CYP17 gene polymorphism and prostate cancer susceptibility in a Tunisian population

Prostate cancer (PCa) formation has been reported to be associated with androgen. Two key steps in the sex steroid synthesis are mediated by the enzyme cytochrome P450c 17α which is encoded in the CYP17 gene. The A2 allele of the CYP17 gene has been thought to be associated with increased functional activity of this steroidogenic enzyme. Consequently, the A2 allele has been examined as a biomarker of individual susceptibility to hormone-related diseases among men. We prospectively assessed the association between the A2 allele of CYP17 and PCa risk among 125 cases and 125 controls in a case–control study. Our aim was to investigate whether a polymorphism of CYP17 gene could be used as a genetic marker for associating PCa. The result revealed a significant association between the CYP17 polymorphic genotypes and PCa. Therefore, CYP17 gene polymorphism is likely contributed to the pathogenesis of PCa but not to disease severity.     

Polymorphisms of MLH1 in benign prostatic hyperplasia and sporadic prostate cancer

Mismatch repair is one of several DNA repair pathways of which defects may lead to cancer. We hypothesize that polymorphisms of the MLH1 gene can be a risk factor for benign prostatic hyperplasia (BPH) and prostate cancer. The genetic distribution of MLH1 polymorphisms that lead to amino acid changes at codons 132, 219, 384, and 723 were analyzed in BPH and sporadic prostate cancer patients, and compared to healthy controls from an Asian population. These experiments demonstrate a protective role for the codon 384 variant allele against prostate cancer (P = 0.031) but not BPH when compared to normal controls and furthermore, an inverse association was observed with stage (P = 0.074) and grade (P = 0.056) of cancer. This is the first report that demonstrates a protective effect for the race-related MLH1 polymorphism at codon 384 against prostate cancer and these results are important in understanding their role in this disease.     

Polymorphisms of CYP1B1 and COMT in Breast and Endometrial Cancer

CYP1B1 and COMT code for the key enzymes of catecholestrogen biosynthesis and metabolism, and their polymorphisms determine the variation of enzyme activities. RFLP analysis was used to study the allele and genotype frequency distributions of CYP1B1 polymorphisms Arg48Gly, Ala119Ser, and Val432Leu, and COMT polymorphism Val158Met among 210 breast cancer patients, 138 endometrial cancer patients, and 152 healthy women. The COMT polymorphism showed no significant association with breast or endometrial cancer. For the first time, such association was observed for the CYP1B1 polymorphisms. CYP1B1 allele C (Arg48), which codes for the enzyme more active in estradiol 4-hydroxylation, was associated with higher risk of breast (OR = 3.22, CI 2.34–4.43, P = 0.000) and endometrial (OR = 2.43, CI 1.72–3.44, P = 0.000) cancer. Similar data were obtained for CYP1B1 allele G (Ala119): OR = 2.18, CI 1.58–3.01, P = 0.000 in breast cancer and OR = 2.52, CI 1.78–3.56, P = 0.000 in endometrial cancer. Risk of endometrial but not breast cancer was significantly higher in carriers of CYP1B1 genotype Val432/Val. This was explained by stronger estrogen dependence and, consequently, higher estrogen responsiveness of the endometrium as compared with the mammary gland.     

Influence of lifestyle choices on risks of CYP1B1 polymorphisms for prostate cancer

Cytochrome P450 1B1 (CYP1B1) converts xenobiotics to carcinogens and how lifestyle choices may interact with CYP1B1 polymorphisms and affect prostate cancer risk was assessed. Blood genomic DNA from a Caucasian population was analysed at polymorphic sites of the 5′ untranslated region of CYP1B1 using TaqMan genotyping assays. Overall, drinker status and minor alleles at rs2551188, rs2567206 and rs10175368 were associated with prostate cancer. Linkage was observed between rs2551188, rs2567206, rs2567207 and rs10175368, and the G‐C‐T‐G haplotype (major allele at respective sites) was decreased in cancer. Interestingly when classified by lifestyle factors, no associations of genotypes were found for non‐smokers and non‐drinkers, whereas on the contrary, minor type at rs2567206 and rs10175368 increased and major G‐C‐T‐G decreased risk for cancer among smokers and drinkers. Interestingly, rs2551188, rs2567206 and rs10175368 minor genotypes correlated with increased tissue CYP1B1 as determined by immunohistochemistry. Further, rs10175368 enhanced luciferase activity and mobility shift show stronger binding of nuclear factor for the minor allele. These results demonstrate smoking and alcohol consumption to modify the risks of CYP1B1 polymorphisms for prostate cancer which may be through rs10175368, and this is of importance in understanding their role in the pathogenesis and as a biomarker for this disease.     

