Environmental and chemical carcinogenesis

Dietary 5-demethylnobiletin modulates xenobiotic-metabolizing enzymes and ameliorates colon carcinogenesis in benzo[a]pyrene-induced mice

The intake of common polycyclic aromatic hydrocarbons (PAHs), such as benzo[a]pyrene (BaP), is strongly correlated to the initiation of colon cancer. BaP is a well-known pro-carcinogen that is metabolically activated by xenobiotic-metabolizing enzymes. Studies indicate that polymethoxyflavones, including 5-demethylnobiletin (5-DMNB), exhibit anti-inflammatory and anti-carcinogenic properties. However, the effects of 5-DMNB on xenobiotic-metabolizing enzymes and BaP-induced carcinogenesis remain unclear. The combination of BaP and a promoting agent-dextran sulfate sodium (DSS)-has been demonstrated to induce tumors in mouse models. Thus, this study aimed to determine the protective effect of 5-DMNB on carcinogen biotransformation and BaP/DSS-induced colon carcinogenesis. Our results showed that 5-DMNB had a substantial inhibitory effect on CYP1B1 induced by BaP and upregulated the detoxification enzymes UDP-glucuronosyltransferases (UGTs) and glutathione S-transferases (GSTs). Furthermore, subsequent analyses confirmed that the dietary administration of 5-DMNB markedly ameliorated tumor formation in BaP/DSS-treated mice. Exposure to BaP/DSS also significantly elevated TNF-α levels, and the administration of 5-DMNB reversed this increase. Taken together, we determined that 5-DMNB attenuates BaP/DSS-induced colon cancer through the regulation of inflammation and xenobiotic-metabolizing enzymes. These results indicate that 5-DMNB has significant potential as a novel chemopreventive agent for preventing carcinogen activation and inflammation-associated carcinogenesis.

Exploring the Biological Activity and Mechanism of Xenoestrogens and Phytoestrogens in Cancers: Emerging Methods and Concepts

Xenoestrogens and phytoestrogens are referred to as "foreign estrogens" that are produced outside of the human body and have been shown to exert estrogen-like activity. Xenoestrogens are synthetic industrial chemicals, whereas phytoestrogens are chemicals present in the plant. Considering that these environmental estrogen mimics potentially promote hormone-related cancers, an understanding of how they interact with estrogenic pathways in human cells is crucial to resolve their possible impacts in cancer. Here, we conducted an extensive literature evaluation on the origins of these chemicals, emerging research techniques, updated molecular mechanisms, and ongoing clinical studies of estrogen mimics in human cancers. In this review, we describe new applications of patient-derived xenograft (PDX) models and single-cell RNA sequencing (scRNA-seq) techniques in shaping the current knowledge. At the molecular and cellular levels, we provide comprehensive and up-to-date insights into the mechanism of xenoestrogens and phytoestrogens in modulating the hallmarks of cancer. At the systemic level, we bring the emerging concept of window of susceptibility (WOS) into focus. WOS is the critical timing during the female lifespan that includes the prenatal, pubertal, pregnancy, and menopausal transition periods, during which the mammary glands are more sensitive to environmental exposures. Lastly, we reviewed 18 clinical trials on the application of phytoestrogens in the prevention or treatment of different cancers, conducted from 2002 to the present, and provide evidence-based perspectives on the clinical applications of phytoestrogens in cancers. Further research with carefully thought-through concepts and advanced methods on environmental estrogens will help to improve understanding for the identification of environmental influences, as well as provide novel mechanisms to guide the development of prevention and therapeutic approaches for human cancers.

Identification of anticancer drug target genes using an outside competitive dynamics model on cancer signaling networks

Each cancer type has its own molecular signaling network. Analyzing the dynamics of molecular signaling networks can provide useful information for identifying drug target genes. In the present study, we consider an on-network dynamics model—the outside competitive dynamics model—wherein an inside leader and an opponent competitor outside the system have fixed and different states, and each normal agent adjusts its state according to a distributed consensus protocol. If any normal agent links to the external competitor, the state of each normal agent will converge to a stable value, indicating support to the leader against the impact of the competitor. We determined the total support of normal agents to each leader in various networks and observed that the total support correlates with hierarchical closeness, which identifies biomarker genes in a cancer signaling network. Of note, by experimenting on 17 cancer signaling networks from the KEGG database, we observed that 82% of the genes among the top 3 agents with the highest total support are anticancer drug target genes. This result outperforms those of four previous prediction methods of common cancer drug targets. Our study indicates that driver agents with high support from the other agents against the impact of the external opponent agent are most likely to be anticancer drug target genes.

Anticancer, antiplatelet, gastroprotective and hepatoprotective effects of camel urine: A scoping review

Camel urine has traditionally been used to treat multiple human diseases and possesses the most beneficial effects amongst the urine of other animals. However, scientific review evaluating the anticancer, antiplatelet, gastroprotective and hepatoprotective effects of camel urine is still scarce. Thus, this scoping review aimed to provide scientific evidence on the therapeutic potentials of camel urine. Three databases were searched to identify relevant articles (Web of Science, PubMed and Scopus) up to September 2020. Original articles published in English that investigated the effects of camel urine in various diseases were included. The literature search identified six potential articles that met all the inclusion criteria. Three articles showed that camel urine possesses cytotoxic activities against different types of cancer cells. Two studies revealed camel urine's protective effects against liver toxicity and gastric ulcers, whilst another study showed the role of camel urine as an antiplatelet agent. All studies demonstrated significant positive effects with different effective dosages. Thus, camel urine shows promising therapeutic potential in treating human diseases, especially cancer. However, the standardised dosage and potential side effects should be determined before camel urine could be offered as an alternative treatment.

Chemoprotective Effects of Xanthohumol against the Carcinogenic Mycotoxin Aflatoxin B1

The present study addresses the chemoprotective effects of xanthohumol (XN), a prenylated flavonoid found in the female inflorescences (hops) of the plant Humulus lupulus L., against the carcinogenic food contaminant aflatoxin B1 (AFB1). The chemical reactions of XN and its derivatives (isoxanthohumol (IXN), 8-prenylnaringenin (8-PN), and 6-prenylnaringenin (6-PN)) with the AFB1 metabolite, aflatoxin B1 exo-8,9-epoxide (AFBO), were investigated in silico, by calculating activation free energies (ΔG^‡) at the Hartree–Fock level of theory in combination with the 6-311++G(d,p) basis set and two implicit solvation models. The chemoprotective effects of XN were investigated in vitro in the metabolically competent HepG2 cell line, analyzing its influence on AFB1-induced cytotoxicity using the MTS assay, genotoxicity using the comet and γH2AX assays, and cell cycle modulation using flow cytometry. Our results show that the ΔG^‡ required for the reactions of XN and its derivatives with AFBO are comparable to the ΔG^‡ required for the reaction of AFBO with guanine, indicating that XN, IXN, 8-PN, and 6-PN could act as scavengers of AFBO, preventing DNA adduct formation and DNA damage induction. This was also reflected in the results from the in vitro experiments, where a reduction in AFB1-induced cytotoxicity and DNA single-strand and double-strand breaks was observed in cells exposed to combinations of AFB1 and XN, highlighting the chemoprotective effects of this phytochemical.

Predicting Lung Cancer in the United States: A Multiple Model Examination of Public Health Factors

In this research, we take a multivariate, multi-method approach to predicting the incidence of lung cancer in the United States. We obtain public health and ambient emission data from multiple sources in 2000–2013 to model lung cancer in the period 2013–2017. We compare several models using four sources of predictor variables: adult smoking, state, environmental quality index, and ambient emissions. The environmental quality index variables pertain to macro-level domains: air, land, water, socio-demographic, and built environment. The ambient emissions consist of Cyanide compounds, Carbon Monoxide, Carbon Disulfide, Diesel Exhaust, Nitrogen Dioxide, Tropospheric Ozone, Coarse Particulate Matter, Fine Particulate Matter, and Sulfur Dioxide. We compare various models and find that the best regression model has variance explained of 62 percent whereas the best machine learning model has 64 percent variance explained with 10% less error. The most hazardous ambient emissions are Coarse Particulate Matter, Fine Particulate Matter, Sulfur Dioxide, Carbon Monoxide, and Tropospheric Ozone. These ambient emissions could be curtailed to improve air quality, thus reducing the incidence of lung cancer. We interpret and discuss the implications of the model results, including the tradeoff between transparency and accuracy. We also review limitations of and directions for the current models in order to extend and refine them.

