Suppression of pulmonary CYP2A13 expression by carcinogen-induced lung tumorigenesis in a CYP2A13-humanized mouse model

Suppression of NNK Metabolism by Anthocyanin-Rich Haskap Berry Supplementation Through Modulation of P450 Enzymes

Oral supplementation of anthocyanins-rich haskap (Lonicera caerulea) berry (HB) reduces 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)-induced lung tumorigenesis, cytotoxicity, DNA damage, and modulated inflammation in vitro and in vivo. The procarcinogen NNK is metabolically activated by cytochrome P450 (P450) enzymes, producing reactive metabolites that induce lung carcinogenesis. Hypothesis: Therefore, we hypothesized that the HB-modulated protective effect against NNK could be due to its ability to suppress P450 enzymes. Methods: HB (6 mg of cyanidin-3-O-glucoside [C3G] in 0.2 g of HB/mouse/day) was given to A/J mice as a dietary supplement following subsequent administration of NNK (100 mg/kg body weight). The liver tissues of mice were analyzed to determine the expression of P450s and metabolites. Results: HB upregulated the expression of cyp2a4 and cyp2a5 mRNA and nuclear receptor/transcription factor (PPARα) in NNK-deprived hepatic tissues. With NNK, HB downregulated the expression of cyp2a4 and cyp2a5 and facilitated the formation of non-carcinogenic NNK metabolites. Molecular docking indicated a high binding affinity and strong hydrophobic interactions between C3G and its major metabolites, peonidin-3-O-glucoside, petunidin-3-O-glucoside, peonidin and cyanidin with Cyp2a5 and with human P450 homologue CYP2A13. Conclusions: HB could be a potential dietary supplement to inhibit the P450 activated NNK carcinogenic metabolites formation. Hence, inhibiting the activation of NNK by lung CYP2A13 through dietary HB supplementation could be a strategy to reduce lung carcinogenesis among smokers. Understanding the effect of HB on the activity of CYP2A13 in human studies is necessary before recommending these natural compounds as therapeutics.

Luteolin Alleviates Oxidative Stress in Chronic Obstructive Pulmonary Disease Induced by Cigarette Smoke via Modulation of the TRPV1 and CYP2A13/NRF2 Signaling Pathways

The current study aims to investigate the therapeutic potential of luteolin (Lut), a naturally occurring flavonoid found in various medicinal plants, for treating chronic obstructive pulmonary disease (COPD) through both in vitro and in vivo studies. The results demonstrated that Lut increased body weight, reduced lung tissue swelling and lung damage indices, mitigated systemic oxidative stress levels, and decreased alveolar fusion in cigarette smoke (CS)- and lipopolysaccharide (LPS)-induced COPD mice. Additionally, Lut was observed to downregulate the expression of the TRPV1 and CYP2A13 proteins while upregulating SIRT6 and NRF2 protein expression in CS + LPS-induced COPD mice and cigarette smoke extract (CSE)-treated A549 cells. The concentrations of total reactive oxygen species (ROS) and mitochondrial ROS in A549 cells induced by CSE significantly increased. Moreover, CSE caused a notable elevation of intracellular Ca2+ levels in A549 cells. Importantly, Lut exhibited inhibitory effects on the inward flow of Ca2+ and attenuated the overproduction of mitochondrial and intracellular ROS in A549 cells treated with CSE. In conclusion, Lut demonstrated a protective role in alleviating oxidative stress and inflammation in CS + LPS-induced COPD mice and CSE-treated A549 cells by regulating TRPV1/SIRT6 and CYP2A13/NRF2 signaling pathways.

Detection of Transgene Location in the CYP2A13/2B6/2F1-transgenic Mouse Model using Optical Genome Mapping Technology

