficacy towards SCLC and NSCLC. Here, we assessed the impact of etoposide on glycolytic metabolism in SCLC and NSCLC cell lines and investigated the role of metabolic rewiring in mediating etoposide resistance.

METHODS

glycolytic differences of drug-treated cancer cells were determined by extracellular acidification rate (ECAR), glucose consumption, lactate production and western blot. DNA damage was evaluated by the comet assay and western blot. Chemoresistant cancer cells were analyzed by viability, apoptosis and western blot. Chromatin immunoprecipitation (ChIP) was used for analysis of DNA-protein interaction.

RESULTS

Here we showed that exposure to chemotherapeutic drug etoposide induces an exacerbation of ROS production which activates HIF-1α-mediated the metabolic reprogramming toward increased glycolysis and lactate production in non-small cell lung cancer (NSCLC). We identified lactic acidosis as the key that confers multidrug resistance through upregulation of multidrug resistance-associated protein 1 (MRP1, encoded by ABCC1), a member of ATP-binding cassette (ABC) transporter family. Mechanistically, lactic acid coordinates TGF-β1/Snail and TAZ/AP-1 pathway to induce formation of Snail/TAZ/AP-1 complex at the MRP1/ABCC1 promoter. Induction of MRP1 expression inhibits genotoxic and apoptotic effects of chemotherapeutic drugs by increasing drug efflux. Furthermore, titration of lactic acid with NaHCO₃ was sufficient to overcome resistance.

CONCLUSIONS

The chemotherapeutic drug etoposide induces the shift toward aerobic glycolysis in the NSCLC rather than SCLC cell lines. The increased lactic acid in extracellular environment plays important role in etoposide resistance through upregulation of MRP expression. These data provide first evidence for the increased lactate production, upon drug treatment, contributes to adaptive resistance in NSCLC and reveal potential vulnerabilities of lactate metabolism and/or pathway suitable for therapeutic targeting. Video Abstract The chemotherapeutic drug etoposide induces metabolic reprogramming towards glycolysis in the NSCLC cells. The secreted lactic acid coordinates TGF-β1/Snail and TAZ/AP-1 pathway to activate the expression of MRP1/ABCC1 protein, thus contributing to chemoresistance in NSCLC.

The Role of TRPC1 in Modulating Cancer Progression

Calcium ions (Ca²⁺) play an important role as second messengers in regulating a plethora of physiological and pathological processes, including the progression of cancer. Several selective and non-selective Ca²⁺-permeable ion channels are implicated in mediating Ca²⁺ signaling in cancer cells. In this review, we are focusing on TRPC1, a member of the TRP protein superfamily and a potential modulator of store-operated Ca²⁺ entry (SOCE) pathways. While TRPC1 is ubiquitously expressed in most tissues, its dysregulated activity may contribute to the hallmarks of various types of cancers, including breast cancer, pancreatic cancer, glioblastoma multiforme, lung cancer, hepatic cancer, multiple myeloma, and thyroid cancer. A range of pharmacological and genetic tools have been developed to address the functional role of TRPC1 in cancer. Interestingly, the unique role of TRPC1 has elevated this channel as a promising target for modulation both in terms of pharmacological inhibition leading to suppression of tumor growth and metastasis, as well as for agonistic strategies eliciting Ca²⁺ overload and cell death in aggressive metastatic tumor cells.

Metabolic reprogramming by tobacco-specific nitrosamines (TSNAs) in cancer

Metabolic reprogramming is a hallmark of cancer and the link between oncogenes activation, tumor supressors inactivation and bioenergetics modulation is well established. However, numerous carcinogenic environmental factors are responsible for early cancer initiation and their impact on metabolic reprogramming just starts to be deciphered. For instance, it was recently shown that UVB irradiation triggers metabolic reprogramming at the pre-cancer stage with implication for skin cancer detection and therapy. These observations foster the need to study the early changes in tissue metabolism following exposure to other carcinogenic events. According to the International Agency for Research on Cancer (IARC), tobacco smoke is a major class I-carcinogenic environmental factor that contains different carcinogens, but little is known on the impact of tobacco smoke on tissue metabolism and its participation to cancer initiation. In particular, tobacco-specific nitrosamines (TSNAs) play a central role in tobacco-smoke mediated cancer initiation. Here we describe the recent advances that have led to a new hypothesis regarding the link between nitrosamines signaling and metabolic reprogramming in cancer.

