Gene Summary

Gene:CYP1A1; cytochrome P450 family 1 subfamily A member 1
Aliases: AHH, AHRR, CP11, CYP1, CYPIA1, P1-450, P450-C, P450DX
Summary:This gene, CYP1A1, encodes a member of the cytochrome P450 superfamily of enzymes. The cytochrome P450 proteins are monooxygenases which catalyze many reactions involved in drug metabolism and synthesis of cholesterol, steroids and other lipids. This protein localizes to the endoplasmic reticulum and its expression is induced by some polycyclic aromatic hydrocarbons (PAHs), some of which are found in cigarette smoke. The enzyme's endogenous substrate is unknown; however, it is able to metabolize some PAHs to carcinogenic intermediates. The gene has been associated with lung cancer risk. A related family member, CYP1A2, is located approximately 25 kb away from CYP1A1 on chromosome 15. Alternative splicing results in multiple transcript variants encoding distinct isoforms. [provided by RefSeq, Jan 2016]
Databases:OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:cytochrome P450 1A1
Source:NCBIAccessed: 31 August, 2019


What does this gene/protein do?
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Pathways:What pathways are this gene/protein implicaed in?
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Cancer Overview

Research Indicators

Publications Per Year (1994-2019)
Graph generated 31 August 2019 using data from PubMed using criteria.

Literature Analysis

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Tag cloud generated 31 August, 2019 using data from PubMed, MeSH and CancerIndex

Specific Cancers (7)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications: CYP1A1 (cancer-related)

Vyhlídalová B, Poulíková K, Bartoňková I, et al.
Mono-methylindoles induce CYP1A genes and inhibit CYP1A1 enzyme activity in human hepatocytes and HepaRG cells.
Toxicol Lett. 2019; 313:66-76 [PubMed] Article available free on PMC after 01/10/2019 Related Publications
Mono-methylindoles (MMI) were described as agonists and/or antagonists of the human aryl hydrocarbon receptor (AhR). Here, we investigated the effects of MMI on AhR-CYP1A pathway in human hepatocytes and HepaRG cells derived from human progenitor hepatic cells. All MMI, except of 2-methylindole, strongly induced CYP1A1 and CYP1A2 mRNAs in HepaRG cells. Induction of CYP1A genes was absent in AhR-knock-out HepaRG cells. Consistently, CYP1A1 and CYP1A2 mRNAs and proteins were induced by all MMIs (except 2-methylindole), in human hepatocytes. The enzyme activity of CYP1A1 was inhibited by MMIs in human hepatocytes and LS180 colon cancer cells in a concentration-dependent manner (IC

Zajda K, Rak A, Ptak A, Gregoraszczuk EL
Compounds of PAH mixtures dependent interaction between multiple signaling pathways in granulosa tumour cells.
Toxicol Lett. 2019; 310:14-22 [PubMed] Related Publications
Mechanism of PAH mixtures, using granulosa tumour cells, was investigated. Cells were exposed to a mixture of all 16 priority PAHs (M1) or a mixture of five PAHs not classified as human carcinogens (M2). The effect of siAHR, siAHRR and siNFKB2 on the expression of CYP1A1, CYP1B1, GSTM1, ERα, AR and cell proliferation was described. M1 decreased AhR and CYP1A1, while increased AhRR and ARNT expression. M2 also decreased AhR and CYP1A1 but had no effect on AhRR expression. siAHRR reversed the inhibitory effect of M1 on AhR and CYP1A1,while inhibitory effect of M2 was still observed. siNFKB2 reversed inhibitory effect of both mixtures on AhR and CYP1A1 expression and stimulatory effect of M1 on AhRR expression. siAHR reversed stimulatory effect of both mixtures on ERα expression. Stimulatory effect of M1 on cell proliferation was not observed in siAHR, was still observed in siESR1 cells. M2 had no effect on cell proliferation, however stimulatory effect was appeared in siAHR and siESR1cells. In conclusion: M1 by activation of AhRR and NFkB p52, but M2 only by activation of NFκB attenuated AhR signalling and ligand-induced CYP1A1 expression. Interaction between AhR and ER following M1 and M2 exposure is primarily initiated through AhR.

Shahi RB, De Brakeleer S, Caljon B, et al.
Identification of candidate cancer predisposing variants by performing whole-exome sequencing on index patients from BRCA1 and BRCA2-negative breast cancer families.
BMC Cancer. 2019; 19(1):313 [PubMed] Article available free on PMC after 01/10/2019 Related Publications
BACKGROUND: In the majority of familial breast cancer (BC) families, the etiology of the disease remains unresolved. To identify missing BC heritability resulting from relatively rare variants (minor allele frequency ≤ 1%), we have performed whole exome sequencing followed by variant analysis in a virtual panel of 492 cancer-associated genes on BC patients from BRCA1 and BRCA2 negative families with elevated BC risk.
METHODS: BC patients from 54 BRCA1 and BRCA2-negative families with elevated BC risk and 120 matched controls were considered for germline DNA whole exome sequencing. Rare variants identified in the exome and in a virtual panel of cancer-associated genes [492 genes associated with different types of (hereditary) cancer] were compared between BC patients and controls. Nonsense, frame-shift indels and splice-site variants (strong protein-damaging variants, called PDAVs later on) observed in BC patients within the genes of the panel, which we estimated to possess the highest probability to predispose to BC, were further validated using an alternative sequencing procedure.
RESULTS: Exome- and cancer-associated gene panel-wide variant analysis show that there is no significant difference in the average number of rare variants found in BC patients compared to controls. However, the genes in the cancer-associated gene panel with nonsense variants were more than two-fold over-represented in women with BC and commonly involved in the DNA double-strand break repair process. Approximately 44% (24 of 54) of BC patients harbored 31 PDAVs, of which 11 were novel. These variants were found in genes associated with known or suspected BC predisposition (PALB2, BARD1, CHEK2, RAD51C and FANCA) or in predisposing genes linked to other cancer types but not well-studied in the context of familial BC (EXO1, RECQL4, CCNH, MUS81, TDP1, DCLRE1A, DCLRE1C, PDE11A and RINT1) and genes associated with different hereditary syndromes but not yet clearly associated with familial cancer syndromes (ABCC11, BBS10, CD96, CYP1A1, DHCR7, DNAH11, ESCO2, FLT4, HPS6, MYH8, NME8 and TTC8). Exome-wide, only a few genes appeared to be enriched for PDAVs in the familial BC patients compared to controls.
CONCLUSIONS: We have identified a series of novel candidate BC predisposition variants/genes. These variants/genes should be further investigated in larger cohorts/case-control studies. Other studies including co-segregation analyses in affected families, locus-specific loss of heterozygosity and functional studies should shed further light on their relevance for BC risk.