Most transgenic mouse models are generated through random integration of the transgene. The location of the transgene provides valuable information for assessing potential effects of the transgenesis on the host and for designing genotyping protocols that can amplify across the integration site, but it is challenging to identify. Here, we report the successful utility of optical genome mapping technology to identify the transgene insertion site in a CYP2A13/2B6/2F1-transgenic mouse model, which produces three human cytochrome P450 (P450) enzymes (CYP2A13, CYP2B6, and CYP2F1) that are encoded by neighboring genes on human chromosome 19. These enzymes metabolize many drugs, respiratory toxicants, and chemical carcinogens. Initial efforts to identify candidate insertion sites by whole genome sequencing was unsuccessful, apparently because the transgene is located in a region of the mouse genome that contains highly repetitive sequences. Subsequent utility of the optical genome mapping approach, which compares genome-wide marker distribution between the transgenic mouse genome and a reference mouse (GRCm38) or human (GRCh38) genome, localized the insertion site to mouse chromosome 14, between two marker positions at 4451324 base pair and 4485032 base pair. A transgene-mouse genome junction sequence was further identified through long-polymerase chain reaction amplification and DNA sequencing at GRCm38 Chr.14:4484726. The transgene insertion (∼2.4 megabase pair) contained 5-7 copies of the human transgenes, which replaced a 26.9-33.4 kilobase pair mouse genomic region, including exons 1-4 of Gm3182, a predicted and highly redundant gene. Finally, the sequencing results enabled the design of a new genotyping protocol that can distinguish between hemizygous and homozygous CYP2A13/2B6/2F1-transgenic mice. SIGNIFICANCE STATEMENT: This study characterizes the genomic structure of, and provides a new genotyping method for, a transgenic mouse model that expresses three human P450 enzymes, CYP2A13, CYP2B6, and CYP2F1, that are important in xenobiotic metabolism and toxicity. The demonstrated success in applying the optical genome mapping technology for identification of transgene insertion sites should encourage others to do the same for other transgenic models generated through random integration, including most of the currently available human P450 transgenic mouse models.

Genetic and Enzymatic Characteristics of CYP2A13 in Relation to Lung Damage

Cytochrome P450 2A13 is an omitted brother of CYP2A6 that has an important role in the drug metabolism of liver. Due to extrahepatic expression, it has gained less attention than CYP2A6, despite the fact that it plays a significant role in toxicant-induced pulmonary lesions and, therefore, lung cancer. The purpose of this mini-review is to summarize the basic knowledge about this enzyme in relation to the substrates, inhibitors, genetic polymorphisms, and transcriptional regulation that are known so far (September 2021).

Identification of Key Functional Modules and Immunomodulatory Regulators of Hepatocellular Carcinoma

Despite the advances in the treatment of hepatocellular carcinoma (HCC), the prognosis of HCC patients remains unsatisfactory due to postsurgical recurrence and treatment resistance. Therefore, it is important to reveal the mechanisms underlying HCC and identify potential therapeutic targets against HCC, which could facilitate the development of novel therapies. Based on 12 HCC samples and 12 paired paracancerous normal tissues, we identified differentially expressed mRNAs and lncRNAs using the "limma" package in R software. Moreover, we used the weighted gene coexpression network analysis (WGCNA) to analyze the expression data and screened hub genes. Furthermore, we performed pathway enrichment analysis based on the Kyoto Encyclopedia of Genes and Genomes (KEGG) database. In addition, the relative abundance of a given gene set was estimated by single-sample Gene Set Enrichment Analysis. We identified 687 differentially expressed mRNAs and 260 differentially expressed lncRNAs. A total of 6 modules were revealed by WGCNA, and MT1M and MT1E genes from the red module were identified as hub genes. Moreover, pathway analysis revealed the top 10 enriched KEGG pathways of upregulated or downregulated genes. Additionally, we also found that CD58 might act as an immune checkpoint gene in HCC via PD1/CTLA4 pathways and regulate the levels of tumor-infiltrating immune cells in HCC tissues, which might be an immunotherapeutic target in HCC. Our research identified key functional modules and immunomodulatory regulators for HCC, which might offer novel diagnostic biomarkers and/or therapeutic targets for cancer immunotherapy.