Identification of lncRNA Signature Associated With Pan-Cancer Prognosis

Long noncoding RNAs (lncRNAs) have emerged as potential prognostic markers in various human cancers as they participate in many malignant behaviors. However, the value of lncRNAs as prognostic markers among diverse human cancers is still under investigation, and a systematic signature based on these transcripts that related to pan-cancer prognosis has yet to be reported. In this study, we proposed a framework to incorporate statistical power, biological rationale, and machine learning models for pan-cancer prognosis analysis. The framework identified a 5-lncRNA signature (ENSG00000206567, PCAT29, ENSG00000257989, LOC388282, and LINC00339) from TCGA training studies (n = 1,878). The identified lncRNAs are significantly associated (all P ≤ 1.48E-11) with overall survival (OS) of the TCGA cohort (n = 4,231). The signature stratified the cohort into low- and high-risk groups with significantly distinct survival outcomes (median OS of 9.84 years versus 4.37 years, log-rank P = 1.48E-38) and achieved a time-dependent ROC/AUC of 0.66 at 5 years. After routine clinical factors involved, the signature demonstrated better performance for long-term prognostic estimation (AUC of 0.72). Moreover, the signature was further evaluated on two independent external cohorts (TARGET, n = 1,122; CPTAC, n = 391; National Cancer Institute) which yielded similar prognostic values (AUC of 0.60 and 0.75; log-rank P = 8.6E-09 and P = 2.7E-06). An indexing system was developed to map the 5-lncRNA signature to prognoses of pan-cancer patients. In silico functional analysis indicated that the lncRNAs are associated with common biological processes driving human cancers. The five lncRNAs, especially ENSG00000206567, ENSG00000257989 and LOC388282 that never reported before, may serve as viable molecular targets common among diverse cancers.

Natural Products: Implication in Cancer Prevention and Treatment through Modulating Various Biological Activities

Cancer is one of the most leading causes of death worldwide. It is one of the primary global diseases that cause morbidity and mortality in millions of people. It is usually caused by different carcinogenic agents that damage the genetic material and alter the cell signaling pathways. Carcinogens are classified into two groups as genotoxic and non-genotoxic agents. Genotoxic carcinogens are capable of directly altering the genetic material, while the non-genotoxic carcinogens are capable of producing cancer by some secondary mechanisms not related to direct gene damage. There is undoubtedly the greatest need to utilize some novel natural products as anticancer agents, as these are within reach everywhere. Interventions by some natural products aimed at decreasing the levels and conditions of these risk factors can reduce the frequency of cancer incidences. Cancer is conventionally treated by surgery, radiation therapy and chemotherapy, but such treatments may be fast-acting and causes adverse effects on normal tissues. Alternative and innovative methods of cancer treatment with the least side effects and improved efficiency are being encouraged. In this review, we discuss the different risk factors of cancer development, conventional and innovative strategies of its management and provide a brief review of the most recognized natural products used as anticancer agents globally.

A highly sensitive method for simultaneous detection of hAAG and UDG activity based on multifunctional dsDNA probes mediated exponential rolling circle amplification

DNA glycosylase is an indispensable DNA damage repair enzyme which can recognize and excise the damaged bases in the DNA base excision-repair pathway. The dysregulation of DNA glycosylase activity will give rise to the dysfunction of base excision-repair and lead to abnormalities and diseases. The simultaneous detection of multiple DNA glycosylases can help to fully understand the normal physiological functions of cells, and determine whether the cells are abnormal in pre-disease. Regrettably, the synchronous detection of functionally similar DNA glycosylases is a great challenge. Herein, we developed a multifunctional dsDNA probe mediated exponential rolling circle amplification (E-RCA) method for the simultaneously sensitive detection of human alkyladenine DNA glycosylase (hAAG) and uracil-DNA glycosylase (UDG). The multifunctional dsDNA probe contains the hypoxanthine sites and the uracil sites which can be recognized by hAAG and UDG respectively to generate apyrimidinic (AP) sites in the dsDNA probe. Then the AP sites will be recognized and cut by endonuclease Ⅳ (Endo IV) to release corresponding single-stranded primer probes. Subsequently, two padlock DNA templates are added to initiate E-RCA to generate multitudinous G-quadruplexes and/or double-stranded dumbbell lock structures, which can combine N-methyl mesoporphyrin IX (NMM) and SYBR Green Ⅰ (SGI) for the generation of respective fluorescent signals. The detection limits are obtained as low as 0.0002 U mL^-1 and 0.00001 U mL^-1 for hAAG and UDG, respectively. Notably, this method can realize the simultaneous detection of two DNA glycosylases without the use of specially labeled probes. Finally, this method is successfully applied to detect hAAG and UDG activities in the lysates of HeLa cells and Endo1617 cells at single-cell level, and to detect the inhibitors of DNA glycosylases.

Defective apoptotic cell contractility provokes sterile inflammation, leading to liver damage and tumour suppression

Apoptosis is characterized by profound morphological changes, but their physiological purpose is unknown. To characterize the role of apoptotic cell contraction, ROCK1 was rendered caspase non-cleavable (ROCK1nc) by mutating aspartate 1113, which revealed that ROCK1 cleavage was necessary for forceful contraction and membrane blebbing. When homozygous ROCK1nc mice were treated with the liver-selective apoptotic stimulus of diethylnitrosamine, ROCK1nc mice had more profound liver damage with greater neutrophil infiltration than wild-type mice. Inhibition of the damage-associated molecular pattern protein HMGB1 or signalling by its cognate receptor TLR4 lowered neutrophil infiltration and reduced liver damage. ROCK1nc mice also developed fewer diethylnitrosamine-induced hepatocellular carcinoma (HCC) tumours, while HMGB1 inhibition increased HCC tumour numbers. Thus, ROCK1 activation and consequent cell contraction are required to limit sterile inflammation and damage amplification following tissue-scale cell death. Additionally, these findings reveal a previously unappreciated role for acute sterile inflammation as an efficient tumour-suppressive mechanism.

Pancreatic Cancer Exposome Profile to Aid Early Detection and Inform Prevention Strategies

Pancreatic cancer (PCa) is associated with a poor prognosis and high mortality rate. The causes of PCa are not fully elucidated yet, although certain exposome factors have been identified. The exposome is defined as the sum of all environmental factors influencing the occurrence of a disease during a life span. The development of an exposome approach for PCa has the potential to discover new disease-associated factors to better understand the carcinogenesis of PCa and help with early detection strategies. Our systematic review of the literature identified several exposome factors that have been associated with PCa alone and in combination with other exposures. A potential inflammatory signature has been observed among the interaction of several exposures (i.e., smoking, alcohol consumption, diabetes mellitus, obesity, and inflammatory markers) that further increases the incidence and progression of PCa. A large number of exposures have been identified such as genetic, hormonal, microorganism infections and immune responses that warrant further investigation. Future early detection strategies should utilize this information to assess individuals' risk for PCa.