Nigam K, Sanyal S, Gupta S, et al.
Alteration of the Risk of Oral Pre-Cancer and Cancer in North India Population by CYP1A1 Polymorphism Genotypes and Haplotype
Asian Pac J Cancer Prev. 2019; 20(2):345-354 [PubMed] Related Publications
Background: The aim of this study was to evaluate any association between CYP1A1 (T6235C and C4887A, A4889G) gene polymorphisms and the risk of oral pre-cancer and cancer. Methods: In the present study, 250 patients with oral pre-cancer and/or cancer and 250 healthy controls were genotyped for CYP1A1 T6235C, C4887A and A4889G polymorphisms by the PCR-RFLP method. Results: None of the CYP1A1 polymorphisms were associated with the risk of either oral cancer or pre cancer. Nor were any links with clinical parameters of oral cancer found. However, among the consumers of areca nut/pan masala the TC, CA and AG genotypes respectively for the CYP1A1 T6235C,C4887Aand A4889G polymorphisms were significantly more frequent in controls compared to cases (p values for cases vs. controls of 0.0032, 0.0019 and 0.0009, respectively). Similarly, compared to the haplotype TCA, TAG constituted by CYP1A1 T6235C and C4887A and A4889G was more common in controls (6.88%) than in cases (4.07%). Conclusion: Our results suggest that genotypes regarding CYP1A1 polymorphisms may modulate the risk of oral cancer and pre-cancer among the areca nut/pan masala consumers. The haplotype may also exert an influence in our north Indian population.

Soriano A, Masanas M, Boloix A, et al.
Functional high-throughput screening reveals miR-323a-5p and miR-342-5p as new tumor-suppressive microRNA for neuroblastoma.
Cell Mol Life Sci. 2019; 76(11):2231-2243 [PubMed] Article available free on PMC after 01/10/2019 Related Publications
Current therapies for most non-infectious diseases are directed at or affect functionality of the human translated genome, barely 2% of all genetic information. By contrast, the therapeutic potential of targeting the transcriptome, ~ 70% of the genome, remains largely unexplored. RNA therapeutics is an emerging field that widens the range of druggable targets and includes elements such as microRNA. Here, we sought to screen for microRNA with tumor-suppressive functions in neuroblastoma, an aggressive pediatric tumor of the sympathetic nervous system that requires the development of new therapies. We found miR-323a-5p and miR-342-5p to be capable of reducing cell proliferation in multiple neuroblastoma cell lines in vitro and in vivo, thereby providing a proof of concept for miRNA-based therapies for neuroblastoma. Furthermore, the combined inhibition of the direct identified targets such as CCND1, CHAF1A, INCENP and BCL-XL could reveal new vulnerabilities of high-risk neuroblastoma.

Yamaguchi M, Hankinson O
2,3,7,8‑tetrachlorodibenzo‑p‑dioxin suppresses the growth of human colorectal cancer cells in vitro: Implication of the aryl hydrocarbon receptor signaling.
Int J Oncol. 2019; 54(4):1422-1432 [PubMed] Article available free on PMC after 01/10/2019 Related Publications
Human colorectal cancer is the third most common cancer disease with a 5‑year survival rate of 55% in USA in 2016. The investigation to identify novel biomarker factors with molecular classification may provide notable clinical information to prolong the survival of patients with colorectal cancer. The aryl hydrocarbon receptor (AHR) binds the AHR nuclear translocator in the cytoplasm of various types of cells, including liver cells, and then binds to the xenobiotic responsive element on various genes. AHR was initially discovered via its ligand, the polychlorinated hydrocarbon, 2,3,7,8‑tetrachlorodibenzo‑p‑dioxin (TCDD). The present study was undertaken to determine whether TCDD, an agonist of AHR signaling, impacts the growth of RKO human colorectal cancer cells in vitro. Treatment with TCDD (0.1‑100 nM) revealed suppressive effects on colony formation and proliferation of RKO cells, and stimulated death of these cells with subconfluence. These effects of TCDD were abolished by pretreatment with CH223191, an inhibitor of AHR signaling. Western blot analysis demonstrated that TCDD treatment decreased AHR levels and elevated cytochrome P450 family 1 subfamily A member 1 (CYP1A1) levels, indicating a stimulation of AHR signaling. TCDD treatment caused an increase in nuclear factor‑κB p65 and β‑catenin levels, although it did not have an effect on Ras levels. Notably, TCDD treatment increased the levels of p53, retinoblastoma, p21 and regucalcin, which are depressors of carcinogenesis. Additionally, action of TCDD on cell proliferation and death were not revealed in regucalcin‑overexpressing RKO cells, and regucalcin overexpression depressed AHR signaling associated with CYP1A1 expression. Thus, AHR signaling suppresses the growth of colorectal cancer cells, indicating a role as a significant targeting molecule for colorectal cancer.

An D, Song Z, Yi Y, et al.
Oroxylin A, a methylated metabolite of baicalein, exhibits a stronger inhibitory effect than baicalein on the CYP1B1-mediated carcinogenic estradiol metabolite formation.
Phytother Res. 2019; 33(4):1033-1043 [PubMed] Related Publications
Human cytochrome P450 1B1 (CYP1B1)-mediated formation of 4-hydroxyestradiol (4-OHE2) from 17β-estradiol plays an important role in the progression of human breast cancer, while the biotransformation of 17β-estradiol to 2-hydroxyestradiol mediated by cytochrome P450 1A1 (CYP1A1) is considered as a less harmful pathway. In this study, inhibitory effects of flavonoids baicalein and oroxylin A, a metabolite of baicalein in human body, on CYP1A1 and 1B1 activities were investigated in vitro. The inhibition intensities of baicalein and oroxylin A towards CYP1B1 were greater than towards CYP1A1 with a mixed mechanism. In addition, oroxylin A showed a stronger inhibitory effect than baicalein towards the CYP1B1-mediated 17β-estradiol 4-hydroxylation, with the IC

Cheng H, Huang C, Tang G, et al.
Emerging role of EPHX1 in chemoresistance of acute myeloid leukemia by regurlating drug-metabolizing enzymes and apoptotic signaling.
Mol Carcinog. 2019; 58(5):808-819 [PubMed] Related Publications
Microsomal epoxide hyrolase 1 (EPHX1) is a critical biotransformation enzyme and participants in both the detoxification and activation of potentially genotoxic epoxides. In this study, we firstly aimed to investigate the role of EPHX1 in the chemoresistance of acute myeloid leukemic cells to aclarubicin (ACM) and mitoxantrone (MIT). EPHX1 mRNA expression and prognosis were measured in acute myeloid leukemia (AML) patients, and the function of EPHX1 in leukemic cell viability and apoptosis induced by ACM and MIT was also measured. Our results found that EPHX1 expression is obviously associated with recurrence rate, overall survival and time of obtaining first complete remission in AML patients. EPHX1 silencing promoted ACM and MIT induced decrease in cell viability and cell apoptosis of HL-60, K562, and THP-1 that was inhibited by EPHX1 overexpression. EPHX1 reduced the susceptibility of leukemic cells to ACM and MIT by regulating drug-metabolizing enzymes (CYP1A1, GSTM1, and GSTT1) and apoptotic signaling (Bax, Bcl-2, Caspase-3, Caspase-9, and PARP1). Moreover, Nrf2 overexpression significantly increased EPHX1 expression and leukemic cell viability and decreased leukemic cell apoptosis. Taken together, we summarized the recent findings about the chemoresistance-promoting role of EPHX1, and the potential of targeting EPHX1 was proposed to counteract drug resistance in leukemia treatment.