Association of interleukin-1B (IL-1B) gene polymorphisms with risk of gastric cancer in Chinese population

The incidence of gastric cancer (GC) in China is among the highest in the world. In present work, 154 patients with GC and 166 healthy controls in population of north-western China were investigated to evaluate the genetic associations of IL-1B gene single nucleotide polymorphisms (SNP) and variable number tandem repeat (VNTR) polymorphisms of IL-1RN gene with increased risk of GC. The frequency of IL-1B+3954C/T was significantly higher in GC cases group (25.97%) than that in controls (4.82%) with odds ratio (OR)=6.93 (95% confidence interval [CI] 3.13-15.36); the frequencies of IL-1B-31C/T, IL-1B-31C/C and IL-1B-511C/T genotypes were also higher in GC cases group (51.95%, 23.38% and 50.65%) than those in controls (46.99%, 19.88% and 42.77%) with OR=1.48 (95% CI 0.88-2.49), OR=1.58 (95% CI 0.84-2.95) and OR=1.39 (95% CI 0.80-2.41), respectively. The results show that these SNPs of IL-1B gene are associated with significantly increased risk of GC. This is the first report that IL-1B+3954C/T heterozygote is associated with greatly increased risk of GC. The results of this study did not support the report that IL-1RN*2+ genotypes were associated with increased risk of GC in Chinese population.     

Constitutive and inducible expression of cytochromes P4501A (CYP1A1 and CYP1A2) in normal prostate and prostate cancer cells

Constitutive and benzo[a]pyrene (B[a]P) inducible expression of CYP1A1 and CYP1A2 in prostate cancer and normal prostate epithelial cells were examined by immunoblotting. Androgen independent prostate cancer cell lines DU145 and PC3 have constitutive expression of CYP1A and CYP1A1 and CYP1A2, respectively. Four micromolar B[a]P did not appear to induce CYP1A1 or CYP1A2 expression in DU145 or PC3 cells. The androgen dependent prostate cancer cell line, LnCap, also has constitutive expression of CYP1A1 and CYP1A2. However, both CYP1A1 and CYP1A2 are induced by treatment of LnCap cells with 4 microM B[a]P. Untreated normal prostate and primary prostate tumor cells have no detectable CYP1A1 expression. Treatment with 4 microM B[a]P induced CYP1A1 expression in both normal and primary tumor prostate cells. Constitutive CYP1A2 expression was detected in normal prostate cells with little or no induction by exposure to 4 microM B[a]P. Primary prostate tumor cells did not show constitutive expression of CYP1A2. However, CYP1A2 was induced by 4 microM B[a]P in primary prostate tumor cells. These observations indicate that hormonal and cancer specific factors affect the expression and induction of the phase I metabolic enzymes, CYP1A1 and CYP1A2 in prostate cells. These observations may be related to the potential smoking-linked higher risk of prostate cancer development and morbidity of prostate cancer patients who smoke.     