Endocrine-Disrupting Chemicals and Infectious Diseases: From Endocrine Disruption to Immunosuppression

Endocrine-disrupting chemicals (EDCs) are hormonally active compounds in the environment that interfere with the body's endocrine system and consequently produce adverse health effects. Despite persistent public health concerns, EDCs remain important components of common consumer products, thus representing ubiquitous contaminants to humans. While scientific evidence confirmed their contribution to the severity of Influenza A virus (H1N1) in the animal model, their roles in susceptibility and clinical outcome of the coronavirus disease (COVID-19) cannot be underestimated. Since its emergence in late 2019, clinical reports on COVID-19 have confirmed that severe disease and death occur in persons aged ≥65 years and those with underlying comorbidities. Major comorbidities of COVID-19 include diabetes, obesity, cardiovascular disease, hypertension, cancer, and kidney and liver diseases. Meanwhile, long-term exposure to EDCs contributes significantly to the onset and progression of these comorbid diseases. Besides, EDCs play vital roles in the disruption of the body's immune system. Here, we review the recent literature on the roles of EDCs in comorbidities contributing to COVID-19 mortality, impacts of EDCs on the immune system, and recent articles linking EDCs to COVID-19 risks. We also recommend methodologies that could be adopted to comprehensively study the role of EDCs in COVID-19 risk.

Extension of Diagnostic Fragmentation Filtering for Automated Discovery in DNA Adductomics

Development of high-resolution/accurate mass liquid chromatography-coupled tandem mass spectrometry (LC-MS/MS) methodology enables the characterization of covalently modified DNA induced by interaction with genotoxic agents in complex biological samples. Constant neutral loss monitoring of 2'-deoxyribose or the nucleobases using data-dependent acquisition represents a powerful approach for the unbiased detection of DNA modifications (adducts). The lack of available bioinformatics tools necessitates manual processing of acquired spectral data and hampers high throughput application of these techniques. To address this limitation, we present an automated workflow for the detection and curation of putative DNA adducts by using diagnostic fragmentation filtering of LC-MS/MS experiments within the open-source software MZmine. The workflow utilizes a new feature detection algorithm, DFBuilder, which employs diagnostic fragmentation filtering using a user-defined list of fragmentation patterns to reproducibly generate feature lists for precursor ions of interest. The DFBuilder feature detection approach readily fits into a complete small-molecule discovery workflow and drastically reduces the processing time associated with analyzing DNA adductomics results. We validate our workflow using a mixture of authentic DNA adduct standards and demonstrate the effectiveness of our approach by reproducing and expanding the results of a previously published study of colibactin-induced DNA adducts. The reported workflow serves as a technique to assess the diagnostic potential of novel fragmentation pattern combinations for the unbiased detection of chemical classes of interest.

Lung Cancer Occurrence-Correlation with Serum Chromium Levels and Genotypes

Lung cancer is the leading cause of cancer-related death worldwide. Exposure to environmental and occupational carcinogens is an important cause of lung cancer. One of these substances is chromium, which is found ubiquitously across the planet. The International Agency for Research on Cancer has classified chromium(VI) as a human carcinogen. The aim of this study was to assess whether serum chromium levels, as well as DNA variants in selected genes involved in carcinogenesis, xenobiotic-metabolism, and oxidative stress could be helpful in the detection of lung cancer. We conducted a study using 218 lung cancer patients and 218 matched healthy controls. We measured serum chromium levels and genotyped ten genetic variants in ERCC2, XRCC1, MT1B, GSTP1, ABCB1, NQ01, CRTC3, GPX1, SOD2 and CAT. The odds ratios of being diagnosed with lung cancer were calculated using conditional logistic regression with respect to serum chromium level and genotypes. The odds ratio for the occurrence of lung cancer increased with increasing serum chromium levels. The difference between the quartiles with the lowest vs. highest chromium level was more than fourfold in the entire group (OR 4.52, CI 2.17-9.42, p < 0.01). This correlation was significantly increased by more than twice when specific genotypes were taken into consideration (ERCC-rs12181 TT, OR 12.34, CI 1.17-130.01, p = 0.04; CRTC3-rs12915189 non GG, OR 9.73, CI 1.58-60.10, p = 0.01; GSTP1-rs1695 non AA, OR 9.47, CI 2.06-43.49, p = < 0.01; CAT-rs1001179 non CC, OR 9.18, CI 1.64-51.24, p = 0.01). Total serum chromium levels > 0.1 μg/L were correlated with 73% (52/71) of lung cancers diagnosed with stage I disease. Our findings support the role of chromium and the influence of key proteins on lung cancer burden in the general population.

Relationships among smoking, oxidative stress, inflammation, macromolecular damage, and cancer

Smoking is a major risk factor for a variety of diseases, including cancer and immune-mediated inflammatory diseases. Tobacco smoke contains a mixture of chemicals, including a host of reactive oxygen- and nitrogen species (ROS and RNS), among others, that can damage cellular and sub-cellular targets, such as lipids, proteins, and nucleic acids. A growing body of evidence supports a key role for smoking-induced ROS and the resulting oxidative stress in inflammation and carcinogenesis. This comprehensive and up-to-date review covers four interrelated topics, including 'smoking', 'oxidative stress', 'inflammation', and 'cancer'. The review discusses each of the four topics, while exploring the intersections among the topics by highlighting the macromolecular damage attributable to ROS. Specifically, oxidative damage to macromolecular targets, such as lipid peroxidation, post-translational modification of proteins, and DNA adduction, as well as enzymatic and non-enzymatic antioxidant defense mechanisms, and the multi-faceted repair pathways of oxidized lesions are described. Also discussed are the biological consequences of oxidative damage to macromolecules if they evade the defense mechanisms and/or are not repaired properly or in time. Emphasis is placed on the genetic- and epigenetic alterations that may lead to transcriptional deregulation of functionally-important genes and disruption of regulatory elements. Smoking-associated oxidative stress also activates the inflammatory response pathway, which triggers a cascade of events of which ROS production is an initial yet indispensable step. The release of ROS at the site of damage and inflammation helps combat foreign pathogens and restores the injured tissue, while simultaneously increasing the burden of oxidative stress. This creates a vicious cycle in which smoking-related oxidative stress causes inflammation, which in turn, results in further generation of ROS, and potentially increased oxidative damage to macromolecular targets that may lead to cancer initiation and/or progression.

A Retrospective Chart Review Evaluating the Relationship between Cancer Diagnosis and Residential Water Source on the Lower Eastern Shore of Maryland, USA

Well water contamination in heavily agricultural regions has previously been linked with increased cancer incidence and mortality. The lower Eastern shore of Maryland is a rural, agricultural region with some of the highest rates of cancer in Maryland and the United States. Our study sought to characterize residential private well water use among cancer patients on the lower Eastern shore of Maryland, and to compare private well water utilization between cancer patients and the general regional population. Retrospective chart review was conducted to identify patients diagnosed with colon, lung, melanoma or breast cancer at a regional hospital from 1 January 2017 through 31 December 2018. Residential water source was determined using residential address and municipal water records. Fisher’s exact test was used to compare residential private well water utilization between our study population and the baseline regional population. The majority of cancer patients (57%) lived in homes supplied by private well water (428/746). Cancer patients were more likely to live in homes supplied by private well water compared to individuals in the general regional population (57% vs. 32%, p < 0.001). In conclusion, cancer patients on the lower Eastern shore of Maryland were more likely to live in homes supplied by residential private well water than the regional population. Additional studies are needed to evaluate well water use and cancer risk in this vulnerable region.

