生物学标志物在大肠癌化学预防中的应用研究

建立大鼠大肠癌动物模型,选用一系列生物学标志物,观察茶对大肠癌的化学预防效果。结果 表明,与阳性对照组相比,在１６和３２周,绿茶组和茶色素组动物大肠细胞增殖细胞核抗原（ＰＣＮＡ）标记指数和核仁组成区嗜银蛋白（ＡｇＮＯＲｓ）颗粒数目显著减少,ｒａｓ－ｐ２１蛋白表达也降低;而且,绿茶和茶色素还抑制了Ｂｃｌ－２蛋白的表达,诱导了Ｂａｘ蛋白的表达。     

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。     

幽门螺杆菌感染与大肠肿瘤的发生及临床病理特点的关系

目的探讨幽门螺杆菌感染与大肠肿瘤的发生及其临床病理特点的关系,为幽门螺杆菌在大肠肿瘤发病中的作用提供依据。方法选择2014年1月-2016年12月医院收治的大肠癌患者70例作为大肠癌组,大肠腺瘤患者70例作为大肠腺瘤组,结直肠镜及组织病理学结果正常者70名作为对照组;统计分析三组临床病理特点资料。结果大肠癌组和大肠腺瘤组幽门螺杆菌感染率分别为68.6%、71.4%,高于对照组的51.4%(P<0.05);大肠癌组患者幽门螺杆菌感染与患者的性别、年龄、肿瘤大小、病理分级、病理类型、淋巴结转移无关;大肠腺瘤组患者幽门螺杆菌感染与患者性别、年龄、肿瘤大小、肿瘤数目、肿瘤蒂部情况、肿瘤病理分型无关。结论幽门螺杆菌感染与大肠癌及大肠腺瘤的发生有关,但与大肠癌及大肠腺瘤的临床病理特点无关。     

茶多酚对二甲肼诱发小鼠大肠肿瘤的抑制作用

用二甲肼诱发ＩＣＲ小鼠大肠癌，同时服用０．４％茶多酚２０周。结果发现茶多酚组结肠肿瘤发生率少于阳性对照组，平均肿瘤数及腺癌百分比均低于阳性对照组；花多酚组小鼠肝微粒体细胞色素Ｐ４５０含量低于阴性对照组和阳性对照组，而肝组织超氧化物歧化酶活性高于阳性对照组，仍低于阴性对照组；茶多酚对小鼠结肠粘膜上皮细胞的增殖指数无明显影响。结果表明，茶多酚对实验性大肠癌有显著的预防作用，其作用机理可能与降低肝脏细胞     

精氨酸对大肠肿瘤增殖细胞核抗原、生存素表达的影响

目的探讨精氨酸(Arg)对大肠肿瘤增殖细胞核抗原和生存素表达的影响。方法将大肠腺瘤和大肠癌患者各60例随机分成两组:试验组、对照组各30例;试验组患者每日口服25%Arg120ml,对照组每日口服5%葡萄糖液120ml,连续3天。干预前、后1日内取肿瘤组织、瘤旁组织和正常大肠黏膜,观察其增殖细胞核抗原和生存素的表达。免疫组织化学法观察增殖细胞核抗原(PCNA)、生存素的表达,表达结果用标记指数表示。结果试验组增殖细胞核抗原标记指数干预前、后分别为腺癌[(78.8±5.6)%,(70.5±4.7)%]、腺瘤[(60.3±6.5)%,(52.9±4.2)%]、癌旁组织[(40.2±4.4)%,(32.7±4.1)%],干预后显著低于干预前(P<0.01)。对照组干预前后差异无显著性。腺瘤瘤旁组织和两组的正常黏膜增殖细胞核抗原表达干预前后差异无显著性。试验组生存素标记指数干预前后分别为腺癌[(67.2±3.8)%,(55.7±6.3)%]、腺瘤[(80.5±6.1)%,(68.4±5.6)%],干预后显著低于干预前(P<0.01)。对照组差异无显著性。结论Arg能够抑制大肠癌和大肠腺瘤高增殖活性及凋亡抑制蛋白生存素的表达,表明Arg对大肠肿瘤的发生和发展可能具有抑制作用。     

