The role of cytochrome P450 in tumour development and progression and its potential in therapy

CYP1A inhibitors: Recent progress, current challenges, and future perspectives

Mammalian cytochrome P450 1A (CYP1A) are key phase I xenobiotic-metabolizing enzymes that play a distinctive role in metabolic activation or metabolic clearance of a variety of procarcinogens, drugs, and endogenous substances. Human CYP1A subfamily contains two members (hCYP1A1 and hCYP1A2), which are known to catalyze the oxidative activation of some environmental procarcinogens into carcinogenic species. Increasing evidence has demonstrated that CYP1A inhibitor therapies are promising strategies for cancer chemoprevention or overcoming CYP1A-associated drug toxicity and resistance. Herein, we reviewed recent advances in the discovery and characterization of hCYP1A inhibitors, from the discovery approaches to structural features and biomedical applications of hCYP1A inhibitors. The inhibition potentials, inhibition modes, and inhibition constants of all reported hCYP1A inhibitors are comprehensively summarized. Meanwhile, the structural features and structure-activity relationships of different classes of hCYP1A1 and hCYP1A2 inhibitors are analyzed and discussed in depth. Furthermore, the major challenges and future directions for this field are presented and highlighted. Collectively, the information and knowledge presented here will strongly facilitate the researchers to discover and develop more efficacious CYP1A inhibitors for specific purposes, such as chemo-preventive agents or as tool molecules in hCYP1A-related fundamental studies.

Research Progress on the Synergistic Anti-Tumor Effect of Natural Anti-Tumor Components of Chinese Herbal Medicine Combined with Chemotherapy Drugs

The application of chemotherapy drugs in tumor treatment has a long history, but the lack of selectivity of drugs often leads to serious side effects during chemotherapy. The natural anti-tumor ingredients derived from Chinese herbal medicine are attracting increased attention due to their diverse anti-tumor effects, abundant resources, and minimal side effects. An effective anti-tumor strategy may lie in the combination of these naturally derived anti-tumor ingredients with conventional chemotherapy drugs. This approach could potentially inhibit tumor growth and the development of drug resistance in tumor cells while reducing the adverse effects of chemotherapy drugs. This review provides a comprehensive overview of the combined therapy strategies integrating natural anti-tumor components from Chinese herbal medicine with chemotherapy drugs in current research. We primarily summarize various compounds in Chinese herbal medicine exhibiting natural anti-tumor activities and the relevant mechanisms in synergistic anti-tumor combination therapy. The focus of this paper is on underlining that this integrative approach, combining natural anti-tumor components of Chinese herbal medicine with chemotherapy drugs, presents a novel cancer treatment methodology, thereby providing new insights for future oncological research.

Design and Synthesis of Novel Near-Infrared Fluorescence Probes Based on an Open Conformation of a Cytochrome P450 1B1 Complex for Molecular Imaging of Colorectal Tumors

Cytochrome P450 1B1 (CYP1B1) is induced during the early stage of cancer and is universally overexpressed in tumors. Thus, it was considered as a potential biomarker for the monitoring of cancer. In this study, we designed and synthesized CYP1B1-targeted near-infrared (NIR) fluorescence molecular probes based on the latest reported open conformation of the CYP1B1-α-naphthoflavone (ANF) complex. According to the architecture of the open channel, we introduced linkers and a Cy5.5 fragment at the 5' position of ANF derivatives with strong CYP1B1 inhibitory activity to obtain probes 19-21. Then, in vitro cell-based studies showed that the probes could be enriched in tumor cells by binding to CYP1B1. During in vivo and ex vivo imaging in a xenograft mouse model, probe 19 with the best binding affinity was proven to be able to identify tumor sites in both fluorescence imaging and photoacoustic imaging modes.

Benzo[a]pyrene represses synaptic vesicle exocytosis by inhibiting P/Q-type calcium channels in hippocampal neurons

Humans are exposed to the common carcinogen benzo[a]pyrene (BaP) by ingesting contaminated foods and water or inhaling polluted air. Given the enriched lipids and reduced antioxidative properties in the brain and the accumulation of BaP in the brain due to its high lipophilicity, the brain is susceptible to BaP-induced toxicity. Exposure to BaP leads to impairments in learning and memory, increased anxiety behavior, and neuronal death. It induces protein dysfunctions in neuronal compartments that play essential roles in neuronal activity or physiology. However, the neurotoxicity of BaP on presynaptic terminals, which is crucial to neurotransmission by releasing synaptic vesicles that contain neurotransmitters, has not yet been investigated. In the present study, we investigated the toxicity of BaP at presynaptic terminals in living hippocampal neurons. These neurons were sourced from transgenic mice pups (postnatal 1-day, a total of 12 pups, equal numbers for each sex) that endogenously express synaptic vesicle-fused pHluorin, which is a green fluorescent protein that enables monitoring of synaptic vesicle dynamics. We observed that BaP suppressed synaptic vesicle exocytosis by inhibiting presynaptic Ca2+ entry via P/Q-type Ca2+ channels. Together with molecular docking simulation, we speculate that BaP and metabolites may bind to the P/Q Ca2+ channels. These results suggest the toxic mechanism of BaP exposure-induced abnormal behavior that provides a basis to evaluate the risk assessment of BaP-induced neurotoxicity.

Therapeutic Potential of Targeting the Cytochrome P450 Enzymes Using Lopinavir/Ritonavir in Colorectal Cancer: A Study in Monolayers, Spheroids and In Vivo Models

Cytochrome P450 (CYP450) enzyme has been shown to be expressed in colorectal cancer (CRC) and its dysregulation is linked to tumor progression and a poor prognosis. Here we investigated the therapeutic potential of targeting CYP450 using lopinavir/ritonavir in CRC. The integrative systems biology method and RNAseq were utilized to investigate the differential levels of genes associated with patients with colorectal cancer. The antiproliferative activity of lopinavir/ritonavir was evaluated in both monolayer and 3-dimensional (3D) models, followed by wound-healing assays. The effectiveness of targeting CYP450 was examined in a mouse model, followed by histopathological analysis, biochemical tests (MDA, SOD, thiol, and CAT), and RT-PCR. The data of dysregulation expressed genes (DEG) revealed 1268 upregulated and 1074 down-regulated genes in CRC. Among the top-score genes and dysregulated pathways, CYPs were detected and associated with poor prognosis of patients with CRC. Inhibition of CYP450 reduced cell proliferation via modulating survivin, Chop, CYP13a, and induction of cell death, as detected by AnnexinV/PI staining. This agent suppressed the migratory behaviors of cells by induction of E-cadherin. Moreover, lopinavir/ritonavir suppressed tumor growth and fibrosis, which correlated with a reduction in SOD/thiol levels and increased MDA levels. Our findings illustrated the therapeutic potential of targeting the CYP450 using lopinavir/ritonavir in colorectal cancer, supporting future investigations on this novel therapeutic approach for the treatment of CRC.

A new class of CYP1B1 inhibitors derived from bentranil

Cytochrome P450 1B1 (CYP1B1) is highly expressed in a variety of tumors and implicated to drug resistance. More and more researches have suggested that CYP1B1 is a new target for cancer prevention and therapy. Various CYP1B1 inhibitors with a rigid polycyclic skeleton have been developed, such as flavonoids, trans-stilbenes, and quinazolines. To obtain a new class of CYP1B1 inhibitors, we designed and synthesized a series of bentranil analogues, moreover, IC₅₀ determinations were performed for CYP1B1 inhibition of five of these compounds and found that 6o and 6q were the best inhibitors, with IC₅₀ values in the nM range. The selectivity index (SI) of CYP1B1 over CYP1A1 and CYP1A2 was 30-fold higher than that of α-naphthoflavone (ANF). The molecular docking results showed that compound 6q fitted better into the CYP1B1 binding site than other compounds, which was consistent with our experimental results. On the basis of 6o and 6q, it is expected to develop CYP1B1 inhibitors with stronger affinity, higher selectivity and better solubility.