Aging and leukemic evolution of hematopoietic stem cells under various stress conditions

Hematopoietic stem cells (HSCs) have self-renewal capacity and differentiation potential into all lineages of blood cells throughout the lifetime of an organism. The function of HSCs gradually changes during aging. To date, various stress factors influencing HSC aging have been identified. The increased production of reactive oxygen species and DNA damage responses are causatively attributed to HSC aging. The increased apolarity is a prominent feature of aged HSCs, whereas it is less obvious in young HSCs. The bone marrow (BM) microenvironment niche is a crucial factor for HSC aging. Mesenchymal stem cells show skewed differentiation during aging, which leads to decreased bone formation and increased adipogenesis. The accumulation of adipocytes confers negative effects on hematopoiesis. Loss of sympathetic nerve fibers or adrenoreceptor β3 signaling induces premature HSC and niche aging. Epigenetic regulators such as polycomb group proteins and the sirtuin family of proteins act to prevent premature aging. Targeting these factors, several rejuvenation strategies for aged HSCs have been employed in mice. However, we still do not know whether these strategies can be extrapolated to human HSCs. Aging is frequently accompanied by the development of clonal hematopoiesis, which is called age-related clonal hematopoiesis (ARCH) or clonal hematopoiesis of indeterminate potential (CHIP). Most ARCH/CHIP mutations occur in genes encoding epigenetic regulators including DNMT3A, TET2, and ASXL1, which suggests the relevance of epigenetic drift during the aging process. ARCH/CHIP is a strong risk factor for subsequent hematologic cancer. Notably, it also has an impact on the development of non-malignant disorders such as coronary heart disease. Further studies are warranted to decipher the complete picture of molecular crosstalk that regulates HSC aging.

Association between the methylation of the STAT1 and SOCS3 in peripheral blood and gastric cancer

BACKGROUND AND AIM

DNA methylation is an important epigenetic modification that can promote the development of various cancers. The STAT1 and SOCS3 have been observed to be hypermethylated in tumor tissues and peripheral blood. This study aimed to explore the relationship between the methylation status of the STAT1 and SOCS3 in peripheral blood and gastric cancer (GC).

METHODS

This hospital-based case-control study involved 372 patients with GC and 379 controls. The methylation status of the STAT1 and SOCS3 was semiquantitatively determined using the methylation-sensitive high-resolution melting method. Logistic regression analysis was used to analyze the relationship between the STAT1 and SOCS3 methylation status and GC susceptibility. Moreover, propensity scores were used to control confounding factors.

RESULTS

Compared with negative methylation, the positive methylation of SOCS3 significantly increased the risk of GC (OR_a  = 1.820, 95% CI: 1.247-2.658, P = 0.002). This trend was also found via stratified analysis, and methylation positivity of the SOCS3 significantly increased the risk of GC in the < 60 years group, in the ≥ 60 years group, and in the positive Helicobacter pylori infection group (OR_a  = 1.654, 95% CI: 1.029-2.660, P = 0.038; OR_a  = 1.957, 95% CI: 1.136-3.376, P = 0.016; OR_a  = 2.084, 95% CI: 1.270-3.422, P = 0.004, respectively). Additionally, no significant association was found between STAT1 methylation and GC risk (OR_a  = 0.646, 95% CI: 0.363-1.147, P = 0.135). This study found that the interaction between the methylation status of STAT1 and SOCS3 and environmental factors did not have an impact on GC risk.

CONCLUSION

SOCS3 methylation may serve as a new potential biomarker for GC susceptibility.

Rapid Quantification of Oxidation and UV Induced DNA Damage by Repair Assisted Damage Detection-(Rapid RADD)

Knowing the amount and type of DNA damage is of great significance for a broad range of clinical and research applications. However, existing methods are either lacking in their ability to distinguish between types of DNA damage or limited in their sensitivity and reproducibility. The method described herein enables rapid and robust quantification of type-specific single-strand DNA damage. The method is based on repair-assisted damage detection (RADD) by which fluorescent nucleotides are incorporated into DNA damage sites using type-specific repair enzymes. Up to 90 DNA samples are then deposited on a multiwell glass slide, and analyzed by a conventional slide scanner for quantification of DNA damage levels. Accurate and sensitive measurements of oxidative or UV-induced DNA damage levels and repair kinetics are presented for both in vitro and in vivo models.

Ailanthone: A novel potential drug for treating human cancer

Cancer is the second leading cause of death after cardiovascular disease. In 2015, >8.7 million people died worldwide due to cancer, and by 2030 this figure is expected to increase to ~13.1 million. Tumor chemotherapy drugs have specific toxicity and side effects, and patients can also develop secondary drug resistance. To prevent and treat cancer, scientists have developed novel drugs with improved antitumor effects and decreased toxicity. Ailanthone (AIL) is a quassinoid extract from the traditional Chinese medicine plant Ailanthus altissima, which is known to have anti-inflammatory and antimalarial effects. An increasing number of studies have focused on AIL due to its antitumor activity. AIL can inhibit cell proliferation and induce apoptosis by up- or downregulating cancer-associated molecules, which ultimately leads to cancer cell death. Antitumor effects of AIL have been observed in melanoma, acute myeloid leukemia, bladder, lung, breast, gastric and prostate cancer and vestibular neurilemmoma. To the best of our knowledge, the present study is the first review to describe the antitumor mechanisms of AIL.

Safety evaluation of Ochratoxin A and Citrinin after 28 days repeated dose oral exposure to Wistar rats

Mycotoxins, ochratoxin A (OTA), and citrinin (CTN) are toxic metabolites of filamentous fungi. The most common fungal species that produce OTA and CTN belong to genera Aspergillus, Penicillium, Fusarium, and Monascus, and these fungal species are found to be contaminant a wide range of grains, food, and food product. The aim of our study was to evaluate the sub-acute repeated dose oral toxicity of OTA and CTN in experimental rodents by following OECD test guidelines for testing chemicals no. 407 with minor modifications. Twenty-five rats of each sex were divided equally into five groups; vehicle control, OTA 25 μg/kg b. wt., OTA 100 μg/kg b. wt., CTN 25 μg/kg b.wt. and CTN 100 μg/kg b. wt. The results of this study showed no abnormal clinical signs during 28 days of the experimental period. We did not found any significant changes in body weight gain, food consumption pattern, organ weight, hematology except few parameters, and biochemical values in any of the treatment and control groups. However, histopathological observations revealed severe nephrotoxicity and mild follicular depletion in the spleen of 100 μg/kg b. wt. treated groups of both OTA and CTN mycotoxins. The findings of our study are of its first kind that reports the systemic toxicity of OTA and CTN oral exposure to laboratory rodents.

Mechanisms and rejuvenation strategies for aged hematopoietic stem cells

Hematopoietic stem cell (HSC) aging, which is accompanied by reduced self-renewal ability, impaired homing, myeloid-biased differentiation, and other defects in hematopoietic reconstitution function, is a hot topic in stem cell research. Although the number of HSCs increases with age in both mice and humans, the increase cannot compensate for the defects of aged HSCs. Many studies have been performed from various perspectives to illustrate the potential mechanisms of HSC aging; however, the detailed molecular mechanisms remain unclear, blocking further exploration of aged HSC rejuvenation. To determine how aged HSC defects occur, we provide an overview of differences in the hallmarks, signaling pathways, and epigenetics of young and aged HSCs as well as of the bone marrow niche wherein HSCs reside. Notably, we summarize the very recent studies which dissect HSC aging at the single-cell level. Furthermore, we review the promising strategies for rejuvenating aged HSC functions. Considering that the incidence of many hematological malignancies is strongly associated with age, our HSC aging review delineates the association between functional changes and molecular mechanisms and may have significant clinical relevance.

Combination of plasma oxidation process with microbial fuel cell for mineralizing methylene blue with high energy efficiency

Plasma advanced oxidation process (PAOP) has great ability to break recalcitrant pollutants into small molecular compounds but suffers from poor performance and low energy efficiency for mineralizing dyeing pollutants. Combining advanced oxidation process with biodegradation process is an effective strategy to improve mineralization performance and reduce cost. In this study, a combined process using PAOP as pre-treatment followed by microbial fuel cell (MFC) treatment was investigated to mineralize methylene blue (MB). The PAOP could degrade MB by 97.7%, but only mineralize MB by 23.2% under the discharge power of 35 W for 10 min. Besides, BOD₅/COD ratio of MB solution raised from 0.04 to 0.38 while inhibition on E. coli growth decreased from 85.5% to 28.3%. The following MFC process increased MB mineralization percentage to 63.0% with a maximum output power density of 519 mW m^-2. The combined process achieved a mineralization energy consumption of 0.143 KWh gTOC^-1 which was only 41.8% of that of PAOP. FT-IR, UV-vis and pH variation demonstrated that PAOP could break the aromatic and heterocyclic structures in MB molecule to form organic acids. Possible degradation pathways of MB were accordingly proposed based on LC-MS, GC-MS, and density functional theory calculation.

