The environmental carcinogen benzo[a]pyrene induces a Warburg-like metabolic reprogramming dependent on NHE1 and associated with cell survival

Histone lactylation bridges metabolic reprogramming and epigenetic rewiring in driving carcinogenesis: Oncometabolite fuels oncogenic transcription

Heightened lactate production in cancer cells has been linked to various cellular mechanisms such as angiogenesis, hypoxia, macrophage polarisation and T-cell dysfunction. The lactate-induced lactylation of histone lysine residues is noteworthy, as it functions as an epigenetic modification that directly augments gene transcription from chromatin. This epigenetic modification originating from lactate effectively fosters a reliance on transcription, thereby expediting tumour progression and development. Herein, this review explores the correlation between histone lactylation and cancer characteristics, revealing histone lactylation as an innovative epigenetic process that enhances the vulnerability of cells to malignancy. Moreover, it is imperative to acknowledge the paramount importance of acknowledging innovative therapeutic methodologies for proficiently managing cancer by precisely targeting lactate signalling. This comprehensive review illuminates a crucial yet inadequately investigated aspect of histone lactylation, providing valuable insights into its clinical ramifications and prospective therapeutic interventions centred on lactylation.

Azadirachtin Attenuates Carcinogen Benzo(a) Pyrene-Induced DNA Damage, Cell Cycle Arrest, Apoptosis, Inflammatory, Metabolic, and Oxidative Stress in HepG2 Cells

Azadirachtin (AZD), a limonoid from the versatile, tropical neem tree (Azadirachta indica), is well known for its many medicinal, and pharmacological effects. Its effects as an anti-oxidant, anti-inflammatory, and anti-cancer agent are well known. However, not many studies have explored the effects of AZD on toxicities induced by benzo(a)pyrene (B(a)P), a toxic component of cigarette smoke known to cause DNA damage and cell cycle arrest, leading to different kinds of cancer. In the present study, using HepG2 cells, we investigated the protective effects of Azadirachtin (AZD) against B(a)P-induced oxidative/nitrosative and metabolic stress and mitochondrial dysfunction. Treatment with 25 µM B(a)P for 24 h demonstrated an increased production of reactive oxygen species (ROS), followed by increased lipid peroxidation and DNA damage presumably, due to the increased metabolic activation of B(a)P by CYP 450 1A1/1A2 enzymes. We also observed intrinsic and extrinsic apoptosis, alterations in glutathione-dependent redox homeostasis, cell cycle arrest, and inflammation after B(a)P treatment. Cells treated with 25 µM AZD for 24 h showed decreased oxidative stress and apoptosis, partial protection from DNA damage, and an improvement in mitochondrial functions and bioenergetics. The improvement in antioxidant status, anti-inflammatory potential, and alterations in cell cycle regulatory markers qualify AZD as a potential therapeutic in combination with anti-cancer drugs.

Lung cancer associated with combustion particles and fine particulate matter (PM2.5) - The roles of polycyclic aromatic hydrocarbons (PAHs) and the aryl hydrocarbon receptor (AhR)

Air pollution is the leading cause of lung cancer after tobacco smoking, contributing to 20% of all lung cancer deaths. Increased risk associated with living near trafficked roads, occupational exposure to diesel exhaust, indoor coal combustion and cigarette smoking, suggest that combustion components in ambient fine particulate matter (PM2.5), such as polycyclic aromatic hydrocarbons (PAHs), may be central drivers of lung cancer. Activation of the aryl hydrocarbon receptor (AhR) induces expression of xenobiotic-metabolizing enzymes (XMEs) and increase PAH metabolism, formation of reactive metabolites, oxidative stress, DNA damage and mutagenesis. Lung cancer tissues from smokers and workers exposed to high combustion PM levels contain mutagenic signatures derived from PAHs. However, recent findings suggest that ambient air PM2.5 exposure primarily induces lung cancer development through tumor promotion of cells harboring naturally acquired oncogenic mutations, thus lacking typical PAH-induced mutations. On this background, we discuss the role of AhR and PAHs in lung cancer development caused by air pollution focusing on the tumor promoting properties including metabolism, immune system, cell proliferation and survival, tumor microenvironment, cell-to-cell communication, tumor growth and metastasis. We suggest that the dichotomy in lung cancer patterns observed between smoking and outdoor air PM2.5 represent the two ends of a dose-response continuum of combustion PM exposure, where tumor promotion in the peripheral lung appears to be the driving factor at the relatively low-dose exposures from ambient air PM2.5, whereas genotoxicity in the central airways becomes increasingly more important at the higher combustion PM levels encountered through smoking and occupational exposure.

Protective Effect of Aquilaria crassna Leaf Extract against Benzo[a]pyrene-Induced Toxicity in Neuronal Cells and Caenorhabditis elegans: Possible Active Constituent Includes Clionasterol

Aquilaria crassna (AC) is a beneficial plant widely used to alleviate various health ailments. Nevertheless, the neuroprotection, antiaging, and xenobiotic detoxification against high benzo[a]pyrene induction have not been investigated. This study aimed to investigate the effects of ethanolic extract of AC leaves (ACEE) in vitro using SH-SY5Y cells and in vivo using Caenorhabditis elegans (C. elegans). Neuroprotective activities and cell cycle progression were studied using SH-SY5Y cells. Additionally, C. elegans was used to determine longevity, health span, and transcriptional analysis. Furthermore, ACEE possible active compounds were analyzed by gas chromatograph-mass spectrometry (GC-MS) analysis and the possible active compounds were evaluated using a molecular docking study. First, ACEE possessed neuroprotective effects by normalizing cell cycle progression via the regulation of AhR/CYP1A1/cyclin D1 pathway. Next, ACEE played a role in xenobiotic detoxification in high B[a]P-induced C. elegans by the amelioration of lifespan reduction, and body length and size decrease through the reduction in gene expression in hexokinase (hxk) and CYP35 pathway. Finally, phytochemicals of ACEE were identified and we uncovered that clionasterol was the possible active constituent in powerfully inhibiting both CYP1A1 and hexokinase II receptor. Essentially, ACEE was recognized as a potential alternative medicine to defend against high B[a]P effects on neurotoxicity and xenobiotic detoxification.

