利用Tox21通路数据库评估石家庄市大气细颗粒物中多环芳烃激活毒性通路的风险

目的： 采用Tox21毒性检测数据库中通路数据对2017年石家庄市供暖期大气细颗粒物（PM_2.5）中多环芳烃（PAHs）的检测数据进行分析计算，评估PM_2.5引起毒性通路激活的风险。方法： 在石家庄市河北医科大学远离工业污染源设置1个采样点收集大气PM_2.5，通过气相色谱-串联质谱法（GC-MS）检测美国环境保护署优先控制的16种PAHs的浓度。利用MPPD软件计算各PAHs单体在成人肺泡中的沉积量；检索Tox21毒性检测数据库中芳烃受体（AhR）、核因子E2相关因子（Nrf2）、p53和核因子κB（NF-κB）各通路的剂量反应关系数据，计算各PAHs单体激活各通路的单位强度；结合PAHs在肺泡的沉积量和PAHs激活通路的强度，评估PM_2.5激活各个通路的风险。结果： 石家庄市供暖期PM_2.5中PAHs检测结果显示，苯并[a]芘的日均浓度为9.13 ng/m³，日均浓度排名前3的苯并[b]荧蒽、荧蒽和芘的浓度分别为22.88、17.86及14.31 ng/m³。这16种PAHs以苯并[a]芘为参照的毒性当量浓度为17.74 ng/m³。毒性通路激活风险预测结果提示激活强度最大的是NF-κB通路，其次是AhR、Nrf2，p53被激活的可能性最弱，其中相对应的活性暴露比（AER）值分别为1.97、1.71、0.58和0.28。结论： 石家庄市大气细颗粒物中PAHs的暴露，可能通过激活NF-κB和AhR信号通路增加致癌风险。     

PM2.5对HK-2肾细胞部分癌基因和凋亡基因表达的影响

目的： 探讨PM_2.5对人肾上皮细胞（HK-2）部分癌基因和凋亡基因表达的影响。方法： 利用CCK-8试剂盒测定PM_2.5混悬液对HK-2细胞的半数抑制浓度（IC₅₀）;实验设阴性对照组、PM_2.5混悬液低剂量（10 μg/mL）、高剂量（50 μg/mL）染毒组和阳性对照组（Cr⁶⁺ 10 μmol/L）,分别对HK-2细胞处理24 h后利用实时荧光定量PCR （qPCR）和Western blot检测癌基因（c-myc、c-fos、p53）和凋亡基因（Caspase-8、Caspase-9、Bcl-2） mRNA和蛋白的表达水平。结果： PM_2.5混悬液对HK-2细胞的IC₅₀为95.98 μg/mL;经PM_2.5混悬液染毒24 h,qPCR结果显示,与阴性对照组比较,PM_2.5混悬液高剂量组和阳性对照组c-myc、c-fos、Caspase-8、Caspase-9 mRNA表达均升高,差异均有统计学意义（P < 0.01）;p53和Bcl-2 mRNA表达降低,差异均有统计学意义（P < 0.01）。Western blot结果显示,与阴性对照组比较,PM_2.5混悬液高剂量组和阳性对照组c-myc、c-fos、Caspase-8、Caspase-9蛋白表达均升高,差异均有统计学意义（P < 0.01）;p53和Bcl-2蛋白表达均降低,差异均具有统计学意义（P < 0.05）。结论： PM_2.5可引起HK-2细胞中部分癌基因表达上升、抑癌基因表达下降、促凋亡基因表达上升和抑凋亡基因表达下降,提示PM_2.5对HK-2肾细胞部分癌基因和凋亡基因具有一定的促进与激活作用。     

