Treatment Of Polycyclic Aromatic Hydrocarbons Research Articles

Photocatalytic treatment of diverse contaminants of potential concern in oil sands process-affected water

Oil sands process-affected water (OSPW), generated by surface mining in Canada's oil sands, require treatment of environmentally persistent dissolved organic compounds before release to the watershed. Conventional chemical and mechanical treatments have not proved suitable for treating the large quantities of stored OSPW, and the biological recalcitrance of some dissolved organics may not be adequately addressed by conventional passive treatment systems. Previous work has evaluated photocatalytic treatment as a passive advanced oxidation process (P-AOP) for OSPW remediation. This work expands upon this prior research to further characterize the effects of water chemistry on the treatment rate and detoxification threshold. Under artificial sunlight, buoyant photocatalysts (BPCs) detoxified all OSPW samples within 1 week of treatment time with simultaneous treatment of polycyclic aromatic hydrocarbons, naphthenic acid fraction components (NAFCs), and un-ionized ammonia. Overall, these results further demonstrate passive photocatalysis as an effective method for treatment of OSPW contaminants of potential concern (COPCs).

Naphthalene and phenanthrene affect differentially two glutathione S-transferases (GSTs) expression, GST activity, and glutathione content in white shrimp P. vannamei

Polycyclic aromatic hydrocarbons (PAHs) are persistent organic pollutants ubiquitous in coastal ecosystems. The white shrimp Penaeus vannamei naturally inhabits in coastal areas and is cultivated in farms located nearby the oceans. PAHs can damage shrimp health, endanger natural populations, and lower shrimp aquaculture productivity. However, crustaceans have enzymes capable of metabolizing organic xenobiotics as PAHs and to neutralize reactive oxygen species (ROS) produced during xenobiotics metabolism. An important superfamily of xenobiotic-metabolizing and antioxidant enzymes are glutathione S-transferases (GSTs). In white shrimp, some GSTs are known, but they have been scarcely studied in response to PAHs. In this study we report the molecular cloning and bioinformatic characterization of two novel nucleotide sequences corresponding to cytosolic GSTs belonging the Delta and Theta classes (GSTD and GSTT). Both proteins genes have tissue-specific patterns of expression under normal conditions, that do not necessarily relate to GST activity and glutathione content. The expression of the GSTD and GSTT, GST activity and glutathione content was analyzed in juvenile P. vannamei exposed to two PAHs, naphthalene (NAP) and phenanthrene (PHE) in sub-lethal concentrations for 96 h. GSTD expression was up-regulated by the two PAHs, while GSTT expression was only induced by NAP. In contrast, GST activity towards CDNB was only up-regulated by PHE, suggesting differential effects of PAHs at gene and protein level. On the other hand, lower reduced glutathione content (GSH) caused by PAHs indicates its utilization for detoxification or antioxidant defenses. However, the GSH/GSSG did not change by PAHs treatment, indicating that shrimp can maintain redox balance during short-term sub-lethal exposure to NAP and PHE. Despite the variations in the responses to NAP and PHE, all these results suggest that the GSTD and GSTT genes could be useful biomarkers for PAH exposure in P. vannamei.

Fungal Biodegradation of Polycyclic Aromatic Hydrocarbons (PAHs)

For many years, PAHs have been the subject of intense controversy throughout the world, due to their high toxicity and their presence in almost all environmental media. Their hazardous nature has given rise to a number of legal requirements throughout the world aimed at effectively reducing their content in foodstuffs and certain everyday consumer products. However, technologies for remediating PAH-contaminated soils use chemical and mechanical approaches that are extremely costly and not very environmentally friendly. That's why research is currently focusing on biological approaches that can provide effective, low-cost treatment for PAH-contaminated soils, and avoid environmental repercussions as far as possible. The aim of this paper is to shed light on a biological approach to the treatment of PAHs that is still in its infancy, but which is already showing great promise: biodegradation by fungi, which differ from other organisms in that they secrete enzymes that give them the ability to feed in environments inaccessible to other kingdoms, and to absorb toxic PAH chemicals from the soil and transform them into less harmful compounds.