A close relationship between HIF-1α expression and bone metastases in advanced NSCLC, a retrospective analysis

Background: Hypoxia-inducible factor (HIF-1) is a transcription factor produced in hypoxia condition, it is closely associated with tumor angiogenesis and metastasis. Aim: To investigate the expression of HIF-1α in relation with the presence or absence of bone metastasis. Methods A retrospective analysis was carried out on samples deriving from bronchial biopsy and CT-guided trans-thoracic needle biopsy. Detection of HIF-1 expression was performed on tissue sample by a monoclonal murine antibody, comparing patients with or without bone metastases (BM+). Findings: In the total population the main histotype was adenocarcinoma (71.5%), COPD the prevalent comorbidity (73.6%), the mean pack-year was 36.4. Ninety-five histology samples were considered for analysis and comparison. Subdividing the population according to the presence or not of bone metastases, significant differences were found in pack-years (p = 0.02), time to progression (TTP) (p = 0.001) and COPD comorbidity (p = 0.04). The survival comparison between the two subgroups obtained by Kaplan-Meier method showed a longer TTP in patients with visceral metastases with a HR of 1.3 though the comparison by this method was not significant (p = 0.1). A higher intensity and percentage of expression of HIF-1α was recorded in the group with bone metastases (p = 0.02). The main variable affecting HIF expression in a multivariate analysis was the presence of bone metastases (p = 0.01). Interpretation: Patients affected by NSCLC IV stage with bone metastasis have lower survival. There is a very close link between bone metastasis and HIF-1α expression level. The latter could be considered a predictive factor of bone spread and poor prognosis.

Lactate-fueled oxidative metabolism drives DNA methyltransferase 1-mediated transcriptional co-activator with PDZ binding domain protein activation

Activity of transcriptional co‐activator with PDZ binding domain (TAZ) protein is strongly implicated in the pathogenesis of human cancer and is influenced by tumor metabolism. High levels of lactate concentration in the tumor microenvironment as a result of metabolic reprogramming are inversely correlated with patient overall survival. Herein, we investigated the role of lactate in the regulation of the activity of TAZ and showed that glycolysis‐derived lactate efficiently increased TAZ expression and activity in lung cancer cells. We showed that the reactive oxygen species (ROS) generated by lactate‐fueled oxidative phosphorylation (OXPHOS) in mitochondria activated AKT and thereby inhibited glycogen synthase kinase 3 beta/beta‐transducin repeat‐containing proteins (GSK‐3β/β‐TrCP)‐mediated ubiquitination and degradation of DNA methyltransferase 1 (DNMT1). Upregulation of DNMT1 by lactate caused hypermethylation of TAZ negative regulator of the LATS2 gene promoter, leading to TAZ activation. Moreover, TAZ binds to the promoter of DNMT1 and is necessary for DNMT1 transcription. Our study showed a molecular mechanism of DNMT1 in linking tumor metabolic reprogramming to the Hippo‐TAZ pathway and functional significance of the DNMT1‐TAZ feedback loop in the migratory and invasive potential of lung cancer cells.

Mitochondria as a possible target for nicotine action

Mitochondria are multifunctional and dynamic organelles deeply integrated into cellular physiology and metabolism. Disturbances in mitochondrial function are involved in several disorders such as neurodegeneration, cardiovascular diseases, metabolic diseases, and also in the aging process. Nicotine is a natural alkaloid present in the tobacco plant which has been well studied as a constituent of cigarette smoke. It has also been reported to influence mitochondrial function both in vitro and in vivo. This review presents a comprehensive overview of the present knowledge of nicotine action on mitochondrial function. Observed effects of nicotine exposure on the mitochondrial respiratory chain, oxidative stress, calcium homeostasis, mitochondrial dynamics, biogenesis, and mitophagy are discussed, considering the context of the experimental design. The potential action of nicotine on cellular adaptation and cell survival is also examined through its interaction with mitochondria. Although a large number of studies have demonstrated the impact of nicotine on various mitochondrial activities, elucidating its mechanism of action requires further investigation.

Potential effects of nicotine on glioblastoma and chemoradiotherapy: a review

Introduction: Glioblastoma multiforme (GBM) has a poor prognosis despite maximal surgical resection with subsequent multi-modal radiation and chemotherapy. Use of tobacco products following diagnosis and during the period of treatment for non-neural tumors detrimentally affects treatment and prognosis. Approximately, 16-28% of patients with glioblastoma continue to smoke after diagnosis and during treatment. The literature is sparse for information-pertaining effects of smoking and nicotine on GBM treatment and prognosis. Areas covered: This review discusses cellular pathways involved in GBM progression that might be affected by nicotine, as well as how nicotine may contribute to resistance to treatment. Similarities of GBM pathways to those in non-neural tumors are investigated for potential effects by nicotine. English language papers were identified using PubMed, Medline and Scopus databases using a combination of keywords including but not limited to the following: nicotine, vaping, tobacco, e-cigarettes, smoking, vaping AND glioblastoma or brain cancer OR/AND temozolomide, carmustine, methotrexate, procarbazine, lomustine, vincristine, and neural tumor cell lines. Expert opinion: Understanding the impact of nicotine on treatment and resistance to chemotherapeutics should allow physicians to educate their patients with GBM with evidence-based recommendations about the effects of continuing to use nicotine-containing products after diagnosis and during treatment.