Lv JW, Zheng ZQ, Wang ZX, et al.
Pan-cancer genomic analyses reveal prognostic and immunogenic features of the tumor melatonergic microenvironment across 14 solid cancer types.
J Pineal Res. 2019; 66(3):e12557 [PubMed] Related Publications
We performed comprehensive genomic analyses of the melatonergic system within the tumor microenvironment and their clinical relevance across a broad spectrum of solid tumors. RNA-seq data from The Cancer Genome Atlas (TCGA) of 14 solid tumors representing 6658 human samples were analyzed. The tumor melatonergic system was characterized by the rates of melatonin synthesis and metabolism using a two-gene expression model (melatonin synthesis/metabolism Index). We calculated three indexes according to different melatonin metabolism isoenzymes (Index-I [ASMT:CYP1A1], Index-II [ASMT:CYP1A2], and Index-III [ASMT:CYP1B1]). Samples of each cancer type were classified into two subgroups (high vs low) based on median values. Clinical outcomes, mutational burden, and neoepitope abundance were analyzed and compared. We found that the ability of the tumor microenvironment to synthesize and accumulate melatonin varied across cancer types and negatively correlated with tumor burden. Kaplan-Meier survival analyses and multivariable modeling showed that the three indexes played different roles across different cancers and harbored prognostic values in breast cancer (adjusted hazard ratio [AHR]

Zeng Y, Shen Z, Gu W, Wu M
Bioinformatics analysis to identify action targets in NCI-N87 gastric cancer cells exposed to quercetin.
Pharm Biol. 2018; 56(1):393-398 [PubMed] Article available free on PMC after 01/10/2019 Related Publications
CONTEXT: Quercetin exerts antiproliferative effects on gastric cancer. However, its mechanisms of action on gastric cancer have not been comprehensively revealed.
OBJECTIVE: We investigated the mechanisms of action of quercetin against gastric cancer cells.
MATERIALS AND METHODS: Human NCI-N87 gastric cancer cells were treated with 15 μM quercetin or dimethyl sulfoxide (as a control) for 48 h. DNA isolated from cells was sequenced on a HiSeq 2500, and the data were used to identify differentially expressed genes (DEGs) between groups. Then, enrichment analyses were performed for DEGs and a protein-protein interaction (PPI) network was constructed. Finally, the transcription factors (TFs)-DEGs regulatory network was visualized by Cytoscape software.
RESULTS: A total of 121 DEGs were identified in the quercetin group. In the PPI network, Fos proto-oncogene (FOS, degree = 12), aryl hydrocarbon receptor (AHR, degree = 12), Jun proto-oncogene (JUN, degree = 11), and cytochrome P450 family 1 subfamily A member 1 (CYP1A1, degree = 11) with higher degrees highly interconnected with other proteins. Of the 5 TF-DEGs, early growth response 1 (EGR1), FOS like 1 (FOSL1), FOS, and JUN were upregulated, while AHR was downregulated. Moreover, FOSL1, JUN, and Wnt family member 7B (WNT7B) were enriched in the Wnt signaling pathway.
DISCUSSION AND CONCLUSIONS: CYP1A1 highly interconnected with AHR in the PPI network. Therefore, FOS, AHR, JUN, CYP1A1, EGR1, FOSL1, and WNT7B might be targets of quercetin in gastric cancer.

Mazzio EA, Soliman KFA
Whole-transcriptomic Profile of SK-MEL-3 Melanoma Cells Treated with the Histone Deacetylase Inhibitor: Trichostatin A.
Cancer Genomics Proteomics. 2018 Sep-Oct; 15(5):349-364 [PubMed] Article available free on PMC after 01/10/2019 Related Publications
BACKGROUND: Malignant melanoma cells can rapidly acquire phenotypic properties making them resistant to radiation and mainline chemotherapies such as decarbonize or kinase inhibitors that target RAS-proto-oncogene independent auto-activated mitogen-activated protein kinases (MAPK)/through dual specificity mitogen-activated protein kinase (MEK). Both drug resistance and inherent transition from melanocytic nevi to malignant melanoma involve the overexpression of histone deacetylases (HDACs) and a B-Raf proto-oncogene (BRAF) mutation.
MATERIALS AND METHODS: In this work, the effects of an HDAC class I and II inhibitor trichostatin A (TSA) on the whole transcriptome of SK-MEL-3 cells carrying a BRAF mutation was examined.
RESULTS: The data obtained show that TSA was an extremely potent HDAC inhibitor within SK-MEL-3 nuclear lysates, where TSA was then optimized for appropriate sub-lethal concentrations for in vitro testing. The whole-transcriptome profile shows a basic phenotype dominance in the SK-MEL-3 cell line for i) synthesis of melanin, ii) phagosome acidification, iii) ATP hydrolysis-coupled proton pumps and iv) iron transport systems. While TSA did not affect the aforementioned major systems, it evoked a dramatic change to the transcriptome: reflected by a down-regulation of 810 transcripts and up-regulation of 833, with fold-change from -15.27 to +31.1 FC (p<0.00001). Largest differentials were found for the following transcripts: Up-regulated: Tetraspanin 13 (TSPAN13), serpin family i member 1 (SERPINI1), ATPase Na+/K+ transporting subunit beta 2 (ATP1B2), nicotinamide nucleotide adenylyl transferase 2 (NMNAT2), platelet-derived growth factor receptor-like (PDGFRL), cytochrome P450 family 1 subfamily A member 1 (CYP1A1), prostate androgen-regulated mucin-like protein 1 (PARM1), secretogranin II (SCG2), SYT11 (synaptotagmin 11), rhophilin associated tail protein 1 like (ROPN1L); down-regulated: polypeptide N-acetylgalactosaminyltransferase 3 (GALNT3), carbonic anhydrase 14 (CAXIV), BCL2-related protein A1 (BCL2A1), protein kinase C delta (PRKCD), transient receptor potential cation channel subfamily M member 1 (TRPM1), ubiquitin associated protein 1 like (UBAP1L), glutathione peroxidase 8 (GPX8), interleukin 16 (IL16), tumor protein p53 (TP53), and serpin family H member 1 (SERPINH1). There was no change to any of the HDAC transcripts (class I, II and IV), the sirtuin HDAC family (1-6) or the BRAF proto-oncogene v 599 transcripts. However, the data showed that TSA down-regulated influential transcripts that drive the BRAF-extracellular signal-regulated kinase (ERK)1/2 oncogenic pathway (namely PRKCD and MYC proto-oncogene which negatively affected the cell-cycle distribution. Mitotic inhibition was corroborated by functional pathway analysis and flow cytometry confirming halt at the G
CONCLUSION: TSA does not alter HDAC transcripts nor BRAF itself, but down-regulates critical components of the MAPK/MEK/BRAF oncogenic pathway, initiating a mitotic arrest.

