饮茶对香烟中特异性亚硝胺－NNK诱发小鼠肺癌基因表达的影响

通过研究饮茶对香烟中特异性亚硝胺－ＮＮＫ诱发小鼠肺癌基因表达的影响，对饮茶可拮抗香烟致癌作用的结果做进一步验证，并对其作用机理进行探讨。所使用方法为国内外尚属新的技术，即非同位素标记探针测定基因表达。其结果表明阳性小鼠给ＮＮＫ４周后，ｃ－ｍｙｃ和ｃ－ｒａｆ基因表达水平明显增高，而小鼠若同时饮绿茶则可抑制这种增高，抑制率达５０％和２０％，到第８周时阳性对照组的ｃ－ｍｙｃ和ｃ－ｒａｆ基因水平恢复正常。与此相对应，ｃ－Ｈ－ｒａｓ基因在第８周时表达增高，约为阴性组３倍，饮茶对此同样有抑制作用，抑制率为５０％。在第２、４和８周均未见阳性对照组ｖｓｉｓ基因表达水平的改变。     

茶对促癌物（TPA）诱发小鼠皮肤癌基因表达的影响

通过研究在小鼠皮肤上涂抹儿茶素ＥＧＣＧ对促癌物（ＴＰＡ）诱发小鼠皮肤组织某些癌症发生有重要关系的基因（ｃ－ｍｙｃ，ＯＤＣ、蛋白激酶Ｃ即ＰＫＣ基因）表达水平的影响，对茶叶抗皮肤癌的机制做了较深入的探讨。其结果表明阳性小鼠皮肤涂１０ｎｍｏｌＴＰＡ４ｈ后，上皮组织中ＯＤＣ基因表达水平比阴性组高出４．５倍，而ＥＧＣＧ对其有明显的抑制作用，１μｍｏｌ和５μｍｏｌＥＧＣＧ剂量组的抑制率分别为１６％和５６％，有一定的剂量－反应关系。Ｃ－ｍｙｃ与ｐＫＣ基因表达水平在阳性组也有明显的升高，分别为５．０和１．９倍，ＥＧＣＧ同样具有抑制作用，５μｍｏｌ的抑制率分别为２４％和２１％。     

接触苯工人白细胞癌基因激活的研究

应用ＰＣＲ－Ｂｌｏｔ和Ｄｏｔ－Ｂｌｏｔ技术检测了１０３名接触苯工人和７０名对照组工人外周血白细胞ｃ－Ｋｉ－ｒａｓ２基因和ｃ－ｍｙｃ基因。结果表明，１０３名接苯者中有４例其外周血白细胞检出ｃ－Ｋｉ－ｒａｓ２基因１２位点Ｇ→Ｔ突变，其接苯工龄在６～１０年，而７０名对照者未检出该突变；ｃ－Ｋｉ－ｒａｓ２基因１２位点（Ｇ→Ａ突变在两组工人中均未检出阳性；ｃ－ｍｙｃ基因亦未在两组工人中检出扩增现象。结果提示，ｃ－Ｋｉ－ｒａｓ２基因１２位点Ｇ→Ｔ突变与慢性接触苯有关，有可能是苯白血病发生的分子机理。     

苯并芘诱发人肺癌细胞系（BT）的染色体异常及myc，p53及Rb基因研究

本文对由致癌物苯并芘诱发的人肺癌建立的细胞系（ＢＴ）进行了染色体分析及ｍｙｃ，Ｒｂ和ｐ５３基因研究。发现许多异常染色体，以３号，５号，１１号，１３号，１７号染色体改变较多，对定位于这些染色体上的Ｈａ－ｒａｓ，ｒａｆ－１，ｐ５３，Ｒｂ和ｃ－ｍｙｃ的表达、扩增及重排情况进行了分析，发现ｃ－ｍｙｃ，ｐ５３，Ｒｂ三个基因发生了改变，说明染色体异常导致的基因改变与苯并芘诱发人肺癌的发生机制可能密切相关。     