Human CYP1B1 enzyme-mediated, AhR enhanced activation of aflatoxin B1 for its genotoxicity in human cells

Aflatoxin B1 (AFB1) is a human procarcinogen known to be activated by cytochrome P450 (CYP) 1A2 and 3A4. In a previous study AFB1 caused chromosomal rearrangement in a yeast strain genetically engineered for stably expressing human CYP1B1. Yet, further verification of the effect of AFB1 in human cells, a potential role of the aryl hydrocarbon receptor (AhR), and CYP1B1-catalyzed AFB1 metabolism remain unidentified. In this study, a human hepatocyte (L-02) line and a human lymphoblastoid (TK6) cell line were genetically engineered for the expression of human CYP1B1, producing L-02-hCYP1B1 and TK6-hCYP1B1, respectively. They were exposed to AFB1 and analyzed for the formation of micronucleus and elevation of γ-H2AX (indicating double-strand DNA breaks); the metabolites formed by CYP1B1 from AFB1 after incubation of AFB1 with human CYP1B1 isoenzyme microsomes were determined by LC-MS. The results showed significantly more potent induction of micronucleus by AFB1 in L-02-hCYP1B1 and TK6-hCYP1B1 than in the parental (L-02 and TK6) cells, and the effects were reduced by (E)- 2,3',4,5'-tetramethoxystilbene, a specific CYP1B1 inhibitor. In the AFB1- CYP1B1 microsomes incubations AFM1, a known stable metabolite of AFB1, was detected. Moreover, in L-02 and TK6 cells, AFB1 apparently increased the protein levels of AhR, ANRT and CYP1B1, and caused the nuclear translocation of AhR and ARNT, the latter effect being blocked by BAY-218 (an inhibitor of AhR). In conclusion, this study indicates that human CYP1B1 is capable of metabolically activating AFB1 through the AhR signaling pathway.

Potential Role of Oxidative Stress in the Production of Volatile Organic Compounds in Obesity

Obesity is associated with numerous health issues such as sleep disorders, asthma, hepatic dysfunction, cancer, renal dysfunction, diabetes, cardiovascular complications, and infertility. Previous research has shown that the distribution of excess body fat, rather than excess body weight, determines obesity-related risk factors. It is widely accepted that abdominal fat is a serious risk factor for illnesses associated with obesity and the accumulation of visceral fat promotes the release of pro-oxidants, pro-inflammatory, and reactive oxygen species (ROS). The metabolic process in the human body produces several volatile organic compounds (VOCs) via urine, saliva, breath, blood, skin secretions, milk, and feces. Several studies have shown that VOCs are released by the interaction of ROS with underlying cellular components leading to increased protein oxidation, lipid peroxidation, or DNA damage. These VOCs released via oxidative stress in obese individuals may serves as a biomarker for obesity-related metabolic alterations and disease. In this review, we focus on the relationship between oxidative stress and VOCs in obesity.

Potential of cytochrome P450, a family of xenobiotic metabolizing enzymes, in cancer therapy

SIGNIFICANCE

Targeted cancer therapy with minimal off-target consequences has shown promise for some cancer types. Although cytochrome P450 (CYP) consists of 18 families, CYP1-4 families play key role in metabolizing xenobiotics and cancer drugs. This eventually affects the process of carcinogenesis, treatment outcome, and cancer drug resistance. Differential overexpression of CYPs in transformed cells, together with phenotypic alterations in tumors, presents a potential for therapeutic intervention.

RECENT ADVANCES

Recent advances in molecular tools and information technology have helped utilize CYPs as cancer targets. The precise expression in various tumors, X-ray crystal structures, improved understanding of the structure-activity relationship, and new approaches in the development of prodrugs have supported the ongoing efforts to develop CYPs-based drugs with a better therapeutic index.

CRITICAL ISSUES

Narrow therapeutic index, off-target effects, drug resistance, and tumor heterogeneity limit the benefits of CYP-based conventional cancer therapies. In this review, we address the CYP1-4 families as druggable targets in cancer. An emphasis is given to the CYP expression, function, and the possible mechanisms that drive expression and activity in normal and transformed tissues. The strategies that inhibit or activate CYPs for therapeutic benefits are also discussed.

FUTURE DIRECTIONS

Efforts are needed to develop more selective tools that will help comprehend molecular and metabolic alterations in tumor tissues with biological end-points in relation to CYPs. This will eventually translate to developing more specific CYP inhibitors/inducers.

Induction of synergistic apoptosis by tetramethoxystilbene and nutlin-3a in human cervical cancer cells

2,4,3',5'-Tetramethoxystilbene (TMS) is a selective inhibitor of cytochrome P450 1B1 to block the conversion from estradiol to 4-OH-estradiol. Several studies suggested that TMS may act as a potent anti-cancer agent for hormone-related cancer including cervical cancer. Nutlin-3a is a cis-imidazoline analog that interferes with the interaction between mouse double minute 2 homolog (MDM2) and the tumor suppressor p53. The purpose of the study was to compare the cytotoxic effect of TMS and nutlin-3a treatment individually and in combination in HeLa cells. To assess the potential synergistic effects between TMS and nutlin-3a, low concentrations of TMS and nutlin-3a were simultaneously treated in HeLa cells. Based on cell viability, apoptosis assays, and the increase in cleaved caspase-3 and poly (ADP-ribose) polymerase cleavage, it was demonstrated that the combination with TMS and nutlin-3a exerts a synergistic effect on cancer cell death. Isobologram analysis of HeLa cells noted synergism between TMS and nutlin-3a. The combined treatment increased the expression of mitochondrial pro-apoptotic factors such as Bax and Bak, and decreased the expression of the XIAP. In addition, combination treatment significantly enhanced the translocation of AIF to the nucleus in HeLa cells. In conclusion, the results demonstrate that the combination of TMS and nutlin-3a induces synergistic apoptosis in HeLa cells, suggesting the possibility that this combination can be applied as a novel therapeutic strategy for cervical cancer.

Fucoxanthin Is a Potential Therapeutic Agent for the Treatment of Breast Cancer

Breast cancer (BC) is one of the most common cancers diagnosed and the leading cause of cancer-related death in women. Although there are first-line treatments for BC, drug resistances and adverse events have been reported. Given the incidence of BC keeps increasing, seeking novel therapeutics is urgently needed. Fucoxanthin (Fx) is a dietary carotenoid commonly found in seaweeds and diatoms. Both in vitro and in vivo studies show that Fx and its deacetylated metabolite fucoxanthinol (Fxol) inhibit and prevent BC growth. The NF-κB signaling pathway is considered the major pathway contributing to the anti-proliferation, anti-angiogenesis and pro-apoptotic effects of Fx and Fxol. Other signaling molecules such as MAPK, MMP2/9, CYP and ROS are also involved in the anti-cancer effects by regulating the tumor microenvironment, cancer metastasis, carcinogen metabolism and oxidation. Besides, Fx also possesses anti-obesity effects by regulating UCP1 levels and lipid metabolism, which may help to reduce BC risk. More importantly, mounting evidence demonstrates that Fx overcomes drug resistance. This review aims to give an updated summary of the anti-cancer effects of Fx and summarize the underlying mechanisms of action, which will provide novel strategies for the development of Fx as an anti-cancer therapeutic agent.