Sengupta D, Guha U, Mitra S, et al.
Meta-Analysis of Polymorphic Variants Conferring Genetic Risk to Cervical Cancer in Indian Women Supports CYP1A1 as an Important Associated Locus
Asian Pac J Cancer Prev. 2018; 19(8):2071-2081 [PubMed] Article available free on PMC after 01/10/2019 Related Publications
Objective: Association of multiple polymorphic variants with cervical cancer has been elucidated by several candidate gene based as well as genome-wide association studies. However, contradictory outcomes of those studies have failed to estimate the true effect of the polymorphic variants on cervical cancer. Methods: Literature mining of the PubMed database was done to gather all the publications related to genetic association with cervical cancer in India. Out of 98 PubMed hits only 29 genetic association studies were selected for meta-analysis based on specific inclusion criteria. A fixed-effect meta-analysis was performed to evaluate the overall association of the genetic polymorphisms with cervical cancer. Cochran’s Q test was performed to assess between study heterogeneity. Publication bias was also estimated by funnel plots and Egger’s regression test. Further, sub-group analysis was conducted by fixed-effect meta-regression to assess the impact of polymorphisms on cervical cancer in the presence of Human Papilloma Virus (HPV). Result: Following a fixed-effect model, meta-analysis was conducted that revealed 2 polymorphic variants viz. ‘deletion polymorphism (Del2) (OR=1.79, 95% CI= 1.08-2.95, P=0.023) in GSTM1’ and ‘rs1048943 (OR = 2.34, 95% CI=1.37-3.99, P=0.0018) in CYP1A1’ to be associated with cervical cancer. However, multiple testing correction showed only rs1048943 of CYP1A1 to be significantly associated (P-value=0.029) with cervical cancer with significant publication bias (P-value=0.0113) as estimated by Egger’s regression test. The polymorphic variants ‘rs1801131’, ‘rs1801133’, ‘rs2430561’, ‘rs1799782’, ‘rs25486’ and ‘rs25487’ showed significant (p<0.05) evidence of heterogeneity between studies by Cochran’s Q test and also by heterogeneity index (I2) calculation. Conclusion: Therefore, our study revealed significant association of rs1048943 in CYP1A1, but a nominal association of deletion polymorphism (Del2) in GSTM1 with cervical cancer, which provides a comprehensive insight on the true effect of the polymorphisms, reported in various case-control studies, on the risk of the development of cervical cancer in Indian women.

Bulus H, Oguztuzun S, Güler Simsek G, et al.
Expression of CYP and GST in human normal and colon tumor tissues.
Biotech Histochem. 2019; 94(1):1-9 [PubMed] Related Publications
We investigated the immunohistochemical staining characteristics of cytochrome P450 1A1 (CYP1A1), CYPB1, CYP2E1, and glutathione S-transferase P1 (GSTP1), GSTT1, GSTO1, GSTK1 in colon tumor and surrounding normal colon tissues. Tissues were obtained from 47 patients with colon adenocarcinoma and the staining intensity of tumor and control tissues was compared. CYP1A1, CYP1B1, CYP2E1, GSTP1, GSTT1, GSTO1 and GSTK1 expressions in colon cancer cells were significantly greater than those in normal colon epithelial cells. No significant relation was found between the isoenzyme expressions and age, gender, smoking status, tumor grade and tumor stage. The higher expressions of CYP1A1, CYP1B1, CYP2E1, GSTP1, GSTO1, GSTT1 and GSTK1 in tumor than in normal colon tissues may be important for colon cancer progression and development.

Martano M, Stiuso P, Facchiano A, et al.
Aryl hydrocarbon receptor, a tumor grade‑associated marker of oral cancer, is directly downregulated by polydatin: A pilot study.
Oncol Rep. 2018; 40(3):1435-1442 [PubMed] Related Publications
Oral squamous cell carcinoma (OSCC) is one of the most aggressive and deadliest tumors worldwide. The aryl hydrocarbon receptor (AHR) is a nuclear transcription factor known as a dioxin receptor and mediates the toxic effects of industrial contaminants. In addition, AHR has been implicated in multiple cellular processes and its expression has been shown to play a critical role in tumorigenesis, including human oral cancer cell lines. In the present study, we evaluated the expression of AHR/HSP-90 in 25 formalin‑fixed, paraffin-embedded human oral cancer specimens by IHC analysis. CYP1A1 expression was regarded as an AHR reporter gene. The data indicated a complete correlation between AHR expression and cancer grade enabling us to propose AHR as a prognostic marker of oral cancer. Moreover, in OSCC cell line CAL27, we observed the modulatory effect of polydatin, a widespread natural substance and direct precursor of resveratrol, on AHR expression. A computational approach was performed to predict the site of interaction of polydatin on the AHR surface. Our studies confirm the involvement of AHR signaling in the clinicopathological specimens of oral cancer and suggest the use of polydatin for oral cancer prevention.