Short-Term Exposure to Benzo(a)Pyrene Causes Disruption of GnRH Network in Zebrafish Embryos

Benzo(a)pyrene (BaP), a polycyclic aromatic hydrocarbon, is considered a common endocrine disrupting chemical (EDC) with mutagenic and carcinogenic effects. In this work, we evaluated the effects of BaP on the hypothalamo-pituitary-gonadal axis (HPG) of zebrafish embryos. The embryos were treated with 5 and 50 nM BaP from 2.5 to 72 hours post-fertilization (hpf) and obtained data were compared with those from controls. We followed the entire development of gonadotropin releasing hormone (GnRH3) neurons that start to proliferate from the olfactory region at 36 hpf, migrate at 48 hpf and then reach the pre-optic area and the hypothalamus at 72 hpf. Interestingly, we observed a compromised neuronal architecture of the GnRH3 network after the administration of 5 and 50 nM BaP. Given the toxicity of this compound, we evaluated the expression of genes involved in antioxidant activity, oxidative DNA damage and apoptosis and we found an upregulation of these pathways. Consequently, we performed a TUNEL assay and we confirmed an increment of cell death in brain of embryos treated with BaP. In conclusion our data reveal that short-term exposure of zebrafish embryos to BaP affects GnRH3 development likely through a neurotoxic mechanism.

Reprogramming of glycolysis by chemical carcinogens during tumor development

Indiscriminate usage and mismanagement of chemicals in the agricultural and industrial sectors have contaminated different environmental compartments. Exposure to these persistent and hazardous pollutants like heavy metals, endocrine disruptors, aromatic hydrocarbons, and pesticides can result in various health adversities, including cancer. Chemical carcinogens follow a similar pattern of carcinogenesis, like oxidative stress, chromosomal aberration, DNA double-strand break, mismatch repair, and misregulation of oncogenic and/or tumor suppressors. Out of several cancer-associated endpoints, cellular metabolic homeostasis is the commonest to be deregulated upon chemical exposure. Chemical carcinogens hamper glycolytic reprogramming to fuel the malignant transformation of the cells and/or promote cancer progression. Several regulators like Akt, ERK, Ras, c-Myc, HIF-1α, and p53 regulate glycolysis in chemical-induced carcinogenesis. However, the deregulation of the anabolic biochemistry of glucose during chemical-induced carcinogenesis remains to be uncovered. This review comprehensively covers the environmental chemical-induced glycolytic shift during carcinogenesis and its mechanism. The focus is also to fill the major gaps associated with understanding the fairy tale between environmental carcinogens and metabolic reprogramming. Although evidence from studies regarding glycolytic reprogramming in chemical carcinogenesis provides valuable insights into cancer therapy, exposure to a mixture of toxicants and their mechanism of inducing carcinogenesis still needs to be studied.

Carbonaceous Nanoparticle Air Pollution: Toxicity and Detection in Biological Samples

Among the different air pollutants, particulate matter (PM) is of great concern due to its abundant presence in the atmosphere, which results in adverse effects on the environment and human health. The different components of PM can be classified based on their physicochemical properties. Carbonaceous particles (CPs) constitute a major fraction of ultrafine PM and have the most harmful effects. Herein, we present a detailed overview of the main components of CPs, e.g., carbon black (CB), black carbon (BC), and brown carbon (BrC), from natural and anthropogenic sources. The emission sources and the adverse effects of CPs on the environment and human health are discussed. Particularly, we provide a detailed overview of the reported toxic effects of CPs in the human body, such as respiratory effects, cardiovascular effects, neurodegenerative effects, carcinogenic effects, etc. In addition, we also discuss the challenges faced by and limitations of the available analytical techniques for the qualitative and quantitative detection of CPs in atmospheric and biological samples. Considering the heterogeneous nature of CPs and biological samples, a detailed overview of different analytical techniques for the detection of CPs in (real-exposure) biological samples is also provided. This review provides useful insights into the classification, toxicity, and detection of CPs in biological samples.

Advanced Polymeric Nanocomposites for Water Treatment Applications: A Holistic Perspective

Water pollution remains one of the greatest challenges in the modern era, and water treatment strategies have continually been improved to meet the increasing demand for safe water. In the last few decades, tremendous research has been carried out toward developing selective and efficient polymeric adsorbents and membranes. However, developing non-toxic, biocompatible, cost-effective, and efficient polymeric nanocomposites is still being explored. In polymer nanocomposites, nanofillers and/or nanoparticles are dispersed in polymeric matrices such as dendrimer, cellulose, resins, etc., to improve their mechanical, thermophysical, and physicochemical properties. Several techniques can be used to develop polymer nanocomposites, and the most prevalent methods include mixing, melt-mixing, in-situ polymerization, electrospinning, and selective laser sintering techniques. Emerging technologies for polymer nanocomposite development include selective laser sintering and microwave-assisted techniques, proffering solutions to aggregation challenges and other morphological defects. Available and emerging techniques aim to produce efficient, durable, and cost-effective polymer nanocomposites with uniform dispersion and minimal defects. Polymer nanocomposites are utilized as filtering membranes and adsorbents to remove chemical contaminants from aqueous media. This study covers the synthesis and usage of various polymeric nanocomposites in water treatment, as well as the major criteria that influence their performance, and highlights challenges and considerations for future research.

Benzo[a]pyrene—Environmental Occurrence, Human Exposure, and Mechanisms of Toxicity

Benzo[a]pyrene (B[a]P) is the main representative of polycyclic aromatic hydrocarbons (PAHs), and has been repeatedly found in the air, surface water, soil, and sediments. It is present in cigarette smoke as well as in food products, especially when smoked and grilled. Human exposure to B[a]P is therefore common. Research shows growing evidence concerning toxic effects induced by this substance. This xenobiotic is metabolized by cytochrome P450 (CYP P450) to carcinogenic metabolite: 7β,8α-dihydroxy-9α,10α-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (BPDE), which creates DNA adducts, causing mutations and malignant transformations. Moreover, B[a]P is epigenotoxic, neurotoxic, and teratogenic, and exhibits pro-oxidative potential and causes impairment of animals’ fertility. CYP P450 is strongly involved in B[a]P metabolism, and it is simultaneously expressed as a result of the association of B[a]P with aromatic hydrocarbon receptor (AhR), playing an essential role in the cancerogenic potential of various xenobiotics. In turn, polymorphism of CYP P450 genes determines the sensitivity of the organism to B[a]P. It was also observed that B[a]P facilitates the multiplication of viruses, which may be an additional problem with the widespread COVID-19 pandemic. Based on publications mainly from 2017 to 2022, this paper presents the occurrence of B[a]P in various environmental compartments and human surroundings, shows the exposure of humans to this substance, and describes the mechanisms of its toxicity.

