Benzo[a]pyrene (BP) DNA adduct formation in DNA repair-deficient p53 haploinsufficient [Xpa(-/-)p53(+/-)] and wild-type mice fed BP and BP plus chlorophyllin for 28 days

Cetuximab decorated redox sensitive D-alpha-tocopheryl- polyethyleneglycol-1000-succinate based nanoparticles for cabazitaxel delivery: Formulation, lung targeting and enhanced anti-cancer effects

This research work aims to fabricate cetuximab (CTX) decorated cabazitaxel (CBZ) loaded redox-sensitive D-alpha-tocopheryl-polyethyleneglycol-1000-succinate (TPGS-SS) nanoparticles (NPs) for epidermal growth factor receptor (EGFR)-targeted lung tumor therapy.The NPs were prepared using a dialysis bag diffusion method to produce, non-redox sensitive non targeted (TPGS-CBZ-NPs), redox-sensitive nontargeted (TPGS-SS-CBZ-NPs), and targeted redox-sensitive NPs (CTX-TPGS-SS-CBZ-NPs). Developed NPs were characterized for particle sizes, polydispersity, surface charge, surface morphologies, and entrapment efficiency. Moreover, additional in vitro studies have been conducted, including in vitro drug release, cytotoxicity, and cellular uptake studies.The particle size and charge over the surface were found to be in the range of 145.6 to 308.06 nm and -15 to -23 mV respectively. The IC50 values of CBZ clinical injection (Jevtana®), TPGS-CBZ-NPs, TPGS-SS-CBZ-NPs, and CTX-TPGS-SS-NPs were found to be 17.54 ± 3.58, 12.8 ± 2.45, 9.28 ± 1.13 and 4.013 ± 1.05 µg/ml, suggesting the 1.37, 1.89 and 4.37-folds respectively, enhancement of cytotoxicity as compared to CBZ clinical injection, demonstrating a significant augmentation in cytotoxicity. In addition, the in-vitro cellular uptake investigation showed that CTX-TPGS-SS-CMN6-NPs accumulated significantly compared to pure CMN6, TPGS-CMN6-NPs, and TPGS-SS-CMN6-NPs in the A549 cells. Furthermore, the targeting efficiency of developed NPs were analysed by ultrasound/photoacoustic and IVIS imaging.

3,4-Dihydroxyphenylethanol (DPE or Hydroxytyrosol) Counteracts ERK1/2 and mTOR Activation, Pro-Inflammatory Cytokine Release, Autophagy and Mitophagy Reduction Mediated by Benzo[a]pyrene in Primary Human Colonic Epithelial Cells

Understanding the effects induced by carcinogens on primary colonic epithelial cells and how to counteract them might help to prevent colon cancer, which is one of the most frequent and aggressive cancers. In this study, we exposed primary human colonic epithelial cells (HCoEpC) to Benzo[a]pyrene (B[a]P) and found that it led to an increased production of pro-inflammatory cytokines and activated ERK1/2 and mTOR. These pathways are known to be involved in inflammatory bowel disease (IBD), which represents a colon cancer risk factor. Moreover, B[a]P reduced autophagy and mitophagy, processes whose dysregulation has been clearly demonstrated to predispose to cancer either by in vitro or in vivo studies. Interestingly, all the effects induced by B[a]P could be counteracted by 3,4-Dihydroxyphenylethanol (DPE or Hydroxytyrosol, H), the most powerful anti-inflammatory and antioxidant compound contained in olive oil. This study sheds light on the mechanisms that could be involved in colon carcinogenesis induced by a chemical carcinogen and identifies a safe natural product that may help to prevent them.