Nicotine exposure impairs germ cell development in human fetal ovaries cultured in vitro

In the present paper, we found that human fetal ovaries (at ~16 weeks) express the transcripts for several subunits of the nicotinic acetylcholine receptor (nAChR). Exposure to the drug in vitro resulted in the marked increase of apoptosis in the ovaries in a time and dose-dependent manner. Evidence that adverse nicotine effects are potentially due to an increased level of reactive oxygen species (ROS) and consequent DNA damage, both in the ovarian somatic cells and germ cells, are reported. After 4 days of culture, exposure to 1 mM and 10 mM nicotine caused a 50% and 75% decrease, respectively, in the number of oogonia/oocytes present in the fetal ovaries. These results represent the first indication that nicotine may directly cause apoptosis in cells of the fetal human ovary and may lead to a reduction of the ovarian reserve oocytes and consequent precocious menopause in mothers smoking during pregnancy.

Two serine residues of non-metastasis protein 23-H1 are critical in inhibiting signal transducer and activator of transcription 3 activity in human lung cancer cells

Constitutive activation of signal transducer and activator of transcription 3 (STAT3) in numerous cancers, including lung cancer, is one of the major mechanisms of tumor progression and metastasis. The authors previously reported that the metastasis suppressor non-metastasis protein 23-H1 (Nm23-H1) negatively regulates STAT3 activity by inhibiting its phosphorylation on Tyr705. Nm23-H1 is a multifunction protein that has three different kinase activities. By transfecting the five mutants that inactivated three different kinase activities respectively into Nm23-H1 deficient lung cancer cell lines, it was identified that Nm23-H1^S44A (Ser44 to Ala) and Nm23-H1^S120G (Ser120 to Gly) mutant forms were unable to suppress STAT3 phosphorylation on Tyr705, resulting in increased expression of fibronectin and matrix metalloproteinase-9. Notably, protein inhibitor of activated STAT3 was also involved in Nm23-H1^S44A- and Nm23-H1^S120G-mediated suppression of STAT3 phosphorylation. The present results indicated that Ser44 and Ser120 sites of Nm23-H1 may be responsible for its biological suppressive effects of STAT3 and tumor metastasis, which may contribute to illuminate the metastasis suppression function of Nm23-H1 in lung cancer.

[Association of Indoor Air Pollution, Single Nucleotide Polymorphism of HIF-1α Gene with Susceptibility to Lung Cancer in Han Population in Fujian Province]

BACKGROUND

Hypoxia inducible factor-1α (HIF-1α) is associated with the progression and metastasis of lung cancer. There are, however, few studies on the relationship between the single nucleotide polymorphisms of HIF-1α and susceptibility to lung cancer. Therefore, we aimed to investigate the relationship between indoor air pollution, HIF-1α rs2057482, and the susceptibility to primary lung cancer of the Fujian Han population.

METHODS

The present study is a hospital-based case-control study. We recruited 1,096 lung cancer and 1,110 controls that were admitted to the Department of Thoracic Surgery of the First Affiliated Hospital and Union Hospital of Fujian Medical University and Fuzhou General Hospital of Nanjing Military Region from January 2006 to December 2012. The primary lung cancer cases were identified via pathological methods. Both case and control groups received questionnaires. Genotyping of HIF-1α gene rs2057482 locus polymorphism in all subjects were analyzed by MALDI-TOF-MS technique.

RESULTS

Individuals who carried the T-genotype of HIF-1α rs2057482 were more susceptible to small cell carcinoma (odds ratio of 1.725, 95%CI: 1.047-2.842). After adjusting for general and lung cancer-related factors, we found that in the co-dominant genetic model, rs2057482 TT carriers were 2.195 times more likely to develop lung cancer than CC carriers (95%CI: 1.038-4.463) in the population that were exposed to passive smoking. In the dominant genetic model, the risk of lung cancer was 1.911 times (95%CI: 1.121-3.258) that in the carriers of the rs2057482 T allele with a family history of cancer. In the recessive genetic model, rs2057482 TT carriers had a 0.159-fold increased risk of lung cancer (95%CI: 0.028-0.920) than TC+CC carriers in people with a history of lung disease. In the additive genetic model, the risk of lung cancer in rs2057482 TC+TT carriers was 1.542 times (95%CI: 1.107-2.340) that in the CC family of people with a family history of cancer.

CONCLUSIONS

HIF-1α rs2057482 may be associated with lung cancer susceptibility.
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Cigarette smoke reversibly activates hypoxia-inducible factor 1 in a reactive oxygen species-dependent manner

Cigarette smoke (CS) is a major contributor to the development of a large number of fatal and debilitating disorders. However, the precise molecular mechanisms underlying the effects of CS in lung disease are largely unknown. To elucidate these pathophysiological processes, we examined the in vitro and in vivo effects of CS extract (CSE) and CS on the transcription factor, hypoxia-inducible factor 1 (HIF-1). CSE induced concentration- and time-dependent accumulation of HIF-1α protein in human lung epithelial-like cells under non-hypoxic conditions. Genes upregulated by HIF-1, including vascular endothelial growth factor and regulated in development and DNA damage response 1, both of which are involved in smoking-induced emphysematous changes, were increased by CSE treatment under non-hypoxic conditions in vitro and in vivo. Further investigation revealed that reactive oxygen species were generated in cells exposed to CSE and were required for CSE-mediated induction of HIF-1α protein, as was activation of phosphoinositide 3-kinase and mitogen-activated protein kinase pathways. In conclusion, we demonstrated that CSE and CS induced HIF-1 activation in vitro and in vivo, respectively. The evidence warrants further investigation to indicate that HIF-1 plays an important role in CS-induced gene expression, which is deeply involved in pulmonary cellular stress and small airway remodelling.

