Preferential Induction of CYP1A1 over CYP1B1 in Human Breast Cancer MCF-7 Cells after Exposure to Berberine

Estrogens are considered the major breast cancer risk factor, and the carcinogenic potential of estrogens mightbe attributed to DNA modification caused by derivatives formed during metabolism. 17β-estradiol (E2), the mainsteroidal estrogen present in women, is metabolized via two major pathways: formation of 2-hydroxyestradiol(2-OH E2) and 4-hydroxyestradiol (4-OH E2) through the action of cytochrome P450 (CYP) 1A1 and 1B1,respectively. Previous reports suggested that 2-OH E2 has putative protective effects, while 4-OH E2 is genotoxicand has potent carcinogenic activity. Thus, the ratio of 2-OH E2/4-OH E2 is a critical determinant of the toxicityof E2 in mammary cells. In the present study, we investigated the effects of berberine on the expression profileof the estrogen metabolizing enzymes CYP1A1 and CYP1B1 in breast cancer MCF-7 cells. Berberine treatmentproduced significant induction of both forms at the level of mRNA expression, but with increased doses produced16~ to 52~fold greater induction of CYP1A1 mRNA over CYP1B1 mRNA. Furthermore, berberine dramaticallyincreased CYP1A1 protein levels but did not influence CYP1B1 protein levels in MCF-7 cells. In conclusion,we present the first report to show that berberine may provide protection against breast cancer by altering theratio of CYP1A1/CYP1B1, could redirect E2 metabolism in a more protective pathway in breast cancer MCF-7cells.     

<Emphasis Type="Italic">CYP1A1</Emphasis> and <Emphasis Type="Italic">CYP1B1</Emphasis> genetic polymorphisms,smoking and breast cancer risk in a Finnish Caucasian population

We investigated the associations between two CYP1A1 polymorphisms (Ile462Val and Thr461Asn) and one CYP1B1 polymorphism (Leu432Val) and breast cancer risk. The study population consisted of 483 breast cancer patients and 482 healthy population controls, all of homogenous Finnish origin. No statistically significant overall associations were found between the CYP1A1 and CYP1B1 genotypes and breast cancer risk. However, a significant increase in the breast cancer risk was seen for women who had smoked 1–9 cigarettes/day and carried the CYP1B1 432Val allele; the OR was 2.6 (95% CI 1.07–6.46) for women carrying the Leu/Val genotype and 5.1 (95% CI 1.30–19.89, P for trend 0.005) for women with the Val/Val genotype compared to similarly smoking women homozygous for the 432Leu allele. Furthermore, when CYP1B1 genotypes were combined with the previously analyzed N-acetyl transferase (NAT2) genotypes, a significant increase in breast cancer risk was found among women who had at least one CYP1B1 432Val allele together with the NAT2 slow acetylator genotype (OR 1.52; 95% CI 1.03–2.24) compared to women carrying a combination of CYP1B1 Leu/Leu and NAT2 rapid acetylator genotypes. This risk was seen to be confined to ever smokers; the OR was 2.46 (95% CI 1.11–5.45) for ever smokers carrying at least one CYP1B1 432Val allele together with the NAT2 slow acetylator genotype compared to ever smokers with the CYP1B1 Leu/Leu and NAT2 rapid acetylator genotype combination. Our results suggest that the CYP1B1 polymorphism may be an important modifier of breast cancer risk in Finnish Caucasian women who have been exposed to tobacco smoke and/or carry the NAT2 slow acetylator genotype.     

CYP1A1 Polymorphisms and Risk of Lung Cancer in the Ethnic Kashmiri Population

The CYP1A1 category of enzymes plays a central role in the metabolic activation of major tobaccocarcinogens. Several polymorphisms within the CYP1A1 locus have been identified and have been shownto be associated with lung cancer risk, particularly in Asian populations. Here we focused on the influenceof three polymorphisms on lung cancer in ethnic Kashmiris, genotyping 109 lung cancer cases and 163healthy controls by PCR-RFLP methods. While no polymorphic alleles in CYP1A1m4 (exon 7 thr toasn) site were detected in our population, the allele frequency of CYP1A1m1 (Msp1) and CYP1A1m2(exon 7 ile to val) were 30.1 and 26.6 in controls and 44.5 and 38.9 in cases. The CYP1A1m1 andCYP1A1m2 variants were significantly associated with lung cancer susceptibility (ORs; 2.65, CI 95% =1.562-4.49 and 2.24,CI 95%=1.35-3.73).This risk was prominent in case of SCC compared with AC orother types of lung cancer. Stratified analysis showed a multiplicative interaction between tobaccosmoking and variant CYP1A1m1 genotype on the risk of SCC. The ORs of SCC for non-smokers were2.08 and 3.15 for smokers. When stratified by pack years, effect was stronger in the heaviest smokers(ORs=6.00,95% CI=1.672-21.532).The interaction between tobacco smoking and variant CYP1A1m2genotype followed similar pattern. Our findings thus support the conclusion that CYP1A1m1 and m2polymorphisms are associated with the smoking related lung cancer risk in Kashmiri population.     