Transcriptomic analysis in zebrafish larvae identifies iron-dependent mitochondrial dysfunction as a possible key event of NAFLD progression induced by benzo[a]pyrene/ethanol co-exposure

Non-alcoholic fatty liver disease (NAFLD) is a worldwide epidemic for which environmental contaminants are increasingly recognized as important etiological factors. Among them, the combination of benzo[a]pyrene (B[a]P), a potent environmental carcinogen, with ethanol, was shown to induce the transition of steatosis toward steatohepatitis. However, the underlying mechanisms involved remain to be deciphered. In this context, we used high-fat diet fed zebrafish model, in which we previously observed progression of steatosis to a steatohepatitis-like state following a 7-day-co-exposure to 43 mM ethanol and 25 nM B[a]P. Transcriptomic analysis highlighted the potent role of mitochondrial dysfunction, alterations in heme and iron homeostasis, involvement of aryl hydrocarbon receptor (AhR) signaling, and oxidative stress. Most of these mRNA dysregulations were validated by RT-qPCR. Moreover, similar changes were observed using a human in vitro hepatocyte model, HepaRG cells. The mitochondria structural and functional alterations were confirmed by transmission electronic microscopy and Seahorse technology, respectively. Involvement of AhR signaling was evidenced by using in vivo an AhR antagonist, CH223191, and in vitro in AhR-knock-out HepaRG cells. Furthermore, as co-exposure was found to increase the levels of both heme and hemin, we investigated if mitochondrial iron could induce oxidative stress. We found that mitochondrial labile iron content was raised in toxicant-exposed larvae. This increase was prevented by the iron chelator, deferoxamine, which also inhibited liver co-exposure toxicity. Overall, these results suggest that the increase in mitochondrial iron content induced by B[a]P/ethanol co-exposure causes mitochondrial dysfunction that contributes to the pathological progression of NAFLD.

Mitochondrial Dysfunction as a Hallmark of Environmental Injury

Environmental factors including diet, sedentary lifestyle and exposure to pollutants largely influence human health throughout life. Cellular and molecular events triggered by an exposure to environmental pollutants are extremely variable and depend on the age, the chronicity and the doses of exposure. Only a fraction of all relevant mechanisms involved in the onset and progression of pathologies in response to toxicants has probably been identified. Mitochondria are central hubs of metabolic and cell signaling responsible for a large variety of biochemical processes, including oxidative stress, metabolite production, energy transduction, hormone synthesis, and apoptosis. Growing evidence highlights mitochondrial dysfunction as a major hallmark of environmental insults. Here, we present mitochondria as crucial organelles for healthy metabolic homeostasis and whose dysfunction induces critical adverse effects. Then, we review the multiple mechanisms of action of pollutants causing mitochondrial toxicity in link with chronic diseases. We propose the Aryl hydrocarbon Receptor (AhR) as a model of “exposome receptor”, whose activation by environmental pollutants leads to various toxic events through mitochondrial dysfunction. Finally, we provide some remarks related to mitotoxicity and risk assessment.

Impact of pyrene (polycyclic aromatic hydrocarbons) pollutant on metabolites and lipid induction in microalgae Chlorella sorokiniana (UUIND6) to produce renewable biodiesel

Pyrene (polycyclic aromatic hydrocarbon), an anthropogenic organic pollutant prevalent in various ecological units, receives more attention for bioremediation and energy transformation using microalgae. In this study, we have used pyrene pollutant (50-500 ppm) to evaluate the half-maximal inhibitory concentrations (IC₅₀) of Chlorella sorokiniana and the impact on metabolites as well as the induction of lipid biosynthesis to produce renewable biodiesel. Pyrene concentration at 230 ppm (IC₅₀) caused half-maximum inhibition for the 96 h incubation. The harvest in the stationary stage (day 16) for C. sorokiniana revealed a biomass generation of 449 ± 7 mg L^-1 and 444 ± 8 mg L^-1 dcw in the control medium and pyrene IC₅₀ medium, respectively. An insignificant decline in biomass generation (1.2%) was observed due to the stress effect of the pyrene IC₅₀ medium on metabolic biosynthesis. Although contrary to biomass generation, IC₅₀ of pyrene assisted to induce lipid biosynthesis in C. sorokiniana. The improvement in lipid biosynthesis was observed as ~24% higher in pyrene IC₅₀ compared to the control medium. The chemical composition of the microalgae biomass, metabolites, and lipids was examined using FTIR spectra. The extracted lipid was transesterified to produce biodiesel via methanolic-H₂SO₄ catalysis. The renewable biodiesel obtained was evaluated using FTIR and ¹H NMR spectra. The transformation efficiency of the lipid of C. sorokiniana in biodiesel was calculated as ~81%. This research offers the incentive in lipid biosynthesis in microalgae cells using pyrene for the production of renewable and sustainable ecological biofuels along with bioremediation of pyrene.

Greener Monolithic Solid Phase Extraction Biosorbent Based on Calcium Cross-Linked Starch Cryogel Composite Graphene Oxide Nanoparticles for Benzo(a)pyrene Analysis

Benzo(a)pyrene (BaP) has been recognized as a marker for the detection of carcinogenic polycyclic aromatic hydrocarbons. In this work, a novel monolithic solid-phase extraction (SPE) sorbent based on graphene oxide nanoparticles (GO) in starch-based cryogel composite (GO-Cry) was successfully prepared for BaP analysis. Rice flour and tapioca starch (gel precursors) were gelatinized in limewater (cross-linker) under alkaline conditions before addition of GO (filler) that can increase the ability to extract BaP up to 2.6-fold. BaP analysis had a linear range of 10 to 1000 µgL-1 with good linearity (R2 = 0.9971) and high sensitivity (4.1 ± 0.1 a.u./(µgL-1)). The limit of detection and limit of quantification were 4.21 ± 0.06 and 14.04 ± 0.19 µgL-1, respectively, with excellent precision (0.17 to 2.45%RSD). The accuracy in terms of recovery from spiked samples was in the range of 84 to 110% with no significant difference to a C18 cartridge. GO-Cry can be reproducibly prepared with 2.8%RSD from 4 lots and can be reused at least 10 times, which not only helps reduce the analysis costs (~0.41USD per analysis), but also reduces the resultant waste to the environment.