Distribution, quantification and toxicity of cinnamaldehyde in electronic cigarette refill fluids and aerosols

OBJECTIVE

The aim of this study was to evaluate the distribution, concentration and toxicity of cinnamaldehyde in electronic cigarette (e-cigarette) refill fluids and aerosols.

METHODS

The distribution and concentration of cinnamaldehyde were determined in 39 e-cigarette refill fluids plus 6 duplicates using gas chromatography and mass spectrometry (GC/MS). A cinnamaldehyde toxicity profile was established for embryonic and adult cells using a live cell imaging assay, immunocytochemistry, the comet assay and a recovery assay.

RESULTS

Twenty of the 39 refill fluids contained cinnamaldehyde at concentrations that are cytotoxic to human embryonic and lung cells in the MTT assay. Cinnamon Ceylon aerosol produced in a cartomizer-style e-cigarette was cytotoxic. Cinnamon Ceylon aerosols and refill fluid aerosols (80% propylene glycol or cinnamaldehyde/propylene glycol) made using a tank/boxmod e-cigarette were more cytotoxic at 5 V than 3 V. Using GC/MS, aerosols produced at 5 V contained 10 additional peaks not present in aerosol generated at 3 V. One of these, 2,3-butandione (diacetyl), was confirmed with an authentic standard. Cinnamaldehyde depolymerised microtubules in human pulmonary fibroblasts. At concentrations that produced no effect in the MTT assay, cinnamaldehyde decreased growth, attachment and spreading; altered cell morphology and motility; increased DNA strand breaks; and increased cell death. At the MTT IC₅₀ concentration, lung cells were unable to recover from cinnamaldehyde after 2 hours of treatment, whereas embryonic cells recovered after 8 hours.

CONCLUSIONS

Cinnamaldehyde-containing refill fluids and aerosols are cytotoxic, genotoxic and low concentrations adversely affect cell processes and survival. These data indicate that cinnamaldehyde in e-cigarette refill fluids/aerosols may impair homeostasis in the respiratory system.

Current relevance of hypoxia in head and neck cancer

Head and Neck cancer (HNC) is a complex mix of cancers and one of the more common cancers with a relatively poor prognosis. One of the factors that may assist us in predicting survival and allow us to adjust our treatment strategies is the presence of tumor hypoxia. In this overview we aim to evaluate the current evidence and potential clinical relevance of tumor hypoxia in head and neck cancer according to an extensive search of current literature.An abundance of evidence and often contradictory evidence is found in the literature. Even the contradictory evidence and comparisons are difficult to judge as criteria and methodologies differ greatly, furthermore few prospective observational studies exist for verification of the pre-clinical studies. Despite these discrepancies there is clear evidence of associations between prognosis and poor tumor oxygenation biomarkers such as HIF-1α, GLUT-1 and lactate, though these associations are not exclusive. The use of genetic markers is expanding and will probably lead to significantly more and complex evidence. The lack of oxygenation in head and neck tumors is of paramount importance for the prediction of treatment outcomes and prognosis. Despite the wide array of conflicting evidence, the drive towards non-invasive prediction of tumor hypoxia should continue.

Reactive oxygen species induced by non-steroidal anti-inflammatory drugs enhance the effects of photodynamic therapy in gastric cancer cells

Photodynamic therapy is useful for the treatment of cancer because it is minimally invasive for patients. Certain porphyrin compounds and their derivatives have been used as the photosensitizer because they accumulate specifically in cancerous tissues. However, the detailed mechanism of this phenomenon has not been clarified. We previously reported that a proton-coupled folate transporter, HCP1, transported porphyrins and that regulation of the protein was associated with cancer-specific reactive oxygen species from mitochondria (mitROS). Therefore, over-generation of mitROS could increase HCP1 expression and the effect of photodynamic therapy. We investigated whether pretreatment with indomethacin influenced photodynamic therapy by using a rat normal gastric mucosal cell line, RGM1, its cancer-like mutated cell line, RGK1, and a manganese superoxide dismutase (MnSOD)-overexpressing RGK cell line, RGK-MnSOD. Indomethacin promotes the generation of cellular mitROS by inhibiting the electron transport chain, and MnSOD scavenges the mitROS. We elucidated that indomethacin enhanced cancer-specific mitROS generation and increased HCP1 expression. Furthermore, RGK1 cells showed higher cellular incorporation of hematoporphyrin and better therapeutic effect with indomethacin treatment whereas RGK-MnSOD cells did not show a difference. Thus, we concluded that indomethacin improved the effect of photodynamic therapy by inducing increased mitROS generation in cancer cells.