肌醇六磷酸对诱癌大鼠大肠组织抗氧化活性的影响

目的建立大鼠大肠癌动物模型,观察肌醇六磷酸(植酸)对诱癌大鼠大肠组织抗氧化活性的影响。方法30只4周龄雄性Wistar大鼠按体重随机分为植酸组和对照组,每组15只。植酸组饮水添加2%植酸钠,对照组自由饮水。2组大鼠均给予皮下注射1,2-二甲肼(DMH),观察肿瘤发生率、肿瘤的数量及体积;测定大肠组织的超氧化物岐化酶(SOD)、谷胱甘肽过氧化物酶(GSH-Px)活性和丙二醛(MDA)含量。结果植酸组大肠癌发生率与对照组相比差异无显著性,植酸组平均每只鼠的肿瘤个数、肿瘤体积均显著低于对照组(P<0.01,P<0.05);植酸组大鼠大肠组织的SOD、GSH-Px活性比对照组显著升高(P<0.01),MDA含量显著降低(P<0.01)。结论植酸可降低诱癌大鼠大肠肿瘤发生的危险,可能通过其抗氧化作用发挥抗肿瘤作用。     

垂体瘤转化基因、p53蛋白在大肠腺瘤与大肠癌组织中的表达

目的 探讨垂体瘤转化基因(PTTG)和p53蛋白在大肠腺瘤、大肠癌及癌旁正常黏膜组织中的表达及其相关性.方法 采用免疫组化方法检测50例大肠腺瘤和42例大肠癌及癌旁正常黏膜组织中的PTTG、p53蛋白表达水平,并分析两者的相关性以及其与临床病理特征的关系.结果 PTTG在癌旁正常黏膜组织中的阳性表达率为7.14％(3/42),p53蛋白未见阳性表达;PTTG、p53蛋白在大肠腺瘤组织中的阳性表达率分别为82.00％(41/50)和90.00％(45/50),表达强度均未达到过度表达标准;PTTG、p53蛋白在大肠癌组织中的阳性表达率分别为88.10％(37/42)和95.24％( 40/42),其中部分呈过度表达,过度表达率分别为45.24％(19/42)和69.05％( 29/42).PTTG和p53蛋白在大肠癌组织中的阳性表达率显著高于癌旁正常黏膜组织及大肠腺瘤组织,且癌旁正常黏膜组织低于大肠腺瘤组织,差异有统计学意义(P＜ 0.05).在大肠腺瘤组织中,PTTG与p53蛋白的阳性表达密切相关(P＜0.05),但在大肠癌组织中,两者之间的阳性表达无明显相关性(P＞ 0.05).此外,PTTG的过度表达与大肠癌淋巴结转移明显相关(P＜0.01),p53蛋白的过度表达则与大肠癌淋巴结转移无明显相关性(P＞0.05).结论 PTTG、p53蛋白的阳性表达在大肠腺瘤组织中密切相关,两者联合观察可以作为大肠腺瘤癌变的分子指标;PTTG、p53蛋白在大肠癌组织中呈过度表达,PTTG与淋巴结转移有关,PTTG的过度表达可以作为判断大肠癌是否有淋巴结转移的分子指标.     

