Association of PON1-L55M Genetic Variation and Breast Cancer Risk: A Case-Control Trial

Background: Paraoxonase 1 (PON1), a multifactorial antioxidant enzyme, has a defensive role against oxidative stress, which is believed to contribute to cancer development. This study aimed to investigate the association of PON1-L55M functional polymorphism with breast cancer risk. Material and methods: In the experimental study, blood samples were collected from 150 healthy women controls and 150 breast cancer subjects. The L55M genotyping was performed by polymerase chain reaction-restriction fragment length polymorphism. Results: Our analysis showed that the genotypes distribution is in Hardy-Weinberg equilibrium for both case and control groups. Our data revealed that there are significant associations between PON1-L55M polymorphism and breast cancer risk in homozygote (OR= 2.13, 95%CI= 1.14-4.00, p= 0.018), dominant (OR= 1.72, 95%CI= 1.07-2.76, p= 0.024), and allelic (OR= 1.55, 95%CI= 1.12-2.15, p= 0.008) models. Conclusions: Our results suggest that the PON1-L55M genetic variation could be a genetic risk factor for breast cancer risk and it could be considered as a molecular biomarker for screening of susceptible women.     

二乙基对硝基苯磷酯酶2基因G/A148多态性与2型糖尿病及血脂的关系

目的：了解二乙基对硝基苯磷酯酶（PON）2基因G／A148多态性与中国北方地区人群2型糖尿病的相关性及其与血脂等的关系。方法：采用配偶对的病例－对照研究设计，用聚合酶链反应（PCR）－长度多态性的方法检测PON2基因G／A148多态性。结果：PON2基因G／A148多态性的基因型频率和等位基因频率在2型糖尿病组和对照组间差异无显著性意义。与非肥胖、无G等位基因相比，肥胖无G等位基因时，发生2型糖尿病的危害险度（OR）值为2．04；肥胖有G等位基因时，OR增至3．18。在对照人群中，含G等位基因组的总胆固醇（TC）、低密度脂蛋白（LDL）及载脂蛋白B（ApoB)水平均比AA基因型组高。G等位基因对高脂血症的OR为2．48，P＝0．5。结论：在中国北方地区人群中PON2基因G／A148多态性与肥胖有协同促进2型糖尿病发生的作用。在非糖尿病人群中，此多态性与总胆固醇等血脂水平显著相关。     

对氧磷酶2基因多态性（C311S）与2型糖尿病合并冠心病的关系

目的探讨对氧磷酶2（paraoxnase2,PON2）基因多态性（C311S）与2型糖尿病合并冠心病的关系。方法用聚合酶链反应．限制性片段长度多态性（PCR．RFLP）分析法探查PON2基因多态性（C311S）在正常对照组、单纯糖尿病组以及2型糖尿病合并冠心病组中的基因频率,组间频率比较采用X^2检验,数据用SPSS软件进行分析。结果发现检测者存在PON2基因多态性（C311S）,且在2型糖尿病合并冠心病患者中PON2基因的C等位基因频率明显高于正常对照组和单纯糖尿病组（P〈O．01）。结论2型糖尿病患者PON2基因的C等位基因第311位密码子的多态性可能与并发冠心病有关。     

对氧磷脂酶1、载脂蛋白E基因多态性与2型糖尿病患者氧化型低密度脂蛋白水平相关

采用限制性片段长度多态性(RFLP)检测福建地区192例2型糖尿病组、116例单纯动脉粥样硬化(AS)患者和105名正常人对氧磷脂酶1(PON1)、载脂蛋白E(ApoE)基因多态性,血清氧化型低密度脂蛋白(Ox-LDL)水平采用酶联免疫吸附法检测.结果 显示,2型糖尿组Ox-LDL高于单纯AS组及正常对照组[(754.2±279.9对526.1±186.2和421.1±163.2)μg/L,P<0.01].在2型糖尿患者中,PON1基因QQ型Ox-LDL水平高于QR和RR型[(846.6±147.5对763.4±126.7和713.2±132.4)μg/L,P<0.01];ApoE基因ε3/4+ε4/4型Ox-LDL水平高于ε3/3和ε2/2+ε2/3型[(824.3±173.5对741.6±182.5和718.3±167.5)μg/L,P<0.05],而在单纯AS患者中未发现这种差别.多元同归分析显示,病程、PON1、ApoE是2型糖尿患者血浆Ox-LDL增高的危险因素.     