A practical strategy to develop isoform-selective near-infrared fluorescent probes for human cytochrome P450 enzymes

Currently, the development of selective fluorescent probes toward targeted enzymes is still a great challenge, due to the existence of numerous isoenzymes that share similar catalytic capacity. Herein, a double-filtering strategy was established to effectively develop isoenzyme-specific fluorescent probe(s) for cytochrome P450 (CYP) which are key enzymes involving in metabolism of endogenous substances and drugs. In the first-stage of our filtering approach, near-infrared (NIR) fluorophores with alkoxyl group were prepared for the screening of CYP-activated fluorescent substrates using a CYPs-dependent incubation system. In the second stage of our filtering approach, these candidates were further screened using reverse protein-ligand docking to effectively determine CYP isoenzyme-specific probe(s). Using our double-filtering approach, probes S9 and S10 were successfully developed for the real-time and selective detection of CYP2C9 and CYP2J2, respectively, to facilitate high-throughput screening and assessment of CYP2C9-mediated clinical drug interaction risks and CYP2J2-associated disease diagnosis. These observations suggest that our strategy could be used to develop the isoform-specific probes for CYPs.

Cytochrome P450: Implications for human breast cancer

The treatment options for breast cancer include endocrine therapy, targeted therapy and chemotherapy. However, some patients with triple-negative breast cancer cannot benefit from these methods. Therefore, novel therapeutic targets should be developed. The cytochrome P450 enzyme (CYP) is a crucial metabolic oxidase, which is involved in the metabolism of endogenous and exogenous substances in the human body. Some products undergoing the metabolic pathway of the CYP enzyme, such as hydroxylated polychlorinated biphenyls and 4-chlorobiphenyl, are toxic to humans and are considered to be potential carcinogens. As a class of multi-gene superfamily enzymes, the subtypes of CYPs are selectively expressed in breast cancer tissues, especially in the basal-like type. In addition, CYPs are essential for the activation or inactivation of anticancer drugs. The association between CYP expression and cancer risk, tumorigenesis, progression, metastasis and prognosis has been widely reported in basic and clinical studies. The present review describes the current findings regarding the importance of exploring metabolic pathways of CYPs and gene polymorphisms for the development of vital therapeutic targets for breast cancer.

CYP1B1 as a therapeutic target in cardio-oncology

Cardiovascular complications have been frequently reported in cancer patients and survivors, mainly because of various cardiotoxic cancer treatments. Despite the known cardiovascular toxic effects of these treatments, they are still clinically used because of their effectiveness as anti-cancer agents. In this review, we discuss the growing body of evidence suggesting that inhibition of the cytochrome P450 1B1 enzyme (CYP1B1) can be a promising therapeutic strategy that has the potential to prevent cancer treatment-induced cardiovascular complications without reducing their anti-cancer effects. CYP1B1 is an extrahepatic enzyme that is expressed in cardiovascular tissues and overexpressed in different types of cancers. A growing body of evidence is demonstrating a detrimental role of CYP1B1 in both cardiovascular diseases and cancer, via perturbed metabolism of endogenous compounds, production of carcinogenic metabolites, DNA adduct formation, and generation of reactive oxygen species (ROS). Several chemotherapeutic agents have been shown to induce CYP1B1 in cardiovascular and cancer cells, possibly via activating the Aryl hydrocarbon Receptor (AhR), ROS generation, and inflammatory cytokines. Induction of CYP1B1 is detrimental in many ways. First, it can induce or exacerbate cancer treatment-induced cardiovascular complications. Second, it may lead to significant chemo/radio-resistance, undermining both the safety and effectiveness of cancer treatments. Therefore, numerous preclinical studies demonstrate that inhibition of CYP1B1 protects against chemotherapy-induced cardiotoxicity and prevents chemo- and radio-resistance. Most of these studies have utilized phytochemicals to inhibit CYP1B1. Since phytochemicals have multiple targets, future studies are needed to discern the specific contribution of CYP1B1 to the cardioprotective and chemo/radio-sensitizing effects of these phytochemicals.

Screening of cytochrome 4Z1 expression in human non-neoplastic, pre-neoplastic and neoplastic tissues

Background:

Cytochromes P450 (CYPs) constitute an enzyme family involved in the oxidative metabolism of a wide variety of endogenous and exogenous compounds, including anti-cancer drugs and carcinogens. Unlike other human CYPs, CYP4Z1 is highly expressed in human breast carcinoma and is associated with poor prognosis. As a result, CYP4Z1 was hypothesised to be a potential biomarker or drug target for the discovery and development of promising anti-cancer therapies.

Materials and methods:

CYP4Z1 expression was immunohistochemically studied in a set of 100 different human tissues, including normal, benign, malignant and metastatic tissues, which originated from 27 anatomical sites. As a tumour model for CYP4Z1 expression, a panel of different breast cancers was evaluated for CYP4Z1 expression and its relation to histopathological features and prognostic immunohistochemical markers.

Results:

The immunohistochemical results revealed that CYP4Z1 was expressed in only one (4.3%) of the normal tissues from the mammary glands, while the expression of the enzyme was positive in 1 (11%), 12 (19%) and 2 (40%) of the benign, malignant and metastatic tissues, respectively. Interestingly, several tumour entities showed prominent expressions of CYP4Z1, including carcinomas of adrenal cortex, squamous cells of oesophagus, lung and cervix, as well as seminoma, astrocytoma, melanoma and lastly endometrial adenocarcinoma. In breast cancers, CYP4Z1 was expressed in 82% of the cases. Its expression was significantly associated with the pathology of tumour, histological grade and status of lymph node metastasis. Importantly, it was also significantly associated with the expressions of Her2, P53 and Ki-67.

Conclusion:

These findings greatly support future plans for the use of CYP4Z1 as a biomarker or target for anti-cancer drugs. However, large-scale validation studies are needed to better delineate the potential use of CYP4Z1 for therapeutic purposes.

pH- and enzyme-triggered drug release as an important process in the design of anti-tumor drug delivery systems

It is necessary to design a reasonable drug delivery system(DDS) for targeted release to overcome the potential toxicity and poor selectivity of anti-tumor drug. How a drug is released from a DDS is a critical issue that determines whether the DDS is designed successfully. We all know that the microenvironment of tumors is quite different from normal tissues, such as its acidic environment, different expression levels of some enzymes, etc. These features are widely used in the design of DDSs and play an important role in the drug release process in vivo. Numerous DDSs have been designed and synthesized. This article attention to how drugs are released from DDSs. We summarizes and classify the characteristic enzymes and chemical bonds used in the drug release process by browsing a large number of papers, and describes how they are applied in DDSs with specific examples. By understanding these acid-sensitive chemical bonds and over-expressed enzymes in tumors, different DDSs can be designed for different drug structures to solve specific problems of anti-tumor drugs.

Tamoxifen induces toxicity, causes autophagy, and partially reverses dexamethasone resistance in Jurkat T cells

Estrogens demonstrate biological activity in numerous organ systems, including the immune system, and exert their effects through estrogen receptors (ER) of two types: intracellular ERα and ERβ that activate transcriptional factors and membrane G protein-coupled ER GPER. The latter is capable to mediate fast activation of cytosolic signaling pathways, influencing transcriptional events in response to estrogens. Tamoxifen (TAM), widely used in chemotherapy of ERα-positive breast cancer, is considered as an ERα antagonist and GPER agonist. TAM was shown to possess "off-target" cytotoxicity, not related to ER in various tumor types. The present work was designed to study biological effects of TAM on the glucocorticoid (GC)-resistant cell line Jurkat, derived from acute lymphoblastic leukemia of T lineage (T-ALL). We have shown that T-ALL cell lines, in contrast to healthy T cells, express only GPER, but not ERα or ERβ. TAM compromised mitochondrial function and reduced the viability and proliferation of Jurkat cells. Additionally, TAM induced autophagy in a GPER-dependent manner. Gene expression profiling revealed the up-regulation of autophagy-related gene ATG5. Interestingly, TAM sensitized Jurkat cells to dexamethasone (DEX) treatment, which may be related to its capacity to cause autophagy. We suggest that TAM-based adjuvant therapy may represent a novel strategy in T-ALL patients handling.