蛋白激酶在双歧杆菌预防大肠癌中的作用

目的　从信号传导这一层次探索双歧杆菌预防大肠癌生长的机理。　方法　以大肠癌裸鼠移植瘤为运动模型 ,预先用青春型双歧杆菌注射于裸鼠腹腔 ,然后以激光共聚焦显微镜检测大肠癌移植瘤组织MAPK家系中的ERK1/ 2、JNK和p38的含量。　结果　双歧杆菌预防组大肠癌组织EPK1/ 2的平均荧光强度明显低于肿瘤对照组 (P <0 .0 1) ,而JNK和p38的平均荧光强度在两组间差异则无显著意义 (P >0 .0 5 )。　结论　青春型双歧杆菌通过抑制ERK1/ 2的活化来预防大肠癌的生长。     

艰难梭菌感染与大肠癌及大肠腺瘤的相关性分析

目的研究艰难梭菌感染与大肠癌、大肠腺瘤的相关性。方法选择2015年9月-2018年5月温州医科大学附属第二医院收治的大肠腺瘤患者354例,为大肠腺瘤组;大肠癌患者257例,为大肠癌组;体检人群60例,为对照组。观察和记录三组对象艰难梭菌感染阳性率、毒素基因。建立多因素Logistic模型,分析有意义变量。结果大肠腺瘤组大肠癌家族史构成比3.39%,大肠癌组7.00%,对照组为0,三组构成比比较,差异有统计学意义(P<0.05)。大肠癌组艰难梭菌感染率12.06%高于大肠腺瘤组4.80%,大肠腺瘤组高于对照组,差异有统计学意义(P<0.05)。大肠癌组毒素A基因(+)毒素B基因(+)检出率90.32%、二元毒素A基因(+)二元毒素B基因(+)检出率6.45%,均高于大肠腺瘤组(P<0.05)。Logistic分析显示艰难梭菌感染是导致大肠腺瘤发生、进展为大肠癌高危风险因素。结论艰难梭菌感染与大肠腺瘤、大肠癌相关性,可能与毒素A基因、毒素B基因和二元毒素等细胞毒性作用于肠道黏膜上皮细胞而产生损伤、破坏效应机制有关,所以艰难梭菌感染在大肠癌发生、发展中具有关键作用。     

细胞周期调控因子cyclinD1、p27、p16在大肠癌中的表达

目的 通过分析大肠癌中cychn D1、p27和p16的表达情况,以及它们与临床病理特征的关系,探讨三者在大肠癌发生、发展中的作用及意义.方法 采用免疫组织化学一步法,分别检测cyclinD1、p27和p16在53例大肠癌组织(大肠癌组)和30例正常大肠黏膜(对照组)中的表达情况,并进行比较.结果 大肠癌组和对照组中cyclinD1阳性表达率分别为64.15%(34/53)、6.67%(2/30);p27阳性表达率分别为30.19%(16/53)、76.67%(23/30);p16阳性表达率分别为43.40%(23/53)、83.33%(25/30).两组比较差异均有统计学意义(P<0.01).中高分化大肠癌患者与低分化大肠癌患者比较,三项指标的阳性表达率差异均有统计学意义(P<0.05).大肠癌Dukes分期A+B期与C+D期cyclinD1、p27和p16阳性表达率比较差异均有统计学意义(P<0.05).结论 cyclinD1、p27和p16与大肠癌的发生及恶性程度有关,可作为评价大肠癌恶性程度的重要指标,并为大肠癌患者临床生物学行为和预后评价提供重要参考.     