PAH bioremediation with Rhodococcus rhodochrous ATCC 21198: Impact of cell immobilization and surfactant use on PAH treatment and post-remediation toxicity

Polycyclic aromatic hydrocarbons (PAHs) are prevalent environmental contaminants that are harmful to ecological and human health. Bioremediation is a promising technique for remediating PAHs in the environment, however bioremediation often results in the accumulation of toxic PAH metabolites. The objectives of this research were to demonstrate the cometabolic treatment of a mixture of PAHs by a pure bacterial culture, Rhodococcus rhodochrous ATCC 21198, and investigate PAH metabolites and toxicity. Additionally, the surfactant Tween ® 80 and cell immobilization techniques were used to enhance bioremediation. Total PAH removal ranged from 70–95% for fluorene, 44–89% for phenanthrene, 86–97% for anthracene, and 6.5–78% for pyrene. Maximum removal was achieved with immobilized cells in the presence of Tween ® 80. Investigation of PAH metabolites produced by 21198 revealed a complex mixture of hydroxylated compounds, quinones, and ring-fission products. Toxicity appeared to increase after bioremediation, manifesting as mortality and developmental effects in embryonic zebrafish. 21198′s ability to rapidly transform PAHs of a variety of molecular structures and sizes suggests that 21198 can be a valuable microorganism for catalyzing PAH remediation. However, implementing further treatment processes to address toxic PAH metabolites should be pursued to help lower post-remediation toxicity in future studies.

Treatment of PAHs contaminated soil in abandoned industrial site using combined method of improved in situ capping and electrokinetic enhanced-bioremediation

In situ capping and bioremediation are common technologies for treating contaminated soil at industrial sites. However, these two technologies have some shortcomings for treating soil heavily contaminated with organic matter, such as the limited adsorption in capping layer and the low biodegradation efficiency. This study proposed the method of an improved in situ capping combined with electrokinetic enhanced-bioremediation, and investigated its feasibility for treating heavily polycyclic aromatic hydrocarbons (PAHs) contaminated soil at an abandoned industrial site. By analyzing the changes in soil properties, PAHs concentration, and microbial community in experiments with voltages of 0, 0.8, 1.2, and 1.6 V cm−1, it was found that improved in situ capping could effectively sequester PAHs migration by adsorption and biodegradation, and electric field could enhance PAHs removal from contaminated soil and bio-barrier. In the experiments with electric field, soil environment under the voltage of 1.2 V cm−1 was more favorable for the growth and metabolism of microorganisms, and the residual PAHs concentrations (19.47 ± 0.76 mg kg−1 and 619.38 ± 20.05 mg kg−1) in the bio-barrier and contaminated soil of experiment with 1.2 V cm−1 were the lowest, which indicated that optimization of the electric field conditions could lead to better effects.

Electrochemistry-enhanced peroxymonosulfate activation by CoAl-LDH@biochar for simultaneous treatment of heavy metals and PAHs

An EC/CoAl-LDH@biochar/PMS system is proposed in this study for activation of PMS and removal of heavy metals (HMs) and polycyclic aromatic hydrocarbons (PAHs). In this system, over 90% of HMs and PAHs could be effectively removed after 40 min. Compared to other systems, the synergy between CoAl-LDH@biocahr and electrochemistry (EC)-peroxymonosulfate (PMS) had an excellent ability to eliminate the combined pollutants. The precise effect of the experimental parameters, including pH, CoAl-LDH@biochar dose, current density, and PMS concentration, on HMs-PAHs removal was determined, and the system was found to have a broad working pH range. The presence of EC can overcome the inhibition of anions in the degradation of PAHs due to the direct oxidation of PMS and PAHs on the cathode. The scavenging tests confirmed that the free radical and non-radical processes contributed to the degradation of PAHs. It is also revealed that EC can promote the continuous circulation of transition metals, which enhances the activation of PMS. The adsorption on the surface of CoAl-LDH@biochar and electrochemical deposition were the two main mechanisms for HMs removal. Furthermore, the electrode and CoAl-LDH@biochar possessed favorable recyclability in five consecutive cycles. This study has provided a promising and cost-effective approach for treatment of HM-PAH co-contaminated wastewater.