CYP1A1 and CYP2D6 polymorphism and risk of lung cancer in a North Indian population

This case–control study was conducted to examine the association between the CYP1A1 and CYP2D6 genotypes and lung cancer risk among North Indians. The estimated relative risk for lung cancer associated with the CYP1A1 Val/Val allele was 2.68, and was four-fold when cases with small cell lung cancer (SCLC) were considered alone. With regard to the metabolism of debrisoquine, no poor metabolizers were found amongst the subjects. The odds ratio of risk with the heterozygous extensive metabolizer (HEM) genotype was 1.5. However, in the presence of at least a single copy of the variant CYP1A1 MspI allele and the CYP2D6 HEM genotype, the risk was two-fold for squamous cell carcinoma (SQCC). When the CYP1A1 Val/Val and CYP2D6 HEM genotypes were taken together, the risk for SCLC was four-fold. Stratified analysis indicated an interaction between bidi smoking and variant CYP1A1 genotypes on the risk for SQCC and SCLC. Heavy smokers (Brinkman index>400) with Val/Val genotypes were at a very high risk of developing lung cancer (odds ratio 29.30, 95% confidence interval 2.42–355, p=0.008). Heavy smokers with CYP1A1 MspI (CYP1A1*1/2A or CYP1A1*2A/*2A) genotype had a seven-fold risk for SCLC compared with non-smokers. This study is the first to be carried out on a North Indian population, and, although small, suggests that CYP1A1 and CYP2D6 polymorphisms might have a role in determining the risk for lung cancer and should be investigated further.     

萘查耳酮类化合物的设计合成及对CYP1B1酶的抑制活性评价

目的:设计并合成几类新型的萘查耳酮衍生物,初步测定其对CYP1B1酶的抑制活性,筛选具有良好抗癌作用的CYP1B1抑制剂。方法:以1,5-二羟基萘为原料,首先合成两个重要的中间体2-乙酰基-1,4,5,8-四甲氧基萘、1,5,6-三甲氧基-2-萘乙酮,然后利用羟醛缩合反应合成所需要的化合物。结果:合成了19个目标化合物,其结构均经过核磁共振氢谱确证,所有化合物均为全新化合物。对所合成的新化合物均进行了EROD酶实验测定。结论:所合成的化合物均具有较强的CYP1B1酶一抑制活性,其中4-1、4-2、5'-1对CYP1B1的抑制活性强于CYP1B1强抑制剂α-萘黄酮(IC50=11 nmol/L),他们的IC50分别为6.5、0.47、8nmol/L。     

CYP24 splicing variants are associated with different patterns of constitutive and calcitriol-inducible CYP24 activity in human prostate cancer cell lines

24-Hydroxylase (CYP24) activity modulates in vitro and in vivo calcitriol metabolism and biologic effects. We have investigated, in human PC3, DU145 and LNCaP prostate cancer cell lines, the relationship of CYP24 single nucleotide polymorphisms (SNPs) and splicing and the variable patterns of baseline and calcitriol-inducible CYP24 activity. DU145 cells exhibit baseline CYP24 activity that is further induced by calcitriol. Baseline and inducible CYP24 activity were barely detectable in LNCaP cells. In PC3, baseline CYP24 activity was undetectable but induced by calcitriol. A different pattern of SNPs was identified at positions 24, 46, 146 and 198 in the intron between exons 9 and 10 of CYP24 gene in each cancer cell line. DU145 displayed baseline CYP24 splicing between exon 9 and exon 11; splicing was only observed in calcitriol treated LNCaP cells. Untreated PC3 had a mixed picture (splicing and no splicing); only the spliced form was seen after calcitriol treatment. These results demonstrate that calcitriol treatment modulates CYP24 splicing, and suggests that differences in CYP24 splicing are associated with different patterns of CYP24 activity.     