Yu J, Feng Y, Wang Y, An R
Aryl hydrocarbon receptor enhances the expression of miR-150-5p to suppress in prostate cancer progression by regulating MAP3K12.
Arch Biochem Biophys. 2018; 654:47-54 [PubMed] Related Publications
It has been reported that mircoRNAs (miRNAs) can act as tumor inhibitors in multiple malignant tumors. As a tumor suppressor, miR-150-5p has been reported in some cancers. However, the biological impacts of miR-150-5p in prostate cancer is not fully elaborated. This study aims to explore the biological role and mechanism of miR-150-5p in prostate cancer. The expression level of miR-150-5p was examined with Quantitative real time polymerase chain reaction (qRT-PCR). Moreover, Kaplan Meier analysis revealed that downregulation of miR-150-5p predicted unfavorable prognosis for patients with prostate cancer. To identify the inhibitory effects of miR-150-5p on the cellular processes of prostate cancer, gain-of function assay was conducted. Next, the inhibitory effects of Tetrachlorodibenzo-p-dioxin (TCDD) and 3,3'-Diindolylmethane (DIM) on the proliferation and invasion of prostate cancer cells were demonstrated. Knockdown of Ahr reversed the TCDD/DIM-mediated proliferation and invasion. The expression level of CYP1A1 also was measured to confirm that Ahr was activated by TCDD or DIM in prostate cancer cells. Mechanism experiments revealed that MAP3K12 is a target mRNA of miR-150-5p in prostate cancer cells. In conclusion, Aryl hydrocarbon receptor enhances the expression of miR-150-5p to suppress cell proliferation and invasion in prostate cancer by regulating MAP3K12.

Lepri SR, Sartori D, Semprebon SC, et al.
Genistein Affects Expression of Cytochrome P450 (CYP450) Genes in Hepatocellular Carcinoma (HEPG2/C3A) Cell Line.
Drug Metab Lett. 2018; 12(2):138-144 [PubMed] Article available free on PMC after 01/10/2019 Related Publications
BACKGROUND: Genistein (5,7-Dihydroxy-3-(4-hydroxyphenyl)-4H-1-benzopyran-4-one) is the most abundant isoflavone in soybean, which has been associated with a lower risk of development of cancer and cardiovascular diseases. Of particular interest regarding cancer preventive properties of flavonoids is their interaction with cytochrome P450 enzymes (CYPs). However, contradictory data report the effect of genistein on expression of СYPs enzymes.
OBJECTIVE: The aim of this study was to investigate the effects of genistein on cytochrome P450 (CYP) gene expression levels in human hepatocellular carcinoma (HepG2/C3A) and colon adenocarcinoma (HT29) cells.
METHODS: Real-time RT-PCR was used to examine the expression of genes families involved in xenobiotic metabolism, such as CYP1 (CYP1A1, CYP1B1), CYP2 (CYP2E1, CYP2D6), CYP3 (CYP3A4); and of a family involved in the catabolism of the all-trans-retinoic acid (ATRA), CYP26 (CYP26A1, CYP26B1).
RESULTS: RT-qPCR data analysis showed that after 12 h of exposure of HepG2/C3A cells to genistein (5 and 50 µM) there was an upregulation of CYP1A1 and CYP1B1 and downregulation of CYP2D6, CYP26A1 and CYP26B1 mRNA levels. There was no change in the mRNA levels of CYP P450 genes in HT29 cells.
CONCLUSION: Our results suggest that treatment with genistein in non-toxic concentrations may impact the expression level of CYPs involved in the biotransformation of xenobiotics and drug metabolizing enzymes. Moreover, the downregulation of ATRA metabolism-related genes opens a new research path for the study of genistein as retinoic acid metabolism blocking agent for treating cancer and other pathologies.

Kvist AJ, Kanebratt KP, Walentinsson A, et al.
Critical differences in drug metabolic properties of human hepatic cellular models, including primary human hepatocytes, stem cell derived hepatocytes, and hepatoma cell lines.
Biochem Pharmacol. 2018; 155:124-140 [PubMed] Related Publications
Primary human hepatocytes (PHH), HepaRG™, HepG2, and two sources of induced pluripotent stem cell (iPSC) derived hepatocytes were characterized regarding gene expression and function of key hepatic proteins, important for the metabolic fate of drugs. The gene expression PCA analysis showed a distance between the two iPSC derived hepatocytes as well as the HepG2 and HepaRG™ cells to the three PHH donors and PHH pool, which were clustered more closely together. Correlation-based hierarchical analysis clustered HepG2 close to the stem cell derived hepatocytes both when the expression of 91 genes related to liver function or only cytochrome P450 (P450) genes were analyzed indicating the non-liver feature and a similar low P450 profile in these cell models. The specific P450 activities and the metabolic pattern of well-characterized drug substances in the cell models demonstrated that iPSC derived hepatocytes had modest levels of CYP3A and CYP2C9, while CYP1A2, 2B6, 2C8, 2C9, 2C19, and 2D6 were barely detectable. High expression of several extrahepatic P450s such as CYP1A1 and 1B1 detected in the stem cell derived hepatocytes may have significant effects on metabolite profiles. However, one of the iPSC derived hepatocytes demonstrated significant combined P450 and conjugating enzyme activity of certain drugs. HepaRG™ cells showed many metabolic properties similar to PHHs and will in many respects be a good model in studies of metabolic pathways and induction of drug metabolism whereas there is still ground to cover before iPSC derived hepatocytes will be seen as a substitute to PHH in drug metabolism studies.

Tan YQ, Chiu-Leung LC, Lin SM, Leung LK
The citrus flavonone hesperetin attenuates the nuclear translocation of aryl hydrocarbon receptor.
Comp Biochem Physiol C Toxicol Pharmacol. 2018; 210:57-64 [PubMed] Related Publications
The environmental polycyclic aromatic hydrocarbons (PAH) and dioxins are carcinogens and their adverse effects have been largely attributed to the activation of AhR. Hesperetin is a flavonone found abundantly in citrus fruits and has been shown to be a biologically active agent. In the present study, the effect of hesperetin on the nuclear translocation of AhR and the downstream gene expression was investigated in MCF-7 cells. Confocal microscopy indicated that 7, 12-dimethylbenz[α]anthracene (DMBA) or 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) -induced nuclear translocation of AhR was deterred by hesperetin treatment. The reduced nuclear translocation could also be observed in Western analysis. Reporter-gene assay further illustrated that the induced XRE transactivation was weakened by the treatment of hesperetin. Quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) assay demonstrated that the gene expressions of CYP1A1, 1A2, and 1B1 followed the same pattern of AhR translocation. These results suggested that hesperetin counteracted AhR transactivation and suppressed the downstream gene expression.

