Facilitation of 9,10-phenanthrenequinone-elicited neuroblastoma cell apoptosis by NAD(P)H:quinone oxidoreductase 1

Protection Activity of 1,4-Naphthoquinones in Rotenone-Induced Models of Neurotoxicity

The MTS cell viability test was used to screen a mini library of natural and synthetic 1,4-naphthoquinone derivatives (1,4-NQs) from marine sources. This screening identified two highly effective compounds, U-443 and U-573, which showed potential in protecting Neuro-2a neuroblastoma cells from the toxic effects of rotenone in an in vitro model of neurotoxicity. The selected 1,4-NQs demonstrated the capability to reduce oxidative stress by decreasing the levels of reactive oxygen species (ROS) and nitric oxide (NO) in Neuro-2a neuroblastoma cells and RAW 264.7 macrophage cells and displayed significant antioxidant properties in mouse brain homogenate. Normal mitochondrial function was restored and the mitochondrial membrane potential was also regained by 1,4-NQs after exposure to neurotoxins. Furthermore, at low concentrations, these compounds were found to significantly reduce levels of proinflammatory cytokines TNF and IL-1β and notably inhibit the activity of cyclooxygenase-2 (COX-2) in RAW 264.7 macrophages. The results of docking studies showed that the 1,4-NQs were bound to the active site of COX-2, analogically to a known inhibitor of this enzyme, SC-558. Both substances significantly improved the behavioral changes in female CD1 mice with rotenone-induced early stage of Parkinson's disease (PD) in vivo. It is proposed that the 1,4-NQs, U-443 and U-573, can protect neurons and microglia through their potent anti-ROS and anti-inflammatory activities.

Oxygenated polycyclic aromatic hydrocarbons in food: toxicity, occurrence and potential sources

Oxygenated polycyclic aromatic hydrocarbons (OPAHs) are polycyclic aromatic hydrocarbons (PAHs) functionalized with at least one carbonyl group and are generally thought to be more toxic than PAHs. In this review, the physical-chemical properties, toxicity, occurrence, and potential sources of OPAHs in food were comprehensively discussed. The toxicities of 1,2-naphthoquinone, 1,4-naphthoquinone, 6H-benzo[cd]pyren-6-one, benzo[a]anthracene-7,12-quinone and 9,10-phenanthrenequinone were prominent among the OPAHs. Both 1,4-naphthoquinone and 1,2-naphthoquinone exhibited strong genotoxicity, cytotoxicity, and developmental toxicity. 6H-benzo[cd]pyren-6-one and benzo[a]anthracene-7,12-quinone showed high genotoxicity and cardiovascular toxicity. Although 9,10-phenanthrenequinone showed no genotoxicity, it exhibited almost the strongest cytotoxicity. For the majority of foods, the concentrations of OPAHs and PAHs were on the same order of magnitude. OPAHs tend to be positively correlated with the corresponding PAH concentrations in oil and fried food, while for barbequed food and seafood, no obvious correlation was found. In addition, 9-fluorenone, 9,10-anthraquinone, benzanthrone and 1,2-acenaphthenequinone had high abundance in food. Environmental pollution, food composition, storage conditions, heating methods, and other treatments influence the accumulation of OPAHs in food. Furthermore, oxygen and water played an important role in the transformation from PAHs to OPAHs. In short, this review guides the evaluation and further reduction of OPAH-related health risks in food.

ROS-independent cytotoxicity of 9,10-phenanthrenequinone inhibits cell cycle progression and spindle assembly during meiotic maturation in mouse oocytes

Diesel exhaust particles (DEPs) are major components of ambient particulate matter and are associated with various adverse health effects. Typically, DEPs contain a vast number of organic compounds, among which 9,10-phenanthrenequinone (9,10-PQ), the quinone derivative of the polycyclic aromatic hydrocarbon phenanthrene, is one of the most abundant and toxic. 9,10-PQ can produce excessive reactive oxygen species (ROS) via redox cycling and exhibit cytotoxicity in various cells. However, the underlying mechanisms involved in cytotoxicity of 9,10-PQ remain elusive. In this study, we investigated the effects of exposure to 9,10-PQ using mouse oocytes as a model system. We found that 9,10-PQ compromised meiotic maturation by impairing acentriolar microtubule organizing center (MTOC) assembly and subsequent spindle formation during meiotic maturation. Moreover, 9,10-PQ exposure prevented cell cycle progression by inhibiting Cdk1 activation via disturbance of cyclin B1 accumulation. Importantly, meiotic defects induced by 9,10-PQ exposure were not rescued by decreasing ROS levels, revealing that 9,10-PQ has ROS-independent activity that regulates cell cycle progression and spindle assembly. Therefore, our findings reveal that 9,10-PQ has novel activity that regulates cell-cycle progression and spindle formation in an ROS-independent manner during meiotic maturation in mouse oocytes.