Fluorescent spectroscopy paired with parallel factor analysis for quantitative monitoring of phenanthrene biodegradation and metabolite formation

Polycyclic aromatic hydrocarbons (PAHs) are a class of environmental contaminants released into the environment from both natural and anthropogenic sources that are associated with carcinogenic, mutagenic, and teratogenic health effects. Many remediation strategies for the treatment of PAH contaminated material, including bioremediation, can lead to the formation of toxic transformation products. Analytical techniques for PAHs and PAH transformation products often require extensive sample preparation including solvent extraction and concentration, chromatographic separation, and mass spectrometry to identify and quantify compounds of interest. Excitation-emission matrix (EEM) fluorescent spectroscopy paired with parallel factor analysis (PARAFAC) is an approach for analyzing PAHs that eliminates the need for extensive sample preparation and separation techniques before analysis. However, this technique has rarely been applied to monitoring PAH biotransformation and formation of PAH metabolites. The objectives of this research were to compare an established targeted analytical method to two-dimensional fluorescent spectroscopy and combined EEM-PARAFAC methods to monitor phenanthrene degradation by a bacterial pure culture, Mycobacterium Strain ELW1, identify and quantify phenanthrene transformation products, and derive kinetic constants for phenanthrene degradation and metabolite formation. Both phenanthrene and its primary transformation product, trans-9,10-dihydroxy-9,10-dihydrophenanthrene, were identified and quantified with the EEM-PARAFAC method. The value of the EEM-PARAFAC method was demonstrated in the superiority of sensitivity and accuracy of quantification to two-dimensional fluorescent spectroscopy. Quantification of targets and derivation of kinetic constants using the EEM-PARAFAC method were validated with an established gas chromatography-mass spectrometry (GC-MS) method. To the authors’ knowledge, this is the first study to use an EEM-PARAFAC method to monitor, identify, and quantify both PAH biodegradation and PAH metabolite formation by a bacterial pure culture.

Techniques of Bioremediation using bacteria for the treatment of polycyclic aromatic hydrocarbons: A Review

The term "hydrocarbon" is self-explanatory and refers to solely carbon and hydrogen compounds. Hydrocarbons play an important role in our everyday lives. Hydrocarbons, particularly polycyclic aromatic hydrocarbons, harm biota. The relatively fast introduction of xenobiotic compounds, as well as the enormous movement of natural materials to various environmental compartments, can often overwhelm the self-cleaning capabilities of the recipient ecosystem, resulting in pollution and accumulation of hazardous or even lethal levels. Bacteria capable of hydrocarbon degradation are frequently used in the bioremediation of fuel oil-contaminated sites. Presently, multiple sophisticated methodologies, transcriptomics, proteomics and are effectively utilized for the depiction of hydrocarbons degrading microorganisms. These expertises are highly developed, and its integration with bioinformatics tools makes it even more efficient. Though health science and biological science are the major relevant areas for molecular docking, it has been effectively used to explore the process of bio-degradation in ecological remediation in recent years. This review focuses on the sources, fate of PAHs, human exposure, various computational aspects associated with PAHs, and some approaches of synthetic biology related to pollutant degradation and PAH‑degradation by genetically engineered microorganisms.