CDKN1B Val 109 Gly variant is not related to risk of prostate cancer

Association between CDKN1B gene Val 109 Gly polymorphism and prostate cancer (PCa) susceptibility has been investigated in several studies but with inconsistent conclusions. We adopted odds ratios (ORs) and 95% confidence intervals (CIs) to assess the correlation between CDKN1B Val 109 Gly variant and PCa susceptibility. Moreover, we used in-silico tools to evaluate the relationship of CDKN1B expression and overall survival (OS) or disease free survival (DFS) time in PCa patients. The overall results demonstrated no association of the CDKN1B variant on PCa risk [allelic contrast (OR = 0.78, 95% CI = 0.45 − 1.35, P_{heterogeneity} = 0.038); GV vs VV (OR = 0.83, 95% CI = 0.56 − 1.25, P_{heterogeneity} = 0.253); GG vs VV (OR = 0.48, 95% CI = 0.23 − 1.01, P_{heterogeneity} = 0.161); GG+GV vs VV (OR = 0.75, 95% CI = 0.52 −1.08, P_{heterogeneity} = 0.132) and GG vs GV+VV (OR = 0.63, 95% CI = 0.25 − 1.11, P_{heterogeneity} = 0.152)]. In subgroup analysis by ethnicity and source of control, we also identified similar results. In-silico results showed that expression of CDKN1B was decreased in PCa tissue, especially in less advanced PCa (Gleason score = 6 or 7). No significant difference of OS or DFS time was indicated between the low and high expression of CDKN1B. Our present study showed evidence that CDKN1B Val 109 Gly variant is not related to PCa risk. Future studies with large sample size are needed to confirm this correlation in more details.     

干扰FSCN1基因表达对前列腺癌细胞凋亡、活性氧水平影响的研究

目的探讨干扰FSCN1基因表达对前列腺癌细胞凋亡、活性氧(ROS)水平影响及机制。方法以正常前列腺上皮细胞RWPE-1为对照细胞,通过RT-PCR及Western blot检测前列腺癌LNCaP、DU145和PC-3细胞中FSCN1 mRNA及蛋白表达;以LipofectamineTM 2000为载体,DU145细胞分为si-FSCN1组(靶向抑制FSCN1的小干扰RNAs转染DU145细胞)、阴性对照组(随机序列转染DU145细胞)及空白对照组(未转染的细胞),siRNA转染48 h,Western blot检测FSCN1、PCNA、NF-κB p65、p-NF-κB p65、IKKα和p-IKKα的蛋白表达。CCK8检测细胞活力,流式细胞术检测细胞凋亡率及ROS水平。多组间比较采用单因素方差分析,组间两两比较采用SNK-q检验。结果与RWPE-1细胞比较,LNCaP、DU145和PC-3细胞中FSCN1 mRNA(1比2.561±0.189、7.183±0.882、4.796±0.567、4.796±0.567)及蛋白表达(0.053±0.007比0.217±0.013、0.654±0.058、0.316±0.035)均升高,差异具有统计学意义(P均<0.05)。与阴性对照组比较,si-FSCN1组FSCN1表达(0.473±0.052比0.086±0.010)降低,差异具有统计学意义(P均<0.05)。与si-FSCN1组比较,空白对照组、阴性对照组细胞活力(0.302±0.033比0.787±0.069、0.764±0.063)均升高,凋亡率(24.54﹪±1.47﹪比3.04﹪±0.36﹪、3.28﹪±0.40﹪)和ROS相对荧光强度(90.04±5.73比47.88±3.62、49.62±4.11)均降低,差异具有统计学意义(P均<0.05)。与si-FSCN1组比较,空白对照组、阴性对照组PCNA(0.255±0.032比0.654±0.062、0.631±0.058)、NF-κB p65(0.092±0.011比0.296±0.032、0.318±0.037)、p-NF-κB p65(0.042±0.008比0.155±0.018、0.151±0.016)、IKKα(0.112±0.01比0.172±0.020、0.192±0.023)和p-IKKα的蛋白表达(0.051±0.005比0.102±0.011、0.091±0.009)均升高,Cleaved caspase3蛋白表达(0.206±0.018比0.074±0.009、0.085±0.010)均降低,差异具有统计学意义(P均<0.05)。阴性对照组与空白对照组细胞活力、凋亡率、ROS水平及FSCN1、PCNA、Cleaved caspase3、NF-κB p65、p-NF-κB p65、IKKα和p-IKKα的蛋白表达差异均无统计学意义(P>0.05)。结论干扰FSCN1基因表达可降低前列腺癌细胞活力及诱导凋亡,机制可能与ROS水平升高及NF-κB信号下调有关。     