Oral benzo[a]pyrene in Cyp1a1/1b1(–/–) double‐knockout mice: Microarray analysis during squamous cell carcinoma formation in preputial gland duct

Benzo[a]pyrene (BaP) is a prototypical polycyclic aromatic hydrocarbon (PAH) found in combustion processes. Cytochrome P450 1A1 and 1B1 enzymes (CYP1A1, CYP1B1) and other enzymes can activate PAHs to reactive oxygenated intermediates involved in mutagenesis and tumor initiation; also, CYP1 enzymes can detoxify PAHs. Cyp1(+/+) wild‐type (WT) and Cyp1b1(–/–) knockout mice receiving oral BaP (12.5 mg/kg/day) remain healthy for >12 months. In contrast, we found that global knockout of the Cyp1a1 gene (1a1KO) results in proximal small intestine (PSI) adenocarcinoma within 8–12 weeks on this BaP regimen; striking compensatory increases in PSI CYP1B1 likely participate in initiation of adenocarcinoma in 1a1KO mice. Cyp1a1/1b1(–/–) double‐knockout (DKO) mice on this BaP regimen show no PSI adenocarcinoma, but instead preputial gland duct (PGD) squamous cell carcinoma (SCC) occurs by 12 weeks. Herein, we compare microarray expression of PGD genes in WT, 1a1KO and DKO mice at 0, 4, 8, 12 and 16 weeks of oral BaP; about four dozen genes up‐ or down‐regulated during most critical time‐points were further verified by qRT‐PCR. In DKO mice, CYP3A59 was unequivocally identified as the BaP‐inducible and BaP‐metabolizing best candidate responsible for initiation of BaP‐induced SCC. Striking increases or decreases were found in 26 cancer‐related genes plus eight Serpin genes in DKO, but not in 1a1KO or WT, mice on this BaP regimen; of the 26, 8 were RAS‐related oncogenes. The mechanism by which cancer‐related genes are responsible for SCC tumor progression in the PGD remains to be elucidated.     

二甲基氨基偶氮苯对肝脏和大脑组织中CYP2D1基因表达的影响

目的　研究二甲基氨基偶氮苯 (DAB)对大鼠肝脏和大脑组织中CYP2D1基因表达的影响。方法　用二甲基氨基偶氮苯 (DAB)诱发大鼠形成肝癌 ,应用改进的逆转录聚合酶链式反应 (RT -PCR )技术检测CYP2D1mRNA的表达情况。结果　第1次PCR经 3 0轮循环扩增后 ,正常大鼠和肝癌大鼠的肝脏组织中均有CYP2D 1表达 ,而大脑组织中无表达 ;第 2次PCR以前次的产物作为模板 ,再经 3 0轮扩增后 ,可见正常大鼠和肝癌大鼠的肝脏组织及大脑组织中均有CYP2D 1表达 ,大脑组织PCR产物电泳条带密度低于肝脏组织。结论　肝癌大鼠的肝脏组织中有CYP2D1表达 ,其表达水平与正常组织一样 ,大脑组织中CYP2D1虽有表达 ,但是其表达水平明显低于肝脏组织。二甲基氨基偶氮苯不能诱导提高肝脏及大脑组织中CYP2D1基因的表达水平     

CYP1B1 expression is induced by docetaxel: effect on cell viability and drug resistance