Apoptosis Activation in Human Lung Cancer Cell Lines by a Novel Synthetic Peptide Derived from Conus californicus Venom

Lung cancer is one of the most common types of cancer in men and women and a leading cause of death worldwide resulting in more than one million deaths per year. The venom of marine snails Conus contains up to 200 pharmacologically active compounds that target several receptors in the cell membrane. Due to their diversity and specific binding properties, Conus toxins hold great potential as source of new drugs against cancer. We analyzed the cytotoxic effect of a 17-amino acid synthetic peptide (s-cal14.1a) that is based on a native toxin (cal14.1a) isolated from the sea snail Conus californicus. Cytotoxicity studies in four lung cancer cell lines were complemented with measurement of gene expression of apoptosis-related proteins Bcl-2, BAX and the pro-survival proteins NFκB-1 and COX-2, as well as quantification of caspase activity. Our results showed that H1299 and H1437 cell lines treated with s-call4.1a had decreased cell viability, activated caspases, and reduced expression of the pro-survival protein NFκB-1. To our knowledge, this is the first report describing activation of apoptosis in human lung cancer cell lines by s-cal14.1a and we offer insight into the possible mechanism of action.

Expression of GLUT-1 in oral squamous cell carcinoma in tobacco and non-tobacco users

BACKGROUND

GLUTs are a family of proteins that mediate glucose transport through the membrane, expressed in head and neck squamous cell carcinoma. GLUT-1 positivity in malignant cells indicates increased proliferative activity, energy requirements, aggressive behaviour and poor radiation response.

AIM

To observe the expression of GLUT-1 protein in oral squamous cell carcinoma in tobacco and non-tobacco users and to correlate the expression with histopathological grading and pathological staging.

METHODS

50 cases (25 tobacco and 25 non-tobacco) of oral squamous cell carcinoma, selected during period of August 2014 to July 2015. Histopathological grading, TNM and staging were done. Immunohistochemical staining was performed using standard protocol for paraffin embedded sections. Analysis was performed on SPSS software (Windows version 17.0).

RESULTS

Significant association of GLUT-1 expression was found with history of tobacco (p < 0.001), Bryne's grade (p < 0.001), tumour size (p = 0.001), nodal metastasis (p = 0.022) and stage (p < 0.001). Higher GLUT-1 expression in stage II, stage III and stage IV was found as compared to stage I. GLUT-1 immunoexpression also shows progressive switch from membranous to cytoplasmic to combined location correlating with histopathologic grade and pTNM stage.

CONCLUSION

GLUT-1 expression correlates significantly with histological grade and pTNM staging of oral squamous cell carcinoma. It also significantly correlates with tobacco addiction. Thus, GLUT-1 expression may serve as a biomarker for patients of oral squamous cell carcinoma.

Increased S100A4 expression in the vasculature of human COPD lungs and murine model of smoke-induced emphysema

Background

Chronic obstructive lung disease (COPD) is a common cause of death in industrialized countries often induced by exposure to tobacco smoke. A substantial number of patients with COPD also suffer from pulmonary hypertension that may be caused by hypoxia or other hypoxia-independent stimuli - inducing pulmonary vascular remodeling. The Ca²⁺ binding protein, S100A4 is known to play a role in non-COPD-driven vascular remodeling of intrapulmonary arteries. Therefore, we have investigated the potential involvement of S100A4 in COPD induced vascular remodeling.

Methods

Lung tissue was obtained from explanted lungs of five COPD patients and five non-transplanted donor lungs. Additionally, mice lungs of a tobacco-smoke-induced lung emphysema model (exposure for 3 and 8 month) and controls were investigated. Real-time RT-PCR analysis of S100A4 and RAGE mRNA was performed from laser-microdissected intrapulmonary arteries. S100A4 immunohistochemistry was semi-quantitatively evaluated. Mobility shift assay and siRNA knock-down were used to prove hypoxia responsive elements (HRE) and HIF binding within the S100A4 promoter.

Results

Laser-microdissection in combination with real-time PCR analysis revealed higher expression of S100A4 mRNA in intrapulmonary arteries of COPD patients compared to donors. These findings were mirrored by semi-quantitative analysis of S100A4 immunostaining. Analogous to human lungs, in mice with tobacco-smoke-induced emphysema an up-regulation of S100A4 mRNA and protein was observed in intrapulmonary arteries. Putative HREs could be identified in the promoter region of the human S100A4 gene and their functionality was confirmed by mobility shift assay. Knock-down of HIF1/2 by siRNA attenuated hypoxia-dependent increase in S100A4 mRNA levels in human primary pulmonary artery smooth muscle cells. Interestingly, RAGE mRNA expression was enhanced in pulmonary arteries of tobacco-smoke exposed mice but not in pulmonary arteries of COPD patients.

Conclusions

As enhanced S100A4 expression was observed in remodeled intrapulmonary arteries of COPD patients, targeting S100A4 could serve as potential therapeutic option for prevention of vascular remodeling in COPD patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s12931-015-0284-5) contains supplementary material, which is available to authorized users.