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.

Black Raspberry Inhibits Oral Tumors in Mice Treated with the Tobacco Smoke Constituent Dibenzo(def,p)chrysene Via Genetic and Epigenetic Alterations

We previously reported that the environmental pollutant and tobacco smoke constituent dibenzo[def,p]chrysene (DBP) induced DNA damage, altered DNA methylation and induced oral squamous cell carcinoma (OSCC) in mice. In the present study, we showed that 5% dietary black raspberry (BRB) significantly reduced (P < 0.05) the levels of DBP-DNA adducts in the mouse oral cavity with comparable effect to those of its constitutes. Thus, only BRB was selected to examine if aberrant DNA methylation induced by DBP can be altered by BRB. Using comparative genome-wide DNA methylation analysis, we identified 479 hypermethylated and 481 hypomethylated sites (q < 0.01, methylation difference >25%) between the oral tissues of mice treated with DBP and fed control diet or diet containing BRB. Among the 30 differential methylated sites (DMS) induced by DBP, we found DMS mapped to Fgf3, Qrich2, Rmdn2, and Cbarp were hypermethylated by BRB whereas hypomethylated by DBP at either the exact position or proximal sites; DMS mapped to Vamp3, Ppp1rB1, Pkm, and Zfp316 were hypomethylated by BRB but hypermethylated by DBP at proximal sites. In addition to Fgf3, 2 DMS mapped to Fgf4 and Fgf13 were hypermethylated by BRB; these fibroblast growth factors are involved in regulation of the epithelial-mesenchymal transition (EMT) pathway as identified by IPA. Moreover, BRB significantly reduced (P < 0.05) the tumor incidence from 70% to 46.7%. Taken together, the inhibitory effects of BRB on DNA damage combined with its effects on epigenetic alterations may account for BRB inhibition of oral tumorigenesis induced by DBP. SIGNIFICANCE: We provided mechanistic insights that can account for the inhibition of oral tumors by BRB, which could serve as the framework for future chemopreventive trials for addicted smokers as well as non- or former smokers who are exposed to environmental carcinogens.

6-Nitrochrysene-Derived C8-2'-Deoxyadenosine Adduct: Synthesis of Site-Specific Oligodeoxynucleotides and Mutagenicity in Escherichia coli

6-Nitrochrysene (6-NC), the most potent carcinogen evaluated by the newborn mouse assay, is metabolically activated by nitroreduction and a combination of ring oxidation and nitroreduction pathways. The nitroreduction pathway yields three major DNA adducts: at the C8 and N² positions of 2'-deoxyguanosine (dG), N-(dG-8-yl)-6-AC and 5-(dG-N²-yl)-6-AC, and at the C8 position of 2'-deoxyadenosine (dA), N-(dA-8-yl)-6-AC. A nucleotide excision repair assay demonstrated that N-(dA-8-yl)-6-AC is repaired much more slowly than many other bulky DNA adducts, including the other DNA adducts formed by 6-NC. But neither the total synthesis nor evaluation of other biological activities of this dA adduct has ever been reported. Herein, we report a convenient synthesis of the 6-NC-derived dA adduct by employing the Buchwald-Hartwig coupling strategy, which provided a high yield of the protected N-(dA-8-yl)-6-AC. The deprotected nucleoside showed syn conformational preference by NMR spectroscopy. Following DMT protection of the 5'-hydroxyl, N-(dA-8-yl)-6-AC was converted to its 3'-phosphoramidite, which was used to prepare oligonucleotides containing a single N-(dA-8-yl)-6-AC adduct. Circular dichroism spectra of the adducted duplex showed only a slight departure from the B-DNA helix profile of the control duplex. The 15-mer N-(dA-8-yl)-6-AC oligonucleotide was used to construct a single-stranded plasmid vector containing a single adduct, which was replicated in Escherichia coli. Viability of the adducted construct was ∼60% of the control, indicating slower translesion synthesis of the adduct, which increased to nearly 90% upon induction of the SOS functions. Without SOS, the mutation frequency (MF) of the adduct was 5.2%, including 2.9% targeted and 2.3% semi-targeted mutations. With SOS, the targeted MF increased 3-fold to 9.0%, whereas semi-targeted mutation increased only marginally to 3.2%. The major type of targeted mutation was A*→G in both uninduced and SOS-induced cells.

Baicalin Inhibits Cell Viability, Migration and Invasion in Breast Cancer by Regulating miR-338-3p and MORC4

Background

Baicalin is a natural compound from the roots of Scutellaria lateriflora Georgi, which plays anti-cancer role in multiple cancers. However, the exact role and potential underlying mechanism of baicalin in breast cancer (BC) remain poorly understood.

Methods

Thirty BC patients were recruited in this study. MCF-10A, MCF-7 and MDA-MB-231 cells were used to investigate the anti-cancer role of baicalin in vitro. Cell viability, migration, invasion and apoptosis were measured by MTT, trans-well and flow cytometry, respectively. The expression levels of microRNA-338-3p (miR-338-3p) and microrchidia family CW-type zinc-finger 4 (MORC4) were measured by quantitative real-time polymerase chain reaction or Western blot. The interaction between miR-338-3p and MORC4 was explored by luciferase reporter assay and RNA immunoprecipitation.

Results

We found that Baicalin treatment inhibited cell viability, migration and invasion but promoted apoptosis of BC cells. The expression of miR-338-3p was decreased in BC tissues and cells and miR-338-3p overexpression suppressed cell viability, migration and invasion but induced apoptosis. MiR-338-3p expression was reversed by baicalin exposure and inhibition of miR-338-3p attenuated the role of baicalin in viability, apoptosis, migration and invasion. MORC4 mRNA level was increased in BC tissues and cells, which was decreased by baicalin exposure. MORC4 was a target of miR-338-3p and its overexpression alleviated the effect of miR-338-3p on cell viability, apoptosis, migration and invasion.

Conclusion

In conclusion, baicalin suppressed cell viability, migration and invasion but promoted apoptosis in BC cells by regulating miR-338-3p and MORC4, indicating the promising pharmacological value of baicalin in BC treatment.

Curcumin Ameliorates Benzo[a]pyrene-Induced DNA Damages in Stomach Tissues of Sprague-Dawley Rats

Benzo[a]pyrene (BaP) is a well-known carcinogen formed during the cooking process. Although BaP exposure has been implicated as one of the risk factors for lung cancer in animals and humans, there are only limited data on BaP-induced gastrointestinal cancer. Therefore, this study investigated the protective effects of curcumin on BaP-induced DNA damage in rat stomach tissues. BaP (20 mg/kg/day) and curcumin (50, 100, or 200 mg/kg) were administered daily to Sprague-Dawley rats by oral gavage over 30 days. Curcumin was pre-administered before BaP exposure. All rats were euthanized, and liver, kidney, and stomach tissues were removed at 24 h after the last treatment. We observed that aspartate aminotransferase (AST), alanine aminotransferase (ALT), and glucose levels were significantly reduced in rats treated with high dose co-administration of curcumin (200 mg/kg) compared to BaP alone. The expression levels of cytochrome P450 (CYP) 1A1 and CYP1B1 were significantly increased in the liver of rats treated with BaP. However, co-administration of curcumin (200 mg/kg) with BaP markedly reduced CYP1A1 expression in a dose-dependent manner. Furthermore, plasma levels of BaP-diolepoxide (BPDE) and BaP metabolites were significantly reduced by co-administration of curcumin (200 mg/kg). Additionally, co-administration of curcumin (200 mg/kg) with BaP significantly reduced the formation of BPDE-I-DNA and 8-hydroxydeoxy guanosine (8-OHdG) adducts in the liver, kidney, and stomach tissues. The inhibition of these adduct formations were more prominent in the stomach tissues than in the liver. Overall, our observations suggest that curcumin might inhibit BaP-induced gastrointestinal tumorigenesis and shows promise as a chemopreventive agent.