The cytochrome P450 CYP1B1 is consistently overexpressed in tumour cells as compared to their normal counterparts, but its precise role in drug resistance is yet to be defined. It has been reported that transfection of CYP1B1 results in increased resistance to docetaxel in V79 cells (McFadyen et al, 2001). In this study, we analysed changes in expression of CYP1B1 mRNA associated with pulse selection of MCF-7 cells with docetaxel. Docetaxel-selected MCF-7 cells (MCF-7 Txt), which showed increased resistance to this drug as compared to parental MCF-7 cells, showed a noteworthy increase in CYP1B1 mRNA expression, paralleled by increased ethoxyresorufin-O-deethylase (EROD) activity levels. This effect was not observed in cisplatin- or adriamycin-selected MCF-7 cells, or in docetaxel-selected colon, lung or pancreatic carcinoma cells. Short-term treatment with docetaxel induced CYP1B1 mRNA expression in MDA 453 and BT-20 breast carcinoma cells, but not in MCF-7 cells. Transfection of MCF-7 Txt cells with CYP1B1 siRNA did not significantly affect docetaxel-induced toxicity, but it decreased cell survival in the absence of drug. Preincubation of docetaxel with recombinant CYP1B1 did not affect drug toxicity in A549 cells. These results suggest that CYP1B1 does not directly inactivate docetaxel, but rather might promote cell survival in MCF-7 Txt cells, providing an explanation for its association with drug resistance.     

Oncogenic Potential of CYP24A1 in Lung Adenocarcinoma

IntroductionWe have previously demonstrated that a subset of lung cancer cells express higher CYP24A1 mRNA, a metabolizing enzyme for 1,25-D3, compared to benign tumors or surrounding normal lung and that high CYP24A1 mRNA expression is associated with poor prognosis in resected lung adenocarcinoma (AC). We hypothesized that CYP24A1 has oncogenic potential and increased CYP24A1 expression may contribute to tumor growth, whereas, CYP24A1 targeting may reduce tumor burden.MethodsTwo low CYP24A1 expressing human lung cancer cell lines (SK-LU-1 and Calu-6) were stably transfected either with an empty lentiviral vector or with the CYP24A1 expressing vector. Over-expression of mRNA and protein levels of CYP24A1 in SK-LU-1 and Calu-6 were confirmed using qRT-PCR and immunoblotting respectively. Next, effects of targeting CYP24A1 were examined in lung cancer cells (A549 and H441), which express higher basal levels of CYP24A1. Finally, we studied the effects of stable knockdown of CYP24A1 in xenograft models.ResultsOver-expression of CYP24A1 correlated with accelerated cell growth and invasion compared to control vector-transfected cells. CYP24A1 over-expression also increased RAS protein expression. Knockdown of CYP24A1 using either si- or shRNA reduced CYP24A1 mRNA and protein expression and significantly decreased cell proliferation (30-60%) and reduced mitochondrial DNA content compared to non-targeting (NT) si-/shRNA transfected/transduced cells. Transfection with CYP24A1 siRNA also decreased total RAS protein, thus reducing phosphorylated AKT. Importantly, stable knockdown of CYP24A1 in A549 and H441 lung tumor xenograft models resulted in tumor growth delay and smaller tumor size as evident from tumor bioluminescence and tumor volume measurement studies. Such observations were correlated with decreased tumor cell proliferation as evidenced by reduced Ki67 and Cyclin D staining.ConclusionsOur data suggest that CYP24A1 has oncogenic properties mediated by increasing RAS signaling, targeting of which may provide an alternate strategy to treat a subset of lung AC.     

Differential expression of CYP1A1 and CYP1B1 in human breast epithelial cells and breast tumor cells

Human cytochromes P450 1A1 (CYP1A1) and P450 1B1 (CYP1B1) catalyze the metabolic activation of a number of procarcinogens and the hydroxylation of 17beta-estradiol (E2) at the C-2 and C-4 positions, respectively. The aromatic hydrocarbon receptor (AhR) agonist 2,3,7,8- tetrachlorodibenzo-p-dioxin (TCDD) has a marked effect on estrogen metabolism in MCF-7 breast-tumor cells by induction of these two enzymes. To investigate whether induction of CYP1A1 and CYP1B1 by AhR agonists and the associated increase in E2 metabolism are common to all breast epithelial cells and breast-tumor cells, we determined the effects of TCDD on E2 metabolism, and CYP1A1 and CYP1B1 mRNA levels in a series of non-tumor-derived breast epithelial (184A1 and MCF-10A) and breast-tumor (MCF-7, T-47D, ZR-75-1, BT-20, MDA-MB-157, MDA-MB-231 and MDA-MB-436) cell lines. In 184A1 cells, which did not express detectable estrogen receptor (ER) alpha mRNA, CYP1A1 mRNA and activity were induced by TCDD, and enhanced E2 metabolism in TCDD-treated cells was predominantly E2 2-hydroxylation. In MCF-10A, MCF-7, T-47D, ZR-75-1 and BT-20 cells, which expressed varying levels of ER alpha mRNA, both CYP1A1 and CYP1B1 mRNA levels and rates of both E2 2- and 4- hydroxylation were highly elevated following exposure to TCDD. In MDA- MB-157, MDA-MB-231 and MDA-MB-436 cells, which did not express detectable ER alpha mRNA and generally displayed fibroblastic or mesenchymal rather than epithelial morphology, CYP1B1 induction was favored, and the rate of E2 4-hydroxylation exceeded that of 2- hydroxylation in TCDD-treated cells. These results show that breast epithelial cells and tumor cells vary widely with regard to AhR- mediated CYP1A1 and CYP1B1 induction, suggesting that factors in addition to the AhR regulate CYP1A1 and CYP1B1 gene expression. In these cell lines, significant CYP1A1 inducibility was restricted to cultures displaying epithelial morphology, whereas CYP1B1 inducibility was observed in cells of both epithelial and mesenchymal morphology.      