α-conotoxins revealed different roles of nicotinic cholinergic receptor subtypes in oncogenesis of Ehrlich tumor and in the associated inflammation

Multiple injections of conotoxin MII, a blocker of alfa3-ß2 and alfa6-containing subtypes of nicotinic acetylcholine receptors (n-AChRs), as well as conotoxin ArIB11L16D, a blocker of alfa7 subtype n-AChR, at a dose of 1 nmol/kg reduce both the lactate dehydrogenase level in tumor cells and the inflammatory leukocyte infiltration in tumor tissue in mice bearing Ehrlich carcinoma. The first stage of pathomorphism was detected in the tumor tissue after the treatment with the ArIB11L16D conotoxin, whereas the second stage was observed after the treatment with conotoxins RgIA and MII. Only MII injections led to a significant reduction in tumor growth. Our results show the involvement of n-AChRs in the regulation of metabolic processes and cell-cell interactions related to carcinogenesis and tumor-associated inflammation.

Increased oxidative stress and disrupted small intestinal tight junctions in cigarette smoke-exposed rats

Chronic obstructive pulmonary disease (COPD) is a major public health problem, and cigarette smoke (CS) is the primary risk factor. The pathology is often observed in the lung, but COPD is also associated with intestinal barrier disruption, although the underlying mechanisms are poorly understood. To address this, a CS‑exposed rat model was evaluated in the present study by analyzing small intestinal gene expression using reverse transcription‑quantitative polymerase chain reaction. CS exposure caused upregulation of the nicotinamide adenine dinucleotide phosphate‑oxidase subunits nox2 and p22phox in the small intestine, while the antioxidative enzyme superoxide dismutase was downregulated. CS exposure also increased bax expression and decreased bcl‑2 expression. This was associated with an elevation of hypoxia‑inducible factor (HIF)‑1α. Claudin‑1 was decreased and claudin‑2 increased, indicating a loosening of small intestinal tight junctions (TJs). These data suggest that during the development of COPD, HIF‑1α expression is altered in the small intestine, which may be associated with the increased oxidative stress and apoptosis, eventually resulting in disruption of the intestinal TJs.

Impaired mitophagy leads to cigarette smoke stress-induced cellular senescence: implications for chronic obstructive pulmonary disease

Cigarette smoke (CS)-induced cellular senescence is involved in the pathogenesis of chronic obstructive pulmonary disease (COPD). The molecular mechanism by which CS induces cellular senescence is unknown. Here, we show that CS stress (exposure of primary lung cells to CS extract 0.2-0.75% with a half-maximal inhibitory concentration of ∼0.5%) led to impaired mitophagy and perinuclear accumulation of damaged mitochondria associated with cellular senescence in both human lung fibroblasts and small airway epithelial cells (SAECs). Impaired mitophagy was attributed to reduced Parkin translocation to damaged mitochondria, which was due to CS-induced cytoplasmic p53 accumulation and its interaction with Parkin. Impaired Parkin translocation to damaged mitochondria was also observed in mouse lungs with emphysema (6 months CS exposure, 100 mg TPM/m(3)) as well as in lungs of chronic smokers and patients with COPD. Primary SAECs from patients with COPD also exhibited impaired mitophagy and increased cellular senescence via suborganellar signaling. Mitochondria-targeted antioxidant (Mito-Tempo) restored impaired mitophagy, decreased mitochondrial mass accumulation, and delayed cellular senescence in Parkin-overexpressing cells. In conclusion, defective mitophagy leads to CS stress-induced lung cellular senescence, and restoring mitophagy delays cellular senescence, which provides a promising therapeutic intervention in chronic airway diseases.

Celastrol stimulates hypoxia-inducible factor-1 activity in tumor cells by initiating the ROS/Akt/p70S6K signaling pathway and enhancing hypoxia-inducible factor-1α protein synthesis

Celastrol, a tripterine derived from the traditional Chinese medicine plant Tripterygium wilfordii Hook F. (“Thunder of God Vine”), has been reported to have multiple effects, such as anti-inflammation, suppression of tumor angiogenesis, inhibition of tumor growth, induction of apoptosis and protection of cells against human neurodegenerative diseases. However, the mechanisms that underlie these functions are not well defined. In this study, we reported for the first time that Celastrol could induce HIF-1α protein accumulation in multiple cancer cell lines in an oxygen-independent manner and that the enhanced HIF-1α protein entered the nucleus and promoted the transcription of the HIF-1 target genes VEGF and Glut-1. Celastrol did not influence HIF-1α transcription. Instead, Celastrol induced the accumulation of the HIF-1α protein by inducing ROS and activating Akt/p70S6K signaling to promote HIF-1α translation. In addition, we found that the activation of Akt by Celastrol was transient. With increased exposure time, inhibition of Hsp90 chaperone function by Celastrol led to the subsequent depletion of the Akt protein and thus to the suppression of Akt activity. Moreover, in HepG2 cells, the accumulation of HIF-1α increased the expression of BNIP3, which induced autophagy. However, HIF-1α and BNIP3 did not influence the cytotoxicity of Celastrol because the main mechanism by which Celastrol kills cancer cells is through stimulating ROS-mediated JNK activation and inducing apoptosis. Furthermore, our data showed that the dose required for Celastrol to induce HIF-1α protein accumulation and enhance HIF-1α transcriptional activation was below its cytotoxic threshold. A cytotoxic dose of Celastrol for cancer cells did not display cytotoxicity in LO2 normal human liver cells, which indicated that the novel functions of Celastrol in regulating HIF-1 signaling and inducing autophagy might be used in new applications, such as in anti-inflammation and protection of cells against human neurodegenerative diseases. Future studies regarding these applications are required.

