Induction of oxidative stress and DNA damage in cervix in acute treatment with benzo[a]pyrene

Deoxyribose Nucleic Acid Damage and Its Association With Plasma Malondialdehyde Levels Among Patients With Cervical Cancer: A Case-Control Study

Purpose The objective of this research project was to estimate DNA damage in patients diagnosed with cervical cancer using the comet assay, establish a correlation between this quantification and the oxidative stress marker malondialdehyde (MDA; plasma MDA), and compare the resulting parameters between the cases and age-matched controls. Materials and methods This study included 49 cervical cancer cases and 49 age-matched controls to measure DNA damage parameters such as comet length, head diameter, percentage of DNA in the comet head, tail length, percentage of DNA in the comet tail, and oxidative stress marker (plasma MDA) using the thiobarbituric acid reactive substance (TBARS) enzyme-linked immunosorbent assay (ELISA) method. Results Comet metrics suggesting DNA damage, such as comet length, tail length, and percentage of DNA in the comet tail, were considerably higher in cervical cancer cases than in age-matched controls. The proportion of DNA in the comet head, representing undamaged/mild DNA damage, was significantly higher in age-matched controls than in cervical cancer patients. Plasma MDA and comet tail length were shown to have a positive correlation. Compared to the age-matched controls, those between the ages of 30 and 39, with a parity of two to four, who had a history of early age at first pregnancy and a positive family history of cervical cancer, had the highest level of DNA damage. Conclusion The elevated levels of comet parameters and their positive correlation with plasma MDA suggest that individuals diagnosed with cervical cancer have a higher degree of DNA damage compared to the control group. In conjunction with established methods like the PAP smear, this predictive test comprising comet assay and estimation of plasma MDA may be utilized to identify and assess the risk of cervical cancer in individuals aged 30-39 years, with a parity between two and four pregnancies and a prior history of early age at first pregnancy, accompanied by a positive family history of the disease.

Impact of benzo[a]pyrene with other pollutants induce the molecular alternation in the biological system: Existence, detection, and remediation methods

The exposure of benzo [a]pyrene (BaP) in recent times is rather unavoidable than ever before. BaP emissions are sourced majorly from anthropogenic rather than natural provenance from wildfires and volcanic eruptions. A major under-looked source is via the consumption of foods that are deep-fried, grilled, and charcoal smoked foods (meats in particular). BaP being a component of poly aromatic hydrocarbons has been classified as a Group I carcinogenic agent, which has been shown to cause both systemic and localized effects in animal models as well as in humans; has been known to cause various forms of cancer, accelerate neurological disorders, invoke DNA and cellular damage due to the generation of reactive oxygen species and involve in multi-generational phenotypic and genotypic defects. BaP's short and accumulated exposure has been shown in disrupting the fertility of gamete cells. In this review, we have discussed an in-depth and capacious run-through of the various origins of BaP, its economic distribution and its impact as well as toxicological effects on the environment and human health. It also deals with a mechanism as a single compound and its ability to synergize with other chemicals/materials, novel sensitive detection methods, and remediation approaches held in the environment.

Indoor Secondary Pollutants Cannot Be Ignored: Third-Hand Smoke

Smoking has been recognized by the World Health Organization (WHO) as the fifth highest threat to humanity. Smoking, a leading disease promoter, is a major risk factor for non-communicable diseases (NCDs) such as cancer, cardiovascular disease, diabetes, and chronic respiratory diseases. NCDs account for 63% of all deaths worldwide. Passive smoking is also a health risk. Globally, more than a third of all people are regularly exposed to harmful smoke. Air pollution is a common global problem in which pollutants emitted into the atmosphere undergo a series of physical or chemical reactions to produce various oxidation products, which are often referred to as secondary pollutants. Secondary pollutants include ozone (O₃), sulfur trioxide (SO₃), nitrogen dioxide (NO₂), and respirable particulate matter (PM). It is worth mentioning that third-hand smoke (THS), formed by the reaction of nicotine with second-hand smoke (SHS) caused by indoor O₃ or nitrous acid (HONO), is a major indoor secondary pollutant that cannot be ignored. As a form of indoor air pollution that is relatively difficult to avoid, THS exists in any corner of the environment where smokers live. In this paper, we summarize the important research progress on the main components, detection, and toxicity of THS and look forward to future research directions. Scientific understanding of THS and its hazards will facilitate smoking bans in indoor and public places and raise public concern for how to prevent and remove THS.