Untargeted metabolomics and lipidomics analysis identified the role of FOXA1 in remodeling the metabolic pattern of BaP-transformed 16HBE cells

Benzo[a]pyrene (BaP) is a strong carcinogen for lung cancer, and forkhead-box A1 (FOXA1) plays an oncogenic role in BaP-transformed cell THBEc1. To explore the remodeling of metabolic pattern caused by BaP-induced transformation and the possible role FOXA1 might play in it, we compared metabolic patterns between THBEc1 cells and control using untargeted metabolomics and lipidomics analysis, and determined the effects of FOXA1 knockout on the metabolic pattern of THBEc1 cells. Metabolomics and lipidomics identified a total of 15 and 46 differential metabolites and lipids between THBEc1 and 16HBE cells, respectively, and a total of 4 and 1 differential metabolites and lipids between FOXA1 knockout cell THBEc1-ΔFOXA1-c34 and control cell THBEc1-ctrl, respectively. Analysis results of metabolites and metabolic pathways indicated the metabolic pattern remodeling may be related to the alteration in glucose metabolism during BaP-induced transformation. Western blotting revealed the up-regulation of enolase-2 (ENO2), pyruvate carboxylase (PCB), aconitase-2 (ACO2) and phosphorylated extracellular signal-regulated kinase 1/2 (p-ERK1/2) (Thr202/Tyr204), the down-regulation of succinate dehydrogenase complex subunit A (SDHA) and phosphoenolpyruvate carboxykinase 2 (PCK2) in THBEc1 cells. The detection results of metabolites related to glucose metabolism demonstrated the decreasing of lactic acid content in cells, lactic acid production in culture medium and citric acid content in mitochondria, and the increasing of ATP production of THBEc1 cells. FOXA1 knockout partially reversed the changes of ENO2, SDHA, PCK2 and p-ERK1/2 (Thr202/Tyr204) levels, lactic acid release, citric acid content in mitochondria of THBEc1 cells. In conclusion, FOXA1 knockout partially reversed the remodeling of glucose metabolism caused by BaP-induced malignant transformation. Our findings provide a clue for the possible role of FOXA1 in glucose metabolism regulation.

Application of HepG2/C3A liver spheroids as a model system for genotoxicity studies

HepG2 cells continue to be a valuable tool in early drug discovery and pharmaceutical development. In the current study we develop a 3D in vitro liver model, using HepG2/C3A cells that is predictive of human genotoxic exposure. HepG2/C3A cells cultured for 7-days in agarose-coated microplates formed spheroids which were uniform in shape and had well defined outer perimeters and no evidence of a hypoxic core. Quantitative real-time-PCR analysis showed statistically significant transcriptional upregulation of xenobiotic metabolising genes (CYP1A1, CYP1A2, UG1A1, UGT1A3, UGT1A6, EPHX, NAT2) and genes linked to liver function (ALB, CAR) in 3D cultures. In response to three model pro-genotoxicants: benzo[a]pyrene, amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) and 2-aminoanthracene (2-AA), we observed further transcriptional upregulation of xenobiotic metabolising genes (CYP1A1, CYP1A2, NAT1/2, SULT1A2, UGT1A1, UGT1A3) compared to untreated spheroids. Consistent with this, spheroids were more sensitive than 2D monolayers to compound induced single- and double- stranded DNA-damage as assessed by the comet assay and γH2AX phosphorylation respectively. In contrast, levels of DNA-damage induced by the direct acting mutagen 4-nitroquinoline N-oxide (4NQO) was the same in spheroids and monolayers. In support of the enhanced genotoxic response in spheroids we also observed transcriptional upregulation of genes relating to DNA-damage and cellular stress response (e.g. GADD45A and CDKN1A) in spheroids. In conclusion, HepG2/C3A 3D spheroids are a sensitive model for in vitro genotoxicity assessment with potential applications in early stage drug development.

Advances in research on the regulatory mechanism of NHE1 in tumors

Tumors pose a major threat to human health and present with difficulties that modern medicine has yet to overcome. It has been demonstrated that the acid-base balance of the tumor microenvironment is closely associated with the dynamic balance in the human body and that it regulates several processes, such as cell proliferation and differentiation, intracellular enzyme activity, and cytoskeletal assembly and depolymerization. It has been well established that the regulation of intra- and extracellular pH depends on a series of functional ion transporters and hydrogen ion channels, such as the Na⁺/H⁺ exchanger (NHE) protein and thee Cl/HCO₃- exchange protein, among which the NHE1 member of the NHE family has been attracting increasing attention in recent years, particularly in studies on the correlation between pH regulation and tumors. NHE1 is a housekeeping gene encoding a protein that is widely expressed on the surface of all plasma membranes. Due to its functional domain, which determines the pHi at its N-terminus and C-terminus, NHE1 is involved in the regulation of the cellular pH microenvironment. It has been reported in the literature that NHE1 can regulate cell volume, participate in the transmembrane transport of intracellular and extracellular ions, affect cell proliferation and apoptosis, and regulate cell behavior and cell cycle progression; however, research on the role of NHE1 in tumorigenesis and tumor development in various systems is at its early stages. The aim of the present study was to review the current research on the correlation between the NHE family proteins and various systemic tumors, in order to indicate a new direction for antitumor drug development with the pH microenvironment as the target.

Carcinogen-Induced Model of Proangiogenesis in Zebrafish Embryo-Larvae

Tumor angiogenesis is the main target in cancer drug development. Discovery of antiangiogenic agents targeting different mechanisms of action is the major area of research to control tumor growth and metastasis. Zebrafish (in the embryo-larvae stage) acts as an essential preclinical efficacy-toxicity model for antiangiogenic drug discovery. We aimed to develop a carcinogen-induced model of proangiogenesis in zebrafish embryo-larvae using the carcinogens lindane and benzo[a]pyrene. Zebrafish were randomly selected for mating. Postspawning, healthy embryos were staged, dispensed in reverse-osmosis water in a 12-well plate, and incubated at 28.5 °C, wherein 24 h postfertilization they were exposed to sublethal concentrations of the carcinogens. Three days postexposure, embryos were stained with alkaline phosphatase, and the angiogenic basket was imaged using a bright-field microscope. The number of subintestinal vessels, their length from somite to the basket, and other proangiogenic parameters were measured and analyzed. The effective concentrations causing a 30% increase in subintestinal vessels for benzo[a]pyrene and lindane were 2.69 and 2.24 µM, respectively, thus proving their proangiogenic potency. The carcinogen-induced model of proangiogenesis in zebrafish embryo-larvae can be used as an effective high-throughput screening tool to assess the proangiogenic potential of carcinogenic compounds and to screen antiangiogenic drugs for better therapeutic intervention. Environ Toxicol Chem 2021;40:447-453.© 2020 SETAC.

Accumulated ambient air pollution and colon cancer incidence in Thailand

This research examined the relationship between colon cancer risks and pollution in various areas of Thailand, using satellites to gather quantities of aerosols in the atmosphere. Bayesian hierarchical spatio-temporal model and the Poisson log-linear model were used to examine the incidence rates of colon cancer standardized by national references; from the database of the National Health Security Office, Ministry of Public Health of Thailand and NASA's database from aerosol diagnostics model. Modern-Era Retrospective Analysis for Research and Applications, Version 2 (MERRA-2) was used to explore disease-gender-specific spatio-temporal patterns of colon cancer incidences and accumulated air pollution-related cancers in Thailand between 2010 and 2016. A total of 59,605 patients were selected for the study. Due to concerns regarding statistical reliability between aerosol diagnostics model and colon cancer incidences, the posterior probabilities of risk appeared the most in dust PM_2.5. It could be interpreted as relative risk in every increase of 10 μg/m³ in black carbon, organic carbon, and dust-PM_2.5 levels were associated respectively with an increase of 4%, 4%, and 15% in the risks of colon cancer. A significant increase in the incidence of colon cancer with accumulated ambient air quality raised concerns regarding the prevention of air pollution. This study utilized data based on the incidences of colon cancer; the country's database and linked cancer data to pollution. According to the database from NASA's technology, this research has never been conducted in Thailand.