Tea preparations protect against DMBA-induced oral carcinogenesis in hamsters

The preventive effects of green tea, tea pigments, and mixed tea (a composite of whole water extract of green tea, tea polyphenols, and tea pigments) on 7,12-dimethyl-benz[a]anthracene (DMBA)-induced oral carcinogenesis in golden Syrian hamsters were studied. The right buccal pouches of animals were topically treated with 0.5% DMBA three times per week for 15 weeks. Animals were killed separately after 6, 10, and 15 weeks of DMBA treatment. Oral tumors were counted and measured, and mean tumor burden was calculated. The incidence of preneoplastic lesions and micronucleated cells, the number and volume of silver-stained nucleolar organizer regions (AgNOR), the labeling index of proliferating cell nuclear antigen, and the level of epidermal growth factor receptor expression were studied. The results showed that oral administration of 1.5% green tea, 0.1% tea pigments, and 0.5% mixed tea as the sole source of drinking water for two weeks before initiation of the DMBA treatment and until the end of the experiment significantly reduced the mean tumor burden and the incidence of dysplasia and oral carcinoma (p < 0.01). The frequency of micronucleated cells, the number of AgNOR, the total volume of AgNORs, the labeling index of proliferating cell nuclear antigen, and the level of epidermal growth factor receptor expression in the oral mucosal cells were also significantly reduced (p < 0.01). These results clearly indicated that tea preparations could effectively inhibit DMBA-induced oral carcinogenesis in hamsters. Protection from DNA damage and suppression of cell proliferation could be important mechanisms of the anticarcinogenic effects of the tea preparations.     

Effects of green tea on colonic aberrant crypt foci and proliferative indexes in rats.

The present study was designed to investigate the effect of green tea on 1,2-dimethylhydrazine (DMH)-induced aberrant crypt foci (ACF) formation in Wistar rats. Forty-five male weanling Wistar rats were randomly divided into three groups. Rats in Group 1 were injected with DMH (20 mg/kg s.c.) once a week for 10 weeks. Animals in Group 2 received 2% green tea water extract as the sole source of drinking fluid in addition to the same treatment used for Group 1. Group 3 was the negative control group. Animals were killed at the end of Week 16 after the first DMH treatment. ACF were formed in animals in their DMH-treated groups at the end of Week 16. Group 2 had fewer ACF than Group 1. Compared with the positive control group, proliferating cell nuclear antigen labeling index, silver-stained nucleolar organizer regions, and ras-p21 expression were significantly reduced in Group 2. It was concluded that green tea drinking inhibited ACF formation in rats, and such effects may be related to the suppression of cell proliferation in the intestinal crypts.     

茶和姜黄素对二甲基苯并蒽诱发地鼠口腔癌的预防作用

以 0 5 %二甲基苯并蒽 (DMBA) ,涂于地鼠左侧颊囊共 6周 (每周 3次 )。在最后一次涂DMBA后 ,分别给地鼠饮 0 6 %的绿茶粉水 ,涂抹姜黄素 1 0 μmol于左侧颊囊 (每周 3次 )或二者联合处理 1 8周。茶与姜黄素二者联合处理显著降低了口腔肿瘤发病率和癌发病率 ,肉眼肿瘤数目和体积、鳞癌和异常增生及乳头状瘤数目也分别显著降低。绿茶和姜黄素单独处理也分别降低了肿瘤数目、肿瘤体积和鳞癌数目。此外 ,绿茶还降低了异常增生数目和姜黄素降低了鳞癌发病率。茶与姜黄素单独或联合处理均抑制了单纯增生、异常增生和乳头状瘤病损的BrdU增殖指数 ,茶单独或与姜黄素联合增加了异常增生和鳞癌病损的凋亡指数 ,姜黄素单独或与茶联合抑制了乳头状瘤和鳞癌病损的新生血管形成。结果表明 ,茶与姜黄素对DMBA诱发的地鼠口腔癌在启动后阶段均有预防作用 ,其机制与抑制细胞增殖、诱导细胞凋亡和抑制细胞新生血管形成有关     

Green Tea Polyphenols Inhibit Colorectal Tumorigenesis in Azoxymethane-Treated F344 Rats