Age-dependent methylation of ESR1 gene in prostate cancer

The incidence of prostate cancer increases dramatically with age and the mechanism underlying this association is unclear. Age-dependent methylation of estrogen receptor alpha (ESR1) gene has been previously implicated in other cancerous and benign diseases. We evaluated the age-dependent methylation of ESR1 in prostate cancer. The methylation status of ESR1 in 83 prostate cancer samples from patients aged 49 to 77 years (mean age at 67.4 years) was examined using the bisulfite genomic sequencing technique. The samples were divided into three age groups: men aged 60 years and under (n = 14), men aged 61-70 years (n = 40), and men aged over 70 years (n = 29). Overall, ESR1 promoter methylation was detected in 54 out of 83 (65.1%) prostate samples. The methylation rate of ESR1 increased dramatically with age from 50.0% in patients aged 60 years and under to 89.7% for patients aged 70 years and over. Logistic regression analyses revealed that age and Gleason score were the only variables that affect incidence of ESR1 methylation; other clinical factors such as prostate-specific antigen level and clinical stage did not. We also calculated ESR1 methylation density (the percentage of methylated CpGs among all CpGs within the analyzed region) and severity (the percentage of methylated CpG alleles) for each sample analyzed. Multiple regression analyses showed a positive correlation between age and methylation density (beta, 0.35; P, 0.012; 95% CI, 0.26-2.01); while Gleason score was positively associated with methylation severity (beta, 0.45; P, 0.018; 95% CI, 1.04-4.26). These findings suggest that methylation of ESR1 is both age-dependent and tumor differentiation-dependent and age-dependent methylation of ESR1 may represent a mechanism linking aging and prostate cancer.     

miR-27b synergizes with anticancer drugs via p53 activation and CYP1B1 suppression

Liver and kidney cancers are notorious for drug resistance. Due to the complexity, redundancy and interpatient heterogeneity of resistance mechanisms, most efforts targeting a single pathway were unsuccessful. Novel personalized therapies targeting multiple essential drug resistance pathways in parallel hold a promise for future cancer treatment. Exploiting the multitarget characteristic of microRNAs (miRNAs), we developed a new therapeutic strategy by the combinational use of miRNA and anticancer drugs to increase drug response. By a systems approach, we identified that miR-27b, a miRNA deleted in liver and kidney cancers, sensitizes cancer cells to a broad spectrum of anticancer drugs in vitro and in vivo. Functionally, miR-27b enhances drug response by activating p53-dependent apoptosis and reducing CYP1B1-mediated drug detoxification. Notably, miR-27b promotes drug response specifically in patients carrying p53-wild-type or CYP1B1-high signature. Together, we propose that miR-27b synergizes with anticancer drugs in a defined subgroup of liver and kidney cancer patients.     

AH receptor antagonist inhibits constitutive CYP1A1 and CYP1B1 expression in rat BP8 cells

The BP8 variant of the 5L rat hepatoma cell line is completely devoid of aryl hydrocarbon receptor (AHR) and is a useful model to examine AHR function. Previous studies showed that BP8 cells, when transfected with mouse AHR, exhibit induction of a plasmid-based reporter even in the absence of exogenous ligands. We transfected BP8 cells with full-length human AHR and found that presence of the AHR alone was sufficient to induce substantial CYP1A1 and CYP1B1 mRNA without any exogenous AHR ligand. An AHR antagonist, 3,4-dimethoxyflavone, inhibited CYP1A1 and CYP1B1 expression in a dose-dependent manner. When we transfected BP8 cells with a mutated human AHR that is defective in ligand binding, expression of CYP1A1 and CYP1B1 was diminished but not abolished. Inhibition by the AHR antagonist along with the diminished response to the mutated AHR indicates that BP8 cells contain some agent that acts as an agonist ligand for the AHR.     