Protective role of l-carnitine supplementation against exhaustive exercise induced oxidative stress in rats

The objective of this study was to investigate temperature dependent effects of oral l-carnitine supplementation on exhaustive exercise induced oxidative damage in rats. 42 male Spraque Dawley rats were randomly divided into seven experimental groups. These groups were formed as three non-carnitine exercise groups, three carnitine-exercise groups and a sedentary group. l-carnitine was given intraperitoneally to the carnitine-exercise groups 1 h before the exercise in 100 mg/kg. Blood was collected to measure paraoxonase-1 (PON1) activity, plasma malondialdehyde (MDA), low-density lipoprotein (LDL) and cholesterol concentrations. These biomarkers were measured in venous blood samples collected before and after the rats swam in pools at different water temperatures (18 °C, 28 °C and 38 °C). In the non-carnitine group, exercise caused a significant decrease in PON1 activity and a significant elevation in MDA concentration at 28 °C compared to the sedentary group. No significant alterations were evidenced in LDL and cholesterol concentrations upon exercise. The decrease in PON1 activity became higher with increasing temperature whereas the elevation in MDA levels increased at 18 °C. In the l-carnitine supplementation group, recovery in PON1 activity was observed significant at 28 °C and very significant at 38 °C. MDA concentration was almost the same with that of the non-carnitine group at 18 and 38 °C, but it significantly decreased at 28 °C. Considering the recovery in PON1 and MDA levels at 28 °C, which is the temperature of the sedentary group; our results suggest that l-carnitine supplementation has a protective role on exhaustive exercise-induced oxidative stress. Findings of this study also demonstrate influences of thermal stress on these parameters during exhaustive exercise.     

对氧磷酯酶基因多态性与糖尿病肾病的关系

目的探讨对氧磷酯酶2(PON2)基因A148G多态性与糖尿病肾病的关系.方法(1)用聚合酶链反应-限制性片段长度多态性(PCR-RFLP)分析法探查PON2基因A148G多态性在正常对照组、单纯2型糖尿病组、糖尿病肾病组中的基因频率分布;(2)放射免疫法检测血清免疫反应性胰岛素(IRI)、C肽(C-P)水平.结果(1)糖尿病肾病组GG基因型和G等位基因频率明显高于单纯2型糖尿病组(X2=4.26 P＜0.05,X2=4.89P＜0.05)和正常对照组(X2=4.79 P＜0.05,X2=5.49P＜0.01);(2)基因型为GG的糖尿病患者空腹血糖浓度高于基因型为GA和AA的糖尿病患者的空腹血糖浓度(F=3.90 P＜0.05,F=4.23 P＜0.05);(3)Logistic回归分析表明GG基因型是糖尿病肾病的独立变异危险因素(P＜0.05).结论PON2基因多态性与糖尿病肾病的发生有关.     

Paraoxonase 1 (PON1) status and substrate hydrolysis

Paraoxonase 1 (PON1) hydrolyzes a number of organophosphorus (OP) compounds including insecticides and nerve agents. The in vivo efficacy of PON1 to protect against a specific OP exposure depends on the catalytic efficiency of hydrolysis. The Q192R polymorphism affects the catalytic efficiency of hydrolysis of some substrates and not others. While PON1_R192 hydrolyzes paraoxon approximately 9-times as efficiently as PON1_Q192, the efficiency is insufficient to provide in vivo protection against paraoxon/parathion exposure. The two PON1₁₉₂ alloforms have nearly equivalent but higher catalytic efficiencies for hydrolyzing diazoxon (DZO) and provide equivalent in vivo protection against DZO exposures. On the other hand, PON1_R192 is significantly more efficient in hydrolyzing chlorpyrifos oxon (CPO) than PON1_Q192 and provides better protection against CPO exposure. Thus, for some exposures it is only the level of plasma PON1 that is important, whereas for others it is both plasma level and the PON1₁₉₂ alloform(s) present in plasma that are important. In no case is the plasma level of PON1 unimportant, provided that the catalytic efficiency is sufficient to protect against the exposure. Two-substrate enzyme assay/analysis protocols that reveal both PON1 plasma levels and PON1₁₉₂ phenotype (QQ; QR; RR) are designed to optimize the separation of PON1₁₉₂ phenotypes; however, they have not been optimized for evaluating in vivo rates of OP detoxication. This study describes the adaptation of a non-OP, two-substrate determination of PON1 status to the conversion of the PON1 status data to physiologically relevant rates of DZO and CPO detoxication. Conversion factors were generated for rates of hydrolysis of different substrates.     