A Positive Feedback Loop Between c-Myc Upregulation, Glycolytic Shift, and Histone Acetylation Enhances Cancer Stem Cell-like Property and Tumorigenicity of Cr(VI)-transformed Cells

Chronic hexavalent chromium [Cr(VI)] exposure causes lung cancer and other types of cancer; however, the mechanism of Cr(VI) carcinogenesis remains to be clearly defined. Our recent study showed that chronic Cr(VI) exposure upregulates the proto oncogene c-Myc expression, which contributes significantly to Cr(VI)-induced cell transformation, cancer stem cell (CSC)-like property and tumorigenesis. c-Myc is a master regulator of cancer cell abnormal metabolism and accumulating evidence suggests that metabolism dysregulation plays an important role in both cancer development and progression. However, little is known about the role of metabolism dysregulation in Cr(VI) carcinogenesis. This study was performed to investigate the potential role and mechanism of metabolism dysregulation in Cr(VI) carcinogenesis. It was found that Cr(VI)-transformed cells display glycolytic shift, which depends on the upregulation of c-Myc. The glycolytic shift in Cr(VI)-transformed cells led to increased production of acetyl coenzyme A (acetyl-CoA) and elevation of histone acetylation. This, in turn, upregulated the expression of an acetyl-CoA producing key enzyme ATP citrate lyase and c-Myc, forming a positive feedback loop between the upregulation of c-Myc expression, glycolytic shift and increased histone acetylation. It was further determined that glucose depletion not only reverses the glycolytic shift in Cr(VI)-transformed cells, but also significantly reduces their growth, CSC-like property and tumorigenicity. These findings indicate that glycolytic shift plays an important role in maintaining malignant phenotypes of Cr(VI)-transformed cells, suggesting that metabolism dysregulation is critically involved in Cr(VI) carcinogenesis.

Pathophysiology of hepatic Na+/H+ exchange (Review)

Na+/H+ exchangers (NHEs) are a family of membrane proteins that contribute to exchanging one intracellular proton for one extracellular sodium. The family of NHEs consists of nine known members, NHE1-9. Each isoform represents a different gene product that has unique tissue expression, membrane localization, physiological effects, pathological regulation and sensitivity to drug inhibitors. NHE1 was the first to be discovered and is often referred to as the 'housekeeping' isoform of the NHE family. NHEs are not only involved in a variety of physiological processes, including the control of transepithelial Na+ absorption, intracellular pH, cell volume, cell proliferation, migration and apoptosis, but also modulate complex pathological events. Currently, the vast majority of review articles have focused on the role of members of the NHE family in inflammatory bowel disease, intestinal infectious diarrhea and digestive system tumorigenesis, but only a few reviews have discussed the role of NHEs in liver disease. Therefore, the present review described the basic biology of NHEs and highlighted their physiological and pathological effects in the liver.

Genoprotective activities of plant natural substances in cancer and chemopreventive strategies in the context of 3P medicine

Severe durable changes may occur to the DNA structure caused by exogenous and endogenous risk factors initiating the process of carcinogenesis. By evidence, a large portion of malignancies have been demonstrated as being preventable. Moreover, the targeted prevention of cancer onset is possible, due to unique properties of plant bioactive compounds. Although genoprotective effects of phytochemicals have been well documented, there is an evident lack of articles which would systematically present the spectrum of anticancer effects by phytochemicals, plant extracts, and plant-derived diet applicable to stratified patient groups at the level of targeted primary (cancer development) and secondary (cancer progression and metastatic disease) prevention. Consequently, clinical implementation of knowledge accumulated in the area is still highly restricted. To stimulate coherent co-development of the dedicated plant bioactive compound investigation on one hand and comprehensive cancer preventive strategies on the other hand, the current paper highlights and deeply analyses relevant evidence available in the area. Key molecular mechanisms are presented to detail genoprotective and anticancer activities of plants and phytochemicals. Clinical implementation is discussed. Based on the presented evidence, advanced chemopreventive strategies in the context of 3P medicine are considered.

DNA Adducts as Biomarkers To Predict, Prevent, and Diagnose Disease-Application of Analytical Chemistry to Clinical Investigations

Characterization of the chemistry, structure, formation, and metabolism of DNA adducts has been one of the most significant contributions to the field of chemical toxicology. This work provides the foundation to develop analytical methods to measure DNA adducts, define their relationship to disease, and establish clinical tests. Monitoring exposure to environmental and endogenous toxicants can predict, diagnose, and track disease as well as guide therapeutic treatment. DNA adducts are one of the most promising biomarkers of toxicant exposure owing to their stability, appearance in numerous biological matrices, and characteristic analytical properties. In addition, DNA adducts can induce mutations to drive disease onset and progression and can serve as surrogate markers of chemical exposure. In this perspective, we highlight significant advances made within the past decade regarding DNA adduct quantitation using mass spectrometry. We hope to expose a broader audience to this field and encourage analytical chemistry laboratories to explore how specific adducts may be related to various pathologies. One of the limiting factors in developing clinical tests to measure DNA adducts is cohort size; ideally, the cohort would allow for model development and then testing of the model to the remaining cohort. The goals of this perspective article are to (1) provide a summary of analyte levels measured using state-of-the-art analytical methods, (2) foster collaboration, and (3) highlight areas in need of further investigation.

Molecular mechanisms linking environmental toxicants to cancer development: Significance for protective interventions with polyphenols

Human exposure to environmental toxicants with diverse mechanisms of action is a growing concern. In addition to well-recognized carcinogens, various chemicals in environmental and occupational settings have been suggested to impact health, increasing susceptibility to cancer by inducing genetic and epigenetic changes. Accordingly, in this review, we have discussed recent insights into the pathological mechanisms of these chemicals, namely their effects on cell redox and calcium homeostasis, mitochondria and inflammatory signaling, with a focus on the possible implications for multi-stage carcinogenesis and its reversal by polyphenols. Plant-derived polyphenols, such as epigallocatechin-gallate, resveratrol, curcumin and anthocyanins reduce the incidence of cancer and can be useful nutraceuticals for alleviating the detrimental outcomes of harmful pollutants. However, development of therapies based on polyphenol administration requires further studies to validate the biological efficacy, identifying effective doses, mode of action and new delivery forms. Innovative microphysiological testing models are presented and specific proposals for future trials are given. Merging the current knowledge of multifactorial actions of specific polyphenols and chief environmental toxicants, this work aims to potentiate the delivery of phytochemical-based protective treatments to individuals at high-risk due to environmental exposure.