Molecular Design Strategy to Construct the Near-Infrared Fluorescent Probe for Selectively Sensing Human Cytochrome P450 2J2

Cytochrome P450 2J2 (CYP2J2), a key enzyme responsible for oxidative metabolism of various xenobiotics and endogenous compounds, participates in a diverse array of physiological and pathological processes in humans. Its biological role in tumorigenesis and cancer diagnosis remains poorly understood, owing to the lack of molecular tools suitable for real-time monitoring CYP2J2 in complex biological systems. Using molecular design principles, we were able to modify the distance between the catalytic unit and metabolic recognition moiety, allowing us to develop a CYP2J2 selective fluorescent probe using a near-infrared fluorophore ( E)-2-(2-(6-hydroxy-2, 3-dihydro-1 H-xanthen-4-yl)vinyl)-3,3-dimethyl-1-propyl-3 H-indol-1-ium iodide (HXPI). To improve the reactivity and isoform specificity, a self-immolative linker was introduced to the HXPI derivatives in order to better fit the narrow substrate channel of CYP2J2, the modification effectively shortened the spatial distance between the metabolic moiety ( O-alkyl group) and catalytic center of CYP2J2. After screening a panel of O-alkylated HXPI derivatives, BnXPI displayed the best combination of specificity, sensitivity and applicability for detecting CYP2J2 in vitro and in vivo. Upon O-demethylation by CYP2J2, a self-immolative reaction occurred spontaneously via 1,6-elimination of p-hydroxybenzyl resulting in the release of HXPI. Allowing BnXPI to be successfully used to monitor CYP2J2 activity in real-time for various living systems including cells, tumor tissues, and tumor-bearing animals. In summary, our practical strategy could help the development of a highly specific and broadly applicable tool for monitoring CYP2J2, which offers great promise for exploring the biological functions of CYP2J2 in tumorigenesis.

Ligand-Capped Ultrapure Metal Nanoparticle Sensors for the Detection of Cutaneous Leishmaniasis Disease in Exhaled Breath

Human cutaneous leishmaniasis, although designated as one of the most neglected tropical diseases, remains underestimated due to its misdiagnosis. The diagnosis is mainly based on the microscopic detection of amastigote forms, isolation of the parasite, or the detection of Leishmania DNA, in addition to its differential clinical characterization; these tools are not always available in routine daily practice, and they are expensive and time-consuming. Here, we present a simple-to-use, noninvasive approach for human cutaneous leishmaniasis diagnosis, which is based on the analysis of volatile organic compounds in exhaled breath with an array of specifically designed chemical gas sensors. The study was realized on a group of n = 28 volunteers diagnosed with human cutaneous leishmaniasis and a group of n = 32 healthy controls, recruited in various sites from Tunisia, an endemic country of the disease. The classification success rate of human cutaneous leishmaniasis patients achieved by our sensors test was 98.2% accuracy, 96.4% sensitivity, and 100% specificity. Remarkably, one of the sensors, based on CuNPs functionalized with 2-mercaptobenzoxazole, yielded 100% accuracy, 100% sensitivity, and 100% specificity for human cutaneous leishmaniasis discrimination. While AuNPs have been the most extensively used in metal nanoparticle-ligand sensing films for breath sensing, our results demonstrate that chemical sensors based on ligand-capped CuNPs also hold great potential for breath volatile organic compounds detection. Additionally, the chemical analysis of the breath samples with gas chromatography coupled to mass spectrometry identified nine putative breath biomarkers for human cutaneous leishmaniasis.

Profiling cytochrome P450 family 4 gene expression in human hepatocellular carcinoma

Cytochrome P450 family 4 (CYP4) enzymes are known as microsomal omega (ω)-hydroxylases that metabolize fatty acids, eicosanoids, vitamin D and carcinogens. Thus, CYP4 enzymes may influence tumor development and progression. The aim of the present study was to evaluate the CYP4 expression profile in hepatocellular carcinoma (HCC) and its clinical relevance. The present study obtained CYP4 mRNA expression data for 377 HCC cases from The Cancer Genome Atlas cohort and performed Kaplan‑Meier survival, Gene Ontology functional enrichment, and gene set enrichment analysis (GSEA). In addition, the level of CYP4F2 protein expression was evaluated in matched pairs of HCC and non‑tumor tissue samples and the results were correlated with the clinicopathological characteristics of HCC (n=113). HCC survival analyses indicated better overall survival in patients with high CYP4F2, CYP4F12 and CYP4V2 mRNA expression levels; the results for histological grade and Tumor‑Node‑Metastasis stage supported these results. GSEA revealed high levels of CYP4F2, CYP4F12 and CYP4V2 mRNA expression to be negatively correlated with the expression of cell cycle‑associated genes. CYP4F2 protein expression was higher in non‑neoplastic liver tissue than in HCC tissue and positively correlated with favorable pathological tumor stage (I vs. II‑IV; P=0.022) and was a good independent prognostic factor for overall survival (P=0.004). These results demonstrate that the expression levels of the genes CYP4F2, CYP4F12 and CYPV2 are favorable prognostic factors in HCC and suggest the potential predictive diagnostic and prognostic roles of CYP4F2, CYP4F12 and CYPV2 gene expression in HCC.

Cytochrome P450 1B1 inhibition suppresses tumorigenicity of prostate cancer via caspase-1 activation

Cytochrome P450 1B1 (CYP1B1) is recognized as a universal tumor biomarker and a feasible therapeutic target due to its specific overexpression in cancer tissues. Despite its up-regulation in prostate cancer (PCa), biological significance and clinicopathological features of CYP1B1 are still elusive. Here, we show that overexpression or hyperactivation of CYP1B1 stimulated proliferative, migratory and invasive potential of non-tumorigenic PCa cells. Attenuation of CYP1B1 with its specific small hairpin (sh) RNAs greatly reduced proliferation through apoptotic cell death and impaired migration and invasion in PCa cells. Intratumoral injection of CYP1B1 shRNA attenuated growth of pre-existing tumors. The antitumor effect of CYP1B1 shRNA was also observed in prostate tumor xenograft mouse models. Among the genes altered by CYP1B1 knockdown, reduction of caspase-1 (CASP1) activity attenuated the antitumor effect of CYP1B1 inhibition. Indeed, CYP1B1 regulates CASP1 expression or activity. Finally, CYP1B1 expression was increased in higher grades of PCa and overall survival was significantly reduced in patients with high levels of CYP1B1 protein. CYP1B1 expression was reversely associated with CASP1 expression in clinical tissue samples. Together, our results demonstrate that CYP1B1 regulates PCa tumorigenesis by inhibiting CASP1 activation. Thus, the CYP1B1-CASP1 axis may be useful as a potential biomarker and a therapeutic target for PCa.