Exploration of bacterial community-induced polycyclic aromatic hydrocarbons degradation and humus formation during co-composting of cow manure waste combined with contaminated soil

To solve polycyclic aromatic hydrocarbons (PAHs) pollution, composting was chosen as a remediation method. During composting, the dissipation of PAHs was carried out by resource utilization of organic solid waste and its degradation by bacteria. This study was conducted by co-composting with contaminated soil and cow manure. The results showed that the degradation rates of naphthalene (Nap), phenanthrene (Phe), and benzo[α]pyrene (BaP) could reach 82.2%, 79.4%, and 59.6% respectively during composting. Cluster analysis indicated that polyphenol oxidase (PPO), laccase, and protease were important drivers of PAHs transformation. The content of humic substances (HS) was 106.67 g/kg in PAH treatment, which was significantly higher than that in the control group at 65 days. The phylogenetic investigation of communities by reconstruction of unobserved states (PICRUSt) and network analysis was used to infer the degradation mechanism of PAHs by microorganisms. The degradation of PAHs by PPO was found to have a significant contribution to the formation of HS. It was shown that PAHs and metabolic intermediates were more inclined to be oxidized and decomposed by PPO to form quinone, which in turn condensed with amino acids to form HS. Composting could promote the degradation of PAHs while improving the quality of compost, achieving a win-win situation.

The scleractinian coral Pocillopora damicornis relies on neuroendocrine regulation to cope with polycyclic aromatic hydrocarbons under heat stress

Polycyclic aromatic hydrocarbons (PAHs) are highly toxic environmental pollutants and are threatening scleractinian corals. In this study, PAHs treatment did not induce significant physiological responses of the coral Pocillopora damicornis and its algal symbionts, but biological processes including response to toxin, drug metabolic, and oxidation reduction were triggered at the mRNA level. These results implied that PAHs could be a group of slow-acting environmental toxicants, whose effects were moderate but persistent. Besides, it was interesting to find that PAHs activated the neuroendocrine system in the coral by triggering the expression of monoaminergic and acetylcholinergic system related genes, indicating that PAHs might function as environmental hormones. Moreover, the combined treatments of PAHs and heat caused a much obvious effect on the coral and its algal symbionts by elevating antioxidant activity and suppressing photosynthesis in the symbionts. Results from the transcriptome data further indicated that corals might perform stress responses upon PAHs and heat challenges through the TNF and apoptosis pathways, which perhaps was modulated by the neuroendocrine system of corals. Collectively, our survey demonstrates that the PAHs can function as environmental hormones and activate the neuroendocrine regulation in scleractinian corals, which may contribute to the stress responses of symbiotic association by modulating photosynthesis, antioxidation, and apoptosis.

Impact of polycyclic aromatic hydrocarbons on photosynthetic and biochemical functions and its bioremediation by Chlorella vulgaris

Among several pollutants found in the aquatic environment, polycyclic aromatic hydrocarbons (PAHs) can interfere with the normal functioning of the aquatic organisms. The aim of this study was to investigate the application of Chlorella vulgaris for bioremediation of different type of PAHs [2-ring Naphthalene (NAP), 3-ring Anthracene (ANT), and 4-ring Pyrene (PYR)] and their impact on photosynthesis and growth of C. vulgaris. After 7 days of exposure of PAHs, growth of C. vulgaris was affected in the order PYR > ANT > NAP. With regard to biomolecules, all PAHs treatments showed a significant decrease in lipid content, but the toxic effect of PYR was more pronounced. Chl a fluorescence study of algal samples indicated that photosystem II (PSII) performance was unaffected by NAP and ANT toxicity, however, severe disruption of PSII activity by PYR was noted. Interestingly, C. vulgaris was able to remove all three PAHs from the media (~90–92 % NAP, ~90–94 % ANT and ~76 % PYR) within 7 days. After 3 days of cultivation, activity of dehydrogenase was increased in NAP and ANT inoculated culture, reflecting metabolization of these compounds which reduced after 7 days. As compared to control culture (no PAHs) a sharp decline in dehydrogenase activity was noted in PYR treated culture (after 3 and 7 days). Based on the results obtained, C. vulgaris could absorb NAP and ANT (linear PAHs) more efficiently than PYR (angular PAH). These results imply that ability of C. vulgaris to degrade PAHs depends in part on the configuration of the ring structure.