Alhamdow A, Lindh C, Hagberg J, et al.
DNA methylation of the cancer-related genes F2RL3 and AHRR is associated with occupational exposure to polycyclic aromatic hydrocarbons.
Carcinogenesis. 2018; 39(7):869-878 [PubMed] Article available free on PMC after 01/10/2019 Related Publications
Some polycyclic aromatic hydrocarbons (PAH) are known carcinogens and workplace PAH exposure may increase the risk of cancer. Monitoring early cancer-related changes can indicate whether the exposure is carcinogenic. Here, we enrolled 151 chimney sweeps, 152 controls and 19 creosote-exposed male workers from Sweden. We measured urinary PAH metabolites using LC/MS/MS, the cancer-related markers telomere length (TL) and mitochondrial DNA copy number (mtDNAcn) using qPCR, and DNA methylation of lung cancer-related genes F2RL3 and AHRR using pyrosequencing. The median 1-hydroxypyrene (PAH metabolite) concentrations were highest in creosote-exposed workers (8.0 μg/g creatinine) followed by chimney sweeps (0.34 μg/g creatinine) and controls (0.05 μg/g creatinine). TL and mtDNAcn did not differ between study groups. Chimney sweeps and creosote-exposed workers had significantly lower methylation of AHRR CpG site cg05575921 (88.1 and 84.9%, respectively) than controls (90%). Creosote-exposed workers (73.3%), but not chimney sweeps (76.6%) had lower methylation of F2RL3 cg03636183 than controls (76.7%). Linear regression analyses showed that chimney sweeps had lower AHRR cg05575921 methylation (B = -2.04; P < 0.057, adjusted for smoking and age) and lower average AHRR methylation (B = -2.05; P < 0.035), and non-smoking chimney sweeps had lower average F2RL3 methylation (B = -0.81; P < 0.042, adjusted for age) compared with controls. These cancer-related markers were not associated with urinary concentrations of PAH metabolites. In conclusion, although we found no associations with PAH metabolites in urine (short-term exposure), our results suggest dose-response relationship between PAH exposure and DNA hypomethylation of lung cancer-related loci. These findings indicate that further protective measures should be taken to reduce PAH exposure.

Fathi Z, Syn NL, Zhou JG, Roudi R
Molecular epidemiology of lung cancer in Iran: implications for drug development and cancer prevention.
J Hum Genet. 2018; 63(7):783-794 [PubMed] Related Publications
Epidemiological studies undertaken over the past decades reveal a gradual but progressive increase in the incidence and mortality attributable to lung cancer in the Islamic Republic of Iran, a sovereign state geographically situated at the crossroads of Central Eurasia and Western Asia. We identified references published in English and Persian through searches of PubMed, EMBASE, Web of Science, Scopus, and the Scientific Information Database (SID)-a specialized Iranian database, which indexes Iranian scientific journals-between inception and 15 September 2017. Of 1475 references identified through electronic searches, we reviewed the full text of 88 studies, and included 38 studies in the review. Potentially druggable NSCLC targets, which have been studied in Iran include EGFR, ALK, ERBB2, and KIT; but no studies were found, which examined the impact of MET, ROS1, BRAF, PIK3CA, and FGFR1 aberrations. We were able to identify some literature on DNA repair genes and xenobiotic metabolism, including TP53, TP63, ERCC2, XRCC2, SIRT1, PTEN, CYP1A1, CYP1B1, GSTT1, and GSTM1. We also found an increasing amount of research performed in relation to the tumor microenvironment and immune contexture, including CTLA4, MAGE, FOXP3, IFN-γ, and various interleukins, chemokines, and transcription factors; but did not identify any publication concerning the expression of PD-1/PD-L1 in lung cancer. Our survey of research performed in Iran has revealed a dearth of studies in topics, which are otherwise highly pursued in developed countries, but nevertheless, has begun to hint at a distinct biology of lung cancer in this part of the world.

Allam RM, Al-Abd AM, Khedr A, et al.
Fingolimod interrupts the cross talk between estrogen metabolism and sphingolipid metabolism within prostate cancer cells.
Toxicol Lett. 2018; 291:77-85 [PubMed] Related Publications
Sphingolipids are critical regulators of tumor microenvironments and play an important role in estrogen-dependent cancers. Estrogen and estrogen metabolites were found to be involved in prostate cancer. Fingolimod (FTY720) is a sphingokinase-1 (SphK1) inhibitor with anticancer properties against various tumor cell types. Herein, we investigated the interference of FTY720 with the cross talk between sphingolipid metabolism and estrogen metabolism within prostate cancer cells. FTY720 showed cytotoxic antiproliferative effects against androgen-dependent and -independent prostate cancer cells with IC

Ding B, Sun W, Han S, et al.
Cytochrome P450 1A1 gene polymorphisms and cervical cancer risk: A systematic review and meta-analysis.
Medicine (Baltimore). 2018; 97(13):e0210 [PubMed] Article available free on PMC after 01/10/2019 Related Publications
OBJECTIVE: This meta-analysis aims to examine whether the MspI and Ile462Val polymorphisms of cytochrome P450 1A1 (CYP1A1) are associated with cervical cancer risk.
METHODS: Eligible case-control studies were identified dated until July 2017. Pooled odds ratios (ORs) were used to assess the strength of the association between the two variants and cervical cancer risk.
RESULTS: Thirteen studies were eligible (2148 cases and 2252 controls) concerning MspI polymorphism and 8 studies were eligible (1466 cases and 1690 controls) for Ile462Val polymorphism. MspI polymorphism seemed to result in cervical cancer risk in any genetic model (C allele vs T allele: OR = 1.44, 95% confidence interval [CI] = 1.16-1.79; heterozygous model: OR = 1.40, 95% CI = 1.08-1.82; homozygous model: OR = 2.22, 95% CI = 1.48-3.33, dominant model: OR = 1.50, 95% CI = 1.14-1.98 and recessive model: OR = 1.80, 95% CI = 1.35-2.41); similar significantly increased risk was found among Caucasians and Asians. Ile462Val polymorphism was associated with elevated cervical cancer risk (Val allele vs Ile allele: OR = 1.85, 95% CI = 1.27-2.67; heterozygous model: OR = 1.42, 95% CI = 1.28-1.61; homozygous model: OR = 2.94, 95% CI = 1.15-7.54; dominant model: OR = 2.00, 95% CI = 1.33-3.00); this finding was replicated upon Caucasian population.
CONCLUSION: This meta-analysis demonstrated that polymorphisms in MspI and Ile462Val of CYP1A1 were risk factors for developing cervical cancer.