A hydroxylated flavonol, fisetin inhibits the formation of a carcinogenic estrogen metabolite

Fisetin can be found in a wide variety of plants and possesses strong efficacy against many cancers. 17β-Estradiol (E2) is hydrolyzed to 4-hydroxy-E2 (4-OHE2) via cytochrome P450 (CYP) 1B1 in vivo. In estrogen target tissues including the mammary gland, ovaries, and uterus, CYP1B1 is highly expressed, and 4-OHE2 is predominantly formed in cancerous tissues. Herein, we investigated the inhibitory activity of fisetin and flavone against CYP1B1 using estrogen E2 as substrate in vitro to reveal structure-activity relationship between structure of flavonoids and inhibition. The results showed that fisetin possessed inhibitory effect on CYP1B1 activity. Compared with flavone, the inhibition of fisetin was stronger. The V_max and K_i values were 1.950±0.157pmol/μgprotein/min and 4.925±0.689nM for fisetin and 2.277±0.231pmol/μgprotein/min and 9.148±2.150nM for flavone, respectively. By kinetic analyses, both fisetin and flavone displayed mixed inhibition. Taken together the data suggested that fisetin is able to inhibit the formation of carcinogenic 4-OHE2 from E2, which reveals one of its anti-cancer mechanisms and helps to reveal the relationship between the structure of flavonoids and the inhibition CYP1B1 for discovering new drugs in cancer therapy and prevention.

Differentiation between genetic mutations of breast cancer by breath volatolomics

Mapping molecular sub-types in breast cancer (BC) tumours is a rapidly evolving area due to growing interest in, for example, targeted therapy and screening high-risk populations for early diagnosis. We report a new concept for profiling BC molecular sub-types based on volatile organic compounds (VOCs). For this purpose, breath samples were collected from 276 female volunteers, including healthy, benign conditions, ductal carcinoma in situ (DCIS) and malignant lesions. Breath samples were analysed by gas chromatography mass spectrometry (GC-MS) and artificially intelligent nanoarray technology. Applying the non-parametric Wilcoxon/Kruskal-Wallis test, GC-MS analysis found 23 compounds that were significantly different (p < 0.05) in breath samples of BC patients with different molecular sub-types. Discriminant function analysis (DFA) of the nanoarray identified unique volatolomic signatures between cancer and non-cancer cases (83% accuracy in blind testing), and for the different molecular sub-types with accuracies ranging from 82 to 87%, sensitivities of 81 to 88% and specificities of 76 to 96% in leave-one-out cross-validation. These results demonstrate the presence of detectable breath VOC patterns for accurately profiling molecular sub-types in BC, either through specific compound identification by GC-MS or by volatolomic signatures obtained through statistical analysis of the artificially intelligent nanoarray responses.

Loss of miR-200c up-regulates CYP1B1 and confers docetaxel resistance in renal cell carcinoma

Despite high protein expression and enzymatic activity of cytochrome P450 1B1 (CYP1B1) in renal cell cancer (RCC), its functional significance has not been elucidated. Here we explored the functional role and regulatory mechanism of CYP1B1 in RCC. Reduction of CYP1B1 levels fail to prevent in vitro tumorigenicity such as proliferation, apoptosis, and cell cycle progression of RCC cells. Moreover, the expression levels are not associated with tumor type, stage, Fuhrman grade and 5-year survival probability after surgery. Instead, alteration of CYP1B1 expression regulates the chemosensitivity of RCC cells to docetaxel suggesting its critical contribution to the chemoresistance. Additionally, miR-200c, which is significantly down-regulated in RCC regulates CYP1B1 expression and activity. An inverse association was also observed between the expression levels of miR-200c and CYP1B1 protein in RCC tissues. Finally, alteration of miR-200c levels affects the chemosensitivity of RCC cells. Restoration of docetaxel resistance by exogenous expression of CYP1B1 in miR-200c-over-expressing cells indicates that CYP1B1 is a functional target of miR-200c. These results suggest that CYP1B1 up-regulation mediated by low miR-200c is one of the mechanisms underlying resistance of RCC cells to docetaxel. Therefore, expression of CYP1B1 and miR-200c in RCC may be useful as a prediction for docetaxel response.

Hybrid volatolomics and disease detection

This Review presents a concise, but not exhaustive, didactic overview of some of the main concepts and approaches related to "volatolomics"-an emerging frontier for fast, risk-free, and potentially inexpensive diagnostics. It attempts to review the source and characteristics of volatolomics through the so-called volatile organic compounds (VOCs) emanating from cells and their microenvironment. It also reviews the existence of VOCs in several bodily fluids, including the cellular environment, blood, breath, skin, feces, urine, and saliva. Finally, the usefulness of volatolomics for diagnosis from a single bodily fluid, as well as ways to improve these diagnostic aspects by "hybrid" approaches that combine VOC profiles collected from two or more bodily fluids, will be discussed. The perspectives of this approach in developing the field of diagnostics to a new level are highlighted.

Involvement of Cytochrome P450 in Reactive Oxygen Species Formation and Cancer

This review examines the involvement of cytochrome P450 (CYP) enzymes in the formation of reactive oxygen species in biological systems and discusses the possible involvement of reactive oxygen species and CYP enzymes in cancer. Reactive oxygen species are formed in biological systems as byproducts of the reduction of molecular oxygen and include the superoxide radical anion (∙O2-), hydrogen peroxide (H2O2), hydroxyl radical (∙OH), hydroperoxyl radical (HOO∙), singlet oxygen ((1)O2), and peroxyl radical (ROO∙). Two endogenous sources of reactive oxygen species are the mammalian CYP-dependent microsomal electron transport system and the mitochondrial electron transport chain. CYP enzymes catalyze the oxygenation of an organic substrate and the simultaneous reduction of molecular oxygen. If the transfer of oxygen to a substrate is not tightly controlled, uncoupling occurs and leads to the formation of reactive oxygen species. Reactive oxygen species are capable of causing oxidative damage to cellular membranes and macromolecules that can lead to the development of human diseases such as cancer. In normal cells, intracellular levels of reactive oxygen species are maintained in balance with intracellular biochemical antioxidants to prevent cellular damage. Oxidative stress occurs when this critical balance is disrupted. Topics covered in this review include the role of reactive oxygen species in intracellular cell signaling and the relationship between CYP enzymes and cancer. Outlines of CYP expression in neoplastic tissues, CYP enzyme polymorphism and cancer risk, CYP enzymes in cancer therapy and the metabolic activation of chemical procarcinogens by CYP enzymes are also provided.

CYP3A isoforms in Ewing's sarcoma tumours: an immunohistochemical study with clinical correlation

Ewing's sarcoma is an aggressive malignancy of bone and soft tissue with high incidence of metastasis and resistance to chemotherapy. Cytochrome P450 (CYP) monooxygenases are a family of enzymes that are involved in the metabolism of exogenous and endogenous compounds, including anti-cancer drugs, and have been implicated in the aggressive behaviour of various malignancies. Tumour samples and clinical information including age, sex, tumour site, tumour size, clinical stage and survival were collected from 36 adult and paediatric patients with Ewing's sarcoma family tumours. Tissue microarrays slides were processed for immunohistochemical labelling for CYP3A4, CYP3A5 and CYP3A7 using liver sections as positive control. The intensity of staining was scored as negative, low or high expression and was analysed statistically for any association with patients' clinical information. Four cases were later excluded due to inadequate viable tissue. CYP3A4 staining was present in 26 (81%) cases with high expression noted in 13 (40%) of 32 cases. High expression was significantly associated with distant metastases (P < 0.05). CYP3A5 and CYP3A7 were expressed in 5 and 13 cases respectively (15.6%, 40.6%). There was no association between the expression of CYP3A isoforms and age, sex, tumour size, or location (pelvic or extra-pelvic). None of the biomarkers showed any correlation with overall or disease-free survival. In conclusion, expression of CYP3A isoforms is noted in Ewing's sarcoma tumours and high CYP3A4 expression may be associated with metastasis. Additional studies are needed to further investigate the role of CYP3A4 in the prognosis of these tumours.