上皮性卵巢肿瘤C—myc与p53蛋白的表达及意义

用免疫组化ＬＳＡＢ方法检测５例正常卵巢组织和３５例卵巢肿瘤组织中的Ｃ－ｍｙｃ（原癌基因）和ｐ５３（抑癌基因）蛋白的表达水平。结果从良性卵巢腺瘤、交界性到恶性卵巢囊腺癌，Ｃ－ｍｙｃ和ｐ５３阳性表达呈增高趋势。其阳性表达率与卵巢肿瘤的细胞增殖状态、肿瘤分化及临床分期有关。检测卵巢肿瘤中Ｃ－ｍｙｃ及ｐ５３基因表达可了解卵巢囊腺癌的发生、发展，找出原癌基因及抑癌基因表达与卵巢瘤生物学行为间的关系。     

链霉素对缺氧大鼠右心室肥大及C－myc原癌基因表达的影响

本文观察了非选择性阳离子通道阻断剂链霉素（在脊椎动物心肌阻断牵张激活的钠离子跨膜内流）对缺氧大鼠右心室肥大和缺氧大鼠心肌中ｃ─ｍｙｃ基因表达的影响。结果如下：（１）急性缺氧时，右心室收缩压明显增高，慢性间断性缺氧进一步增高右心室收缩压并明显增高右心室重量指数。（２）链霉素对急性缺氧性肺动脉增压反应无影响，但可明显降低慢性缺氧大鼠右心室收缩压和右心室重量指数。（３）缺氧引起右室心肌迅速一过性的ｃ－ｍｙｃ基因表达增强，链霉素可降低ｃ－ｍｙｃ表达水平。提示Ｎａ内流和Ｃ－ｍｙｃ表达可能参与了缺氧性右心室肥大的发生。     

镉对小鼠肢芽细胞增殖细胞核抗原和c—myc基因表达的影响

目的探讨镉对胚胎肢芽细胞增殖抑制的机制。方法运用免疫组化ＳＰ法结合图像分析技术观察了ＣｄＣｌ２对增殖细胞核抗原（ＰＣＮＡ）和ｃ－ｍｙｃ基因表达的影响。结果ＰＣＮＡ和ｃ－ｍｙｃ基因在正常增殖的胚胎肢芽细胞中均呈强阳性免疫反应；０．１～０．８μｇ／ｍｌＣｄＣｌ２对细胞中ＰＣＮＡ和ｃ－ｍｙｃ的表达均有明显的抑制作用，并呈现明显的剂量－效应关系。结论ＣｄＣｌ２可通过抑制ＰＣＮＡ和ｃ－ｍｙｃ的表达而对胚胎细胞增殖产生抑制作用。     

甲基叔丁基醚对原癌基因和功能基因表达的影响

甲基叔丁基醚（ＭＴＢＥ）是一种新型的汽油添加剂,被用来提高汽油燃烧效率,减少汽车尾气中有害物质的排放。ＭＴＢＥ具有一定的动物致癌性,但其机制目前并不清楚。本研究采用免疫组织化学方法,检测了ＭＴＢＥ对体外培养的ＮＩＨ３Ｔ３细胞中ｃ－ｍｙｃ和ｐ２１蛋白表达的影响;采用点杂交方法,从ＲＮＡ水平检测了ＭＴＢＥ亚慢性染毒大鼠肝组织中原癌基因ｃ－ｍｙｃ基因和功能基因ＧＳＴ－Ｐ基因的表达情况。免疫组化结果显示,ＭＴＢＥ可诱导ｃ－ｍｙｃ基因的高表达,对ｐ２１蛋白的表达未见明显影响。点杂交结果显示,ＭＴＢＥ可明显诱导大鼠肝组织中ｃ－ｍｙｃ基因的高表达,而对ＧＳＴ－Ｐ基因的表达未见明显影响。上述结果提示,ＭＴＢＥ可诱导细胞中ｃ－ｍｙｃ基因表达活性增高,可能是其动物致癌性的机制之一。     