PM2.5对HK-2细胞氧化损伤和凋亡的影响

目的：探讨深圳和太原市PM_2.5对人肾上皮细胞（HK-2）氧化损伤和凋亡的影响。方法：用中流量采样器分别采集太原某大学校园和深圳市疾病预防控制中心楼顶空气,将吸附有PM_2.5的滤膜洗脱后制备PM_2.5混悬液。设置阴性对照组、50 μg/mL深圳PM_2.5样品组、50 μg/mL太原PM_2.5样品组和10 μmol/L Cr⁶⁺阳性对照组,分别处理HK-2细胞24 h,测定4组细胞氧化损伤指标丙二醛（MDA）、超氧化物歧化酶（SOD）、还原型谷胱甘肽（GSH）、谷胱甘肽过氧化物酶（GSH-PX）的变化,并应用流式细胞术检测细胞凋亡水平。结果：与阴性对照组相比,深圳PM_2.5样品组、太原PM_2.5样品组和阳性对照组中MDA含量分别升高8.16%、34.51%和72.23%;SOD活性分别降低7.49%、19.67%和29.55%;GSH含量分别降低10.43%、16.39%和37.43%。太原PM_2.5样品组与阴性对照组的差异均有统计学意义（P < 0.05或P < 0.01）。GSH-PX活性分别降低42.70%、61.62%和60.98%,细胞凋亡率分别升高197.25%、301.22%和399.08%,上述3组与阴性对照组间的差异均有统计学意义（P < 0.05或P < 0.01）。结论：深圳和太原市PM_2.5均可引起HK-2细胞发生氧化损伤和细胞凋亡率增加,且太原市PM_2.5的作用更为明显。     

1,25-二羟基维生素D3对PM2.5所致HBE细胞氧化损伤的保护作用

目的： 探讨1，25-二羟基维生素D₃[1，25-（OH）₂D₃]对细颗粒物（PM_2.5）致人支气管上皮细胞（HBE）氧化损伤的保护作用。方法： 根据处理因素不同将细胞分为4组，溶剂（乙醇）对照组、1，25-（OH）₂D₃干预组、乙醇+PM_2.5染毒组、PM_2.5染毒+1，25-（OH）₂D₃干预组。溶剂对照组细胞用0.1%乙醇处理48 h，1，25-（OH）₂D₃干预组用1×10^-9 mol/L 1，25-（OH）₂D₃处理48 h，乙醇+PM_2.5染毒组用0.1%乙醇溶剂处理24 h后更换为含乙醇的PM_2.5（200 μg/mL）染毒液继续处理24 h，PM_2.5染毒+1，25-（OH）₂D₃干预组用1×10^-9 mol/L 1，25-（OH）₂D₃预处理24 h后更换为含1，25-（OH）₂D₃的PM_2.5（200 μg/mL）染毒液继续处理24 h。染毒结束后，用CCK-8试剂盒测定细胞存活率、丙二醛（MDA）和还原型谷胱甘肽（GSH）/氧化型谷胱甘肽（GSSG）-Glo^TM试剂盒分别测定MDA浓度和GSH/GSSG比值，Western blot实验测定维生素D受体（VDR）、转录因子NF-E2相关因子2（Nrf-2）与血红素加氧酶-1（HO-1）蛋白的表达水平。结果： PM_2.5染毒处理后，HBE细胞的存活率降至80.8%，1，25-（OH）₂D₃预处理24 h后再进行PM_2.5染毒的细胞存活率降低至75.8%。与对照相比，PM_2.5染毒后，HBE细胞MDA浓度显著增加（P < 0.05），而GSH/GSSG的比值却明显降低（P < 0.01）。1，25-（OH）₂D₃处理48 h后可显著改善PM_2.5染毒细胞的抗氧化水平（P < 0.05），主要表现为MDA浓度的降低和GSH/GSSG比值的增加。蛋白分析结果发现，PM_2.5可诱导细胞Nrf-2和HO-1蛋白表达的增加。1，25-（OH）₂D₃干预48 h后可上调HBE细胞内VDR水平，并可增加PM_2.5染毒组细胞内Nrf-2和HO-1蛋白的表达水平。结论： PM_2.5可诱导HBE细胞氧化损伤，主要表现为脂质过氧化水平升高、GSH/GSSG比值下降和抗氧化蛋白Nrf-2与HO-1表达水平的增加。在PM_2.5所致细胞氧化应激效应中，1，25-（OH）₂D₃可起到一定的保护作用，这可能与VDR及Nrf-2/HO-1信号通路有关。而1，25-（OH）₂D₃所致细胞存活率的降低可能与其诱导细胞周期阻滞及促进PM_2.5所诱导损伤细胞的凋亡有关。     