A comprehensive review in current developments of benzothiazole-based molecules in medicinal chemistry

Benzothiazole (BTA) and its derivatives are the most important heterocyclic compounds, which are common and integral feature of a variety of natural products and pharmaceutical agents. BTA shows a variety of pharmacological properties, and its analogs offer a high degree of structural diversity that has proven useful for the search of new therapeutic agents. The broad spectrum of pharmacological activity in individual BTA derivative indicates that, this series of compounds is of an undoubted interest. The related research and developments in BTA-based medicinal chemistry have become a rapidly developing and increasingly active topic. Particularly, numerous BTA-based compounds as clinical drugs have been extensively used in practice to treat various types of diseases with high therapeutic potency. This work systematically gives a comprehensive review in current developments of BTA-based compounds in the whole range of medicinal chemistry as anticancer, antibacterial, antifungal, antiinflammatory, analgesic, anti-HIV, antioxidant, anticonvulsant, antitubercular, antidiabetic, antileishmanial, antihistaminic, antimalarial and other medicinal agents. It is believed that, this review article is helpful for new thoughts in the quest for rational designs of more active and less toxic BTA-based drugs, as well as more effective diagnostic agents and pathologic probes.

Assessment, origin, and implementation of breath volatile cancer markers

A new non-invasive and potentially inexpensive frontier in the diagnosis of cancer relies on the detection of volatile organic compounds (VOCs) in exhaled breath samples. Breath can be sampled and analyzed in real-time, leading to fascinating and cost-effective clinical diagnostic procedures. Nevertheless, breath analysis is a very young field of research and faces challenges, mainly because the biochemical mechanisms behind the cancer-related VOCs are largely unknown. In this review, we present a list of 115 validated cancer-related VOCs published in the literature during the past decade, and classify them with respect to their "fat-to-blood" and "blood-to-air" partition coefficients. These partition coefficients provide an estimation of the relative concentrations of VOCs in alveolar breath, in blood and in the fat compartments of the human body. Additionally, we try to clarify controversial issues concerning possible experimental malpractice in the field, and propose ways to translate the basic science results as well as the mechanistic understanding to tools (sensors) that could serve as point-of-care diagnostics of cancer. We end this review with a conclusion and a future perspective.

Cytochrome P450 2E1 (CYP2E1) regulates the response to oxidative stress and migration of breast cancer cells

Introduction

The cytochrome P450 (CYP) enzymes are a class of heme-containing enzymes involved in phase I metabolism of a large number of xenobiotics. The CYP family member CYP2E1 metabolises many xenobiotics and pro-carcinogens, it is not just expressed in the liver but also in many other tissues such as the kidney, the lung, the brain, the gastrointestinal tract and the breast tissue. It is induced in several pathological conditions including cancer, obesity, and type II diabetes implying that this enzyme is implicated in other biological processes beyond its role in phase I metabolism. Despite the detailed description of the role of CYP2E1 in the liver, its functions in other tissues have not been extensively studied. In this study, we investigated the functional significance of CYP2E1 in breast carcinogenesis.

Methods

Cellular levels of reactive oxygen species (ROS) were measured by H₂DCFDA (2 2.9.2 2′,7′-dichlorodihydrofluorescein diacetate) staining and autophagy was assessed by tracing the cellular levels of autophagy markers using western blot assays. The endoplasmic reticulum stress and the unfolded protein response (UPR) were detected by luciferase assays reflecting the splicing of mRNA encoding the X-box binding protein 1 (XBP1) transcription factor and cell migration was evaluated using the scratch wound assay. Gene expression was recorded with standard transcription assays including luciferase reporter and chromatin immunoprecipitation.

Results

Ectopic expression of CYP2E1 induced ROS generation, affected autophagy, stimulated endoplasmic reticulum stress and inhibited migration in breast cancer cells with different metastatic potential and p53 status. Furthermore, evidence is presented indicating that CYP2E1 gene expression is under the transcriptional control of the p53 tumor suppressor.

Conclusions

These results support the notion that CYP2E1 exerts an important role in mammary carcinogenesis, provide a potential link between ethanol metabolism and breast cancer and suggest that progression, and metastasis, of advanced stages of breast cancer can be modulated by induction of CYP2E1 activity.

Characterization of aberrant pathways across human cancers

BACKGROUND

Cancer is a broad group of genetic diseases which account for millions of deaths worldwide each year. Cancers are classified by various clinical, pathological and molecular methods, but even within a well-characterized disease, there is a significant inter-patient variability in survival, response to treatment, and other parameters. Especially in molecular level, tumours of the same category can appear significantly dissimilar due to complex combinations of genetic aberrations leading to a similar malignancy. We extended the current classification methods by studying tumour heterogeneity at pathway level.

METHODS

We computed the rate of alterations in 1994 pathways and 2210 tumours consisting of eight different cancers. Using gene set enrichment analysis, each sample was computed a pathway aberration profile that reflected its molecular state. The profiles were analysed together to infer the characteristic aberration rates for each pathway within each cancer. Subgroups of tumours defined by similar pathway aberrations were identified using clustering analyses. The pathway aberration and gene expression profiles of the subgroups were consecutively compared across all eight cancer types to search for similar tumours crossing the standard classification.

RESULTS

We identified pathways and processes that were common to all cancers as well as traits that are unique to a cancer type or closely related cancers. Studying the gene expression patterns within the pathway context suggested potential alteration mechanisms. Clustering analysis revealed five clinically relevant subgroups of tumours in four cancers that exhibited significant differences in survival compared to others. The cross-cancer analysis of the subgroups resulted in the identification of tumours that shared potentially significant alterations.

CONCLUSIONS

This study represents the first effort to extend the molecular characterizations towards pathway level descriptions across the family of cancers. In addition to providing a proof-of-concept for single sample pathway aberration analysis in this context, we present a comprehensive pathway aberration dataset that can be used to study pathway aberration patterns within or across cancers. Significant similarities between subgroups of different cancers on pathway and gene expression levels provide interesting hypotheses for understanding variable drug response, or transferring treatments across diseases by identifying common druggable pathways or genes, for example.

Antiproliferative effect of the Ginkgo biloba extract is associated with the enhancement of cytochrome P450 1B1 expression in estrogen receptor-negative breast cancer cells

Ginkgo biloba is a dioecious tree and its extract is a complex mixture that has been used for thousands of years to treat a variety of ailments in traditional Chinese medicine. The aim of this study was to present our observations on the inhibitory effects of different Ginkgo biloba extracts on human breast cancer cell proliferation and growth. Our results demonstrated that treatment of MCF-7 and MDA-MB-231 human breast cancer cells with Ginkgo biloba leaves and ginkgo fruit extract inhibited cell proliferation. It was also observed that this inhibition was accompanied by the enhancement of cytochrome P450 (CYP) 1B1 expression in MDA-MB-231 cells. In addition, treatment with ginkgo fruit extract resulted in a higher CYP1B1 expression in MDA-MB-231 cells compared to treatment with the Ginkgo biloba leaves extract. Our results suggested that the inhibitory effects of the Ginkgo biloba extract on estrogen receptor-negative breast cancer proliferation and the induction of CYP1B1 expression may be exerted through an alternative pathway, independent of the estrogen receptor or the aryl hydrocarbon receptor pathway.