Wielsøe M, Eiberg H, Ghisari M, et al.
Genetic Variations, Exposure to Persistent Organic Pollutants and Breast Cancer Risk - A Greenlandic Case-Control Study.
Basic Clin Pharmacol Toxicol. 2018; 123(3):335-346 [PubMed] Related Publications
This study investigated the effects of single nucleotide polymorphisms (SNPs) in xenobiotic and steroid hormone-metabolizing genes in relation to breast cancer risk and explored possible effect modifications on persistent organic pollutants (POPs) and breast cancer associations. The study also assessed effects of Greenlandic BRCA1 founder mutations. Greenlandic Inuit women (77 cases and 84 controls) were included. We determined two founder mutations in BRCA1: Cys39Gly (rs80357164) and 4684delCC, and five SNPs in xenobiotic and oestrogen-metabolizing genes: CYP17A1 -34T>C (rs743572), CYP19A1 *19C>T (rs10046), CYP1A1 Ile462Val (rs1048943), CYP1B Leu432Val (rs1056836) and COMT Val158Met (rs4680). We used chi-square test for comparison of categorical variables between groups. Odds ratio (OR) estimates with 95% confidence interval (95%CI) were obtained using logistic regression models. The variant allele of BRCA1 Cys39Gly increased breast cancer risk (Gly/Cys versus Cys/Cys, OR: 12.2, 95%CI: 1.53; 98.1), and carriers of the variant allele of CYP17A1 -34T>C had reduced risk (CT+CC versus TT, OR: 0.44, 95%CI: 0.21; 0.93). CYP17A1 -34T>C was an effect modifier on the association between perfluoroalkyl acids (PFAAs) and breast cancer risk (∑PFAA, ratio of OR: 0.18, 95%CI: 0.03; 0.97). Non-significant modifying tendencies were seen for the other SNPs on the effect of polychlorinated biphenyls, organochlorine pesticides and PFAAs. In summary, the BRCA1 Cys39Gly and CYP17A1 -34T>C genetic variations were associated with breast cancer risk. Our results indicate that the evaluated genetic variants modify the effects of POP exposure on breast cancer risk; however, further studies are needed to document the data from the relatively small sample size.

Willis AJ, Indra R, Wohak LE, et al.
The impact of chemotherapeutic drugs on the CYP1A1-catalysed metabolism of the environmental carcinogen benzo[a]pyrene: Effects in human colorectal HCT116 TP53(+/+), TP53(+/-) and TP53(-/-) cells.
Toxicology. 2018; 398-399:1-12 [PubMed] Article available free on PMC after 01/10/2019 Related Publications
Polycyclic aromatic hydrocarbons such as benzo[a]pyrene (BaP) can induce cytochrome P450 1A1 (CYP1A1) via a p53-dependent mechanism. The effect of different p53-activating chemotherapeutic drugs on CYP1A1 expression, and the resultant effect on BaP metabolism, was investigated in a panel of isogenic human colorectal HCT116 cells with differing TP53 status. Cells that were TP53(+/+), TP53(+/-) or TP53(-/-) were treated for up to 48 h with 60 μM cisplatin, 50 μM etoposide or 5 μM ellipticine, each of which caused high p53 induction at moderate cytotoxicity (60-80% cell viability). We found that etoposide and ellipticine induced CYP1A1 in TP53(+/+) cells but not in TP53(-/-) cells, demonstrating that the mechanism of CYP1A1 induction is p53-dependent; cisplatin had no such effect. Co-incubation experiments with the drugs and 2.5 μM BaP showed that: (i) etoposide increased CYP1A1 expression in TP53(+/+) cells, and to a lesser extent in TP53(-/-) cells, compared to cells treated with BaP alone; (ii) ellipticine decreased CYP1A1 expression in TP53(+/+) cells in BaP co-incubations; and (iii) cisplatin did not affect BaP-mediated CYP1A1 expression. Further, whereas cisplatin and etoposide had virtually no influence on CYP1A1-catalysed BaP metabolism, ellipticine treatment strongly inhibited BaP bioactivation. Our results indicate that the underlying mechanisms whereby etoposide and ellipticine regulate CYP1A1 expression must be different and may not be linked to p53 activation alone. These results could be relevant for smokers, who are exposed to increased levels of BaP, when prescribing chemotherapeutic drugs. Beside gene-environment interactions, more considerations should be given to potential drug-environment interactions during chemotherapy.

Mescher M, Haarmann-Stemmann T
Modulation of CYP1A1 metabolism: From adverse health effects to chemoprevention and therapeutic options.
Pharmacol Ther. 2018; 187:71-87 [PubMed] Related Publications
The human cytochrome P450 (CYP) 1A1 gene encodes a monooxygenase that metabolizes multiple exogenous and endogenous substrates. CYP1A1 has become infamous for its oxidative metabolism of benzo[a]pyrene and related polycyclic aromatic hydrocarbons, converting these chemicals into very potent human carcinogens. CYP1A1 expression is mainly controlled by the aryl hydrocarbon receptor (AHR), a transcription factor whose activation is induced by binding of persistent organic pollutants, including polycyclic aromatic hydrocarbons and dioxins. Accordingly, induction of CYP1A1 expression and activity serves as a biomarker of AHR activation and associated xenobiotic metabolism as well as toxicity in diverse animal species and humans. Determination of CYP1A1 activity is integrated into modern toxicological concepts and testing guidelines, emphasizing the tremendous importance of this enzyme for risk assessment and regulation of chemicals. Further, CYP1A1 serves as a molecular target for chemoprevention of chemical carcinogenesis, although present literature is controversial on whether its inhibition or induction exerts beneficial effects. Regarding therapeutic applications, first anti-cancer prodrugs are available, which require a metabolic activation by CYP1A1, and thus enable a specific elimination of CYP1A1-positive tumors. However, the application range of these drugs may be limited due to the frequently observed downregulation of CYP1A1 in various human cancers, probably leading to a reduced metabolism of endogenous AHR ligands and a sustained activation of AHR and associated tumor-promoting responses. We here summarize the current knowledge on CYP1A1 as a key player in the metabolism of exogenous and endogenous substrates and as a promising target molecule for prevention and treatment of human malignancies.

Bhardwaj A, Bahl C, Sharma S, et al.
Interactive potential of genetic polymorphism in Xenobiotic metabolising and DNA repair genes for predicting lung cancer predisposition and overall survival in North Indians.
Mutat Res Genet Toxicol Environ Mutagen. 2018; 826:15-24 [PubMed] Related Publications
INTRODUCTION: Cancer, a multi-step, multifactorial and multi-gene disease, not only damages the genomic integrity of the cell but also hinders the DNA repair mechanisms of the body. Gene-gene and gene environment interactions amongst the genetic polymorphisms together modulate the susceptibility towards a cancer. We have studied the high order gene interactions between the genetic polymorphism of detoxifying genes (CYP1A1, Ahr, XRCC and GST1) that play a key role in the metabolism of the xenobiotics and have been proved to be prognostic markers for lung cancer METHODS: 237 cases and 250 controls have been genotyped using PCR-RFLP technique. In order to find out the association, unconditional logistic regression approach was used and to analyse high order interactions MDR and CART was used.
RESULTS: In the MDR analysis, the best model was one factor model which included GSTM1 (CVC 10/10, Prediction error = 0.43, p < .001). The best three factor model comprised of XRCC1 632, XRCC1 206, GSTM1 (CVC 10/10, Prediction error = 0.45, p < .0001). The CART analysis exhibited that Node 1 carrying mutant type of GSTM1 imposed the highest risk towards lung cancer (OR = 11.0, 95%C.I. = 6.05-20.03, p = .000001). Wild type of GSTM1 when combined with mutant type of CYP1A1 M2 and XRCC1 632, an 8 fold risk towards lung cancer was observed (95%C.I. = 4.07-16.29, p = .00001). The high order interactions were used to predict the prognosis of lung cancer patients. Of all the genetic variants, XRCC1 632, GSTM1 and AhR rs2066853 was the most important determinant of overall survival of lung cancer patients CONCLUSION: Through the study we introduced the concept of polygenic approach to get an insight about the various polymorphic variants in determining cancer susceptibility. Lesser number of subjects were found in the high risk subgroups. Further studies with larger sample size are required to warranty the above findings.