Functional evaluation of novel single nucleotide polymorphisms and haplotypes in the promoter regions of CYP1B1 and CYP1A1 genes

Interindividual variation in the expression of the carcinogen- and estrogen-metabolizing enzymes cytochrome P4501B1 and 1A1 (CYP1B1 and CYP1A1) has been detected in human lung. To search for polymorphisms with functional consequences for CYP1B1 and CYP1A1 gene expression, we examined 1.5 kb of the promoter region of each gene. Genomic DNA from 21 Caucasian individuals was amplified by polymerase chain reaction (PCR) for direct cycle sequencing. Eight single nucleotide polymorphisms (SNPs) for CYP1B1 and 13 SNPs for CYP1A1 were found. The majority of polymorphisms occurred as multiSNP combinations for individual subjects. The wild-type sequences were cloned into a luciferase reporter construct. The most frequent polymorphisms were then recreated by iterative site-directed mutagenesis, replicating single polymorphisms and multiSNP combinations. These wild-type and variant constructs were functionally evaluated in transient transfection experiments employing exposures to either the index polycyclic aromatic hydrocarbon (PAH) inducer benzo[a]pyrene (B[a]P), a composite mixture of cigarette smoke extract (CSE), or the repressor chemopreventive agent trans-3,4,5-trihydroxystilbene (reseveratrol). Results indicated that all wild-type and variant constructs responded in qualitatively concordant fashion to the inducers and to the repressor. The CYP1B1 haplotypes and the majority of CYP1A1 haplotypes were shown to have no functional consequence, as compared to those of the wild-type promoter sequences. Two constructs of composite polymorphisms of CYP1A1 appeared to result in a statistically significant increase in basal promoter activity (1.38- and 1.50-fold, respectively), but the degree of functional impact was judged unlikely to be biologically important in vivo. We conclude that the observed promoter region polymorphisms in these genes are common, but are of unclear functional consequence.     

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.     

A variant in CYP26B1 associated with esophageal squamous cell carcinoma risk by affecting retinoic acid metabolism

All-trans retinoic acid (ATRA) is the natural and synthetic analogue of vitamin A, playing an essential tumor suppressive role in multiple cancers including the esophageal squamous cell carcinoma (ESCC). Cytochrome P450 family 26 subfamily B member 1 (CYP26B1) exerts a critical regulator of ATRA levels through specific inactivation of ATRA to hydroxylated forms. Our previous exome-wide analyses revealed a rare missense variant in CYP26B1 significantly associated with ESCC risk in the Chinese population. However, it is still unclear whether there are common variants in CYP26B1 affect the susceptibility of ESCC and the tumor promotion role of CYP26B1 in vivo. In this research, we conducted a two-stage case-control study comprised of 5057 ESCC cases and 5397 controls, followed by a series of biochemical experiments to explore the function of CYP26B1 and its common variants in the tumorigenesis of ESCC. Intriguingly, we identified a missense variant rs2241057[A>G] in the fourth exon of CYP26B1 significantly associated with the ESCC risk (combined odds ratio = 1.28; 95% confidence interval = 1.15–1.42; p = 2.96 × 10⁻⁶). Through further functional analysis, we demonstrated that ESCC cells with the overexpression of rs2241057[G] had a significant lower level of retinoic acid, compared with the overexpression of rs2241057[A] or the control vector. In addition, the CYP26B1 overexpression and knock-out ESCC cells affected cell proliferation rate both in vitro and in vivo. These results highlighted the carcinogenicity of CYP26B1 related to the ATRA metabolism in ESCC risk.     