Comparison of genomic and cDNA sequences of guinea pig CYP2B18 and rat CYP2B2: absence of a phenobarbital-responsive enhancer module in the upstream region of the CYP2B18 gene

Potential mechanisms were investigated whereby CYP2B18, a cytochrome P450 gene exhibiting high constitutive expression but only low levels of phenobarbital-inducibility in the guinea pig liver, may be differentially regulated versus the highly inducible rat CYP2B2 gene. To comparatively assess potential regulatory sequences associated with CYP2B18, a guinea pig genomic library was screened enabling isolation of the CYP2B18 gene. The genomic screening process resulted in the identification of at least four closely-related CYP2B18 genes, designated here as CYP2B18A-D. Of these isolates, CYP2B18A exhibited sequence identical to that of the CYP2B18 cDNA. Further, the deduced amino acid sequence of the CYP2B18 cDNA was identical to that of N-terminal and internally-derived peptide sequences obtained in this investigation from CYP2B18 protein isolated from guinea pig liver. Genomic structural sequences were derived for CYP2B18A, together with the respective 5'-upstream and intronic regions of the gene. Comparison of the CYP2B18A and CYP2B2 gene sequences revealed the lack of repetitive LINE gene sequences in CYP2B18A, putative silencing elements that effect neighboring genes, although these sequences were present in both 5'-upstream and 3'-downstream regions of CYP2B2. We determined that the phenobarbital-responsive enhancer module was absent from the 5'-upstream region as well as the intronic regions of CYP2B18A gene. We hypothesize that the compromised phenobarbital inducibility of CYP2B18A stems from its lack of a functional phenobarbital responsive enhancer module.     

Furanoflavones pongapin and lanceolatin B blocks the cell cycle and induce senescence in CYP1A1-overexpressing breast cancer cells

Expression of cytochrome P450-1A1 (CYP1A1) is suppressed under physiologic conditions but is induced (a) by polycyclic aromatic hydrocarbons (PAHs) which can be metabolized by CYP1A1 to carcinogens, and (b) in majority of breast cancers. Hence, phytochemicals or dietary flavonoids, if identified as CYP1A1 inhibitors, may help in preventing PAH-mediated carcinogenesis and breast cancer. Herein, we have investigated the cancer chemopreventive potential of a flavonoid-rich Indian medicinal plant, Pongamia pinnata (L.) Pierre. Methanolic extract of its seeds inhibits CYP1A1 in CYP1A1-overexpressing normal human HEK293 cells, with IC₅₀ of 0.6?µg/mL. Its secondary metabolites, the furanoflavonoids pongapin/lanceolatin B, inhibit CYP1A1 with IC₅₀ of 20?nM. Although the furanochalcone pongamol inhibits CYP1A1 with IC₅₀ of only 4.4?µM, a semisynthetic pyrazole-derivative P5b, has ～10-fold improved potency (IC₅₀, 0.49?μM). Pongapin/lanceolatin B and the methanolic extract of P. pinnata seeds protect CYP1A1-overexpressing HEK293 cells from B[a]P-mediated toxicity. Remarkably, they also block the cell cycle of CYP1A1-overexpressing MCF-7 breast cancer cells, at the G₀-G₁ phase, repress cyclin D1 levels and induce cellular-senescence. Molecular modeling studies demonstrate the interaction pattern of pongapin/lanceolatin B with CYP1A1. The results strongly indicate the potential of methanolic seed-extract and pongapin/lanceolatin B for further development as cancer chemopreventive agents.     

CYP1B1酶抑制剂的最新研究进展

细胞色素P450(CYP)1B1是CYP1家族的一个亚型,参与多环芳香烃等前致癌物的代谢活化,并在17-β-雌二醇诱导的乳腺癌发生与发展过程中起到了关键性作用。该酶在肿瘤组织中的特异性高表达及在肿瘤细胞耐药中的作用,也已被大量研究证实。该酶的特异性分布及在肿瘤发生与发展中的重要地位,使得它成为抗肿瘤药物研究中的新靶点。其抑制剂研究,在肿瘤预防及克服肿瘤耐药方面具有重要意义。本文综述了近二十年来发现的CYP1B1酶的强选择性抑制剂,同时分析了它们的构效关系,对发现具有肿瘤预防及逆转肿瘤耐药作用的酶抑制剂提供了理论依据。