[Clinical significance of tumor chemosensitivity assay in patients with head and neck cancer]

Objective:To evaluate the clinical significance of OncoDrug-Seq™ tumor gene detection in patients with head and neck malignancies. Methods:A retrospective analysis of 338 patients with locally advanced or unresectable head and neck malignancies admitted to the Department of Otorhinolaryngology Head and Neck Surgery, Chinese PLA General Hospital from April 2011 to February 2021. Among them, 301 patients were pathologically diagnosed as squamous cell carcinoma, 37 cases were non-squamous cell carcinoma. All patients underwent OncoDrug-Seq™ gene detection, combined with the test results and the treatment response after induction chemotherapy to evaluate whether to change the chemotherapy regimen, and to calculate the accuracy of the gene detection and the survival rate of the patient. Results:Among 301 patients with head and neck squamous cell carcinoma, the results of the drug sensitivity test were compared with the actual clinical response, the true positive rate（TP）, true negative rate（TN）, positive predictive value（PPV）, negative predictive value（NPV） and total predictive accuracy rates were 85.37%, 65.45%, 91.70%, 50.00% and 81.73%, respectively. For patients who changed chemotherapy regimen（TN+FP） and did not change（TP+FN）, the 5-year progression-free survival（PFS） was 63.45% and 80.58%（P<0.05）, respectively, the 5-year overall survival（OS） was 54.18% and 84.74%（P<0.05）. Among 37 patients with non-squamous cell carcinoma, the TP, TN, PPV, NPV and total predictive accuracy rates were 88.46%, 72.73%, 88.46%, 72.73%, and 83.78%, respectively. The 5-year PFS of the patients who changed（TN+FP） and did not change the treatment regimen（TP+FN） were 68.57% and 56.00%, and the 5-year OS was 69.26% and 48.72%, the difference was not statistically significant. Conclusion:OncoDrug-Seq™ testing has certain significance in guiding clinicians to formulate personalized chemotherapy regimens. Timely replacement of the treatment plan can enable the patient to obtain a more ideal curative effect. Compared with patients with squamous cell carcinoma, patients with non-squamous cell carcinoma can obtain greater survival benefit from this testing. However, there are still some deviations in the accuracy of the test results compared with the actual clinical situation. Therefore, the decision should be made based on the test results in combination with the clinical reality.

Differences in epithelial-mesenchymal-transition in paraquat-induced pulmonary fibrosis in BALB/C and BALB/C (nu/nu) nude mice

Exposure to the toxic herbicide paraquat (PQ) can lead to the active absorption and enrichment of alveolar epithelial cells, resulting in pulmonary fibrosis and respiratory failure. At present, no effective clinical treatment is available. Notably, however, patients infected with human acquired immunodeficiency virus (HIV) (with T lymphocyte deficiency) do not show pulmonary fibrosis after PQ poisoning, suggesting that T lymphocytes may be involved in the occurrence and pathological development of lung fibers following PQ exposure, although relevant studies remain limited. Here, we found that the degree of pulmonary fibrosis induced by intragastric administration of PQ in congenital immunodeficiency BALB/C (nu/nu) nude (T lymphocyte loss) mice was lower than that in normal mice. However, pulmonary fibrosis was aggravated after transplantation of BALB/C (nu/nu) T lymphocytes into congenital immunodeficiency mice. This study is the first to report on the involvement of T lymphocytes in the occurrence and pathological development of lung fibers induced by PQ exposure. Thus, T cells may be an important cellular target for the clinical treatment of pulmonary fibrosis caused by PQ.

9,10-Phenanthrenequinone provokes dysfunction of brain endothelial barrier through down-regulating expression of claudin-5

Chronic exposure to diesel exhaust particle (DEP) is considered to provoke dysfunction of the blood-brain barrier, but the detailed molecular mechanism remains unclear. In this study, we investigated the toxic effects of five DEP components against human vascular cells and found that, among them, 9,10-phenanthrenequinone (9,10-PQ), a major tricyclic quinone in DEP, most potently elicits the cellular toxicities. Additionally, treatment with 9,10-PQ at its cytolethal concentrations (more than 2 μM) facilitated the production of reactive oxygen species (ROS), caspase activation, and DNA fragmentation in human brain microvascular endothelial (HBME) cells, inferring that high concentrations of 9,10-PQ elicit the cell apoptosis through the ROS-dependent mechanism. Measurement of trans-endothelial electrical resistance and paracellular permeability showed that treatment with sublethal concentrations (less than 1 μM) of 9,10-PQ elevates permeability across HBME cell monolayer. Immunofluorescence observation and Western blotting analysis also revealed that the 9,10-PQ treatment remarkably down-regulated the intercellular localization and expression of claudin-5 (CLDN5), a tight junctional protein that plays a key role in function of the blood-brain barrier, and the down-regulation was markedly recovered by pretreatment with a proteasome inhibitor Z-Leu-Leu-Leu-CHO. This result may indicate that sublethal concentrations of 9,10-PQ facilitate the dysfunction of the endothelial cell barrier through lowering in the expression and proteasomal proteolysis of CLDN5. The treatment with 9,10-PQ promoted nitric oxide (NO) production presumably through the induction of inducible NO synthase. In addition, the 9,10-PQ-mediated down-regulation of CLDN5 was ameliorated and deteriorated by pretreating with a scavenger and donor, respectively, of NO. Similarly to the 9,10-PQ treatment, treatment with a donor of peroxynitrite, a highly reactive oxidant formed by the reaction of NO and superoxide anion, resulted in the marked reduction of CLDN5 expression and elevation of 26S proteasome-based proteolytic activities. Thus, it is suggested that the formation of NO and peroxynitrite participates in the mechanism of brain endothelial cell barrier dysfunction elicited by 9,10-PQ.