茶对小鼠免疫功能的保护作用

目的探讨茶叶防癌的免疫调节机理。方法用致癌剂４甲基亚硝胺１（３吡啶）１丁酮（ＮＮＫ）诱发小鼠肿瘤的实验模型，观察ＮＮＫ所致小鼠免疫功能的改变及绿茶（ＧＴ）、复合茶（ＭＴ）和茶多酚（ＴＰ）的保护作用。结果小鼠注射ＮＮＫ后，在观察的４周内，腹腔巨噬细胞吞噬功能、外周血白细胞化学发光、迟发型变态反应、脾细胞抗体生成细胞数、以及脾ＮＫ活性等免疫指标，与正常对照组比较均出现不同程度的增高或降低；而ＧＴ、ＭＴ和ＴＰ对所有这些免疫功能的不良改变有明显的保护作用。结论茶及其成分对ＮＮＫ诱发小鼠肿瘤过程中早期所致免疫功能的改变具有保护作用     

甲基叔丁基醚对大鼠肝组织基因表达的影响

目的甲基叔丁基醚（ＭＴＢＥ）是一种新型的汽油添加剂,动物试验显示其具有一定的致癌性。为了解其动物致癌性的可能机制,我们检测了经ＭＴＢＥ亚慢性染毒的大鼠肝组织中原癌基因ｃｍｙｃ基因和功能基因谷胱甘肽Ｓ转移酶Ｐ（ＧＳＴＰ）基因的表达情况。方法４０只雄性ＳＤ大鼠,体重１８０～２００ｇ,随机分为４组。将ＭＴＢＥ溶于适量豆油中,灌胃染毒,染毒剂量分别为２００ｍｇ／ｋｇ,６００ｍｇ／ｋｇ,１０００ｍｇ／ｋｇ和对照组。每天１次,每周５天,共１３周。动物肝组织于液氮速冻后,一步法提取总ＲＮＡ。随机引物法地高辛标记ｃｍｙｃ和ＧＳＴＰ探针,与ＲＮＡ进行点杂交,图像分析仪分析结果。结果大鼠肝组织中ｃｍｙｃ基因表达水平明显增高,ＧＳＴＰ基因表达未见增强。结论ＭＴＢＥ可明显诱导ｃｍｙｃ基因的高表达,提示其具有促进细胞增殖的作用,这是其动物致癌性的可能机制之一。     

Green tea and its major components ameliorate immune dysfunction in mice bearing Lewis lung carcinoma and treated with the carcinogen NNK

The protective effects of tea and/or its components on dysfunction of immune functions during tumor growth and carcinogenesis in mice were studied using two experimental models: C57/BL6J mice transplanted with Lewis lung carcinoma (LLC) and Kunming mice treated with a single dose of 4-(methylnitrosamino-)-1-(3-pyridyl)-1-butanone (NNK). In C57/BL6J mice bearing LLC, the weight of the thymus decreased, the proportion of CD4(+)-positive T lymphocytes and the ratio of CD4+ to CD8+ decreased, luminol-enhanced chemiluminescence of white blood cells in peripheral blood stimulated by zymosan increased, and plaque-forming cells (PFC) decreased. However, in LLC-bearing mice given green tea as drinking water, all immune functions were improved, along with inhibition of tumor growth. In Kunming mice treated with NNK, during the four weeks of observation, their immunologic indicators, such as phagocytosis of macrophages in the abdominal cavity, luminol-enhanced chemiluminescence of white blood cells, plaque-forming cells, and delayed-type hypersensitivity, increased or decreased to various extents compared with normal controls. However, these changes were significantly prevented in the mice given green tea, mixed tea, or tea polyphenol as drinking water. In conclusion, tea and its components ameliorated immune dysfunction in mice bearing LLC or treated with the carcinogen NNK.     

4-(甲基亚硝胺基)-1-(3-吡啶基)-1-丁酮接触生物标志物的研究进展

4-(甲基亚硝胺基)-1-(3-吡啶基)-1-丁酮(NNK)是烟草特有亚硝胺(TSNA)中具有强烈致癌性的物质之一,NNK在人体和动物体内产生的主要代谢物是4-(甲基亚硝胺基)-1-(3-吡啶基)-1-丁醇(NNAL)和它的糖苷化合物(NNAL-N-Glucuronidec和NNAL-O-Glucuronide).NN...     