INTEDE: interactome of drug-metabolizing enzymes

Drug-metabolizing enzymes (DMEs) are critical determinant of drug safety and efficacy, and the interactome of DMEs has attracted extensive attention. There are 3 major interaction types in an interactome: microbiome-DME interaction (MICBIO), xenobiotics-DME interaction (XEOTIC) and host protein-DME interaction (HOSPPI). The interaction data of each type are essential for drug metabolism, and the collective consideration of multiple types has implication for the future practice of precision medicine. However, no database was designed to systematically provide the data of all types of DME interactions. Here, a database of the Interactome of Drug-Metabolizing Enzymes (INTEDE) was therefore constructed to offer these interaction data. First, 1047 unique DMEs (448 host and 599 microbial) were confirmed, for the first time, using their metabolizing drugs. Second, for these newly confirmed DMEs, all types of their interactions (3359 MICBIOs between 225 microbial species and 185 DMEs; 47 778 XEOTICs between 4150 xenobiotics and 501 DMEs; 7849 HOSPPIs between 565 human proteins and 566 DMEs) were comprehensively collected and then provided, which enabled the crosstalk analysis among multiple types. Because of the huge amount of accumulated data, the INTEDE made it possible to generalize key features for revealing disease etiology and optimizing clinical treatment. INTEDE is freely accessible at: https://idrblab.org/intede/.

Association between CYP2A13 polymorphisms and lung cancer: A protocol for systematic review and meta-analysis

BACKGROUND

Recently, lung cancer has become the most common cause of cancer-related death, several studies indicate that the cytochrome P450 2A13 (CYP2A13) polymorphisms may be correlated with lung cancer susceptibility, but the results have been inconsistent and inconclusive. Therefore, the aim of this meta-analysis is to provide a precise conclusion on the potential association between CYP2A13 polymorphisms and the risk of lung cancer based on case-control studies.

METHODS

The PubMed, Embase, Cochrane Library, Web of Science, and China National Knowledge Infrastructure (CNKI) databases will be searched for case-control studies published up to September 2020. Odds ratio (OR) and 95% confidence interval (95% CI) were used to determine the effects of the CYP2A13 polymorphism on lung cancer risk, respectively.

RESULTS

The results of this meta-analysis will be submitted to a peer-reviewed journal for publication.

CONCLUSION

This meta-analysis will summarize the association between CYP2A13 polymorphisms and the risk of lung cancer.

INPLASY REGISTRATION NUMBER

INPLASY202090102.

The Influence of Tobacco Smoke/Nicotine on CYP2A Expression in Human and African Green Monkey Lungs

CYP2A enzymes metabolically inactivate nicotine and activate tobacco-derived procarcinogens [e.g., 4-[methylnitrosamino]-1-(3-pyridyl)-1-butanone]. Smoking decreases nicotine clearance, and chronic nicotine reduces hepatic CYP2A activity. However, little is known about the impact of smoking or nicotine on the expression of CYP2A in the lung. We investigated 1) the levels of human lung CYP2A mRNA in smokers versus nonsmokers and 2) the impact of daily nicotine treatment on lung CYP2A protein levels in African green monkeys (AGMs). Lung CYP2A13, CYP2A6, and CYP2A7 (and CYP1A2) mRNA levels in smokers and nonsmokers were assessed in Gene Expression Omnibus data sets (GSE30063, GSE108134, and GSE11784). The impact of chronic, twice-daily, subcutaneous nicotine at two doses (0.3 and 0.5 mg/kg) versus vehicle on lung CYP2A protein levels was assessed. The impact of ethanol self-administration was also investigated, with and without nicotine treatment. Smokers versus nonsmokers (from GSE30063 and GSE108134) had lower (1.04- to 1.12-fold) levels of lung CYP2A13, CYP2A6, and CYP2A7 (and higher CYP1A2) mRNA. Both doses of nicotine tested decreased AGM lung CYP2A protein (3- to 7-fold). Ethanol self-administration had no effect on AGM lung CYP2A protein, and there was no interaction between ethanol and nicotine. Our results suggest that smoking was associated with a reduction in human lung CYP2A13, CYP2A6, and CYP2A7 mRNA, consistent with the role of nicotine treatment in reducing AGM lung CYP2A protein. This regulation by smoking/nicotine will increase interindividual variation in lung CYP2A levels, which may impact the localized metabolism of inhaled drugs and tobacco smoke procarcinogens. SIGNIFICANCE STATEMENT: CYP2A13 and CYP2A6 are expressed in the lung and may contribute to local procarcinogen activation. Smokers had lower lung CYP2A mRNA levels compared with nonsmokers. Lung CYP2A protein expression was decreased by systemic treatment with nicotine. Decreased lung CYP2A expression may alter smoking-related lung cancer risk and tissue damage from other inhaled toxins. This novel regulatory impact of nicotine, including nicotine found in smoking-cessation nicotine-replacement therapies, may have potential benefits on smoking-related lung cancer risk.

