DNA修复基因MGMT启动子区过甲基化与食管鳞状细胞癌

目的：O^6－甲基鸟嘌呤DNA甲基转移酶（MGMT）可以转移DNA加合物O^6－甲基鸟嘌呤中的甲基,从而修复DNA损伤,许多肿瘤中发现MGMT基因启动子过甲基化导致该基因失活,我们研究了MGMT基因启动子甲基化状态与食管癌的关系。方法：采用甲基化特异性聚合酶链反应及测序方法分析食管癌。癌旁组织和正常食管上皮中MGMT启动子甲基化状态。结果：在检测的199例食管癌组织中,46例（38．7％）有MGMT基因启动子过甲基化,相应癌旁组织22例中也有5例（22．7％）出现MGMT基因甲基化,而21例正常食管上皮均无此种改变。结论：MGMT基因启动子过甲基化是食管癌中常见的分子事件,可能发生在癌过程的早期阶段。     

细胞凋亡相关基因在食管上皮癌变中的表达及其意义

 目的　探讨食管上皮癌变过程中多个相关的细胞凋亡调控因子的表达状况及其意义。方法　应用碘化丙啶染色和间接免疫荧光标记方法,采用流式细胞术对60例食管癌组织及相应的癌旁组织进行定量检测。结果　bcl-2、c-FLIP基因蛋白在食管癌中的表达皆显著高于癌旁组织,两者比较差异有统计学意义（P＜0.01）;Fadd、Caspase-8和Caspase-3 蛋白在食管癌中的表达皆显著低于癌旁组织,两者比较差异有统计学意义（P＜0.01）。基因相关性比较结果显示,Fadd 与Caspase-8基因蛋白表达之间呈正相关关系（P＜0.01）,与正常黏膜组织和不典型增生组织相比,癌组织中DNA含量明显增高,异倍体细胞显著增加。结论　细胞凋亡的级联调控机制c-FLIP-Fadd-Caspase-8-Caspase-3-bcl-2在食管上皮癌变过程中起着重要作用。食管上皮癌变过程中,DNA含量及异倍体率增加。     

p53基因在人食管诱发癌中的突变

目的 :了解抑癌基因p5 3在人食管癌及其癌旁组织中的突变和致癌作用。方法 :采用PCR SSCP和DNA序列分析等方法对 2 4例人食管鳞状细胞癌术后标本和 2 1例移植到重度完全性免疫缺陷 (severecombinedimmunodefi cient,SCID)小鼠并用或不用N -戊基 -N -甲基亚硝基胺 (N amyl N methylnitrosamine ,AMN)处理的人食管正常组织标本 ,进行了p5 3基因外显子 4～ 8的突变研究分析。结果 :在食管癌组织及癌旁组织均检测出p5 3基因突变 ,其中食管癌组织标本中有 18个突变 ,癌旁组织标本中有 10个 ( 10 /17,5 8 8% )突变 ,主要的突变为G A转换。在 14例用AMN处理的人食管正常组织标本中出现 6个 ( 4 2 9% )突变 ;其中密码子 2 83的突变为G A转换。在人食管癌及其癌旁组织中p5 3基因的突变概率差异无统计学意义。结论 :环境因素或内源性AMN可能是河南林县食管癌高发的主要原因之一     

p53基因在人食管诱发癌中的突变

目的：了解抑癌基因p53在人食管癌及其癌旁组织中的突变和致癌作用。方法：采用PCR-SSCP和DNA序列分析等方法对24例人食管鳞状细胞癌术后标本和21例移植到重度完全性免疫缺陷(severe：comlbined immunocleficient，SCID)小鼠并用或不用N-戊基-N-甲基亚硝基胺(N-amyrl-N-methylnitrosamine，AMN)处理的人食管正常组织标本，进行了p53基因外显子4～8的突变研究分析。结果：在食管癌组织及癌旁组织均检测出p53基因突变，其中食管癌组织标本中有18个突变，癌旁组织标本中有10个(10／17，58．8％)突变，主要的突变为G-A转换。在14例用AMN处理的人食管正常组织标本中出现6个(42．9％)突变；其中密码子283的突变为G-A转换。在人食管癌及其癌旁组织中p53基因的突变概率差异无统计学意义。结论：环境因素或内源性AMN可能是河南林县食管癌高发的主要原因之一。     