The potential risks and exposure of Qinling giant pandas to polycyclic aromatic hydrocarbon (PAH) pollution

Rapid industrialization and urbanization have created a substantial urban-rural gradient for various pollutants. The Qinling Mountains are highly important in terms of biodiversity, providing habitat for giant pandas, which are endemic to China and are a widely recognized symbol for conservation. Whether polycyclic aromatic hydrocarbon (PAH) exposure risks regarding in situ animal conservation zones are affected by environmental pollution or even enhanced by the mountain-trapping effect requires further research. Our group carried out a large-scale investigation on the area ranging from Xi'an to Hanzhong across the giant panda habitat in the Qinling Mountains by collecting atmosphere, soil, bamboo, and fecal samples from different sites over a two-year period. The total toxicity of atmospheric PAHs and the frequencies of soil PAHs above effect range low (ERL) values showed a decreasing trend from urban areas to the central mountains, suggesting a distance effect from the city. The proportions of total 5- and 6-ring PAHs in the atmosphere were higher in the central mountainous areas than in the urban areas, while this difference was reversed in the soil. Health risk assessments showed that the incremental lifetime carcinogenic risks (ILCR) of PAH exposure by bamboo ingestion ranged from 2.16 × 10^-4 to 3.11 × 10^-4, above the critical level of 10^-4. Bamboo ingestion was the main driver of the PAH exposure risks. The concentration difference between bamboo and fecal samples provided a reference for the level of PAHs absorbed by the panda digestive system. Since the Qinling Mountains possess the highest density of giant pandas and provide habitats to many other endangered animal and plant species, we should not ignore the probability of health risks posed by PAHs. Monitoring the pollution level and reducing the atmospheric emissions of toxic pollutants are recommended actions. Further detailed research should also be implemented on pandas' health effects of contaminant exposure.

Inflammation response, oxidative stress and DNA damage caused by urban air pollution exposure increase in the lack of DNA repair XPC protein

Air pollution represents a considerable threat to health worldwide. The São Paulo Metropolitan area, in Brazil, has a unique composition of atmospheric pollutants with a population of nearly 20 million people and 9 million passenger cars. It is long known that exposure to particulate matter less than 2.5 µm (PM_2.5) can cause various health effects such as DNA damage. One of the most versatile defense mechanisms against the accumulation of DNA damage is the nucleotide excision repair (NER), which includes XPC protein. However, the mechanisms by which NER protects against adverse health effects related to air pollution are largely unknown. We hypothesized that reduction of XPC activity may contribute to inflammation response, oxidative stress and DNA damage after PM_2.5 exposure. To address these important questions, XPC knockout and wild type mice were exposed to PM_2.5 using the Harvard Ambient Particle concentrator. Results from one-single exposure have shown a significant increase in the levels of anti-ICAM, IL-1β, and TNF-α in the polluted group when compared to the filtered air group. Continued chronic PM_2.5 exposure increased levels of carbonylated proteins, especially in the lung of XPC mice, probably as a consequence of oxidative stress. As a response to DNA damage, XPC mice lungs exhibit increased γ-H2AX, followed by severe atypical hyperplasia. Emissions from vehicles are composed of hazardous substances, with polycyclic aromatic hydrocarbons (PAHs) and metals being most frequently cited as the major contributors to negative health impacts. This analysis showed that benzo[b]fluoranthene, 2-nitrofluorene and 9,10-anthraquinone were the most abundant PAHs and derivatives. Taken together, these findings demonstrate the participation of XPC protein, and NER pathway, in the protection of mice against the carcinogenic potential of air pollution. This implicates that DNA is damaged directly (forming adducts) or indirectly (Reactive Oxygen Species) by the various compounds detected in urban PM_2.5.