1,25-二羟基维生素D3对PM2.5所致HBE细胞氧化损伤的保护作用

目的： 探讨1，25-二羟基维生素D₃[1，25-（OH）₂D₃]对细颗粒物（PM_2.5）致人支气管上皮细胞（HBE）氧化损伤的保护作用。方法： 根据处理因素不同将细胞分为4组，溶剂（乙醇）对照组、1，25-（OH）₂D₃干预组、乙醇+PM_2.5染毒组、PM_2.5染毒+1，25-（OH）₂D₃干预组。溶剂对照组细胞用0.1%乙醇处理48 h，1，25-（OH）₂D₃干预组用1×10^-9 mol/L 1，25-（OH）₂D₃处理48 h，乙醇+PM_2.5染毒组用0.1%乙醇溶剂处理24 h后更换为含乙醇的PM_2.5（200 μg/mL）染毒液继续处理24 h，PM_2.5染毒+1，25-（OH）₂D₃干预组用1×10^-9 mol/L 1，25-（OH）₂D₃预处理24 h后更换为含1，25-（OH）₂D₃的PM_2.5（200 μg/mL）染毒液继续处理24 h。染毒结束后，用CCK-8试剂盒测定细胞存活率、丙二醛（MDA）和还原型谷胱甘肽（GSH）/氧化型谷胱甘肽（GSSG）-Glo^TM试剂盒分别测定MDA浓度和GSH/GSSG比值，Western blot实验测定维生素D受体（VDR）、转录因子NF-E2相关因子2（Nrf-2）与血红素加氧酶-1（HO-1）蛋白的表达水平。结果： PM_2.5染毒处理后，HBE细胞的存活率降至80.8%，1，25-（OH）₂D₃预处理24 h后再进行PM_2.5染毒的细胞存活率降低至75.8%。与对照相比，PM_2.5染毒后，HBE细胞MDA浓度显著增加（P < 0.05），而GSH/GSSG的比值却明显降低（P < 0.01）。1，25-（OH）₂D₃处理48 h后可显著改善PM_2.5染毒细胞的抗氧化水平（P < 0.05），主要表现为MDA浓度的降低和GSH/GSSG比值的增加。蛋白分析结果发现，PM_2.5可诱导细胞Nrf-2和HO-1蛋白表达的增加。1，25-（OH）₂D₃干预48 h后可上调HBE细胞内VDR水平，并可增加PM_2.5染毒组细胞内Nrf-2和HO-1蛋白的表达水平。结论： PM_2.5可诱导HBE细胞氧化损伤，主要表现为脂质过氧化水平升高、GSH/GSSG比值下降和抗氧化蛋白Nrf-2与HO-1表达水平的增加。在PM_2.5所致细胞氧化应激效应中，1，25-（OH）₂D₃可起到一定的保护作用，这可能与VDR及Nrf-2/HO-1信号通路有关。而1，25-（OH）₂D₃所致细胞存活率的降低可能与其诱导细胞周期阻滞及促进PM_2.5所诱导损伤细胞的凋亡有关。     

深圳和太原PM2.5样品致突变作用研究

目的：探讨深圳和太原大气细颗粒物（PM_2.5）样品是否具有致突变作用。方法：应用组氨酸缺陷型鼠伤寒沙门氏菌TA97、TA98、TA100、TA102和TA1535,通过平板渗入法同时对广东深圳和山西太原两地的PM_2.5样品进行标准Ames试验。实验设4个PM_2.5剂量组（分别为每皿40、100、200和400 μg）、1个阴性对照组和1个阳性对照组,每种细菌均设立加S9和不加S9两种试验组。结果：深圳PM_2.5样品的Ames试验结果显示,TA97、TA100和TA102在PM_2.5样品处理后菌落回变数显著高于阴性对照组,加S9与不加S9的菌落回变数比较差异有统计学意义（P < 0.01）。太原样品的Ames试验结果显示,TA97、TA98和TA100在PM_2.5样品处理后菌落回变数显著高于阴性对照组,加S9与不加S9的菌落回变数比较差异有统计学意义（P < 0.05或P < 0.01）。但深圳和太原PM_2.5样品对TA1535未见阳性结果,结论：深圳和太原PM_2.5样品均能够引起TA97、TA98、TA100的Ames试验的自发回变数阳性结果,表明深圳和太原PM_2.5样品均具有致基因突变作用。     