hTRT和C-myc的表达在食管上皮增生和癌变过程中的意义

目的：研究食管粘膜上皮癌变过程人端粒酶反转录酶（hTRT）和C－myc蛋白的表达，并探讨其与食管癌发生的关系。方法：应用免疫组化S－P法，观察70例食管癌切除新鲜标本的上切缘正常粘膜，癌旁食管粘膜上皮和食管原位癌组织中hTRT和C－myc蛋白的表达情况。结果：hTRT和C－myc在增生和恶变的食管粘膜上皮细胞表达，两者在食管癌变过程显示相同的分布模式。结论：端粒酶hTRT和C－myc蛋白的表达与食管粘膜上皮的恶性转化密切相关，端粒酶hTRT的重新激活和C－myc的上调表达可能在食管癌的组织发生中起关键性作用。     

食管上皮癌变过程中DNA 含量及细胞周期调控因子表达的定量检测

 目的 探讨食管上皮癌变过程中DNA含量、细胞周期分布的变化及多个相关的细胞周期调控因子的表达状况及其意义. 方法 应用碘化丙啶染色和间接免疫荧光标记方法,采用流式细胞仪对30例食管癌组织及相应的癌旁组织进行定量检测. 结果 与正常黏膜和非典型增生组织相比,癌组织中DNA含量明显增高,异倍体细胞显著增加;G0/G1期细胞明显减少,而S期和G2/M期细胞显著增多,增殖指数（PI）高于癌旁组织;cyclinE、cdk2、p53、E2F基因蛋白过表达,两两之间皆有显著性正相关关系,抑癌基因p21^WAF1基因蛋白表达水平明显降低,与其余基因蛋白之间有明显的负相关. 结论 食管上皮癌变过程中,DNA含量及异倍体率增加,细胞周期分布发生了明显的改变,细胞周期相关基因蛋白表达异常.     

食管拉网细胞端粒酶活性检测及临床应用研究

目的：检测食管拉网细胞中端粒酶活性，探讨其在食管癌诊断及预测预后的临床应用价值。方法：应用端粒重复序列扩增法，对３０例食管拉网细胞标本及相应的癌组织和癌旁正常食管组织进行检测。结果：３０例食管拉网标本中端粒酶活性阳性率为８３．３％（２５／３０），相应癌组织中阳性率为９６．７％（２９／３０），１４例正常食管组织中阳性率为１４．３％（２／１４）。拉网细胞和癌组织中端粒酶阳性率与正常组织相比较差异有显著     

食管HP感染与食管癌的相关性研究

对５９例食管癌的手术切除大体标本和３７例经胃纤维内窥镜活检病理证实食管癌的食管粘膜组织标本（研究组）与对６０例胃炎和２７例溃疡病患者行胃人窥镜活检的食管粘膜组织标本（对照组）用ＨＰＵＴＳＱ－Ｈ１０４进行半定量测试ＨＰ感洒感洒程度的测定结果显示，研究组ＨＰ感洒率（８６．２％）明显高于对照组ＨＰ感染率（２８．７％），随机抽查了２０例食和癌标本用光机电检出癌旁组织ＨＰ感染率１００％。提示食管ＨＰ感染与食     