CYP2A13 Acts as the Main Metabolic CYP450s Enzyme for Activating Leonurine in Human Bronchial Epithelial Cells

Background

Leonurine is an active component of the traditional Chinese medicine Leonurus japonicus. This study aimed to investigate the effects of overexpressed CYP450s on the metabolic activity of leonurine.

Material/Methods

BEAS-2B cells stably expressing CYP1A1, 1A2, 2A13, 2B6, and 3A4 were constructed. CYP450s expression was identified using reverse-transcription PCR and Western blot assay. CCK-8 assay was used to evaluate the effect of leonurine on cell activity. Leonurine was incubated in vitro with CYP1A1, 1A2, 2A13, 2B6, and 3A4 metabolic enzymes to evaluate the clearance rate of CYP450 enzymes for leonurine. UPLC-MS was used to detect changes of drug concentration and discover the main metabolic enzymes affecting leonurine.

Results

BEAS-2B cells stably expressing CYP1A1, 1A2, 2A13, 2B6, and 3A4 were successfully constructed. According to primary mass spectra and secondary mass spectra of leonurine, the main metabolic enzymes were 312.1550 [H+] and 181.0484. Compared to the control group, residue of leonurine in CYP2A13 group was significantly reduced (F=5.307, p=0.024). Compared to the 0-min group, the clearance rate of leonurine in the CYP2A13-treated group was significantly decreased at 120 min after treatment (F=7.273, p=0.007). CCK-8 results also showed that activity of BEAS-2B cells that overexpress CYP2A13 gradually decreased with increased concentration of leonurine. Although CYP2A13 demonstrated good metabolic activity for leonurine, we found that CYP1A1, 1A2, 2B6, and 3A4 had no metabolic effects on leonurine.

Conclusions

Leonurine can be effectively activated through CYP2A13 enzyme metabolism, and further inhibits activity of human lung epithelial cells (BEAS-2B). Therefore, CYP2A13 is a main metabolic enzyme for leonurine in BEAS-2B cells.

In Silico Prediction of the Absorption and Disposition of Cefadroxil in Humans using an Intestinal Permeability Method Scaled from Humanized PepT1 Mice

It is difficult to predict the pharmacokinetics and plasma concentration-time profiles of new chemical entities in humans based on animal data. Some pharmacokinetic parameters, such as clearance and volume of distribution, can be scaled allometrically from rodents, mammals, and nonhuman primates with good success. However, it is far more challenging to predict the oral pharmacokinetics of experimental drug candidates. In the present study, we used in situ estimates of intestinal permeability, obtained in silico and from rat, wild-type (WT), and humanized PepT1 (huPepT1) mice, to predict the systemic exposure of cefadroxil, an orally administered model compound, under a variety of conditions. Using the GastroPlus simulation software program (Simulations Plus, Lancaster, CA), we found that the C max and area under the plasma concentration-time curve from time zero to the last measurable concentration of cefadroxil were better predicted using intestinal permeability estimates (both segmental and jejunal) from huPepT1 than from WT mice, and that intestinal permeabilities based on in silico and rat estimates gave worse predictions. We also observed that accurate predictions were possible for cefadroxil during oral dose escalation (i.e., 5, 15, and 30 mg/kg cefadroxil), a drug-drug interaction study (i.e., 5 mg/kg oral cefadroxil plus 45 mg/kg oral cephalexin), and an oral multiple dose study [i.e., 500 mg (6.7 mg/kg) cefadroxil every 6 hours]. Finally, the greatest amount of cefadroxil was absorbed in duodenal and jejunal segments of the small intestine after a 5 mg/kg oral dose. Thus, by combining a humanized mouse model and in silico software, the present study offers a novel strategy for better translating preclinical pharmacokinetic data to oral drug exposure during first-in-human studies.

P450-Humanized and Human Liver Chimeric Mouse Models for Studying Xenobiotic Metabolism and Toxicity

Preclinical evaluation of drug candidates in experimental animal models is an essential step in drug development. Humanized mouse models have emerged as a promising alternative to traditional animal models. The purpose of this mini-review is to provide a brief survey of currently available mouse models for studying human xenobiotic metabolism. Here, we describe both genetic humanization and human liver chimeric mouse models, focusing on the advantages and limitations while outlining their key features and applications. Although this field of biomedical science is relatively young, these humanized mouse models have the potential to transform preclinical drug testing and eventually lead to a more cost-effective and rapid development of new therapies.