In studying the cancer-preventive activities of green tea polyphenols, we previously demonstrated that dietary administration of polyphenon E (PPE) inhibited the formation of aberrant crypt foci (ACF) in the colon of azoxymethane (AOM)-treated F344 rats. Herein, we reported cancer-preventive activity of PPE using colorectal cancer as an end point. F344 rats were given two weekly injections of AOM, and then maintained on a 20% high-fat diet with or without 0.24% PPE for 34 wk. In the control group, 83% of rats developed colorectal tumors. Dietary PPE treatment significantly increased the plasma and colonic levels of tea polyphenols, and decreased tumor multiplicity and tumor size. Histological analysis indicated that PPE significantly decreased the incidence of adenocarcinoma, and the multiplicity of adenocarcinoma as well as the multiplicity of adenoma. PPE treatment significantly decreased plasma levels of proinflammatory eicosanoids, prostaglandin E2, and leukotriene B4. It also decreased β-catenin nuclear expression, induced apoptosis, and increased expression levels of RXRα, β, and γ in adenocarcinomas. In conclusion, our results convincingly demonstrated the inhibitory effects of orally administered PPE on colon carcinogenesis in AOM-treated rats and suggested possible biomarkers for the biological effects of green tea polyphenols.     

Green Tea and Incidence of Colorectal Cancer: Evidence from Prospective Cohort Studies

A systematic meta-analysis of prospective cohort studies on green tea consumption and colorectal cancer was performed to determine whether green tea has a chemopreventive effect against colorectal cancer. Six eligible cohort studies involving 352,275 participants and 1675 cases of colorectal cancer were identified. Combined relative risk (RR) ratios for the highest vs. lowest and increment of 1 cup/day green tea consumption levels were calculated. The combined RR of 0.90 (95% CI: 0.72–1.08) was found comparing highest vs. lowest green tea consumption levels for colorectal cancer. No significant differences by cancer-site were found, but an inverse association between green tea and incidence of colorectal cancer (RR: 0.70; 95% CI: 0.55–0.85) and colon cancer (RR: 0.69; 95% CI: 0.48–0.98) was demonstrated in Shanghai population. Singapore men had a higher risk of colorectal cancer (RR: 1.36; 95% CI: 1.06–1.74). Furthermore, an increase in green tea consumption of 1 cup/day was not associated with incidence of colorectal cancer (RR: 0.97; 95% CI: 0.91–1.03). Despite the limited evidence from Shanghai studies in support of green tea as potential chemopreventive agents against colorectal cancer, available data from prospective cohort studies are insufficient to conclude that green tea may protect against colorectal cancer.     

Most effective colon cancer chemopreventive agents in rats: a systematic review of aberrant crypt foci and tumor data,ranked by potency

Potential chemopreventive agents for colorectal cancer are assessed in rodents. We speculated that the magnitude of the effect is meaningful and ranked all published agents according to their potency. Data were gathered systematically from 137 articles with the aberrant crypt foci (ACF) end point and from 146 articles with the tumor end point. The potency of each agent to reduce the number of ACF is listed in one table and the potency of each agent to reduce the tumor incidence in another table. Both tables are shown in this review and on a website with sorting abilities (http://www.inra.fr/reseau-nacre/sci-memb/corpet/indexan.html). Potency was estimated as the ratio of the value in control rats to the value in treated rats. From each article, only the most potent agent was kept, except in articles reporting the effect of more than seven agents. Among the 186 agents in the ACF table, the median agent reduced the number of ACF by one-half. The most potent agents to reduce azoxymethane-induced ACF were Pluronic, polyethylene glycol, perilla oil with beta-carotene, and sulindac sulfide. Among the 160 agents in the tumor table, the median agent reduced the tumor incidence in rats by one-half. The most potent agents to reduce the incidence of azoxymethane-induced tumors were celecoxib, a protease inhibitor from soy, difluoromethylornithine with piroxicam, polyethylene glycol, and a thiosulfonate. For the 57 agents present in both tables, a significant correlation (r) was found between the potencies against ACF and tumors (r = 0.45, P < 0.001); without celecoxib, a major outlying point in the correlation, r = 0.68 (P < 0.001, n = 56). In conclusion, this review gathers most known chemopreventive agents, ranks the most promising agents against colon carcinogenesis in rats or mice, and further supports the use of ACF as a surrogate end point for tumors in rats.     