Evaluation of oxidative and methylating DNA damage in painters occupationally exposed to organic solvents and paints

Introduction: The exposure to organic solvents and paints has been associated with genotoxicity and a greater risk of neoplasms. However, the type of DNA damage induced in humans by the exposure to these compounds, which would help explain the mechanisms of their genotoxicity, is still not fully characterized. Due to inadequate practices of occupational safety, car painters in the informal sector are a highly exposed group to organic solvents and paints. Objective: To identify the oxidative and methylating damage in the DNA of lymphocytes of car painters exposed to organic solvents and paints. Materials and methods: Isolated peripheral blood lymphocytes from 62 painters and 62 unexposed subjects were analyzed by the modified high-throughput comet assay with the Fpg and AlkA enzymes. The categories used for the evaluation of the DNA damage were basal damage (without enzymes), oxidative and methylating damage. The measurement parameter used to establish the damage was the percentage of DNA in the tail. Results: The percentage of DNA in the tail was higher in the exposed group compared to the unexposed group (p<0.05). In the exposed group, this percentage was higher in the oxidative damage category than the baseline (16.50 vs. 12.87; p<0.001), whereas methylating damage did not show significant differences (14.00 vs. 12.87; p>0.05). Conclusion: In this study, exposure to organic solvents and paints was associated with an increase in oxidative lesions in the DNA of car painters’ lymphocytes, such as the production of 8-oxodG and other formamidopyrimidine products which are considered highly mutagenic.

Development and validation of a prediction rule for estimating gastric cancer risk in the Chinese high-risk population: a nationwide multicentre study

OBJECTIVE

To develop a gastric cancer (GC) risk prediction rule as an initial prescreening tool to identify individuals with a high risk prior to gastroscopy.

DESIGN

This was a nationwide multicentre cross-sectional study. Individuals aged 40-80 years who went to hospitals for a GC screening gastroscopy were recruited. Serum pepsinogen (PG) I, PG II, gastrin-17 (G-17) and anti-Helicobacter pylori IgG antibody concentrations were tested prior to endoscopy. Eligible participants (n=14 929) were randomly assigned into the derivation and validation cohorts, with a ratio of 2:1. Risk factors for GC were identified by univariate and multivariate analyses and an optimal prediction rule was then settled.

RESULTS

The novel GC risk prediction rule comprised seven variables (age, sex, PG I/II ratio, G-17 level, H. pylori infection, pickled food and fried food), with scores ranging from 0 to 25. The observed prevalence rates of GC in the derivation cohort at low-risk (≤11), medium-risk (12-16) or high-risk (17-25) group were 1.2%, 4.4% and 12.3%, respectively (p<0.001).When gastroscopy was used for individuals with medium risk and high risk, 70.8% of total GC cases and 70.3% of early GC cases were detected. While endoscopy requirements could be reduced by 66.7% according to the low-risk proportion. The prediction rule owns a good discrimination, with an area under curve of 0.76, or calibration (p<0.001).

CONCLUSIONS

The developed and validated prediction rule showed good performance on identifying individuals at a higher risk in a Chinese high-risk population. Future studies are needed to validate its efficacy in a larger population.

Dietary Inflammatory Index and Non-Communicable Disease Risk: A Narrative Review

There are over 1,000,000 publications on diet and health and over 480,000 references on inflammation in the National Library of Medicine database. In addition, there have now been over 30,000 peer-reviewed articles published on the relationship between diet, inflammation, and health outcomes. Based on this voluminous literature, it is now recognized that low-grade, chronic systemic inflammation is associated with most non-communicable diseases (NCDs), including diabetes, obesity, cardiovascular disease, cancers, respiratory and musculoskeletal disorders, as well as impaired neurodevelopment and adverse mental health outcomes. Dietary components modulate inflammatory status. In recent years, the Dietary Inflammatory Index (DII®), a literature-derived dietary index, was developed to characterize the inflammatory potential of habitual diet. Subsequently, a large and rapidly growing body of research investigating associations between dietary inflammatory potential, determined by the DII, and risk of a wide range of NCDs has emerged. In this narrative review, we examine the current state of the science regarding relationships between the DII and cancer, cardiometabolic, respiratory and musculoskeletal diseases, neurodevelopment, and adverse mental health outcomes. We synthesize the findings from recent studies, discuss potential underlying mechanisms, and look to the future regarding novel applications of the adult and children's DII (C-DII) scores and new avenues of investigation in this field of nutritional research.

Interspecies Variation in NCMN-O-Demethylation in Liver Microsomes from Various Species

NCMN (N-(3-carboxy propyl)-4-methoxy-1,8-naphthalimide), a newly developed ratiometric two-photon fluorescent probe for human Cytochrome P450 1A (CYP1A), shows the best combination of specificity and reactivity for real-time detection of the enzymatic activities of CYP1A in complex biological systems. This study aimed to investigate the interspecies variation in NCMN-O-demethylation in commercially available liver microsomes from human, mouse, rat, beagle dog, minipig and cynomolgus monkey. Metabolite profiling demonstrated that NCMN could be O-demethylated in liver microsomes from all species but the reaction rate varied considerably. CYP1A was the major isoform involved in NCMN-O-demethylation in all examined liver microsomes based on the chemical inhibition assays. Furafylline, a specific inhibitor of mammalian CYP1A, displayed differential inhibitory effects on NCMN-O-demethylation in all tested species. Kinetic analyses demonstrated that NCMN-O-demethylation in liver microsomes form rat, minipig and cynomolgus monkey followed biphasic kinetics, while in liver microsomes form human, mouse and beagle dog obeyed Michaelis-Menten kinetics, the kinetic parameters from various species are much varied, while NCMN-O-demethylation in MLM exhibited the highest similarity of specificity, kinetic behavior and intrinsic clearance as that in HLM. These findings will be very helpful for the rational use of NCMN as a practical tool to decipher the functions of mammalian CYP1A or to study CYP1A associated drug-drug interactions in vivo.

Prognostic analysis of patients with mutant and wild-type EGFR gene lung adenocarcinoma

Purpose

The purpose of this study was to investigate the relationship between epidermal growth factor receptor (EGFR) gene mutation and clinicopathological features of lung adenocarcinoma, and the prognostic and therapeutic value of EGFR.

Methods

EGFR gene mutations were detected in 424 patients with lung adenocarcinoma by amplification refractory mutation system (ARMS).

Results

The total EGFR gene mutation rate was 55.2% (234/424) and EGFR gene mutation rates were statistically different in gender, smoking status, and pathological degree (P<0.05). The overall survival (OS) time of lung adenocarcinoma patients with mutation of exon 18 was lower than those with mutation of exon 19 and exon 21 (both P<0.05), but no significant difference was seen between those with mutation of exon 19 and exon 21 (P>0.05). Among 424 cases of lung adenocarcinoma, multivariate analysis showed that EGFR gene mutation, age, gender, clinical stages, and pathological degree (P<0.05) were statistically significant prognostic factors. In multivariate analysis, prognostic factors of patients with EGFR gene mutation were associated with EGFR-TKI treatment, surgery treatment, pathological degree, clinical stages, and age (P<0.05), whereas in patients without EGFR gene mutation, prognostic factors were related to surgery treatment, pathological degree, clinical stages, gender, age, and smoking status (P<0.05).