Melatonin alleviates benzo(a)pyrene-induced ovarian corpus luteum dysfunction by suppressing excessive oxidative stress and apoptosis

Benzo(a)pyrene (B(a)P) is a widespread persistent organic pollutant (POP) and a well-known endocrine disruptor. Exposure to BaP is known to disrupt the steroid balance and impair embryo implantation, but the mechanism under it remains unclear. The corpus luteum (CL), the primary source of progesterone during early pregnancy, plays a pivotal role in embryo implantation and pregnancy maintenance. The inappropriate luteal function may result in implantation failure and spontaneous abortions. Therefore, this study was conducted to assess the effects and potential mechanisms of B(a)P on the CL function. Our results showed that pregnant mice received B(a)P displayed impaired embryo implantation and dysfunction of ovarian CL. The estrogen and progesterone levels decreased by B(a)P. In vitro, exposure to BPDE, which is the metabolite of B(a)P, affected the luteinization of granular cell KK-1. Additionally, melatonin and its receptors, which are important for ovarian function and anti-oxidative damage, were affected by B(a)P or BPDE. B(a)P or BPDE-treated alone impaired antioxidant capacity of ovarian granulosa cells, caused an increasing of ROS and cell apoptosis, and disrupted the PI3K/AKT/GSK3β signaling pathway in vivo and in vitro. Co-treatment with melatonin alleviated B(a)P or BPDE-induced CL dysfunction by ameliorating oxidative stress, counteracting phosphorylation of PI3K/AKT/GSK3β signaling pathway, decreasing the apoptosis of the ovarian cells. Moreover, activation of the melatonin receptor by ramelteon in KK-1 cells exhibits an analogous protective effect as melatonin. In conclusion, our findings not only firstly clarify the potential mechanisms of BaP-induced CL dysfunction, but also extend the understanding about the ovarian protection of melatonin and its receptors against B(a)P exposure.

Induction of proliferative and mutagenic activity by benzo(a)pyrene in PC-3 cells via JAK2/STAT3 pathway

Environmental carcinogen benzo(a)pyrene (BaP) is a representative compound of polycyclic aromatic hydrocarbons (PAHs). BaP is strongly associated with prostate carcinogenesis. However, the molecular mechanism of BaP in development of prostate carcinoma remains largely unknown. The aim of this study was to investigate the effect and mechanism of BaP on the development in prostate cancer. PC-3 cells were exposed to different concentrations of BaP for 24, 48, 72 h, respectively. We analyzed the effect of BaP on PC-3 cell viability, cell cycle, DNA strand breaks, mutagenic activity, and migration. The expression of associated regulatory genes and the effect of JAK2/STAT3 signaling were also measured to explore the relationships among BaP metabolism, the JAK2/STAT3 pathway and proliferative activity in PC-3 cells. We observed significant effects on proliferation, DNA strand breaks and mutagenic activity after BaP exposure in PC-3 cells, and inhibitors of CYP1 and the AhR transcription factor α -naphthoflavone (ANF) and CH223191 treatment clearly reduced both cell survival and mutagenesis associated with BaP exposure. Reduction in G0-G1 phase population and elevation in S phase were observed after BaP exposure. Migratory cells for PC-3 were significantly increased. The results were further confirmed by the expression of mRNA levels in the significant increments of Snail, Slug, MMP-9, CYP1A1, CYP1B1, CycilnD1, CDK4 and significant reduction of E-cadherin. Significant enhancements were found in the expression of JAK2, STAT3 after BaP treatment. Additionally, activator IL-6 significantly enhanced the effect of BaP on cell survival, mutagenic activity, Cyclin D1, CDK4, Snail, and JAK2/STAT3 expression in PC-3 cells. Significant reductions in cell survival, mutagenic activity, Cyclin D1, CDK4, Snail, and JAK2/STAT3 expression were found after inhibitor AG490, ANF and CHJ223191 treatment. These findings reveal that BaP enhances the proliferative and mutagenic activity via JAK2-STAT3 pathway in PC-3 cells, and provide the additional evidence to understand the crucial role of BaP in prostate cancer carcinogenesis.