NADPH-quinone oxidoreductase-1 mediates Benzo-[a]-pyrene-1,6-quinone-induced cytotoxicity and reactive oxygen species production in human EA.hy926 endothelial cells

Numerous studies conducted in the past have reported deaths in the human population due to cardiovascular diseases (CVD) on exposure to air particulate matter (APM). BP-1,6-quinone (BP-1,6-Q) is one of the significant components of APM. However, the mechanism(s) by which it can exert its toxicity in endothelial cells is not yet completely understood. NAD(P)H: quinone oxidoreductase-1 (NQO1) is expressed highly in myocardium and vasculature tissues of the heart and plays a vital role in maintaining vascular homeostasis. This study, demonstrated that BP-1,6-Q diminishes NQO1 enzyme activity in a dose-dependent manner in human EA.hy926 endothelial cells. The decrease in the NQO1 enzyme causes potentiation in BP-1,6-Q-mediated toxicity in EA.hy926 endothelial cells. The enhancement of NQO1 in endothelial cells showed cytoprotection against BP-1,6-Q-induced cellular toxicity, lipid, and protein damage suggesting an essential role of NQO1 in cytoprotection against BP-1,6-Q toxicity. Using various biochemical assays and genetic approaches, results from this study further demonstrated that NQO1 also plays a crucial role in BP-1,6-Q-induced production of reactive oxygen species (ROS). These findings will contribute to elucidating BP-1,6-Q mediated toxicity and its role in the development of atherosclerosis.

Role of nucleotide excision repair and p53 in zidovudine (AZT)-induced centrosomal deregulation

The nucleoside reverse transcriptase inhibitor zidovudine (AZT) induces genotoxic damage that includes centrosomal amplification (CA > 2 centrosomes/cell) and micronucleus (MN) formation. Here we explored these end points in mice deficient in DNA repair and tumor suppressor function to evaluate their effect on AZT-induced DNA damage. We used mesenchymal-derived fibroblasts cultured from C57BL/6J mice that were null and wild type (WT) for Xpa, and WT, haploinsufficient and null for p53 (6 different genotypes). Dose-responses for CA formation, in cells exposed to 0, 10, and 100 μM AZT for 24 hr, were observed in all genotypes except the Xpa((+/+)) p53((+/-)) cells, which had very low levels of CA, and the Xpa((-/-)) p53((-/-)) cells, which had very high levels of CA. For CA there was a significant three-way interaction between Xpa, p53, and AZT concentration, and Xpa((-/-)) cells had significantly higher levels of CA than Xpa((+/+)) cells, only for p53((+/-)) cells. In contrast, the MN and MN + chromosomes (MN + C) data showed a lack of AZT dose response. The Xpa((-/-)) cells, with p53((+/+)) or ((+/-)) genotypes, had levels of MN and MN + C higher than the corresponding Xpa((+/+)) cells. The data show that CA is a major event induced by exposure to AZT in these cells, and that there is a complicated relationship between AZT and CA formation with respect to gene dosage of Xpa and p53. The loss of both genes resulted in high levels of damage, and p53 haploinsufficicency strongly protected Xpa((+/+)) cells from AZT-induced CA damage.

Mechanistic relationships between hepatic genotoxicity and carcinogenicity in male B6C3F1 mice treated with polycyclic aromatic hydrocarbon mixtures

The genotoxicity of a complex mixture [neutral fraction (NF)] from a wood preserving waste and reconstituted mixture (RM) mimicking the NF with seven major polycyclic aromatic hydrocarbons (PAHs) and benzo(a)pyrene (BaP) was investigated by determining DNA adducts and tumor incidence in male B6C3F1 mice exposed to three different doses of the chemical mixtures. The peak values of DNA adducts were observed after 24 h, and the highest levels of PAH-DNA adducts were exhibited in mice administered NF + BaP, and the highest tumor incidence and mortality were also observed in this group. DNA adduct levels after 1, 7, or 21 days were significantly correlated with animal mortality and incidence of total tumors including liver, lung, and forestomach. However, only hepatic DNA adducts after 7 days significantly correlated with liver tumor incidence. Most proteins involved in DNA repair including ATM, pATR, Chk1, pChk1, DNA PKcs, XRCC1, FANCD2, Ku80, Mre11, and Brca2 were significantly lower in liver tumor tissue compared to non-tumor tissue. Expressions of proteins involved in apoptosis and cell cycle regulation were also significantly different in tumor versus non-tumor tissues, and it is possible that PAH-induced changes in these gene products are important for tumor development and growth.