(-)-Epigallocatechin-3-gallate in Camellia sinensis leaves from Himalayan region of Sikkim: inhibitory effects against biochemical events and tumor initiation in Sencar mouse skin.

Recently, we and others showed that the components of green tea may be useful cancer chemopreventive agents. It has been suggested that (-)-epigallocatechin-3-gallate (EGCG), the major constituent in green tea, may possess antitumor-promoting and/or anticarcinogenic effects in rodent tumor bioassay systems. During the chemical analysis of various green tea products, we found a traditionally preserved preparation of green tea used by tribes in the Himalayan region of Sikkim, India that was rich in EGCG. EGCG was isolated from this tea product, and its inhibitory effects were evaluated against the binding of topically applied 3H-labeled polycyclic aromatic hydrocarbons (PAHs) to epidermal DNA and 12-O-tetradecanoylphorbol-13-acetate (TPA) caused induction of epidermal ornithine decarboxylase (ODC) activity in Sencar mice, the short-term markers of tumor initiation and tumor promotion, respectively. Preapplication of EGCG resulted in significant inhibition (p less than 0.05) in the binding of [3H]PAH to epidermal DNA. Similarly, the topical application of EGCG resulted in significant inhibition (p less than 0.005) in TPA-caused induction of epidermal ODC activity. In further studies, we assessed the anti-skin tumor-initiating effect of EGCG in Sencar mice in an initiation-promotion protocol. The application of EGCG before challenge with 7,12-dimethylbenz[a]anthracene as tumor initiator resulted in significant reduction both in percentage of mice with tumors and number of tumors per mouse compared with a non-EGCG-pretreated group of animals. The results of the present study suggest that the green tea preparation from Sikkim may be a good source for the isolation of EGCG and that this compound may have significant potential as a cancer chemopreventive agent.     

Tea as a potential chemopreventive agent in PhIP carcinogenesis: effects of green tea and black tea on PhIP-DNA adduct formation in female F-344 rats

The heterocyclic amine 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) is formed during the cooking of proteinaceous animal foods (meat, chicken, and fish). PhIP is a carcinogen in the Fischer 344 (F-344) rat; it induces mammary tumors in female rats and lymphomas and colon and prostate tumors in male rats. In F-344 rats, PhIP forms DNA adducts in various organs, including the target organs. Inhibition of PhIP-DNA adduct formation is likely to lead to inhibition of PhIP tumorigenicity. We have examined the chemopreventive properties of green tea and black tea in PhIP carcinogenesis by evaluating their effects on PhIP-DNA adduct formation in the female F-344 rat. Young adult animals were maintained on powdered AIN-76A diet while receiving regular drinking water or 2% (wt/vol) infusions of green tea or black tea for a total of six weeks. During Weeks 3, 4, and 5, all animals received PhIP by gavage (1 mg/kg/day). Three rats per group were euthanized on Days 1 and 8 after termination of PhIP exposure. DNA was isolated from a number of organs and analyzed for PhIP-DNA adducts by 32P-postlabeling assays. Compared with animals on regular drinking water, PhIP-DNA adduct formation was inhibited in small intestine, colon, liver, and mammary epithelial cells (MECs) of animals receiving green tea or black tea as the sole source of drinking fluid. Green tea inhibited adduct formation in colon, liver, and MECs (33.3-80.0%) on both days, but only on Day 8 (54.4%) in small intestine. Black tea inhibited adduct formation on both days in liver (71.4-80.0%), on Day 1 in colon (40.0%), and on Day 8 in small intestine (81.8%); it had no effect on MEC adducts. Neither green tea nor black tea had an effect on adduct levels in pancreas, lungs, white blood cells, heart, kidneys, spleen, cecum, or stomach. Similarly, these teas did not affect the rate of adduct removal (percent change from Day 1 to Day 8) in any organ. It is concluded that green tea and black tea are potential chemopreventive agents in PhIP-induced tumorigenesis in the F-344 rat.