Nuclear receptors in the cross-talk of drug metabolism and inflammation

Inflammation and infection have long been known to affect the activity and expression of enzymes involved in hepatic and extrahepatic drug clearance. Significant advances have been made to elucidate the molecular mechanisms underlying the complex cross-talk between inflammation and drug-metabolism alterations. The emergent role of ligand-activated transcriptional regulators, belonging to the nuclear receptor (NR) superfamily, is now well established. The NRs, pregnane X receptor, constitutive androstane receptor, retinoic X receptor, glucocorticoid receptor, and hepatocyte nuclear factor 4, and the basic helix-loop-helix/Per-ARNT-Sim family member, aryl hydrocarbon receptor, are the main regulators of the detoxification function. According to the panel of mediators secreted during inflammation, a cascade of numerous signaling pathways is activated, including nuclear factor kappa B, mitogen-activated protein kinase, and the Janus kinase/signal transducer and activator of transcription pathways. Complex cross-talk is established between these signaling pathways regulating either constitutive or induced gene expression. In most cases, a mutual antagonism between xenosensor and inflammation signaling occurs. This review focuses on the molecular and cellular mechanisms implicated in this cross-talk.

Estradiol 17β and its metabolites stimulate cell proliferation and antagonize ascorbic acid-suppressed cell proliferation in human ovarian cancer cells

Estradiol 17β (E2β) and ascorbic acid (AA) have been implicated in cancer progression. However, little is known about the actions of biologically active metabolites of E2β, 2-hydroxyestradiol (2OHE2), 4-hydroxyestradiol (4OHE2), 2-methoxyestradiol (2ME2), and 4-methoxyestradiol (4ME2) synthesized sequentially by cytochrome P450, family 1, subfamily A (CYP1A1) and B (CYP1B1), polypeptide 1, and catechol-O-methyltransferase (COMT) on ovarian cancer. Herein, we examined the expression of CYP1A1, CYP1B1, COMT, and estrogen receptor α (ERα) and β (ERβ) in human ovarian surface epithelial (IOSE-385) and cancer cell lines (OVCAR-3, SKOV-3, and OVCA-432). We also investigated the roles of E2β, 2OHE2, 4OHE2, 2ME2, and 4ME2 in cell proliferation, and their interactive effects with AA on ovarian cells. We found the expression of CYP1A1, CYP1B1, COMT, ERα, and ERβ in most cell lines tested. Treating cells with physiological concentrations of E2β and its metabolites promoted (13%-42% of the control) IOSE-385 and OVCAR-3 proliferation. The ER blockade inhibited IOSE-385 (∼76%) and OVCAR-3 (∼87%) proliferative response to E2β but not to its metabolites. The ERα blockade inhibited (∼85%) E2β-stimulated OVCAR-3 proliferation, whereas ERβ blockade attenuated (∼83%) E2β-stimulated IOSE-385 proliferation. The AA at ≥250 μmol/L completely inhibited serum-stimulated cell proliferation in all cell lines tested; however, such inhibition in IOSE-385, OVCAR-3, and OVCA-432 was partially (∼10%-20%) countered by E2β and its metabolites. Thus, our findings indicate that E2β and its metabolites promote cell proliferation and antagonize the AA-suppressed cell proliferation in a subset of ovarian cancer cells, suggesting that blocking the actions of E2β and its metabolites may enhance AA's antiovarian cancer activity.

Insights on cytochrome p450 enzymes and inhibitors obtained through QSAR studies

The cytochrome P450 (CYP) superfamily of heme enzymes play an important role in the metabolism of a large number of endogenous and exogenous compounds, including most of the drugs currently on the market. Inhibitors of CYP enzymes have important roles in the treatment of several disease conditions such as numerous cancers and fungal infections in addition to their critical role in drug-drug interactions. Structure activity relationships (SAR), and three-dimensional quantitative structure activity relationships (3D-QSAR) represent important tools in understanding the interactions of the inhibitors with the active sites of the CYP enzymes. A comprehensive account of the QSAR studies on the major human CYPs 1A1, 1A2, 1B1, 2A6, 2B6, 2C9, 2C19, 2D6, 2E1, 3A4 and a few other CYPs are detailed in this review which will provide us with an insight into the individual/common characteristics of the active sites of these enzymes and the enzyme-inhibitor interactions.

Inhibition of cytochrome p450 enzymes by quinones and anthraquinones

In silico docking studies and quantitative structure-activity relationship analysis of a number of in-house cytochrome P450 inhibitors have revealed important structural characteristics that are required for a molecule to function as a good inhibitor of P450 enzymes 1A1, 1A2, 2B1, and/or 2A6. These insights were incorporated into the design of pharmacophores used for a 2D search of the Chinese medicine database. Emodin, a natural anthraquinone isolated from Rheum emodi and known to be metabolized by cytochrome P450 enzymes, was one of the hits and was used as the lead compound. Emodin was found to inhibit P450s 1A1, 1A2, and 2B1 with IC(50) values of 12.25, 3.73, and 14.89 μM, respectively. On the basis of the emodin molecular structure, further similarity searches of the PubChem and ZINC chemical databases were conducted resulting in the identification of 12 emodin analogues for testing against P450s 1A1-, 1A2-, 2B1-, and 2A6-dependent activities. 1-Amino-4-chloro-2-methylanthracene-9,10-dione (compound 1) showed the best inhibition potency for P450 1A1 with an IC(50) value of 0.40 μM. 1-Amino-4-chloro-2-methylanthracene-9,10-dione (compound 1) and 1-amino-4-hydroxyanthracene-9,10-dione (compound 2) both inhibited P450 1A2 with the same IC(50) value of 0.53 μM. In addition, compound 1 acted as a mechanism-based inhibitor of cytochrome P450s 1A1 and 1A2 with K(I) and K(inactivation) values of 5.38 μM and 1.57 min(-1) for P450 1A1 and 0.50 μM and 0.08 min(-1) for P450 1A2. 2,6-Di-tert-butyl-5-hydroxynaphthalene-1,4-dione (compound 8) directly inhibited P450 2B1 with good selectivity and inhibition potency (IC(50) = 5.66 μM). Docking studies using the 3D structures of the enzymes were carried out on all of the compounds. The binding modes of these compounds revealed the structural characteristics responsible for their potency and selectivity. Compound 1, which is structurally similar to compound 2 with the presence of an amino group at position 1, showed a difference in the mechanism of inhibition toward P450s 1A1 and 1A2. The mechanism-based inhibition seen for compound 1 may be attributed to the presence of the methyl group at the 2-position, in close proximity to the amino group. Compound 2, which is otherwise similar, lacks that methyl moiety and did not show mechanism-based inhibition.

An introduction to the molecular basics of aryl hydrocarbon receptor biology

Depending on their chemical structure and properties, environmental chemicals and other xenobiotics that enter the cell can affect cellular function by either nonselective binding to cellular macromolecules or by interference with cellular receptors, which would initiate a more defined cell biological response. One of these intracellular chemosensor molecules is the aryl hydrocarbon receptor (AhR), a transcription factor of the bHLH/PAS family that is known to mediate the biochemical and toxic effects of dioxins, polyaromatic hydrocarbons and related compounds. Numerous investigations have revealed that the AhR is not only a master regulator of drug metabolism activated by anthropogenic chemicals, but is also triggered by natural and endogenous ligands and can influence cell biological endpoints such as growth and differentiation. Cutting-edge research has identified new intriguing functions of the AhR, such as during proteasomal degradation of steroid hormone receptors, the cellular UVB stress response and the differentiation of certain T-cell subsets. In this review we provide both a survey of the fundamental basics of AhR biology and an insight into new functional aspects of AhR signaling to further stimulate research on this intriguing transcription factor at the interface between toxicology, cell biology and immunology.