成束蛋白和膜联蛋白I在食管鳞状细胞癌癌前病变中的表达

背景与目的：研究食管鳞状细胞癌癌变早期异常改变的蛋白质以发现与食管癌早期病变相关的特征性标志分子。探讨了成束蛋白和膜联蛋白Ⅰ在食管癌癌前病变中的表达情况。方法：应用免疫组化方法分析食管癌高发现场癌前病变样本中成束蛋白和膜联蛋白Ⅰ的表达水平，用X^2检验对比成束蛋白和膜联蛋白Ⅰ在不同程度癌前病变和食管癌中的表达差异。其中包括，食管鳞状细胞癌癌前病变54例、正常食管上皮8例和中晚期食管癌9例成束蛋白的表达水平；以及食管鳞状细胞癌前病变52例、正常食管上皮11例和中晚期食管癌7例的膜联蛋白Ⅰ表达水平。结果：与正常食管鳞状上皮相比，成束蛋白在食管癌及其癌前病变中表达增强，其表达阳性率为低度癌前病变（轻度和中度不典型增生）85．7％（24／28）、高度癌前病变（重度不典型增生和原位癌）84．6％（22／26）和中晚期食管癌88．9％（8／9）。然而，膜联蛋白Ⅰ在食管癌及其癌前病变中表达降低或丢失，其表达阳性率分别为低度癌前病变14．3％（4／28）、高度癌前病变8．3％（2／24）和中晚期食管癌0％（0／7）。与正常食管上皮相比，成束蛋白和膜联蛋白Ⅰ在食管低度癌前病变中表达程度的异常均具有显著意义，P值分别为0．003和0．000。结论：成束蛋白异常增强和膜联蛋白Ⅰ的丢失与食管癌癌前病变相关。     

人端粒酶hTRT在癌旁黏膜上皮和食管鳞癌组织中的表达及其意义

目的 研究食管黏膜鳞状上皮和食管鳞癌组织中端粒酶hTRT的表达，并探讨其与食管癌发生、发展的关系。方法 应用免疫组化S—P法，观察10例正常食管黏膜、35例癌旁食管黏膜上皮，120例食管癌组织微阵列中端粒酶hTRT的表达情况。结果 正常食管黏膜鳞状上皮细胞末见端粒酶hTRT阳性表达，癌旁黏膜上皮和癌组织端粒酶hTRT阳性表达串分别为94．3％和81．7％。癌组织hTRT的表达与癌组织的组织学分级、浸润深度和淋巴结转移无关(P＞0．05)。结论 端粒酶hTRT的激活表达与食管黏膜上皮的恶性转化密切相关，端粒酶hTRT的重新激活可能在食管癌的组织发生中起关键性作用。     

Lobe-specific increases in malondialdehyde DNA adduct formation in the livers of mice following infection with Helicobacter hepaticus

Helicobacter hepaticus infection is associated with chronic hepatitis and the development of liver tumours in mice. The underlying mechanism of this liver carcinogenesis is not clear but the oxidative stress associated with H. hepaticus infection may result in induction of lipid peroxidation and the generation of malondialdehyde. Malondialdehyde can react with deoxyguanosine in DNA resulting in the formation of the cyclic pyrimidopurinone N-1,N(2) malondialdehyde-deoxyguanosine (M1dG) adduct. This adduct has the potential to cause mutations that may ultimately lead to liver carcinogenesis. The objective of this study was to determine the control and infection-related levels of M1dG in the liver DNA of mice over time, using an immunoslot-blot procedure. The level of M1dG in control A/J mouse livers at 3, 6, 9 and 12 months averaged 37.5, 36.6, 24.8 and 30.1 adducts per 10(8) nucleotides, respectively. Higher levels of M1dG were detected in the liver DNA of H. hepaticus infected A/JCr mice, with levels averaging 40.7, 47.0, 42.5 and 52.5 adducts per 10(8) nucleotides at 3, 6, 9 and 12 months, respectively. There was a significant age dependent increase in the level of M1dG in the caudate and median lobes of the A/JCr mice relative to control mice. A lobe specific distribution of the M1dG adduct in both infected and control mice was noted, with the left lobe showing the lowest level of the adduct compared with the right and median lobes at all time points. In a separate series of mice experimentally infected with H. hepaticus, levels of 8-hydroxy-deoxyguanosine were significantly greater in the median compared with the left lobe at 12 weeks after treatment. In conclusion, these results suggest that M1dG occurs as a result of oxidative stress associated with H. hepaticus infection of mice, and may contribute to liver carcinogenesis in this model.     