Adolescence benzo[a]pyrene treatment induces learning and memory impairment and anxiolytic like behavioral response altering neuronal morphology of hippocampus in adult male Wistar rats

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Intraperitoneal B[a]P administration induces anxiolytic like behavior in rats.

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B[a]P induces oxidative stress and reduces antioxidant enzyme activity.

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Exposure to B[a]P-induces decrease in dendrite length and spine density through oxidative stress affecting antioxidant defence system.

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Alteration in the neuronal architecture of the hippocampal cells after B[a]P administration is associated with learning and memory defict.

Exposure to benzo[a]pyrene (B[a]P), a prototype of polycyclic aromatic hydrocarbons (PAHs) easily cross blood brain barrier (BBB) and is associated with impaired learning and memory in adult rats. However, there is no symmetric study reported on association between B[a]P exposure during the early development and hippocampal dendritic architecture causing behavioral changes like learning and memory deficit of adult rats. We investigated a fourteen day consecutive B[a]P administration, intraperitonial (i.p.), with two different doses (0.1 and 1μM) during early adolescence at PND30-44 and learning behavior assessed between PND 45-60 in adult male rats. The anxiolytic like behavioural analysis was done by LDPT. Depressive like behaviour was estimated through sucrose preference and learning and memory by T-maze. After B[a]P administration oxidative stress markers like glutathione S-transferase (GST), glutathione reductase (GR), glutathione peroxidase (GPx), reduced (GSH) and oxidized glutathione (GSSG) were evaluated. To parallel these behavioral and antioxidant level changes to alteration in dendritic morphology, Golgi-Cox staining was performed in the hippocampus. Our study showed anxiolytic like behavioral response with significant increase in time spent in light zone and significant (p < 0.05) decrease in preference for sucrose and a reduction in percentage of spontaneous responses in T-maze test in B[a]P administered group as compared to vehicle control. B[a]P exposed male rats showed significant increase in GST activity (p < 0.05) and concentration of GSSG with a decay in GSH, GPx and GR in both the groups as compared to control. B[a]P administered rats showed significant loss in total dendritic length and number (28%) with reduced spine density (18%) in both higher and lower doses. These results suggested that B[a]P administration can be associated with an increase ROS production showing altered antioxidant defence system through glutathione biosynthesis and causing profound alterations in dendritic length and spine density of hippocampal neurons leading towards learning and memory deficits in adult rats.

Acute benzo[a]pyrene treatment causes different antioxidant response and DNA damage in liver, lung, brain, stomach and kidney

Acute effects of oxidative damage induced by benzo[a]pyrene (B[a]P) on various organs are still not clear. In this study, we investigated oxidative stress and DNA damage in liver, lung, stomach, brain and kidney of ICR male mice induced by acute B[a]P treatment. B[a]P treatment led to a significant decrease at the different doses in body weight. For the variations of superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST), glutathione (GSH) and GSH/GSSG, significant increases were observed at 24 h, then decreased till 72 h after B[a]P injection. The increase percent indicated in a dose- dependent decrease manner. However, glutathione peroxidase (GPx), GSSG and MDA were significantly increased in a time- and dose-dependent increase manner. DNA damage showed the significant and top levels at 24 h, and increased in proportion to the doses of B[a]P treatment. The total induction could be indicated by the variation of MDA at 24 h after B[a]P injection and showed the following order of predominance: lung > liver > kidney = stomach > brain. This was further certificated by histopathological changes in the examined organs. Additionally, the levels of serum glutamic-oxaloacetic transaminase (GOT), glutamic-pyruvic transaminase (GPT), and blood urea nitrogen (UN), creatinine were also significantly increased at 24 h after B[a]P injection. These findings suggested the disturbance of antioxidant responses and aggravation of DNA damages, and the different responses on various organs induced by acute B[a]P treatment in organism.