Profiling the expression of cytochrome P450 in breast cancer

AIMS

The cytochrome P450s (P450) are key oxidative enzymes that metabolize many carcinogens and anticancer drugs. Thus, these enzymes influence tumour development, tumour response to therapy and are putative tumour biomarkers. The aim was to define the P450 expression profile in breast cancer and establish the significance of P450 expression in this tumour type.

METHODS AND RESULTS

A tissue microarray containing 170 breast cancers of no special type was immunostained for a panel of 21 P450s. The highest percentage of strong immunopositivity in breast cancers was seen for CYP4X1 (50.8%), CYP2S1 (37.5%) and CYP2U1 (32.2%), while CYP2J (98.6%) and CYP3A43 (70.7%) were the P450s that most frequently displayed no immunoreactivity. CYP4V2 (P = 0.01), CYP4X1 (P = 0.01) and CYP4Z1 (P = 0.01) showed correlations with tumour grade. CYP1B1 (P = 0.001), CYP3A5 (P = 0.001) and CYP51 (P = 0.005) showed the most significant correlations with oestrogen receptor status. Correlations with survival were identified for CYP2S1 (P = 0.03), CYP3A4 (P = 0.025), CYP4V2 (P = 0.026) and CYP26A1 (P = 0.03), although none of these P450s was an independent marker of prognosis.

CONCLUSIONS

This study has defined the expression profile of cytochrome P450s in breast cancer and may offer their potential application as biomarkers to aid decisions regarding optimal adjuvant hormonal therapy.

Update information on drug metabolism systems--2009, part II: summary of information on the effects of diseases and environmental factors on human cytochrome P450 (CYP) enzymes and transporters

The present paper is an update of the data on the effects of diseases and environmental factors on the expression and/or activity of human cytochrome P450 (CYP) enzymes and transporters. The data are presented in tabular form (Tables 1 and 2) and are a continuation of previously published summaries on the effects of drugs and other chemicals on CYP enzymes (Rendic, S.; Di Carlo, F. Drug Metab. Rev., 1997, 29(1-2), 413-580., Rendic, S. Drug Metab. Rev., 2002, 34(1-2), 83-448.). The collected information presented here is as stated by the cited author(s), and in cases when several references are cited the latest published information is included. Inconsistent results and conclusions obtained by different authors are highlighted, followed by discussion of the major findings. The searchable database is available as an Excel file, for information about file availability contact the corresponding author.

Ultrafine carbon particles down-regulate CYP1B1 expression in human monocytes

BACKGROUND

Cytochrome P450 monoxygenases play an important role in the defence against inhaled toxic compounds and in metabolizing a wide range of xenobiotics and environmental contaminants. In ambient aerosol the ultrafine particle fraction which penetrates deeply into the lungs is considered to be a major factor for adverse health effects. The cells mainly affected by inhaled particles are lung epithelial cells and cells of the monocyte/macrophage lineage.

RESULTS

In this study we have analyzed the effect of a mixture of fine TiO2 and ultrafine carbon black Printex 90 particles (P90) on the expression of cytochrome P450 1B1 (CYP1B1) in human monocytes, macrophages, bronchial epithelial cells and epithelial cell lines. CYP1B1 expression is strongly down-regulated by P90 in monocytes with a maximum after P90 treatment for 3 h while fine and ultrafine TiO2 had no effect. CYP1B1 was down-regulated up to 130-fold and in addition CYP1A1 mRNA was decreased 13-fold. In vitro generated monocyte-derived macrophages (MDM), epithelial cell lines, and primary bronchial epithelial cells also showed reduced CYP1B1 mRNA levels. Benzo[a]pyrene (BaP) is inducing CYB1B1 but ultrafine P90 can still down-regulate gene expression at 0.1 muM of BaP. The P90-induced reduction of CYP1B1 was also demonstrated at the protein level using Western blot analysis.

CONCLUSION

These data suggest that the P90-induced reduction of CYP gene expression may interfere with the activation and/or detoxification capabilities of inhaled toxic compounds.

Identification of genes associated with non-small-cell lung cancer promotion and progression

Lung cancer is the most common cause of neoplasia-related death worldwide. One of the crucial early events in carcinogenesis is the induction of genomic instability and mutator phenotype. We investigated genomic instability in 30 patients with non-small-cell lung cancer (NSCLC) by comparing DNA fingerprints of paired tumor and normal tissues using arbitrarily primed polymerase chain reaction (AP-PCR). Selected 21 DNA bands with altered mobility were isolated from polyacrylamide gels, cloned and sequenced. Obtained sequences were submitted to homology search in GenBank database which revealed the following genes: TSPAN14, CDH12, RDH10, CYP4Z1, KIR, E2F4, PHACTR3, PHF20, PRAME family member and SLC2A13. Following the identification of these genes we examined their relation to the clinicopathological parameters and survival of the patients. Our study revealed that genetic alterations of TSPAN14, SLC2A13 and PHF20 appeared prevalently in tumors of grade 1, stage I suggesting that structural changes of these genes could play a role in NSCLC promotion. Contrary to this CYP4Z1, KIR and RDH10 were prevalently mutated in tumors of grade 3, stage III suggesting that they could play a role in NSCLC progression. E2F4, PHACTR3, PRAME family member and CDH12 most probably play important role in NSCLC geneses. In conclusion, our study revealed altered genes previously not described in regard to this type of cancer.

Drug metabolism by tumours: its nature, relevance and therapeutic implications

Drug-metabolising enzymes (DMEs) are present in tumours and are capable of biotransforming a variety of antineoplastics. Tumoural drug metabolism is both a potential mechanism of resistance and a means of achieving optimal therapy. This review addresses the classes of DMEs, their cytotoxic substrates and distribution in specific malignancies. The limitations of preclinical and clinical studies are highlighted. Their role in predicting therapeutic response, the activation of prodrugs and the potential for their modulation for gain is also addressed. The contribution of tumoural DMEs to cancer therapy can only be ascertained through large prospective studies and supported by new technologies. Only then can efforts be concentrated in the design of better prodrugs or combination therapy to optimise individual therapy.

Targeting cytochrome P450 enzymes: a new approach in anti-cancer drug development

Cytochrome P450s (CYPs) represent a large class of heme-containing enzymes that catalyze the metabolism of multitudes of substrates both endogenous and exogenous. Until recently, however, CYPs have been largely overlooked in cancer drug development, acknowledged only for their role in phase I metabolism of chemotherapeutics. The first successful strategy targeting CYP enzymes in cancer therapy was the development of potent inhibitors of CYP19 (aromatase) for the treatment of breast cancer. Aromatase inhibitors ushered in a new era in hormone ablation therapy for estrogen dependent cancers, and have paved the way for similar strategies (i.e., inhibition of CYP17) that combat androgen dependent prostate cancer. Identification of CYPs involved in the inactivation of anti-cancer metabolites of vitamin D(3) and vitamin A has triggered development of agents that target these enzymes as well. The discovery of the over-expression of exogenous metabolizing CYPs, such as CYP1B1, in cancer cells has roused interest in the development of inhibitors for chemoprevention and of prodrugs designed to be activated by CYPs only in cancer cells. Finally, the expression of CYPs within tumors has been utilized in the development of bioreductive molecules that are activated by CYPs only under hypoxic conditions. This review offers the first comprehensive analysis of strategies in drug development that either inhibit or exploit CYP enzymes for the treatment of cancer.