Recent advances in the treatment of PAHs in the environment: Application of nanomaterial-based technologies

Polycyclic aromatic hydrocarbons (PAHs) are one of the most frequent petroleum hydrocarbons detected in the environment. PAHs are receiving global attention due to their toxicity, environmental persistence, and potential bioaccumulation. PAHs contamination occurs mainly due to anthropogenic sources related to the disposal of industrial and domestic run-offs or atmospheric emissions from plants or vehicles. Once PAHs are introduced into the environment, they undergo different processes either physical, chemical, or biological transformations, which are collectively known as weathering processes. These weathering processes are highly dependent on the nature and the physiochemical properties of PAHs molecules and the surrounding environment, which eventually will determine their transport, fate, and distribution in the environment either through adsorption to soil/sediments, or volatilization to the atmosphere, or dissolution in the water. Different treatment strategies for PAHs pollution have been introduced. Each remediation technology has its advantages and disadvantages. To choose a treatment, a full analysis of the case study should be provided, including the properties of the target pollutant, site description, and treatment procedure. As the treatment of PAHs contaminated sites is usually a difficult and expensive task, it would be a good choice to go for treatment, which is adaptive, sustainable, eco-friendly, efficient, and cost-effective. In this review, the transport, fate, and distribution processes of PAHs in the environment with their dependent factors were elaborated. In addition, this paper provided an overview of different traditional and advanced potential treatment approaches used to treat PAHs-contaminated sites such as thermal, chemical, electrokinetic, nano-adsorption, and biological treatments.

Shifts of the new functional marker gene (pahE) of polycyclic aromatic hydrocarbons (PAHs) degrading bacterial population and its relationship with PAHs biodegradation

Identification of polycyclic aromatic hydrocarbons (PAHs) degrading bacterial populations and understanding their responses to PAHs are crucial for the designing of appropriate bioremediation strategies. In this study, the responses of PAHs-degrading bacterial populations to different PAHs were studied in terms of the compositions and abundance variations of their new functional marker gene (pahE) by gene-targeted metagenomic and qPCR analysis. Overall, PAHs species significantly affected the composition and abundance of pahE gene within the PAHs-degrading bacteria in each treatment and different pahE of PAHs-degrading bacteria involved in the different stages of PAHs degradation. Noted that new pahE genotypes were also discovered in all PAHs treatment groups, indicating that some potential new PAHs-degrading bacterial genera were also involved in PAHs degradation. Besides, all three PAH removal rates were significantly positively related with pahE gene abundances (R2 = 0.908 ~ 0.922, p < 0.01), demonstrating that pahE could be a good indicator of PAHs degradation activity or potential. This is the first study focusing on the dynamic changes of the pahE gene within PAHs-degrading bacterial community during the degradation of PAHs in mangrove sediment, providing novel insights into the use of pahE gene as the functional marker to indicate PAH degradation.

Profiling How the Gut Microbiome Modulates Host Xenobiotic Metabolism in Response to Benzo[a]pyrene and 1-Nitropyrene Exposure.

The gut microbiome is a key contributor to xenobiotic metabolism. Polycyclic aromatic hydrocarbons (PAHs) are an abundant class of environmental contaminants that have varying levels of carcinogenicity depending on their individual structures. Little is known about how the gut microbiome affects the rates of PAH metabolism. This study sought to determine the role that the gut microbiome has in determining the various aspects of metabolism in the liver, before and after exposure to two structurally different PAHs, benzo[a]pyrene and 1-nitropyrene. Following exposures, the metabolic rates of PAH metabolism were measured, and activity-based protein profiling was performed. We observed differences in PAH metabolism rates between germ-free and conventional mice under both unexposed and exposed conditions. Our activity-based protein profiling (ABPP) analysis showed that, under unexposed conditions, there were only minor differences in total P450 activity in germ-free mice relative to conventional mice. However, we observed distinct activity profiles in response to corn oil vehicle and PAH treatment, primarily in the case of 1-NP treatment. This study revealed that the repertoire of active P450s in the liver is impacted by the presence of the gut microbiome, which modifies PAH metabolism in a substrate-specific fashion.