Dietary phytochemicals as the potential protectors against carcinogenesis and their role in cancer chemoprevention

Health-threatening consequences of carcinogen exposure are mediated via occurrence of electrophiles or reactive oxygen species. As a result, the accumulation of biomolecular damage leads to the cancer initiation, promotion or progression. Accordingly, there is an association between lifestyle factors including inappropriate diet or carcinogen formation during food processing, mainstream, second or third-hand tobacco smoke and other environmental or occupational carcinogens and malignant transformation. Nevertheless, increasing evidence supports the protective effects of naturally occurring phytochemicals against carcinogen exposure as well as carcinogenesis in general. Isolated phytochemicals or their mixtures present in the whole plant food demonstrate efficacy against malignancy induced by carcinogens widely spread in our environment. Phytochemicals also minimize the generation of carcinogenic substances during the processing of meat and meat products. Based on numerous data, selected phytochemicals or plant foods should be highly recommended to become a stable and regular part of the diet as the protectors against carcinogenesis.

Identification of Differentially Expressed Hematopoiesis-associated Genes in Term Low Birth Weight Newborns by Systems Genomics Approach

Background

Low Birth Weight (LBW) (birth weight <2.5 Kg) newborns are associated with a high risk of infection, morbidity and mortality during their perinatal period. Compromised innate immune responses and inefficient hematopoietic differentiation in term LBW newborns led us to evaluate the gene expression status of hematopoiesis.

Materials and Methods

In this study, we compared our microarray datasets of LBW-Normal Birth Weight (NBW) newborns with two reference datasets to identify hematopoietic stem cells genes, and their differential expression in the LBW newborns, by hierarchical clustering algorithm using gplots and RcolorBrewer package in R.

Results

Comparative analysis revealed 108 differentially expressed hematopoiesis genes (DEHGs), of which 79 genes were up-regulated, and 29 genes were down-regulated in LBW newborns compared to their NBW counterparts. Moreover, protein-protein interactions, functional annotation and pathway analysis demonstrated that the up-regulated genes were mainly involved in cell proliferation and differentiation, MAPK signaling and Rho GTPases signaling, and the down-regulated genes were engaged in cell proliferation and regulation, immune system regulation, hematopoietic cell lineage and JAK-STAT pathway. The binding of down-regulated genes (LYZ and GBP1) with growth factor GM-CSF using docking and MD simulation techniques, indicated that GM-CSF has the potential to alleviate the repressed hematopoiesis in the term LBW newborns.

Conclusion

Our study revealed that DEHGs belonged to erythroid and myeloid-specific lineages and may serve as potential targets for improving hematopoiesis in term LBW newborns to help build up their weak immune defense against life-threatening infections.

The SLC9A-C Mammalian Na+/H+ Exchanger Family: Molecules, Mechanisms, and Physiology

Na⁺/H⁺ exchangers play pivotal roles in the control of cell and tissue pH by mediating the electroneutral exchange of Na⁺ and H⁺ across cellular membranes. They belong to an ancient family of highly evolutionarily conserved proteins, and they play essential physiological roles in all phyla. In this review, we focus on the mammalian Na⁺/H⁺ exchangers (NHEs), the solute carrier (SLC) 9 family. This family of electroneutral transporters constitutes three branches: SLC9A, -B, and -C. Within these, each isoform exhibits distinct tissue expression profiles, regulation, and physiological roles. Some of these transporters are highly studied, with hundreds of original articles, and some are still only rudimentarily understood. In this review, we present and discuss the pioneering original work as well as the current state-of-the-art research on mammalian NHEs. We aim to provide the reader with a comprehensive view of core knowledge and recent insights into each family member, from gene organization over protein structure and regulation to physiological and pathophysiological roles. Particular attention is given to the integrated physiology of NHEs in the main organ systems. We provide several novel analyses and useful overviews, and we pinpoint main remaining enigmas, which we hope will inspire novel research on these highly versatile proteins.

Disturbances in H+ dynamics during environmental carcinogenesis

Despite the improvement of diagnostic methods and anticancer therapeutics, the human population is still facing an increasing incidence of several types of cancers. According to the World Health Organization, this growing trend would be partly linked to our environment, with around 20% of cancers stemming from exposure to environmental contaminants, notably chemicals like polycyclic aromatic hydrocarbons (PAHs). PAHs are widespread pollutants in our environment resulting from incomplete combustion or pyrolysis of organic material, and thus produced by both natural and anthropic sources; notably benzo[a]pyrene (B[a]P), i.e. the prototypical molecule of this family, that can be detected in cigarette smoke, diesel exhaust particles, occupational-related fumes, and grilled food. This molecule is a well-recognized carcinogen belonging to group 1 carcinogens. Indeed, it can target the different steps of the carcinogenic process and all cancer hallmarks. Interestingly, H⁺ dynamics have been described as key parameters for the occurrence of several, if not all, of these hallmarks. However, information regarding the role of such parameters during environmental carcinogenesis is still very scarce. The present review will thus mainly give an overview of the impact of B[a]P on H⁺ dynamics in liver cells, and will show how such alterations might impact different aspects related to the finely-tuned balance between cell death and survival processes, thereby likely favoring environmental carcinogenesis. In total, the main objective of this review is to encourage further research in this poorly explored field of environmental molecular toxicology.

Transcriptome analysis reveals novel insights into the response of low-dose benzo(a)pyrene exposure in male tilapia

Despite a wide number of toxicological studies that describe benzo[a]pyrene (BaP) effects, the metabolic mechanisms that underlie these effects in fish are largely unknown. Of great concern is the presence of BaP in aquatic systems, especially those in close proximity to human activity leading to consumption of potentially contaminated foods. BaP is a known carcinogen and it has been reported to have adverse effects on the survival, development and reproduction of fish. The purpose of this study was to investigate if a low dose of BaP can alter genes and key metabolic pathways in the liver and testis in male adult tilapia, and whether these could be associated with biological endpoints disruption. We used both high-throughput RNA-Sequencing to assess whole genome gene expression following repeated intraperitoneal injections of 3 mg/kg of BaP (every 6 days for 26 days) and morphometric endpoints as indicators of general health. Condition factor (K) along with hepatosomatic and gonadosomatic indices (morphometric parameters) were significantly lower in BaP-treated fish than in controls. BaP exposure induced important changes in the gene expression pattern in liver and testis as revealed by both Pathway and Gene Ontology (GO) analyses. Alterations that were shared by both tissues included arachidonic acid metabolism, androgen receptor to prostate-specific antigen signaling, and insulin-associated effects on lipogenesis. The most salient liver-specific effects included: biological processes involved in detoxification, IL6-associated insulin resistance, mTOR hyperactivation, mitotic cytokinesis, spindle pole and microtubule binding. BaP effects that were confined to the testis included: immune system functions, inflammatory response, estrogen and androgen metabolic pathways. Taken together, gene expression and morphometric end point data indicate that the reproductive success of adult male tilapia could be compromised as a result of BaP exposure. These results constitute new insights on the mechanism of action of low dose BaP in a non-model organism (tilapia).