Carbonyl reductase sniffer from the model organism daphnia: Cloning, substrate determination and inhibitory sensitivity

Carbonyl reductases (CRs) represent a fundamental enzymatic defense mechanism against oxidative stress. While commonly two carbonyl reductases (CBR1 and CBR3) are found in mammalian genomes, invertebrate model organisms like Drosophila melanogaster express no CR but a functional homolog to human CBR1, termed sniffer. The importance of sniffer could be demonstrated in D. melanogaster where it protected against age-dependent neurodegeneration. Interestingly, the microcrustacean Daphnia harbors four copies of the CR gene (CR1, CR2, CR3, CR4) in addition to one sniffer gene. Due to this unique equipment Daphnia is an ideal model organism to investigate the function of sniffer. Recombinant sniffer from D. magna und D. pules were produced in E. coli, purified by Ni-affinity chromatography and tested with a variety of aliphatic and aromatic diketones, reactive aldehydes and precursors of advanced glycation end products (AGE). The highest catalytic activities were determined for sniffer from D. pulex with the aromatic dicarbonyls 9,10-phenanthrenequinone (k_cat/K_m = 2.6 s^-1 x μM^-1) and isatin (k_cat/K_m = 1.5 s^-1 x μM^-1). While sniffer from D. magna displayed preference for the same two substances, the respective catalytic activities were noticeably lower. Kinetic constants with aliphatic diketones were generally lower than those with aromatic dicarbonyls for both sniffer enzymes. The best aliphatic diketone as substrate for sniffer from D. magna and D. pulex was hexane-3,4-dione with k_cat/K_m = 0.23 s^-1 μM^-1 and k_cat/K_m = 0.35 s^-1 μM^-1, respectively. Poor or no detectable activity of the two sniffer enzymes was seen with the aliphatic diketones 2,5-hexanedione and 3,5-heptanedione, the aldehydes butanal, hexanal, decanal, crotonaldehyde, acrolein, trans-2-hexenal, and the AGE precursors glyoxal, methylglyoxal, furfural and glyceraldehyde, indicating no physiological function in the metabolism of short-chain aldehydes. Substrate inhibition for both sniffer enzymes was observed with the quinone substrates 1,4-naphthoquinone and 2-methyl-1,4-benzoquinone. From a variety of pesticides endosulfan turned out as an effective inhibitor of the sniffer enzymes (Ki = 9.2 μM for sniffer from D. magna, Ki = 12.0 μM for sniffer from D. pulex). In conclusion, the present results on sniffer from the protein superfamily of the short-chain dehydrogenases/reductases (SDR) in Daphnia ssp. complement earlier studies on carbonyl reductases in the same species and indicate that Daphnia is an interesting model to study the overall response to carbonyl stress.

Cytotoxicity of Air Pollutant 9,10-Phenanthrenequinone: Role of Reactive Oxygen Species and Redox Signaling

Atmospheric pollution has been a principal topic recently in the scientific and political community due to its role and impact on human and ecological health. 9,10-phenanthrenequinone (9,10-PQ) is a quinone molecule found in air pollution abundantly in the diesel exhaust particles (DEP). This compound has studied extensively and has been shown to develop cytotoxic effects both in vitro and in vivo. 9, 10-PQ has been proposed to play a critical role in the development of cytotoxicity via generation of reactive oxygen species (ROS) through redox cycling. This compound also reduces expression of glutathione (GSH), which is critical in Phase II detoxification reactions. Understanding the underlying cellular mechanisms involved in cytotoxicity can allow for the development of therapeutics designed to target specific molecules significantly involved in the 9,10-PQ-induced ROS toxicity. This review highlights the developments in the understanding of the cytotoxic effects of 9, 10-PQ with special emphasis on the possible mechanisms involved.