紫杉醇作用卵巢癌细胞系HO-8910后CYP1B1 mRNA及蛋白表达差异的研究

背景与目的:用紫杉醇(paclitaxel,PTX)对卵巢癌细胞系HO-8910进行体外化疗后,观察CYP1B1表达的变化,以期探讨CYP1B1基因表达与肿瘤细胞耐药的关系. 材料与方法:以不同浓度PTX(分别为30、15、7.5、3.75、1.88、0.94、0.47 μg/mi)处理H0-8910细胞.采用四甲基偶氮唑蓝(MTT)比色法检测PTX对HO-8910细胞体外生长的抑制作用,实验同时设只加培养液的对照组.以5 μg/ml PTX分别处理HO-8910细胞24 h、48 h、72 h和50#g/ml PTX处理细胞24 h后,用RT-PCR技术检测存活的卵巢癌细胞中CYP1B1 mRNA的表达水平,用Western blot检测细胞CYP1B1蛋白表达.结果:PTX能抑制HO-8910细胞生长,7种不同浓度的PTX作用72 h后,细胞的抑制率分别为89.10%、76.82%、67.39%、57.27%、46.21%、37.02%、17.56%,随着药物浓度的下降,其抑制率明显降低,各浓度组细胞抑制率间的差异具有统计学意义(P<0.05).经PTX处理后存活的HO-8910细胞中CYP1B1 mRNA及蛋白的表达量增加,高于对照组;5 μg/ml PTX处理HO-8910细胞48 h、72 h和50 μg/ml的PTX处理24 h组,CYP1B1蛋白的表达量高于5 μg/ml PTX处理24 h组(P<0.05).结论:CYP1B1在卵巢癌细胞系中呈高表达,CYP1B1基因在卵巢癌细胞系H0-8910体外PTX化疗中起抑制作用.     

Expression of cytochrome P-450 1A1 in human fetal adrenal cells

It is well known that cytochrome P-450 (CYP) 1A was thought to be responsible for activation of the majority of precarcinogens and premutagens in human liver. The level of CYP1A may serve as a potential indicator of carcinogenesis.[1] Therefore, study of CYP1A expression in human fetal liver and extrahepatic tissue still seems to be important with respect to the possible toxicological significance. Our previous work demonstrated the greater activities of drug-metabolizing enzymes in human…     

CYP1 A1 mRNA在大鼠脑内的分布以及溴氰菊酯对其影响的研究

目的 :研究CYP1A1mRNA在大鼠脑内的分布以及溴氰菊酯对其影响。方法 :采用RT -PCR及cDNAdotblot方法检测大鼠不同脑区CYP1A1mRNA的表达。结果 :大鼠脑区CYP1A1mRNA分布不一致 ,在所检测的脑区中 ,下丘脑最丰富 ,其次是皮层、小脑 ;在溴氰菊酯 1/ 10LD50 (12 .5mg .kg-1.d-1)腹腔注射连续 5d的作用下 ,溴氰菊酯对大鼠脑内CYP1A1mRNA有明显的抑制作用 ,并以皮层和下丘脑为甚。结论 :CYP1A1mRNA在大鼠脑内的分布不一致 ,溴氰菊酯抑制脑内CPY1A1mRNA的表达     

Genetically high susceptibility to oral squamous cell carcinoma in terms of combined genotyping of CYP1A1 and GSTM1 genes

An association of oral squamous cell carcinoma (SCC) susceptibility with an MspI restriction site polymorphism of the CYP1A1 gene and GSTM1 polymorphism were reported in our previous study (Sato M, Sato T, Izumo T, Amagasa T. Genetic polymorphism of drug-metabolizing enzymes and susceptiblility to oral cancer. Carcinogenesis 1999;20:1927-31). We report here that genetic risk for oral SCC was associated with another isoleucine-valine (Ile-Val) polymorphism, which resulted in an Ile-Val amino acid replacement in the heme-binding region of CYP1A1, and combined genotyping of CYP1A1 and GSTM1 genes in relation to the cumulative cigarette-smoking dose. The genetic polymorphisms of CYP1A1 and GSTM1 genes in oral cancer susceptibility were assessed by examining polymorphic prevalences in 142 oral SCC patients and 142 healthy controls who were individually matched to the patients with respect to sex and age (+/-1 year). Individuals with a combined genotype of Val/Val and GSTM1(-) were at an increased risk for oral SCC compared with other combined genotypes, in particular, at a low dose level of cigarette smoking.