Stewart MD, Zelin E, Dhall A, et al.
BARD1 is necessary for ubiquitylation of nucleosomal histone H2A and for transcriptional regulation of estrogen metabolism genes.
Proc Natl Acad Sci U S A. 2018; 115(6):1316-1321 [PubMed] Article available free on PMC after 01/10/2019 Related Publications
Missense mutations that disrupt the RING domain of the tumor suppressor gene

Baker SC, Arlt VM, Indra R, et al.
Differentiation-associated urothelial cytochrome P450 oxidoreductase predicates the xenobiotic-metabolizing activity of "luminal" muscle-invasive bladder cancers.
Mol Carcinog. 2018; 57(5):606-618 [PubMed] Article available free on PMC after 01/10/2019 Related Publications
Extra-hepatic metabolism of xenobiotics by epithelial tissues has evolved as a self-defence mechanism but has potential to contribute to the local activation of carcinogens. Bladder epithelium (urothelium) is bathed in excreted urinary toxicants and pro-carcinogens. This study reveals how differentiation affects cytochrome P450 (CYP) activity and the role of NADPH:P450 oxidoreductase (POR). CYP1A1 and CYP1B1 transcripts were inducible in normal human urothelial (NHU) cells maintained in both undifferentiated and functional barrier-forming differentiated states in vitro. However, ethoxyresorufin O-deethylation (EROD) activity, the generation of reactive BaP metabolites and BaP-DNA adducts, were predominantly detected in differentiated NHU cell cultures. This gain-of-function was attributable to the expression of POR, an essential electron donor for all CYPs, which was significantly upregulated as part of urothelial differentiation. Immunohistology of muscle-invasive bladder cancer (MIBC) revealed significant overall suppression of POR expression. Stratification of MIBC biopsies into "luminal" and "basal" groups, based on GATA3 and cytokeratin 5/6 labeling, showed POR over-expression by a subgroup of the differentiated luminal tumors. In bladder cancer cell lines, CYP1-activity was undetectable/low in basal POR

Vacher S, Castagnet P, Chemlali W, et al.
High AHR expression in breast tumors correlates with expression of genes from several signaling pathways namely inflammation and endogenous tryptophan metabolism.
PLoS One. 2018; 13(1):e0190619 [PubMed] Article available free on PMC after 01/10/2019 Related Publications
Increasing epidemiological and animal experimental data provide substantial support for the role of aryl hydrocarbon receptor (AhR) in mammary tumorigenesis. The effects of AhR have been clearly demonstrated in rodent models of breast carcinogenesis and in several established human breast cancer cell lines following exposure to AhR ligands or AhR overexpression. However, relatively little is known about the role of AhR in human breast cancers. AhR has always been considered to be a regulator of toxic and carcinogenic responses to environmental contaminants such as TCDD (dioxin) and benzo[a]pyrene (BaP). The aim of this study was to identify the type of breast tumors (ERα-positive or ERα-negative) that express AHR and how AhR affects human tumorigenesis. The levels of AHR, AHR nuclear translocator (ARNT) and AHR repressor (AHRR) mRNA expression were analyzed in a cohort of 439 breast tumors, demonstrating a weak association between high AHR expression and age greater than fifty years and ERα-negative status, and HR-/ERBB2 breast cancer subtypes. AHRR mRNA expression was associated with metastasis-free survival, while AHR mRNA expression was not. Immunohistochemistry revealed the presence of AhR protein in both tumor cells (nucleus and/or cytoplasm) and the tumor microenvironment (including endothelial cells and lymphocytes). High AHR expression was correlated with high expression of several genes involved in signaling pathways related to inflammation (IL1B, IL6, TNF, IL8 and CXCR4), metabolism (IDO1 and TDO2 from the kynurenine pathway), invasion (MMP1, MMP2 and PLAU), and IGF signaling (IGF2R, IGF1R and TGFB1). Two well-known ligands for AHR (TCDD and BaP) induced mRNA expression of IL1B and IL6 in an ERα-negative breast tumor cell line. The breast cancer ER status likely influences AhR activity involved in these signaling pathways. The mechanisms involved in AhR activation and target gene expression in breast cancers are also discussed.

Endo-Tsukude C, Sasaki JI, Saeki S, et al.
Population Pharmacokinetics and Adverse Events of Erlotinib in Japanese Patients with Non-small-cell Lung Cancer: Impact of Genetic Polymorphisms in Metabolizing Enzymes and Transporters.
Biol Pharm Bull. 2018; 41(1):47-56 [PubMed] Related Publications
Determinants of interindividual variability in erlotinib pharmacokinetics (PK) and adverse events remain to be elucidated. This study with 50 Japanese non-small-cell lung cancer patients treated with oral erlotinib at a standard dose of 150 mg aimed to investigate whether genetic polymorphisms affect erlotinib PK and adverse events. Single nucleotide polymorphisms (SNPs) in genes encoding metabolizing enzymes (CYP1A1, CYP1A2, CYP2D6, CYP3A4, CYP3A5, UGT1A1, UGT2B7, GSTM1, and GSTT1) or efflux transporters (ABCB1, and ABCG2) were analyzed as covariates in a population PK model. The ABCB1 1236C>T (rs1128503) polymorphism, not ABCB1*2 haplotype (1236TT-2677TT-3455TT, rs1128503 TT-rs2032582 TT-rs1045642 TT), was a significant covariate for the apparent clearance (CL/F), with the TT genotype showing a 29.4% decrease in CL/F as compared with the CC and the CT genotypes. A marginally higher incidence of adverse events (mainly skin rash) was observed in the TT genotype group; however, patients with high plasma erlotinib exposure did not always experience skin rash. None of the other SNPs affected PK or adverse events. The ABCB1 genotype is a potential predictor for erlotinib adverse events. Erlotinib might be used with careful monitoring of adverse events in patients with ABCB1 polymorphic variants.

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