Conclusion

The OS time of patients with mutation of exon 18 was lower than those of exon 19 and exon 21. EGFR-TKI treatment was an independent positive predictor in patients with EGFR gene mutation. Surgery treatment, age, clinical stages, and pathological degree were independent prognostic factors in Chinese patients with lung adenocarcinoma no matter whether with EGFR gene mutation or not.

Differences in mutational processes and intra-tumour heterogeneity between organs: The local selective filter hypothesis

Extensive diversity (genetic, cytogenetic, epigenetic and phenotypic) exists within and between tumours, but reasons behind these variations, as well as their consistent hierarchical pattern between organs, are poorly understood at the moment. We argue that these phenomena are, at least partially, explainable by the evolutionary ecology of organs' theory, in the same way that environmental adversity shapes mutation rates and level of polymorphism in organisms. Organs in organisms can be considered as specialized ecosystems that are, for ecological and evolutionary reasons, more or less efficient at suppressing tumours. When a malignancy does arise in an organ applying strong selection pressure on tumours, its constituent cells are expected to display a large range of possible surviving strategies, from hyper mutator phenotypes relying on bet-hedging to persist (high mutation rates and high diversity), to few poorly variable variants that become invisible to natural defences. In contrast, when tumour suppression is weaker, selective pressure favouring extreme surviving strategies is relaxed, and tumours are moderately variable as a result. We provide a comprehensive overview of this hypothesis. Lay summary: Different levels of mutations and intra-tumour heterogeneity have been observed between cancer types and organs. Anti-cancer defences are unequal between our organs. We propose that mostly aggressive neoplasms (i.e. higher mutational and ITH levels), succeed in emerging and developing in organs with strong defences.

[Oral microbiological diversity in patients with salivary adenoid cystic carcinoma]

OBJECTIVE

The aim of this study was to identify the differences in microbial diversity and community in patients with salivary adenoid cystic carcinoma (SACC).

METHODS

Saliva was collected from 13 patients with SACC confirmed by histopathological diagnosis and 10 healthy control subjects. Total metagenomic DNA was extracted. The DNA amplicons of the V3-V4 hypervariable regions of the 16S rRNA gene were generated and subjected to high-throughput sequencing. Microbial diversity and community structure were analyzed with Mothur software.

RESULTS

A total of 16 genera of dominant bacteria in the SACC group were found, including Streptococcus (36.68%), Neisseria (8.55%), Prevotella_7 (7.53%), and Veillonella (6.37%), whereas 15 dominant bacteria in the control group were found, including Streptococcus (18.41%), Neisseria (18.20%), Prevotella_7 (8.89%), Porphyromonas (6.20%), Fusobacterium (5.86%) and Veillonella (5.82%). The statistically different phyla between the two groups were Firmicutes, Proteobacteria and Fusobacterium (P<0.05). The statistically different genera between the two groups were Streptococcus, Neisseria and Porphyromonas (P<0.05), and Capnocytophaga was only detected in patients with SACC.

CONCLUSIONS

Significant differences were observed in the oral microorganisms between the two groups.

Error-prone replication of a 5-formylcytosine-mediated DNA-peptide cross-link in human cells

DNA-protein cross-links can interfere with chromatin architecture, block DNA replication and transcription, and interfere with DNA repair. Here we synthesized a DNA 23-mer containing a site-specific DNA-peptide cross-link (DpC) by cross-linking an 11-mer peptide to the DNA epigenetic mark 5-formylcytosine in synthetic DNA and used it to generate a DpC-containing plasmid construct. Upon replication of the DpC-containing plasmid in HEK 293T cells, approximately 9% of progeny plasmids contained targeted mutations and 5% semitargeted mutations. Targeted mutations included C→T transitions and C deletions, whereas semitargeted mutations included several base substitutions and deletions near the DpC lesion. To identify DNA polymerases involved in DpC bypass, we comparatively studied translesion synthesis (TLS) efficiency and mutagenesis of the DpC in a series of cell lines with TLS polymerase knockouts or knockdowns. Knockdown of either hPol ι or hPol ζ reduced the mutation frequency by nearly 50%. However, the most significant reduction in mutation frequency (50%-70%) was observed upon simultaneous knockout of hPol η and hPol κ with knockdown of hPol ζ, suggesting that these TLS polymerases play a critical role in error-prone DpC bypass. Because TLS efficiency of the DpC construct was not significantly affected in TLS polymerase-deficient cells, we examined a possible role of replicative DNA polymerases in their bypass and determined that hPol δ and hPol ϵ can accurately bypass the DpC. We conclude that both replicative and TLS polymerases can bypass this DpC lesion in human cells but that mutations are induced mainly by TLS polymerases.

The role of phase I and II genetic polymorphisms, smoking, alcohol and cancer family history, in the risk of developing testicular cancer

BACKGROUND

Testicular cancer (TCa) is a malignant tumor with highest incidence and mortality rates in Chile. The genes coding for cytochrome P450, glutathione-S-transferases (GSTs), and UDP glucuronyl transferases (UGT) participate in the biotransformation and detoxification of xenobiotics. Mutations in these genes have been associated with a high incidence of various types of cancer and an increased risk of presenting adverse reactions to drugs.

OBJECTIVE

The aim of this study was to relate the presence of genetic polymorphisms in cytochrome P450 1A1 (CYP1A1), CYP3A4, GSTM1, GSTP1, GSTT1, and UGT1A1 genes and nongenetic factors with the risk of developing TCa.

METHODS

A total of 276 volunteers from the Chilean general population and 251 Chilean TCa patients were recruited for the study. Genotypic analyses were performed using qPCR and PCR-RFLP.

RESULTS

Variant alleles found to increase the risk of developing TCa were CYP1A1*2C (rs1048943), GSTP1 (rs1695), and GSTT1null, especially when in conjunction with a cancer family history and/or a smoking habit. The results of the multivariate analysis showed that the presence of variant alleles of GSTP1 (rs1695) together with a smoking habit and a family history of cancer accounted for a 15.9% risk of developing TCa in the Chilean population. CYP1A1*2C, GSTM1null, GSTT1null, and GSTP1 (rs1695) are statistically related to the risk of appearance of TCa, alone or associated with nongenetic factors.

CONCLUSION

Therefore, phase I and II variant alleles might be useful in evaluating susceptibility to TCa in the studied population.

An Interactive Resource to Probe Genetic Diversity and Estimated Ancestry in Cancer Cell Lines

Recent work points to a lack of diversity in genomics studies from genome-wide association studies to somatic (tumor) genome analyses. Yet, population-specific genetic variation has been shown to contribute to health disparities in cancer risk and outcomes. Immortalized cancer cell lines are widely used in cancer research, from mechanistic studies to drug screening. Larger collections of cancer cell lines better represent the genomic heterogeneity found in primary tumors. Yet, the genetic ancestral origin of cancer cell lines is rarely acknowledged and often unknown. Using genome-wide genotyping data from 1,393 cancer cell lines from the Catalogue of Somatic Mutations in Cancer (COSMIC) and Cancer Cell Line Encyclopedia (CCLE), we estimated the genetic ancestral origin for each cell line. Our data indicate that cancer cell line collections are not representative of the diverse ancestry and admixture characterizing human populations. We discuss the implications of genetic ancestry and diversity of cellular models for cancer research and present an interactive tool, Estimated Cell Line Ancestry (ECLA), where ancestry can be visualized with reference populations of the 1000 Genomes Project. Cancer researchers can use this resource to identify cell line models for their studies by taking ancestral origins into consideration.