PON1基因L55M多态性和缺血性脑卒中关系的系统评价和Meta分析

目的使用系统评价方法评价PON1基因L55M多态性与缺血性脑卒中的关系。方法检索中英文数据库以发现合格研究,使用随机或固定效应模型计算合并比值比(OR值),使用Q检验评估研究之间的异质性,Egger’s(埃格)检验和漏斗图评估发表偏倚。结果 11个研究纳入meta分析,在所有人群中,没有发现PON1基因L55M多态性与缺血性卒中发病风险具有相关性,也没有发现研究之间异质性。结论现有证据表明,L55M多态性对缺血性卒中的发病风险无影响,该结论需大样本研究进一步验证。     

Paraoxonase Gene Polymorphism in South-western Korean Population

Paraoxonase (PON) has anti-atherogenic activity. Considering the important role of polymorphism in the genetic susceptibility to cardiovascular disease and the variability of its allele frequencies in different ethnic groups, the distribution of genotypes and allele frequencies of PON1M55L, PON1Q192R, PON2A148G, and PON2S311C polymorphisms was analyzed in a total 988 South-western Koreans and determined their effects on lipid parameters. The genotype distribution of PON1 at position 55 was LL=0.886, LM=0.114; and at position 192 was QQ=0.406, QR=0.594. The frequencies of the PON1 55L allele and the PON1 192R allele were similar to those seen in Chinese populations and Western populations, respectively. The genetic distribution of PON2 at position 148 was AA=0.619, AG=0.345, GG=0.035; and at position 311 was CC=0.035, SC=0.345, SS=0.619. The frequencies of the PON2 148G and 311S alleles were similar to those seen in Chinese populations. The concentrations of LDL and ApoB were significantly different between the PON2A148G (P<0.05) and PON2 S311C polymorphisms (P<0.01). PON polymorphisms and allele frequencies were described in Koreans living south-western part of Korea. These ethnic variations are considered important in the interpretation of diseases associated with PON polymorphisms.     

Paraoxonase 1 (PON1) modulates the toxicity of mixed organophosphorus compounds

A transgenic mouse model of the human hPON1_Q192R polymorphism was used to address the role of paraoxonase (PON1) in modulating toxicity associated with exposure to mixtures of organophosphorus (OP) compounds. Chlorpyrifos oxon (CPO), diazoxon (DZO), and paraoxon (PO) are potent inhibitors of carboxylesterases (CaE). We hypothesized that a prior exposure to these OPs would increase sensitivity to malaoxon (MO), a CaE substrate, and the degree of the effect would vary among PON1 genotypes if the OP was a physiologically significant PON1 substrate in vivo. CPO and DZO are detoxified by PON1. For CPO hydrolysis, hPON1_R192 has a higher catalytic efficiency than hPON1_Q192. For DZO hydrolysis, the two alloforms have nearly equal catalytic efficiencies. For PO hydrolysis, the catalytic efficiency of PON1 is too low to be physiologically relevant. When wild-type mice were exposed dermally to CPO, DZO, or PO followed 4-h later by increasing doses of MO, toxicity was increased compared to mice receiving MO alone, presumably due to CaE inhibition. Potentiation of MO toxicity by CPO and DZO was greater in PON1^−/− mice, which have greatly reduced capacity to detoxify CPO or DZO. Potentiation by CPO was more pronounced in hPON1_Q192 mice than in hPON1_R192 mice due to the decreased efficiency of hPON1_Q192 for detoxifying CPO. Potentiation by DZO was similar in hPON1_Q192 and hPON1_R192 mice, which are equally efficient at hydrolyzing DZO. Potentiation by PO was equivalent among all four genotypes. These results indicate that PON1 status can have a major influence on CaE-mediated detoxication of OP compounds.