The Nrf2-ARE pathway is associated with Schisandrin b attenuating benzo(a)pyrene-Induced HTR cells damages in vitro

As is ubiquitous in the environmental sources, benzo(a)pyrene (BaP) has been reported to induce reprotoxicity in previous studies. Toxicity to trophoblast cells may be one key factor, but evidences were absent. We speculated that BaP can induce cytotoxicity in human trophoblast HTR-8/SVneo (HTR) cells, and Schisandrin B (Sch B) as a potential protector can inhibit the cytotoxicity. MTS assay identified that BaP induced HTR cells death while Sch B played a cytoprotective role. And after Nrf2 interference, the ability of Sch B-induced cytoprotection was declined. Furthermore, PCR, western blot, ELISA, and SOD assays were found that Sch B significantly increased the mRNA and protein expression of Nrf2, HO1, NQO1, and SOD in the Nrf2-ARE pathway, and the extents of increase were declined after Nrf2 interference. These results demonstrated that the Nrf2-ARE pathway plays an important role in Sch B attenuating BaP-induced HTR cells damages in vitro. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1439-1449, 2016.

The synergistic effect of benzo[a]pyrene and lead on learning and memory of mice

In the present study, the single and combined neurotoxic effects of benzo[a]pyrene ([BaP] 0.0, 0.5, and 5.0 mg/kg body weight; intragastric administration) and lead acetate (0.0, 5.4, and 54.0 mg/L; by drinking water) were examined on KunMing mice. In the Morris water maze, results showed that BaP and lead induced synergistic effects on the escape latency and the time spent in the target quadrant but also showed an additive effect on the number of times animal crossing the original platform. Also, BaP and lead induced a synergistic effect on DNA damage in the single-cell gel electrophoresis. However, BaP plus lead showed additive effects on the levels of malondialdehyde, superoxide dismutase, and glutathione. These results suggested that the combination of BaP and lead can lead to a synergistic effect on spatial learning and memory impairments, and the mechanisms of the synergistic effects on behavioral deficits may be due to the oxidative stress injury.

Early postnatal benzo(a)pyrene exposure in Sprague-Dawley rats causes persistent neurobehavioral impairments that emerge postnatally and continue into adolescence and adulthood

Previous studies have demonstrated that benzo(a)pyrene (BaP) may disrupt the development of key biological systems, thus leaving children more vulnerable to functional impairments in adulthood. The current study was conducted to determine whether neurotoxic effects of postnatal BaP exposure on behavioral performance persist in juvenile and young adult stages. Therefore, neonate Sprague-Dawley pups were given oral doses of BaP (0.02, 0.2, and 2 mg/kg/day) continuing through a period of rapid brain development (on postnatal days [PNDs] 5-11). Further, developmental milestones and behavioral endpoints assessing sensory and motor maturation were examined. Also, in this study, Morris water maze and elevated plus maze were used for evaluating the cognitive function and anxiety-like behavior. Our results showed that there was altered ontogeny in a few measures of neuromotor development; however, other developmental milestones and sensory responses were not altered significantly. Moreover, the locomotor activity deficit in BaP-treated pups was evident at PND 36 and was most pronounced in the PND 69. Also, exposure to BaP during early postnatal development had an adverse effect on adult rats (PND 70) in the elevated plus maze, and the swim maze suggests that low doses of BaP impair spatial learning functions at adult test period. In contrast, BaP exposure had no evident effect on behaviors in these two mazes for adolescent animals. These data clearly indicate that behavioral impairments resulting from postnatal BaP exposure are potentially long-lasting and may not be apparent in juveniles, but are present in young adulthood.

A common carcinogen benzo[a]pyrene causes p53 overexpression in mouse cervix via DNA damage

Benzo[a]pyrene (BaP) is cytotoxic and/or genotoxic to lung, stomach and skin tissue in the body. However, the effect of BaP on cervical tissue remains unclear. The present study detected DNA damage and the expression of the p53 gene in BaP-induced cervical tissue in female mice. Animals were intraperitoneally injected and orally gavaged with BaP at the doses of 2.5, 5, and 10mg/kg twice a week for 14 weeks. The single-cell gel electrophoresis (SCGE) assay was used to detect the DNA damage. Immunohistochemistry (IHC) and in situ hybridization (ISH) were used to detect the expression of p53 protein and p53 mRNA, respectively. The results showed that BaP induced a significant and dose-dependent increase of the number of cells with DNA damaged and the tail length as well as Comet tail moment in cervical tissue. The expression level of p53 protein and mRNA was increased. The results demonstrate that BaP may show toxic effect on the cervix by increasing DNA damage and the expression of the p53 gene.