Possible Involvement of Mitochondrial Dysfunction and Oxidative Stress in a Cellular Model of NAFLD Progression Induced by Benzo[a]pyrene/Ethanol CoExposure

Exposure to xenobiotics could favor the transition of nonalcoholic fatty liver (NAFL) to nonalcoholic steatohepatitis in obese patients. Recently, we showed in different models of NAFL that benzo[a]pyrene (B[a]P) and ethanol coexposure induced a steatohepatitis-like state. One model was HepaRG cells incubated with stearate and oleate for 2 weeks. In the present study, we wished to determine in this model whether mitochondrial dysfunction and reactive oxygen species (ROS) overproduction could be involved in the occurrence of this steatohepatitis-like state. CRISPR/Cas9-modified cells were also used to specify the role of aryl hydrocarbon receptor (AhR), which is potently activated by B[a]P. Thus, nonsteatotic and steatotic HepaRG cells were treated with B[a]P, ethanol, or both molecules for 2 weeks. B[a]P/ethanol coexposure reduced mitochondrial respiratory chain activity, mitochondrial respiration, and mitochondrial DNA levels and induced ROS overproduction in steatotic HepaRG cells. These deleterious effects were less marked or absent in steatotic cells treated with B[a]P alone or ethanol alone and in nonsteatotic cells treated with B[a]P/ethanol. Our study also disclosed that B[a]P/ethanol-induced impairment of mitochondrial respiration was dependent on AhR activation. Hence, mitochondrial dysfunction and ROS generation could explain the occurrence of a steatohepatitis-like state in steatotic HepaRG cells exposed to B[a]P and ethanol.

Membrane Remodeling as a Key Player of the Hepatotoxicity Induced by Co-Exposure to Benzo[a]pyrene and Ethanol of Obese Zebrafish Larvae

The rise in prevalence of non-alcoholic fatty liver disease (NAFLD) constitutes an important public health concern worldwide. Including obesity, numerous risk factors of NAFLD such as benzo[a]pyrene (B[a]P) and ethanol have been identified as modifying the physicochemical properties of the plasma membrane in vitro thus causing membrane remodeling—changes in membrane fluidity and lipid-raft characteristics. In this study, the possible involvement of membrane remodeling in the in vivo progression of steatosis to a steatohepatitis-like state upon co-exposure to B[a]P and ethanol was tested in obese zebrafish larvae. Larvae bearing steatosis as the result of a high-fat diet were exposed to ethanol and/or B[a]P for seven days at low concentrations coherent with human exposure in order to elicit hepatotoxicity. In this condition, the toxicant co-exposure raised global membrane order with higher lipid-raft clustering in the plasma membrane of liver cells, as evaluated by staining with the fluoroprobe di-4-ANEPPDHQ. Involvement of this membrane’s remodeling was finally explored by using the lipid-raft disruptor pravastatin that counteracted the effects of toxicant co-exposure both on membrane remodeling and toxicity. Overall, it can be concluded that B[a]P/ethanol co-exposure can induce in vivo hepatotoxicity via membrane remodeling which could be considered as a good target mechanism for developing combination therapy to deal with steatohepatitis.

6-mercaptopurine promotes energetic failure in proliferating T cells

The anticancer drug 6-mercaptopurine (6-MP) inhibits de novo purine synthesis and acts as an antiproliferative agent by interfering with protein, DNA and RNA synthesis and promoting apoptosis. Metabolic reprogramming is crucial for tumor progression to foster cancer cells growth and proliferation, and is regulated by mechanistic target of rapamycin (mTOR) and AMP-activated protein kinase (AMPK) as well as the oncogenes Myc and hypoxia inducible factor 1α (HIF-1α). We hypothesized that 6-MP impacts metabolic remodeling through its action on nucleotide synthesis. The aim of our study is to provide a comprehensive characterization of the metabolic changes induced by 6-MP in leukemic T cells. Our results indicate that exposition to 6-MP rapidly reduces intracellular ATP concentration, leading to the activation of AMPK. In turn, mTOR, an AMPK target, was inhibited, and the expression of HIF-1α and Myc was reduced upon 6-MP incubation. As a consequence of these inhibitions, glucose and glutamine fluxes were strongly decreased. Notably, no difference was observed on glucose uptake upon exposition to 6-MP. In conclusion, our findings provide new insights into how 6-MP profoundly impacts cellular energetic metabolism by reducing ATP production and decreasing glycolytic and glutaminolytic fluxes, and how 6-MP modifies human leukemic T cells metabolism with potential antiproliferative effects.

Role of protein kinase N2 (PKN2) in cigarette smoke-mediated oncogenic transformation of oral cells

Smoking is the leading cause of preventable death worldwide. Though cigarette smoke is an established cause of head and neck cancer (including oral cancer), molecular alterations associated with chronic cigarette smoke exposure are poorly studied. To understand the signaling alterations induced by chronic exposure to cigarette smoke, we developed a cell line model by exposing normal oral keratinocytes to cigarette smoke for a period of 12 months. Chronic exposure to cigarette smoke resulted in increased cellular proliferation and invasive ability of oral keratinocytes. Proteomic and phosphoproteomic analyses showed dysregulation of several proteins involved in cellular movement and cytoskeletal reorganization in smoke exposed cells. We observed overexpression and hyperphosphorylation of protein kinase N2 (PKN2) in smoke exposed cells as well as in a panel of head and neck cancer cell lines established from smokers. Silencing of PKN2 resulted in decreased colony formation, invasion and migration in both smoke exposed cells and head and neck cancer cell lines. Our results indicate that PKN2 plays an important role in oncogenic transformation of oral keratinocytes in response to cigarette smoke. The current study provides evidence that PKN2 can act as a potential therapeutic target in head and neck squamous cell carcinoma, especially in patients with a history of smoking.