Attenuation of Polycyclic Aromatic Hydrocarbon (PAH)-Mediated Pulmonary DNA Adducts and Cytochrome P450 (CYP)1B1 by Dietary Antioxidants, Omega-3 Fatty Acids, in Mice.

Numerous human and animal studies have reported positive correlation between carcinogen-DNA adduct levels and cancer occurrence. Therefore, attenuation of DNA adduct levels would be expected to suppress tumorigenesis. In this investigation, we report that the antioxidants omega 3-fatty acids, which are constituents of fish oil (FO), significantly decreased DNA adduct formation by polycyclic aromatic hydrocarbons (PAHs). B6C3F1 male mice were fed an FO or corn oil (CO) diet, or A/J male mice were pre-fed with omega-3 fatty acids eicosapentaenoic acid (EPA) and/or docosahexaenoic acid (DHA). While the B6C3F1 mice were administered two doses of a mixture of seven carcinogenic PAHs including benzo(a)pyrene (BP), the A/J mice were treated i.p. with pure benzo[a]pyrene (BP). Animals were euthanized after 1, 3, or 7 d after PAH treatment. DNA adduct levels were measured by the 32P-postlabeling assay. Our results showed that DNA adduct levels in the lungs of mice 7 d after treatment were significantly decreased in the FO or EPA/DHA groups compared with the CO group. Interestingly, both qPCR and Western blot analyses revealed that FO, DHA and EPA/DHA significantly decreased the expression of cytochrome P450 (CYP) 1B1. CYP1B1 plays a critical role in the metabolic activation of BP to DNA-reactive metabolites. qPCR also showed that the expression of some metabolic and DNA repair genes was induced by BP and inhibited by FO or omega-3 fatty acids in liver, but not lung. Our results suggest that a combination of mechanism entailing CYP1B1 inhibition and the modulation of DNA repair genes contribute to the attenuation of PAH-mediated carcinogenesis by omega 3 fatty acids.

Treatment of Water Contaminated with Polycyclic Aromatic Hydrocarbons (PAHs): A Review of Various Techniques, Constraints, and Field Procedures

Clean water is vital in the creation of energy and sustenance of life. However, the pollution of water and the absence of potable water are global problems resulting from agricultural and industrial activities. We have witnessed significant growth in the pollution of water by organic compounds like PAH. Experts have made an effort to establish favorable techniques for the treatment of PAH polluted water. These techniques are either thermal, biological, physical or chemical. Bioremediation, chemical oxidation, solid-phase extraction, coagulation, photocatalytic degradation and adsorption using graphenes, mesoporous silica and agricultural wastes are techniques that are already in use in the field treatment of PAHs while electrokinetic remediation and nanoremediation are still in their developmental stage. Several reviews on the treatment of sediments and soils contaminated with PAHs have been published, but only a few reviews center mainly on the removal of PAHs in water. Therefore, this review aims to provide information on the techniques used in the treatment of water contaminated with PAHs. Techniques that are already in use and those that are in their developmental stage were reviewed. The successes of these methods, limitations, constraints and field procedures were analyzed and this will help to inform decision making.

Treatment of polycyclic aromatic hydrocarbons (PAHs) from aqueous solutions by flotation using colloidal gas aphrons

Aqueous solutions contaminated with polycyclic aromatic hydrocarbons (PAHs) pose severe environmental risks, making their removal necessary. Flotation with colloidal gas aphrons (CGAs) has recently demonstrated high removal efficiencies for various pollutants present in aqueous solutions. This study determined the efficacy of CGAs in removing low-ring PAHs (naphthalene, fluorene, and phenanthrene) from aqueous solutions. CGAs were produced from different surfactants, such as anionic sodium dodecylbenzene sulfonate (SDBS), cationic hexadecyl trimethylammonium bromide (HTAB), and natural surfactant obtained from the leaves of Ziziphus spina-christi (ZSC). PAHs removal efficiency was studied by varying different parameters, such as type of surfactant, PAHs solution pH, CGAs flow rate, and PAHs and CGAs solution temperature. Results showed that at pH 5.6 and 25 °C, fluorene and phenanthrene were fully removed using CGAs (flow rate of 100 mL/min) derived from cationic HTAB surfactant, while naphthalene was removed to the extent of approximately 88.4% under similar conditions. These findings suggest that CGAs derived from cationic HTAB surfactant have a greater capacity for extracting low-ring PAHs from aqueous media.