PM2.5对HBE细胞致癌致突变相关基因表达的影响

目的：采用基因芯片技术与生物信息学分析方法，筛选PM_2.5染毒后的人支气管上皮细胞（HBE）与未染毒细胞比较的差异表达基因和通路，为进一步研究PM_2.5对HBE细胞致癌致突变作用的相关机制提供科学依据。方法：用50 μg/mL的PM_2.5水溶液处理HBE细胞，染毒24 h，用未染毒的细胞作为空白对照组，设立3组平行样品。提取RNA，荧光标记与纯化后进行芯片杂交，用Rosetta Resolver-System（Rosetta Biosoftware）进行数据前处理与统计分析，得到差异表达基因。将数据经过Cluster Profiler软件进行主成分和聚类分析、Pathway及GO（Gene Ontolog）分析，初步探讨PM_2.5染毒前后HBE细胞中基因的差异表达；通过String蛋白互作数据库分析差异表达基因的蛋白互作关系，筛选出节点数最多的核心蛋白。结果：根据预设的筛选条件，筛选出245个PM_2.5染毒前后HBE细胞中的差异表达基因，其中上调基因27个，下调基因218个，经过进一步分析，筛选出PHACTR2、SFRP1、WFDC1等排名前10的上调和下调的核心基因。排名前10的核心差异基因通过GO功能注释富集分析显示，差异表达基因主要富集在跨膜受体活性、受体活性、细胞信号传导、细胞分子传导等分子功能。同时富集于离子跨膜转运、细胞对脂多糖无机离子跨膜转运、细胞营养转运等生物过程；排名前10的差异表达基因通过KEGG富集分析显示，差异表达基因主要富集在涉及肿瘤细胞迁移、胆汁代谢相关、神经活性、遗传毒性等方面的7个核心通路；蛋白互作用网络图筛选出SST、BDNF、NCAM1、SSTR1和Bcl2L11等5个核心蛋白。结论：PM_2.5可引起HBE细胞致癌致突变相关基因的差异表达，可为进一步研究PM_2.5的致癌致突变作用机制提供科学依据。     

PM2.5染毒HBE细胞前后差异表达的microRNAs及其生物信息学分析

目的：采用microRNA（miRNA）测序和生物信息学方法，分析大气细颗粒物（PM_2.5）染毒人支气管上皮HBE细胞前后差异表达的miRNAs，预测差异miRNAs的生物学功能和信号转导途径。方法：用50 μg/mL的PM_2.5混悬液染毒HBE细胞，以未染毒组作为对照组，处理24 h后提取总RNA样品，Small RNA样品预处理试剂盒构建文库，并利用illumina HiSeq^TM 2500/MiSeq测序平台进行高通量测序。以调整后P < 0.05的筛选标准得到差异miRNAs，使用miRanda和RNAhybrid两个软件共同预测差异miRNAs的靶基因并进行GO和KEGG功能富集分析，利用STRING数据库和Cytoscape软件对miRNAs和靶基因及靶基因之间的相互作用关系进行可视化分析。结果：高通量测序方法共检测到PM_2.5染毒前后的包含1 137个miRNAs的表达谱，27个为差异表达的miRNAs，其中7个上调，20个下调。GO和KEGG富集分析发现，这些差异miRNAs主要参与细胞代谢、酶活性调节等生物学过程，聚集于胞内如细胞质、细胞器等，涉及代谢途径、PI3K-Akt信号通路、Ras信号通路、MAPK信号通路等与细胞增殖、分化、凋亡及癌症发生等相关的重要信号通路。此外，通过构建相互作用网络图，鉴定了miR-371b-3p、miR-371a-5p、miR-27a-3p、miR-7-5p、miR-372-3p等相互作用数量前11位的核心miRNAs，以及3个核心靶基因（VEGFA、MAPK3、CCR5）。结论：PM_2.5染毒HBE细胞后引起了27个miRNAs的差异表达，涉及PI3K-Akt信号通路、Ras信号通路及MAPK信号通路等与癌症发生发展相关的重要信号通路，其中筛选了11个核心miRNAs和3个核心基因，为深入研究PM_2.5致癌毒理作用机制提供了实验依据。     