A comprehensive characterization of the impact of mycophenolic acid on the metabolism of Jurkat T cells

Metabolic reprogramming is critical for T cell fate and polarization and is regulated by metabolic checkpoints, including Myc, HIF-1α, AMPK and mTORC1. Our objective was to determine the impact of mycophenolic acid (MPA) in comparison with rapamycin (Rapa), an inhibitor of mTORC1, on the metabolism of Jurkat T cells. We identified a drug-specific transcriptome signature consisting of the key enzymes and transporters involved in glycolysis, glutaminolysis or nucleotide synthesis. MPA produced an early and transient drop in the intracellular ATP content related to the inhibition of de novo synthesis of purines, leading to the activation of the energy sensor AMPK. MPA decreases glycolytic flux, consistent with a reduction in glucose uptake, but also in the oxidation of glutamine. Additionally, both drugs reduce aerobic glycolysis. The expression of HIF-1α and Myc, promoting the activation of glycolysis and glutaminolysis, was inhibited by MPA and Rapa. In conclusion, we report that MPA profoundly impacts the cellular metabolism of Jurkat T cells by generating an energetic distress, decreasing the glycolytic and glutaminolytic fluxes and by targeting HIF-1α and Myc. These findings open interesting perspectives for novel combinatorial therapeutic strategies targeting metabolic checkpoints to block the proliferation of T cells.

Role for the ATPase inhibitory factor 1 in the environmental carcinogen-induced Warburg phenotype

Most tumors undergo metabolic reprogramming towards glycolysis, the so-called Warburg effect, to support growth and survival. Overexpression of IF1, the physiological inhibitor of the F0F1ATPase, has been related to this phenomenon and appears to be a relevant marker in cancer. Environmental contributions to cancer development are now widely accepted but little is known about the underlying intracellular mechanisms. Among the environmental pollutants humans are commonly exposed to, benzo[a]pyrene (B[a]P), the prototype molecule of polycyclic aromatic hydrocarbons (PAHs), is a well-known human carcinogen. Besides apoptotic signals, B[a]P can also induce survival signals in liver cells, both likely involved in cancer promotion. Our previous works showed that B[a]P elicited a Warburg-like effect, thus favoring cell survival. The present study aimed at further elucidating the molecular mechanisms involved in the B[a]P-induced metabolic reprogramming, by testing the possible involvement of IF1. We presently demonstrate, both in vitro and in vivo, that PAHs, especially B[a]P, strongly increase IF1 expression. Such an increase, which might rely on β2-adrenergic receptor activation, notably participates to the B[a]P-induced glycolytic shift and cell survival in liver cells. By identifying IF1 as a target of PAHs, this study provides new insights about how environmental factors may contribute to related carcinogenesis.

Cellular acidification as a new approach to cancer treatment and to the understanding and therapeutics of neurodegenerative diseases

During the last few years, the understanding of the dysregulated hydrogen ion dynamics and reversed proton gradient of cancer cells has resulted in a new and integral pH-centric paradigm in oncology, a translational model embracing from cancer etiopathogenesis to treatment. The abnormalities of intracellular alkalinization along with extracellular acidification of all types of solid tumors and leukemic cells have never been described in any other disease and now appear to be a specific hallmark of malignancy. As a consequence of this intracellular acid-base homeostatic failure, the attempt to induce cellular acidification using proton transport inhibitors and other intracellular acidifiers of different origins is becoming a new therapeutic concept and selective target of cancer treatment, both as a metabolic mediator of apoptosis and in the overcoming of multiple drug resistance (MDR). Importantly, there is increasing data showing that different ion channels contribute to mediate significant aspects of cancer pH regulation and etiopathogenesis. Finally, we discuss the extension of this new pH-centric oncological paradigm into the opposite metabolic and homeostatic acid-base situation found in human neurodegenerative diseases (HNDDs), which opens novel concepts in the prevention and treatment of HNDDs through the utilization of a cohort of neural and non-neural derived hormones and human growth factors.

Polycyclic Aromatic Hydrocarbons In Edible Mushrooms from Niger Delta, Nigeria: Carcinogenic and Non-Carcinogenic Health Risk Assessment

In the oil-rich Niger Delta, hydrocarbon pollution and oil spillages, gas flaring and sundry anthropogenic activities constitute sources of polycyclic aromatic hydrocarbons (PAHs), with food contamination playing a major role in human exposure. In this study we assessed PAH levels in wild and cultivated edible mushroom species consumed by the general population from the oil producing Niger Delta, Nigeria. The concentrations of USEPA-16 PAHs were determined by gas chromatography and carcinogenic and non-carcinogenic health risks were calculated. The concentrations of USEPA-16 PAHs ranged from 0.02 mg/kg – 3.37 mg/kg. The dietary intake of carcinogenic and non-carcinogenic USEPA-16 PAHs (Naphthalene, Acenaphthylene, Acenaphthene, Anthracene, Phenanthrene, Flourene, Flouranthene, Pyrene, Benzo[a]Anthracene, Chrysene, Benzo[a]Pyrene, Benzo[b]Flouranthene, Benzo[K]Flouranthene, Benzo[g, h, i]Perylene, Dibenz[a, h]Anthracene and Ideno[1,2,3-cd]Pyrene) for adults, adolescents and seniors ranged from 0.00 – 0.05 mg/kg/day, 0.00 – 0.06 mg/kg/day and 0.00 – 0.07 mg/kg/day. The BaPeq ranged from 0.02 – 2.76 with margin of exposure MOE values of BaP ranging from 3,500,000 to 700,000, 3,500,000 and 3,500,000 to 7,000,000 for adults, adolescents and seniors indicating very insignificant health risk. The incremental lifetime cancer risk was within the safe range of 1.56x10-8 – 1.73x10-6 with the highest calculated risk found for wild Pleurotus ostreatus mushroom species from the study area.

Environmental carcinogenesis and pH homeostasis: Not only a matter of dysregulated metabolism

According to the World Health Organization, around 20% of all cancers would be due to environmental factors. Among these factors, several chemicals are indeed well recognized carcinogens. The widespread contaminant benzo[a]pyrene (B[a]P), an often used model carcinogen of the polycyclic aromatic hydrocarbons' family, has been suggested to target most, if not all, cancer hallmarks described by Hanahan and Weinberg. It is classified as a group I carcinogen by the International Agency for Research on Cancer; however, the precise intracellular mechanisms underlying its carcinogenic properties remain yet to be thoroughly defined. Recently, the pH homeostasis, a well known regulator of carcinogenic processes, was suggested to be a key actor in both cell death and Warburg-like metabolic reprogramming induced upon B[a]P exposure. The present review will highlight those data with the aim of favoring research on the role of H⁺ dynamics in environmental carcinogenesis.