Increased antigen presentation but impaired T cells priming after upregulation of interferon-beta induced by lipopolysaccharides is mediated by upregulation of B7H1 and GITRL

Dendritic cells are able to present Ag-derived peptides on MHC class I and II molecules and induce T cells priming. Lipopolysaccharides (LPS), an activator of Toll-like 4 receptor (TLR4) signaling, has been demonstrated to facilitate Ag-presentation, up-regulate surface molecules expression but impair T cells priming. In this study, we investigated the effect of LPS on nicotine-enhanced DCs-dependent T cells priming and the mechanisms of LPS orchestrating the immunosuppressive program. We could demonstrate that the treatment with LPS resulted in increased surface molecules expression, enhanced Ag-presentation, up-regulated release of TGF-beta, TNF-alpha, IL-6, and IFN-beta. Concomititantly, the upregulation of IFN-beta in DCs induces the up-regulation of coinhibitory molecules B7H1 and GITRL, which cause an impaired activation of naïve Ag-specific T cells and the induction of T cell tolerance by enhancing B7H1-PD-1 interactions and promoting GITRL-GITL facilitated Treg generation, respectively. These data provide a mechanistic basis for the immunomodulatory action of IFN-beta which might open new possibilities in the development of therapeutic approaches aimed at the control of excessive immune response and persistent infection.

AG1478 inhibits the migration and invasion of cisplatin-resistant human lung adenocarcinoma cells via the cell cycle regulation by matrix metalloproteinase-9

AG1478 is a specific epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor. The effect of AG1478 on the A549/DDP (cisplatin-resistant human lung adenocarcinoma) cell line is unknown. The aim of the present study was to investigate the effects of AG1478 on the A549/DDP cell line and its sensitive parental A549 cell line. The two cell lines were treated with AG1478 and the growth, proliferation, migration and invasion of the tumor cell lines were measured using flow cytometry, as well as 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, wound healing and Transwell system assays. The expression of metastasis-associated genes and proteins was evaluated by quantitative-polymerase chain reaction and western blot analysis. The molecular mechanisms were investigated using short-interfering RNAs (siRNAs). The phosphorylation status of the key cell cycle protein, retinoblastoma (Rb), was also investigated. The results revealed that AG1478 inhibited the growth of the two cell lines with varying potency, and that the A549/DDP cell line was more sensitive to AG1478 than the A549 cell line. Cell migration and invasion, as well as matrix metalloproteinase (MMP)-9 and E2F1 expression were significantly inhibited. However, MMP-9 expression was also significantly suppressed in the two cell lines following transfection with E2F1-targeting siRNA. In addition, AG1478 significantly arrested A549/DDP and A549 cells in G₁ phase, with a corresponding reduction in the S phase. The phosphorylation of Rb protein at various sites was selectively inhibited by AG1478 at various time points. The results indicate that AG1478 may provide a clinical therapeutic approach for certain types of cisplatin-resistant lung cancer.

Connections of nicotine to cancer

This Opinion article discusses emerging evidence of direct contributions of nicotine to cancer onset and growth. The list of cancers reportedly connected to nicotine is expanding and presently includes small-cell and non-small-cell lung carcinomas, as well as head and neck, gastric, pancreatic, gallbladder, liver, colon, breast, cervical, urinary bladder and kidney cancers. The mutagenic and tumour-promoting activities of nicotine may result from its ability to damage the genome, disrupt cellular metabolic processes, and facilitate growth and spreading of transformed cells. The nicotinic acetylcholine receptors (nAChRs), which are activated by nicotine, can activate several signalling pathways that can have tumorigenic effects, and these receptors might be able to be targeted for cancer therapy or prevention. There is also growing evidence that the unique genetic makeup of an individual, such as polymorphisms in genes encoding nAChR subunits, might influence the susceptibility of that individual to the pathobiological effects of nicotine. The emerging knowledge about the carcinogenic mechanisms of nicotine action should be considered during the evaluation of regulations on nicotine product manufacturing, distribution and marketing.

Methylome-wide association study of schizophrenia: identifying blood biomarker signatures of environmental insults

IMPORTANCE

Epigenetic studies present unique opportunities to advance schizophrenia research because they can potentially account for many of its clinical features and suggest novel strategies to improve disease management.

OBJECTIVE

To identify schizophrenia DNA methylation biomarkers in blood.