PM2.5染毒HBE细胞前后差异表达的microRNAs及其生物信息学分析

目的：采用microRNA（miRNA）测序和生物信息学方法，分析大气细颗粒物（PM_2.5）染毒人支气管上皮HBE细胞前后差异表达的miRNAs，预测差异miRNAs的生物学功能和信号转导途径。方法：用50 μg/mL的PM_2.5混悬液染毒HBE细胞，以未染毒组作为对照组，处理24 h后提取总RNA样品，Small RNA样品预处理试剂盒构建文库，并利用illumina HiSeq^TM 2500/MiSeq测序平台进行高通量测序。以调整后P < 0.05的筛选标准得到差异miRNAs，使用miRanda和RNAhybrid两个软件共同预测差异miRNAs的靶基因并进行GO和KEGG功能富集分析，利用STRING数据库和Cytoscape软件对miRNAs和靶基因及靶基因之间的相互作用关系进行可视化分析。结果：高通量测序方法共检测到PM_2.5染毒前后的包含1 137个miRNAs的表达谱，27个为差异表达的miRNAs，其中7个上调，20个下调。GO和KEGG富集分析发现，这些差异miRNAs主要参与细胞代谢、酶活性调节等生物学过程，聚集于胞内如细胞质、细胞器等，涉及代谢途径、PI3K-Akt信号通路、Ras信号通路、MAPK信号通路等与细胞增殖、分化、凋亡及癌症发生等相关的重要信号通路。此外，通过构建相互作用网络图，鉴定了miR-371b-3p、miR-371a-5p、miR-27a-3p、miR-7-5p、miR-372-3p等相互作用数量前11位的核心miRNAs，以及3个核心靶基因（VEGFA、MAPK3、CCR5）。结论：PM_2.5染毒HBE细胞后引起了27个miRNAs的差异表达，涉及PI3K-Akt信号通路、Ras信号通路及MAPK信号通路等与癌症发生发展相关的重要信号通路，其中筛选了11个核心miRNAs和3个核心基因，为深入研究PM_2.5致癌毒理作用机制提供了实验依据。     

新冠肺炎前后福州市区大气颗粒物污染与居民非意外死亡的关系

目的：研究新冠肺炎前后福州市区大气颗粒物污染与居民非意外死亡的关系。方法：收集2016—2020年福州市大气污染数据、气象数据和死因监测数据，采用基于Quasi-Poisson回归广义线性模型的时间序列法，并调整长期趋势、季节性等混杂因素，分析比较新冠肺炎前后大气颗粒物-非意外死亡关系的变化。结果：新冠肺炎发生后，福州市PM_2.5浓度显著降低。新冠肺炎前，PM_2.5致居民非意外总死亡数的超额危险度于滞后2d内有显著性，而且在第1天效应最大，分别为[ER=1.69%，95%CI(0.79%，2.59%)]和[ER=0.93%，95%CI(0.49%，1.38%)]。而新冠肺炎后PM_2.5对居民非意外总死亡数无显著影响。新冠肺炎前，PM_2.5对呼吸系统疾病死亡于滞后第1天有显著影响[ER=3.01%，95%CI(0.35%，5.74%)]，新冠后则无显著影响。新冠肺炎前后，PM_2.5浓度的降低对循环系统和心血管系统死亡风险的改变无明显影响。结论：新冠肺炎后PM_2.5浓度的降低对居民非意外死亡尤其是呼吸系统疾病死亡风险的降低具有显著影响，提示大气污染治理的必要性和有效性。     

Nitrated polycyclic aromatic hydrocarbons: potent bacterial mutagens and stimulators of DNA repair synthesis in cultured human cells

Ten polycyclic aromatic hydrocarbons (PAHs), viz. anthracenepyrene, chrysene, perylene, fluoranthene, benzo[e]pyrene, benzo[a]pyrene,benz[a]anthracene, benzo[ghi]perylene, benzo[k]fluoranthene,have been nitrated using concentrated nitric acid and the crudenitrated mixture examined for biological activity. All the nitroPAHs examined were mutagenic to Salmonella typhimurium in theabsence of a rat liver preparation. Addition of Aroclor-1254induced liver had little effect on mutagenicity. Mutagenic potencydiffered for the various nitrated mixtures with nitrated pyreneand nitrated fluoranthene the most potent and nitrated anthracenethe least potent. Both frame-shift and base-substitution mutationswere induced by the nitrated PAHs. The nitrated PAHs were alsoable to induce DNA repair synthesis in cultured HeLa cells inthe absence of liver, indicating that these cells have the necessaryenzymes to activate nitro PAHs. Potency again varied from compoundto compound with nitrated pyrene appearing to be the most active.Isolation of individual components from the crude nitrated mixtureshas not been carried out in this study. In view of the possiblewide-spread distribution of nitrated PAHs in the environmentfurther work is required to assess the carcinogenic potencyof these compounds which possibly pose a risk to man.     