Mechanism-based structure-activity relationship (SAR) analysis of aromatic amines and nitroaromatics carcinogenicity via statistical analyses based on CPDB

Cancer is a leading cause of human mortality around the globe. In this study, mechanism-based SAR (Structure-Activity Relationship) was employed to investigate the carcinogenicity of aromatic amines and nitroaromatics based on CPDB. Principal component analysis and cluster analysis were used to construct the SAR model. Principle component analysis generated three principal components from 12 mechanism-based descriptors. The extracted principal components were later used for cluster analysis, which divided the selected 55 chemicals into six clusters. The three principal components were proposed to describe the "transport", "reactivity" and "electrophilicity" properties of the chemicals. Cluster analysis indicated that the relevant "transport" properties positively correlated with the carcinogenic potential and were contributing factors in determining the carcinogenicity of the studied chemicals. The mechanism-based SAR analysis suggested the electron donating groups, electron withdrawing groups and planarity are significant factors in determining the carcinogenic potency for studied aromatic compounds. The present study may provide insights into the relationship between the three proposed properties and the carcinogenesis of aromatic amines and nitroaromatics.

Human exposure to bisphenol AF and diethylhexylphthalate increases susceptibility to develop differentiated thyroid cancer in patients with thyroid nodules

Pollutants represent potential threats to the human health, being ubiquitous in the environment and exerting toxicity even at low doses. This study aims at investigating the role of fifteen multiclass organic pollutants, assumed as markers of environmental pollution, most of which exerting endocrine-disrupting activity, in thyroid cancer development. The increasing incidence of differentiated thyroid cancer (DTC) may be related to the rising production and environmental dissemination of pollutants. Fifty-five patients, twenty-seven with diagnosis of benign thyroid nodules and twenty-eight suffering from differentiated thyroid cancer, were enrolled and the concentration levels of seven bisphenols, two phthalates (i.e. di(2-ethylhexyl) phthalate (DEHP) and its main metabolite, mono-(2-ethyl-hexyl) phthalate) (MEHP)), two chlorobenzenes, (1,4-dichlorobenzene and 1,2,4,5-tetrachlorobenzene), and 3 phenol derivatives (2-chlorophenol, 4- nonylphenol, and triclosan) were determined in their serum by using a validated analytical method based on high performance liquid chromatography with ultraviolet tandem fluorescence detection. A significant relationship was found between malignancy and the detection in the serum of both bisphenol AF and DEHP. Indeed, their presence confers a more than fourteen times higher risk of developing differentiated thyroid cancer. Relationship between these two pollutants and the risk of malignancy was dose-independent and not mediated by higher thyroid stimulating hormone levels. Even if a conclusive evidence cannot still be drawn and larger prospective studies are needed, the exposure to low doses of environmental endocrine-disrupting contaminants can be considered consistent with the development of thyroid cancer.

Regulation of cytochrome P450 expression by microRNAs and long noncoding RNAs: Epigenetic mechanisms in environmental toxicology and carcinogenesis

Environmental exposures to hazardous chemicals are associated with a variety of human diseases and disorders, including cancers. Phase I metabolic activation and detoxification reactions catalyzed by cytochrome P450 enzymes (CYPs) affect the toxicities of many xenobiotic compounds. Proper regulation of CYP expression influences their biological effects. Noncoding RNAs (ncRNAs) are involved in regulating CYP expression, and ncRNA expression is regulated in response to environmental chemicals. The mechanistic interactions between ncRNAs and CYPs associated with the toxicity and carcinogenicity of environmental chemicals are described in this review, focusing on microRNA-dependent CYP regulation. The role of long noncoding RNAs in regulating CYP expression is also presented and new avenues of research concerning this regulatory mechanism are described.

Oxymatrine exhibits anti-tumor activity in gastric cancer through inhibition of IL-21R-mediated JAK2/STAT3 pathway

Oxymatrine (OMT) as a type of alkaloids collected from Sophora flavescens Ait exerts some biological functions including anticancer properties. Here, we investigated the therapeutic effects of OMT in gastric cancer cells (HGC 27 and AGS). As a result, the exposure of gastric cancer (GC) cells to OMT contributed to the suppression of cell proliferation and invasion. Interleukin 21 receptor (IL-21R) was identified to be differentially expressed between OMT treatment group (4 mg/mL) and control group (0 mg/mL), and knockdown of IL-21R repressed cell proliferation and invasion via inactivation of the JAK2/STAT3 pathway. The rescue experiment showed that IL-21R overexpression attenuated the anti-tumor effects of OMT through activation of the JAK2/STAT3 pathway. Moreover, the expression of IL-21R was significantly upregulated in GC samples compared with the adjacent normal tissues and associated with overall survival (OS) and tumor recurrence of GC patients. Taken together, in this study, we evaluated the anti-tumor effects of OMT on GC by investigating proliferation and invasion ability changes, and our findings show that OMT exhibits effects via regulation of JAK/STAT signaling pathway. Through the mechanism study, we may enlighten the potential therapeutic target for treatment of GC.

Human AP-endonuclease (Ape1) activity on telomeric G4 structures is modulated by acetylatable lysine residues in the N-terminal sequence

Loss of telomeres stability is a hallmark of cancer cells. Exposed telomeres are prone to aberrant end-joining reactions leading to chromosomal fusions and translocations. Human telomeres contain repeated TTAGGG elements, in which the 3' exposed strand may adopt a G-quadruplex (G4) structure. The guanine-rich regions of telomeres are hotspots for oxidation forming 8-oxoguanine, a lesion that is handled by the base excision repair (BER) pathway. One key player of this pathway is Ape1, the main human endonuclease processing abasic sites. Recent evidences showed an important role for Ape1 in telomeric physiology, but the molecular details regulating Ape1 enzymatic activities on G4-telomeric sequences are lacking. Through a combination of in vitro assays, we demonstrate that Ape1 can bind and process different G4 structures and that this interaction involves specific acetylatable lysine residues (i.e. K^27/31/32/35) present in the unstructured N-terminal sequence of the protein. The cleavage of an abasic site located in a G4 structure by Ape1 depends on the DNA conformation or the position of the lesion and on electrostatic interactions between the protein and the nucleic acids. Moreover, Ape1 mutants mimicking the acetylated protein display increased cleavage activity for abasic sites. We found that nucleophosmin (NPM1), which binds the N-terminal sequence of Ape1, plays a role in modulating telomere length and Ape1 activity at abasic G4 structures. Thus, the Ape1 N-terminal sequence is an important relay site for regulating the enzyme's activity on G4-telomeric sequences, and specific acetylatable lysine residues constitute key regulatory sites of Ape1 enzymatic activity dynamics at telomeres.

IL-21R functions as an oncogenic factor and is regulated by the lncRNA MALAT1/miR-125a-3p axis in gastric cancer

Interleukin-21 receptor (IL-21R) is involved in the immunological regulation of immune cells and tumor progression in multiple malignancies. However, the potential molecular mechanisms through which non-coding RNAs (ncRNAs) modulate IL-21R signaling in gastric cancer (GC) remain elusive. In this study, the expression of IL-21R was detected by RT-qPCR and western blot analysis in GC cell lines. The association between IL-21R expression and clinicopathological characteristics and the prognosis of patients with GC was analyzed by immunohistochemistry and Kaplan-Meier plotter analysis. The biological functions of IL-21R were analyzed by a series of in vitro and in vivo experiments, and its regulation by ncRNAs was predicted by bioinformatics analysis and confirmed by luciferase assays and rescue experiments. As a result, the expression of IL-21R was found to be significantly increased in GC cell lines and tissues as compared with normal tissues, and was associated with tumor size and lymphatic metastasis, acting as an independent prognostic factor of poor survival and recurrence in patients with GC. The knockdown of IL-21R markedly suppressed GC cell proliferation and invasion, and IL-21R expression was further validated to be negatively regulated by miR-125a-3p (miR-125a). The overexpression of IL-21R reversed the tumor suppressive effects of miR-125a in vitro and in vivo. Moreover, lncRNA metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) acted as a sponge of miR-125a to modulate the IL-21R signaling pathway in GC cells and represented a risk factor for survival and recurrence in patients with GC. Taken together, the findings of this study reveal an oncogenic role for IL-21R in gastric tumorigenesis and verify that its activation is partly due to the dysregulation of the lncRNA MALAT1/miR-125a axis. These findings may provide a potential prognostic marker for patients with GC.