DESIGN, SETTING, AND PARTICIPANTS

The sample consisted of 759 schizophrenia cases and 738 controls (N = 1497) collected in Sweden. We used methyl-CpG-binding domain protein-enriched genome sequencing of the methylated genomic fraction, followed by next-generation DNA sequencing. We obtained a mean (SD) number of 68 (26.8) million reads per sample. This massive data set was processed using a specifically designed data analysis pipeline. Critical top findings from our methylome-wide association study (MWAS) were replicated in independent case-control participants using targeted pyrosequencing of bisulfite-converted DNA.

MAIN OUTCOMES AND MEASURES

Status of schizophrenia cases and controls.

RESULTS

Our MWAS suggested a considerable number of effects, with 25 sites passing the highly conservative Bonferroni correction and 139 sites significant at a false discovery rate of 0.01. Our top MWAS finding, which was located in FAM63B, replicated with P = 2.3 × 10-10. It was part of the networks regulated by microRNA that can be linked to neuronal differentiation and dopaminergic gene expression. Many other top MWAS results could be linked to hypoxia and, to a lesser extent, infection, suggesting that a record of pathogenic events may be preserved in the methylome. Our findings also implicated a site in RELN, one of the most frequently studied candidates in methylation studies of schizophrenia.

CONCLUSIONS AND RELEVANCE

To our knowledge, the present study is one of the first MWASs of disease with a large sample size using a technology that provides good coverage of methylation sites across the genome. Our results demonstrated one of the unique features of methylation studies that can capture signatures of environmental insults in peripheral tissues. Our MWAS suggested testable hypotheses about disease mechanisms and yielded biomarkers that can potentially be used to improve disease management.

Nicotine promotes cell proliferation and induces resistance to cisplatin by α7 nicotinic acetylcholine receptor‑mediated activation in Raw264.7 and El4 cells

Although nicotine is a risk factor for carcinogenesis and atherosclerosis, epidemiological data indicate that nicotine has therapeutic benefits in treating Alzheimer's disease. Our previous studies also showed that nicotine-treated dendritic cells have potential antitumor effects. Hence, the precise effects of nicotine on the biological characterizations of cells are controversial. The aim of the present study was to assess the roles of α7 nicotinic acetylcholine receptors (nAChRs), Erk1/2-p38-JNK and PI3K-Akt pathway in nicotine-mediated proliferation and anti-apoptosis effects. The results firstly showed that nicotine treatment clearly augmented cell viability and upregulated PCNA expression in both Raw264.7 and El4 cells. Meanwhile, nicotine afforded protection against cisplatin-induced toxicity through inhibiting caspase-3 activation and upregulating anti-apoptotic protein expression. Further exploration demonstrated that nicotine efficiently abolished cisplatin-promoted mitochondria translocation of Bax and the release of cytochrome c. The pretreatment of α-bungarotoxin and tubocurarine chloride significantly attenuated nicotine-augmented cell viability, abolished caspase-3 activation and α7 nAChR upregulation. Both Erk-JNK-p38 and PI3K-Akt signaling pathways could be activated by nicotine treatment in Raw264.7 and El4 cells. Notably, when Erk-JNK and PI3K-Akt activities were inhibited, nicotine-augmented cell proliferation and anti-apoptotic effects were abolished accordingly. The results presented here indicate that nicotine could achieve α7 nAChR-mediated proliferation and anti-apoptotic effects by activating Erk-JNK and PI3K-Akt pathways respectively, providing potential therapeutic molecules to deal with smoking-associated human diseases.

NADPH oxidase-mitochondria axis-derived ROS mediate arsenite-induced HIF-1α stabilization by inhibiting prolyl hydroxylases activity

Arsenic exposure has been shown to induce hypoxia inducible factor 1α (HIF-1α) accumulation, however the underlying mechanism remains unknown. In the present study, we tested the hypothesis that arsenic exposure triggered the interaction between NADPH oxidase and mitochondria to promote reactive oxygen species (ROS) production, which inactivate prolyl hydroxylases (PHDs) activity, leading to the stabilization of HIF-1α protein. Exposure of human immortalized liver cell line HL-7702 cells to arsenite induced HIF-1α accumulation in a dose-dependent manner, which was abolished by SOD mimetic MnTMPyP. Inhibition of NADPH oxidase with diphenyleneiodonium chloride (DPI) or inhibition of mitochondrial respiratory chain with rotenone significantly blocked arsenite-induced ROS production, and the mitochondria appeared to be the major source of ROS production. Arsenite treatment inhibited HIF-1α hydroxylation by prolyl hydroxylases (PHDs) and increased HIF-1α stabilization, but did not affect HIF-1α mRNA expression and Akt activation. Supplementation of ascorbate or Fe(II) completely abolished arsenite-induced PHDs inhibition and HIF-1α stabilization. In conclusion, these results define a unique mechanism of HIF-1α accumulation following arsenic exposure, that is, arsenic activates NADPH oxidase-mitochondria axis to produce ROS, which deplete intracellular ascorbate and Fe(II) to inactivate PHDs, leading to HIF-1α stabilization.