Inhibition of lung carcinogenesis and effects on angiogenesis and apoptosis in A/J mice by oral administration of green tea

Oral administration of tea (Camellia sinensis) has been shown to inhibit the formation and growth of several tumor types in animal models. The present study investigated the effects of treatment with different concentrations of green tea on 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)-induced lung tumorigenesis in female A/J mice. Two days after a single dose of NNK (100 mg/kg body weight, i.p.), the mice were given 0.1, 0.2, 0.4, and 0.6% green tea solution (1, 2, 4, and 6 g of tea solids, respectively, dissolved in 1 l of water), 0.02% caffeine, or water as the sole source of drinking fluid until the termination of the experiment. Only the treatment with 0.6% tea preparation significantly reduced lung tumor multiplicity (mean +/- SE, 6.07 +/- 0.77 vs. 8.60 +/- 0.50 tumors per mouse, P = 0.018). Treatment with 0.6% tea also inhibited angiogenesis, as indicated by the lower microvessel density (number of blood vessels/mm2) based on immunostaining for the von Willebrand factor antigen (81.9 +/- 9.5 vs. 129.4 +/- 8.2, P = 0.0018) and anti-CD31 antibody staining (465.3 +/- 61.4 vs. 657.1 +/- 43.6, P = 0.0012). Significantly lower vascular endothelial growth factor immunostaining scores were also observed in the 0.6% tea-treated group (0.98 +/- 0.17 vs. 1.43 +/- 0.07, P = 0.006). The apoptosis index was significantly higher in lung adenomas from 0.6% tea-treated mice based on morphological analysis of cell apoptosis (2.51 +/- 0.18% vs. 1.57 +/- 0.11%, P = 0.00005), and the result was further confirmed using the TUNEL method. Inhibition of angiogenesis and the induction of apoptosis by green tea may be closely related to the inhibition of pulmonary carcinogenesis.     

Effects of oral administration of tea, decaffeinated tea, and caffeine on the formation and growth of tumors in high-risk SKH-1 mice previously treated with ultraviolet B light.

Treatment of SKH-1 mice with ultraviolet B light (UV-B, 30 mJ/cm2) twice a week for 22-23 weeks resulted in tumor-free animals with a high risk of developing malignant and nonmalignant tumors during the next several months in the absence of further UV-B treatment (high-risk mice). In three separate experiments, oral administration of green tea or black tea (4-6 mg tea solids/ml) as the sole source of drinking fluid for 18-23 weeks to these high-risk mice inhibited the formation and decreased the size of nonmalignant squamous cell papillomas and keratoacanthomas as well as the formation and size of malignant squamous cell carcinomas. In one experiment all these inhibitory effects of tea were statistically significant, whereas in the two other experiments many but not all of the inhibitory effects of tea were statistically significant. The decaffeinated teas were inactive or less effective inhibitors of tumor formation than the regular teas, and adding caffeine back to the decaffeinated teas restored biological activity. Oral administration of caffeine alone (0.44 mg/ml) as the sole source of drinking fluid for 18-23 weeks inhibited the formation of nonmalignant and malignant tumors, and this treatment also decreased tumor size in these high-risk mice.     

ERK信号转导通路在CdCl2诱导HEK293细胞低剂量兴奋效应中的作用

目的 探讨ERK信号转导通路在CdCl2诱导HEK293细胞低剂量兴奋效应过程中的作用.方法 以0、0.0005、0.005、0.05、0.5、5、50和500μmol/L浓度的氯化镉(CdCl2)分别染毒HEK293细胞12h和24h;在染毒前分别用ERK1/2抑制剂PD98059(100μmol/L)、U0126(...     

Tea catechins prevent the development of atherosclerosis in apoprotein E-deficient mice