Tumorigenic activity of non-alternant polynuclear aromatic hydrocarbons in newborn mice

The tumorigenic activity of benzo[b]fluoranthene, benzo[j]fluoranthene, benzo[k]fluoranthene, and indeno-[1,2,3-cd]pyrene was evaluated in newborn CD-1 mice. The total doses of these non-alternant polycyclic aromatic hydrocarbons employed in this study ranged from 0.5 to 2.1 mumol per mouse. The results of this assay indicate that both benzo[b]fluoranthene and benzo[j]fluoranthene exhibit significant tumorigenic activity. In contrast to these results, neither benzo[k]fluoranthene nor indeno[1,2,3-cd]pyrene were tumorigenic under these assay conditions.     

A pilot study of detection of DNA adducts in white blood cells of roofers by 32P-postlabelling

To assess the utility of DNA adducts as biomarkers of exposure to carcinogens in an industrial population, a pilot study of roofers occupationally exposed to a mixture of polycyclic aromatic hydrocarbons was conducted. DNA was isolated from peripheral white blood cells of roofers and non-occupationally exposed subjects matched for age, sex and smoking status. Occupational exposures to anthracene, fluoranthene, pyrene, benzanthracene, benzo[a]pyrene, benzo[b]fluoranthene, benzo[g,h,i]perylene and benzo[k]fluoranthene were assessed by personal breathing zone air sampling and skin wipes. Exposures to benzo[a]pyrene in air of exposed subjects ranged from 0.60 microgram/m3 to 1.39 micrograms/m3, and exposures to total polycyclic aromatic hydrocarbon (the sum of eight hydrocarbons) ranged from 6.0 micrograms/m3 to 13.8 micrograms/m3 on the day before blood collection. In the biomarker studies 10 of 12 roofers, but only 2 of 12 comparison subjects, had detectable levels of aromatic DNA adducts by 32P-postlabelling assay (p less than 0.01). The two non-roofers with detectable adducts had levels at or near the detection limit of 2 adducts per 10(9) nucleotides. In two roofer samples which were studied in a mixing experiment, the major adduct spots did not co-migrate with the guanosine N2 adduct of benzo[a]pyrene diol epoxide. These results suggest that the 32P-postlabelling assay may be useful for monitoring exposures to complex mixtures of aromatic hydrocarbons in industrial populations.     

High levels of carcinogenic polycyclic aromatic hydrocarbons in mate drinks.

BACKGROUND: Drinking mate has been associated with cancers of the esophagus, oropharynx, larynx, lung, kidney, and bladder. We conducted this study to determine whether drinking mate could lead to substantial exposure to polycyclic aromatic hydrocarbons (PAH), including known carcinogens, such as benzo[a]pyrene. METHODS: The concentrations of 21 individual PAHs were measured in dry leaves of eight commercial brands of yerba mate and in infusions made with hot (80 degrees C) or cold (5 degrees C) water. Measurements were done using gas chromatography/mass spectrometry, with deuterated PAHs as the surrogates. Infusions were made by adding water to the leaves, removing the resulting infusion after 5 min, and then adding more water to the remaining leaves. This process was repeated 12 times for each infusion temperature. RESULTS: The total concentrations of the 21 PAHs in different brands of yerba mate ranged from 536 to 2,906 ng/g dry leaves. Benzo[a]pyrene concentrations ranged from 8.03 to 53.3 ng/g dry leaves. For the mate infusions prepared using hot water and brand 1, 37% (1,092 of 2,906 ng) of the total measured PAHs and 50% (25.1 of 50 ng) of the benzo[a]pyrene content were released into the 12 infusions. Similar results were obtained for other hot and cold infusions. CONCLUSION: Very high concentrations of carcinogenic PAHs were found in yerba mate leaves and in hot and cold mate infusions. Our results support the hypothesis that the carcinogenicity of mate may be related to its PAH content.     

Modulation of gene expression and DNA adduct formation in HepG2 cells by polycyclic aromatic hydrocarbons with different carcinogenic potencies