Peroxy-Acid Treatment of Polycyclic Aromatic Hydrocarbons: Degradation Kinetics, Thermodynamics, and Predictive Modeling

AbstractPolycyclic aromatic hydrocarbons (PAHs) are potentially carcinogenic organic compounds that are persistent in the environment. The peroxy-acid treatment is an advanced oxidation process (AO...

Polycyclic Aromatic Hydrocarbons Detected in Processed Meats Cause Genetic Changes in Colorectal Cancers.

Polycyclic aromatic hydrocarbons (PAHs) are commonly ingested via meat and are produced from high-temperature cooking of meat. Some of these PAHs have potential roles in carcinogenesis of colorectal cancer (CRC). We aimed to investigate PAH concentrations in eight types of commonly consumed ready-to-eat meat samples and their potential effects on gene expressions related to CRC. Extraction and clean-up of meat samples were performed using QuEChERS method, and PAHs were detected using GC-MS. Nine different PAHs were found in meat samples. Interestingly, roast turkey contained the highest total PAH content, followed by salami meat. Hams of varying levels of smokedness showed a proportional increase of phenanthrene (PHEN), anthracene (ANTH), and fluorene (FLU). Triple-smoked ham samples showed significantly higher levels of these PAHs compared to single-smoked ham. These three PAHs plus benzo[a]pyrene (B[a]P), being detected in three meat samples, were chosen as treatments to investigate in vitro gene expression changes in human colon cells. After PAH treatment, total RNA was extracted and rtPCR was performed, investigating gene expression related to CRC. B[a]P decreased mRNA expression of TP53. In addition, at high concentrations, B[a]P significantly increased KRAS expression. Treatments with 1 µM PHEN, 25 µM, and 10 µM FLU significantly increased KRAS mRNA expression in vitro, implying the potential basis for PAH-induced colorectal carcinogenesis. Opposingly, the ANTH treatment led to increased TP53 and APC expression and decreased KRAS expression, suggesting an anti-carcinogenic effect. To conclude, PAHs are common in ready-to-eat meat samples and are capable of significantly modifying the expression of key genes related to CRC.

Polycyclic aromatic hydrocarbons induce endothelial injury through miR‐155 to promote atherosclerosis

Polycyclic aromatic hydrocarbons (PAHs) are considered as an external factor that induces atherosclerotic cardiovascular disease. Although miR-155 is known to be involved in cardiovascular disease, whether it is involved in PAH-induced arteriosclerosis remains unclear. We evaluated the effects of PAHs on vascularization, permeability, and miR-155 expression in HUVECs. We found that PAHs-induced sclerosis of HUVECs was characterized by increasing permeability, decreasing proliferation, and vascular lumen number. The expression of miR-155 was upregulated by PAHs treatment, and transfection with miR-155 inhibitor could reverse above effect of PAHs-induced sclerosis. Meanwhile, transcriptome sequencing revealed that 63 genes were downregulated in the group of PAHs treatment alone, and were then upregulated in the miR-155 inhibitor group. These genes were mainly involved in complement and coagulation cascades, cytokine-cytokine receptor interaction, TNF signaling pathway, and NF-kappa B signaling pathway. Among these 63 genes, SERPIND1 was directly targeted and regulated by miR-155. Further in vivo experiments in ApoE-/- mice confirmed that PAH accelerates the development of arteriosclerosis by promoting the expression of miR-155 to downregulate the SERPIND1. Therefore, PAH exaggerates atherosclerosis by activating miR-155-dependent endothelial injury. This study provides a fundamental insight on the miR-155 mechanism for PAHs enhancing atherosclerosis and miR-155 potentially serving as a novel drug target.