Green tea contains various antioxidative flavan-3ols (tea catechins), such as (-)-epigallocatechin gallate (EGCg, the major catechin), which exert potent inhibitory effects on LDL oxidation in vitro and ex vivo in humans. In this study, the antiatherogenic effects of tea catechins were examined in atherosclerosis-susceptible C57BL/6J, apoprotein (apo)E-deficient mice. Male apoE-deficient mice (10 wk old) were fed an atherogenic diet for 14 wk; during that time, one group (tea) was supplied drinking water supplemented with green tea extract (0.8 g/L), and another group (control) was offered the vehicle only. The tea extract consisted of the following (g/100 g): EGCg, 58.4; (-)-epigallocatechin (EGC), 11.7; (-)-epicatechin (EC), 6.6; (-)-gallocatechingallate (GCg), 1.6; (-)-epicatechin gallate (ECg), 0.5; and caffeine, 0.4. The estimated actual intake of tea catechin was 1.7 mg/(d. mouse). Tea ingestion did not influence plasma cholesterol or triglyceride concentrations. Plasma lipid peroxides were reduced in the tea group at wk 8, suggesting that the in vivo oxidative state is improved by tea ingestion. Atheromatous areas in the aorta from the arch to the femoral bifurcation and aortic weights were both significantly attenuated by 23% in the tea group compared with the control group. Aortic cholesterol and triglyceride contents were 27 and 50% lower, respectively, in the tea group than in the control group. These results suggest that chronic ingestion of tea extract prevents the development of atherosclerosis without changing the plasma lipid level in apoE-deficient mice, probably through the potent antioxidative activity of the tea.     

茶对二甲基苯并蒽诱发金黄色地鼠口腔癌预防作用的研究

选用二甲基苯并蒽（ Ｄ Ｍ Ｂ Ａ）诱发的金黄色地鼠口腔癌模型,研究绿茶、茶色素和混合茶对口腔癌的预防作用,并探讨其防癌机制。试验设阳性对照组（局部涂０５％ Ｄ Ｍ Ｂ Ａ,每周３次,共１５周）、３个饮茶试验组（在涂 Ｄ Ｍ Ｂ Ａ２周前开始分别饮１５％ 绿茶、０１％ 茶色素和０５％ 混合茶至１５周实验结束）和阴性对照组（仅涂丙酮）。结果表明,与阳性对照组相比,绿茶、茶色素和混合茶组对平均瘤数目的抑制率分别为４２６％ 、５０８％ 和６７２％ ,平均瘤负荷抑制率分别为７９４％ 、８８５％ 和９５５％ ;在３组中以混合茶对口腔癌的抑制效果最强。在涂 Ｄ Ｍ Ｂ Ａ 后的第６、１０和１５周,３个茶试验组中均见到口腔上皮细胞微核形成,每核银染核仁组织区（ Ａｇ Ｎ Ｏ Ｒ）颗粒数目和表皮生长因子受体（ Ｅ Ｇ Ｆ Ｒ）的表达低于阳性对照组。表明饮茶对 Ｄ Ｍ Ｂ Ａ 诱发的动物口腔癌有明显的预防作用,而茶预防 Ｄ Ｍ Ｂ Ａ 引起的粘膜细胞 Ｄ Ｎ Ａ 损伤和抑制粘膜细胞增殖可能是其预防口腔癌的重要作用机制。     

Lack of effects of selenium on N-nitrosomethylbenzylamine-induced tumorigenesis, DNA methylation, and oncogene expression in rats and mice.

The effects of dietary selenium deficiency and excess on N-nitrosomethylbenzylamine-(NMBA) induced esophageal neoplasia in rats and forestomach tumors in mice and the effects of dietary selenium on DNA adduct formation and on the activities of DNA adduct-repairing enzyme and oncogene expression in rat esophagus were investigated. The esophageal and forestomach tumors were induced by administration of NMBA by gavage with a total dose of 39 mg/kg body wt in rats and 12 mg/kg body wt in mice. Neither selenium dietary deficiency (Se < 0.02 ppm) nor selenium excess (2.0 ppm) showed any significant effect on the incidence of tumors or number of tumors per tumor-bearing animal. For the DNA adduct formation studies, rats were given a dose of NMBA intraperitoneally after six weeks on the different selenium-containing diets. No significant difference in the amount of the DNA adduct O6-methyldeoxyguanosine was found among the different selenium-treated groups. In a parallel group of rats that did not receive NMBA, the levels of esophageal O6-methyldeoxyguanosine DNA methyltransferase were not significantly altered by dietary selenium levels. The c-myc oncogene expression in rat esophagus was induced by the administration of NMBA (3 mg/kg body wt) by gavage once a week for eight weeks. Dietary selenium did not show any effects on its expression. On the basis of the results of these studies, dietary selenium has no effects in the NMBA-induced tumor model.