Polycyclic aromatic hydrocarbons (PAHs) can occur in relatively high concentrations in the air, and many PAHs are known or suspected carcinogens. In order to better understand differences in carcinogenic potency between PAHs, we investigated modulation of gene expression in human HepG2 cells after 6 h incubation with varying doses of benzo[a]pyrene (B[a]P), benzo[b]fluoranthene (B[b]F), fluoranthene (FA), dibenzo[a,h]anthracene (DB[a,h]A), 1-methylphenanthrene (1-MPA) or dibenzo[a,l]pyrene (DB[a,l]P), by using cDNA microarrays containing 600 toxicologically relevant genes. Furthermore, DNA adduct levels induced by the compounds were assessed with (32)P-post-labeling, and carcinogenic potency was determined by literature study. All tested PAHs, except 1-MPA, induced gene expression changes in HepG2 cells, although generally no dose-response relationship could be detected. Clustering and principal component analysis showed that gene expression changes were compound specific, since for each compound all concentrations grouped together. Furthermore, it showed that the six PAHs can be divided into three groups, first FA and 1-MPA, second B[a]P, B[b]F and DB[a,h]A, and third DB[a,l]P. This grouping corresponds with the carcinogenic potencies of the individual compounds. Many of the modulated genes are involved in biological pathways like apoptosis, cholesterol biosynthesis and fatty acid synthesis. The order of DNA adduct levels induced by the PAHs was: B[a]P > DB[a,l]P > B[b]F > DB[a,h]A > 1-MPA >/= FA. When comparing the expression change of individual genes with DNA adduct levels, carcinogenic potency or Ah-receptor antagonicity (the last two were taken from literature), several highly correlated genes were found, of which CYP1A1, PRKCA, SLC22A3, NFKB1A, CYP1A2 and CYP2D6 correlated with all parameters. Our data indicate that discrimination of high and low carcinogenic PAHs by gene expression profiling is feasible. Also, the carcinogenic PAHs induce several pathways that were not affected by the least carcinogenic PAHs.     

Polycyclic aromatic hydrocarbons induce migration in human hepatocellular carcinoma cells (HepG2) through reactive oxygen species-mediated p38 MAPK signal transduction

Although polycyclic aromatic hydrocarbons (PAHs) are carcinogenic and have been extensively studied with regard to tumor formation, few studies have investigated the involvement of these environmental chemicals in tumor migration and invasion. Polycyclic aromatic hydrocarbons induce reactive oxygen species (ROS) and activate MAPK signal transduction. The p38 signaling transduction pathway, one of the most typical MAPK pathways, plays an essential role in regulating cell migration. Therefore, we investigated whether three PAHs, benzo[a]anthracene (B[a]A), benzo[k]fluoranthene (B[k]F), and indeno[1,2,3-c,d]pyrene (IND), induce migration in human hepatocellular carcinoma cell line HepG2 through ROS-mediated p38 MAPK signal transduction. Reactive oxygen species generation and p38 MAPK activity both increased in a dose-dependent manner and were prevented by SB203580, an inhibitor of p38 MAPK, and N-acetylcysteine (NAC), a ROS scavenger. Expression of migration-related genes was also increased by B[a]A, B[k]F, and IND in a dose-dependent manner and was inhibited by SB203580 and NAC. The migration of HepG2 cells, observed using the Transwell migration assay, also increased in a dose-dependent manner and was prevented by SB203580 and NAC. Our results indicate that the ROS-mediated p38 MAPK signaling pathway plays an essential role in the PAH-induced migration of HepG2 cells.     

Arylhydrocarbon receptor-dependent induction of liver and lung cytochromes P450 1A1, 1A2, and 1B1 by polycyclic aromatic hydrocarbons and polychlorinated biphenyls in genetically engineered C57BL/6J mice

Arylhydrocarbon receptor knock-out, AhR(-/-), mice have recently been shown to be rather resistant to benzo[a]pyrene (B[a]P)-induced tumor formation, probably reflecting the inability of these mice to express significant levels of cytochrome P450 (P450 or CYP) 1A1 that activates B[a]P to reactive metabolites (Y. Shimizu, Y. Nakatsuru, M. Ichinose, Y. Takahashi, H. Kume, J. Mimura, Y. Fujii-Kuriyama and T. Ishikawa (2000) PROC: Natl Acad. Sci. USA, 97, 779-782). However, it is not precisely determined whether CYP1B1, another enzyme that is also active in activating B[a]P, plays a role in the B[a]P carcinogenesis in mice. To understand the basis of roles of CYP1A1 and CYP1B1 in the activation of chemical carcinogens, we compared levels of induction of liver and lung CYP1A1, 1A2, and 1B1 by various polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls in AhR(+/+) and AhR(-/-) mice. Liver and lung CYP1A1 and 1B1 mRNAs were highly induced in AhR(+/+) mice by a single intraperitoneal injection of each of the carcinogenic PAHs, such as B[a]P, 7,12-dimethylbenz[a]anthracene, dibenz[a,l]pyrene, 3-methylcholanthrene, 1,2,5,6-dibenzanthracene, benzo[b]fluoranthene, and benzo[a]anthracene and by a co-planar PCB congener 3,4,3',4'-tetrachlorobiphenyl. We also found that 6-aminochrysene, chrysene, benzo[e]pyrene, and 1-nitropyrene weakly induced the mRNA expression of CYP1A1 and 1B1, whereas anthracene, pyrene, and fluoranthene that have been reported to be non-carcinogenic in rodents, were very low or inactive in inducing these P450s. The extents of induction of liver CYP1A2 by these chemicals were less than those of CYP1A1 and 1B1 in AhR(+/-/+/-) mice. In AhR(-/-) mice, there was no induction of these P450s by PAHs and polychlorinated biphenyls. Liver microsomal activities of 7-ethoxyresorufin and 7-ethoxycoumarin O-deethylations and of mutagenic activation of (+/-)-trans-7,8-dihydroxy-7,8-dihydro-B[a]P to DNA-damaging products were found to correlate with levels of CYP1A1 and 1B1 mRNAs in the liver. Our results suggest that carcinogenicity potencies of PAHs may relate to the potencies of these compounds to induce CYP1A1 and 1B1 through AhR-dependent manner and that these induced P450s participate in the activation of B[a]P and related carcinogens causing initiation of cancers in mice.     