Nicotine Component of Cigarette Smoke Extract (CSE) Decreases the Cytotoxicity of CSE in BEAS-2B Cells Stably Expressing Human Cytochrome P450 2A13

Cytochrome P450 2A13 (CYP2A13), an extrahepatic enzyme mainly expressed in the human respiratory system, has been reported to mediate the metabolism and toxicity of cigarette smoke. We previously found that nicotine inhibited 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) metabolism by CYP2A13, but its influence on other components of cigarette smoke remains unclear. The nicotine component of cigarette smoke extract (CSE) was separated, purified, and identified using high-performance liquid chromatography (HPLC) and ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS), splitting CSE into a nicotine section (CSE-N) and nicotine-free section (CSE-O). Cell viability and apoptosis by Cell Counting Kit-8 (CCK-8) and flow cytometry assays were conducted on immortalized human bronchial epithelial (BEAS-2B) cells stably expressing CYP2A13 (B-2A13) or vector (B-V), respectively. Interestingly, CSE and CSE-O were toxic to BEAS-2B cells whereas CSE-N showed less cytotoxicity. CSE-O was more toxic to B-2A13 cells than to B-V cells (IC₅₀ of 2.49% vs. 7.06%), which was flatted by 8-methoxypsoralen (8-MOP), a CYP inhibitor. CSE-O rather than CSE or CSE-N increased apoptosis of B-2A13 cells rather than B-V cells. Accordingly, compared to CSE-N and CSE, CSE-O significantly changed the expression of three pairs of pro- and anti-apoptotic proteins, Bcl-2 Associated X Protein/B cell lymphoma-2 (Bax/Bcl-2), Cleaved Poly (Adenosine Diphosphate-Ribose) Polymerase/Poly (Adenosine Diphosphate-Ribose) Polymerase (C-PARP/PARP), and C-caspase-3/caspase-3, in B-2A13 cells. In addition, recombination of CSE-N and CSE-O (CSE-O/N) showed similar cytotoxicity and apoptosis to the original CSE. These results demonstrate that the nicotine component decreases the metabolic activation of CYP2A13 to CSE and aids in understanding the critical role of CYP2A13 in human respiratory diseases caused by cigarette smoking.

Inhibition of Carcinogen-Activating Cytochrome P450 Enzymes by Xenobiotic Chemicals in Relation to Antimutagenicity and Anticarcinogenicity

A variety of xenobiotic chemicals, such as polycyclic aromatic hydrocarbons (PAHs), aryl- and heterocyclic amines and tobacco related nitrosamines, are ubiquitous environmental carcinogens and are required to be activated to chemically reactive metabolites by xenobiotic-metabolizing enzymes, including cytochrome P450 (P450 or CYP), in order to initiate cell transformation. Of various human P450 enzymes determined to date, CYP1A1, 1A2, 1B1, 2A13, 2A6, 2E1, and 3A4 are reported to play critical roles in the bioactivation of these carcinogenic chemicals. In vivo studies have shown that disruption of Cyp1b1 and Cyp2a5 genes in mice resulted in suppression of tumor formation caused by 7,12-dimethylbenz[a]anthracene and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone, respectively. In addition, specific inhibitors for CYP1 and 2A enzymes are able to suppress tumor formation caused by several carcinogens in experimental animals in vivo, when these inhibitors are applied before or just after the administration of carcinogens. In this review, we describe recent progress, including our own studies done during past decade, on the nature of inhibitors of human CYP1 and CYP2A enzymes that have been shown to activate carcinogenic PAHs and tobacco-related nitrosamines, respectively, in humans. The inhibitors considered here include a variety of carcinogenic and/or non-carcinogenic PAHs and acethylenic PAHs, many flavonoid derivatives, derivatives of naphthalene, phenanthrene, biphenyl, and pyrene and chemopreventive organoselenium compounds, such as benzyl selenocyanate and benzyl selenocyanate; o-XSC, 1,2-, 1,3-, and 1,4-phenylenebis( methylene)selenocyanate.