Monooxygenase induction by various xenobiotics and its influence on rat liver microsomal metabolism of chrysene in comparison to benz[a]anthracene

The potencies of various xenobiotics for induction of monooxygenases and their influence on the rat liver microsomal metabolite profile of the environmentally relevant weak carcinogen, chrysene, was determined. Among the widely distributed chemicals, polychlorinated biphenyls (PCB) and preferentially 3,3',4,4'-tetrachlorobiphenyl as well as PAHs and their heterocyclic analogues such as benzo[a]pyrene, benzo[b]- and -[j]fluoranthene, indeno[1,2,3-cd]pyrene, dibenz[a,h]acridine, benzo[b]naphtho-[2,1-d]thiophene, and 5,6-benzoflavone were found to be potent inducers stimulating the formation of the proximate, and some of them also the ultimate carcinogen of chrysene. Lindane, carbaryl, DDT, and pentachlorophenol were found to be inefficient or weak inducers. With the exception of phenobarbital no inducers were found among the pharmaceuticals investigated. Sex-dependent metabolism was found for Wistar-rats. No 1,2-oxidation was observed in females, and turnover rates were lower than in males. These findings confirm the results previously obtained with benz[a]anthracene as substrate. The inducing potencies of various compounds tested were similar for both of these substrates. It is interesting to note that in most cases the same effective xenobiotic induces the bay-region diolepoxide in both, chrysene and benz[a]anthracene.     

Oncogenic interaction of carcinogenic and non-carcinogenic polycyclic aromatic hydrocarbons in mice.

To evaluate possible interactions between PAH occurring in automobile exhaust condensates with regard to their tumour forming potency, the following experiments were performed. Six different doses of benzo[a]pyrene (3-100 microgram) and of dibenzo]a,h]anthracene (2-75 microgram) and mixtures thereof were tested subcutaneously on female NMRI mice. In addition, mixtures of 10 non-carcinogenic hydrocarbons were applied: benzo[e]pyrene, benzo[a]anthracene, phenanthrene, anthracene, pyrene, fluoranthene, chrysene, perylene, benzo[ghi]perylene and coronene. Mixtures of all 12 PAH were also applied. The proportion of PAH in all mixtures used was the same as in automobile exhaust condensates; benzo[a]pyrene was used as reference substance. The most important results were as follows: 1. Small doses of dibenzo[a,h]anthracene have a greater tumour promoting effect than do comparable doses of benzo[a]pyrene. Increased doses increase the effect of benzo[a]pyrene more than that of dibenzo[a,h]anthracene. 2. The mixture of benzo[a]pyrene and dibenzo[a,h]anthracene is 1.4 time more active than dibenzo[a,h]anthracene alone. 3. The mixture of all PAH has a lower efficacy than dibenzo[a,h]anthracene alone, amounting to only 0.03 that of dibenzanthracene; however, the activity of dibenzo[a,h]anthracene within the mixture of the 12 PAH increases by a factor of 3.1. 4. The activity of a mixture of dibenzo[a,h]anthracene and benzo[a]pyrene depends to about 40% on dibenzo[a,h]anthracene; and that of 12 PAH to 30% on dibenzo[a,h]anthracene alone or to 80% on a mixture of dibenzo[a,h]anthracene and benzo[a]pyrene.