DNA adducts in tumour, normal peripheral lung and bronchus, and peripheral blood lymphocytes from smoking and non-smoking lung cancer patients: correlations between tissues and detection by 32P-postlabelling and immunoassay

Smoking is a major risk factor for lung cancer. This comparative study of smoking-related carcinogen-DNA adducts in pulmonary tissues and peripheral blood lymphocytes aims to further explore the primary DNA damaging processes by cigarette smoke in target and surrogate tissues. Samples of tumour and normal peripheral lung tissue, normal bronchial tissue and peripheral blood lymphocytes were obtained from a total of 85 lung cancer patients who underwent lung resection. Bulky DNA adducts were determined by 32P-postlabelling, and polycyclic aromatic hydrocarbon (PAH)-DNA adducts were detected by (+/-)-7beta, 8alpha-dihydroxy-9alpha,10alpha-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene-DNA chemiluminescence immunoassay (BPDE-DNA CIA) in smaller subsets of tissue samples subject to availability of DNA. Bulky DNA adduct levels ranged between 0.3 and 27.8 adducts/10(8) nucleotides (nt) with mean adduct levels between 2.8 and 11.5 adducts/10(8) nt. Mean PAH-DNA adduct levels were 2.6-6.2 adducts/10(8) nt. Significantly higher bulky DNA adduct levels were detected in smokers' lungs as compared with non-smokers' (P < 0.02). PAH-DNA adduct levels appeared higher in the lungs of smokers compared with non-smokers but the difference was not significant. Lung tumour contained on average a 50% lower DNA adduct level compared with normal lung tissue. A statistically significant positive correlation was found between the DNA adduct levels of the corresponding tumour and normal lung tissue samples in both smokers and non-smokers using both methodologies. Bulky DNA adduct levels in normal lung and blood lymphocytes correlated significantly in non-smokers only (r = 0.55, P = 0.023). In lung tumour DNA samples there was a weak correlation between values obtained by 32P-postlabelling and by the BPDE-DNA immunoassay (r = 0.27, P = 0.054). However, with normal lung DNA samples, values obtained by the two assays did not correlate.     

DNA adduct level in lung tissue may act as a risk biomarker of lung cancer

Lung cancer is a leading cause of mortality in Taiwan. We hypothesised that high susceptibility to DNA damage in the target organ acts as a risk biomarker for the development of lung cancer. To verify this hypothesis, the aromatic/hydrophobic DNA adduct levels of non-tumorous adjacent lung tissues from 73 primary lung cancer patients and 33 non-cancer controls were evaluated by 32P-postlabelling assay. Wilcoxon rank sum test showed that DNA adduct levels in lung cancer patients (49.58+/-33.39 adducts/10(8) nucleotides) were significantly higher than those in non-cancer controls (18.00+/-15.33 adducts/10(8) nucleotides, P<0.001). The DNA adduct levels among lung cancer and non-cancer samples were not influenced by smoking behaviour and cigarette consumption. Our data also showed that the polymorphisms of cytochrome P4501A1 (CYP1A1) Msp1, glutathione S-transferase M1 (GSTM1) and the combination of both genetic polymorphisms were not related to the DNA adduct levels. Interestingly, positive association between CYP1A1 protein expression and DNA adduct levels was found when CYP1A1 protein expression in lung specimens from lung cancer patients was examined by immunohistochemistry. Multivariate linear regression analysis indicated that the DNA adduct level was not associated with gender, smoking behaviour, or genetic polymorphisms of CYP1A1 and GSTM1. Moreover, multivariate logistic regression analysis showed that persons with high DNA adduct levels (>48.66 adducts/10(8) nucleotides) had an approximately 25-fold risk of lung cancer compared with persons with low DNA adduct levels (相似文献   

DNA adducts in normal tissue adjacent to breast cancer: a review

To identify possible extrinsic and intrinsic DNA-damaging factors involved in breast cancer etiology, we measured the level of aromatic and lipid peroxidation-related DNA adducts in samples of normal tissue adjacent to breast tumors obtained from 87 breast cancer patients using 32P postlabeling. Twenty-nine cancer-free women who underwent reduction mammoplasty served as controls. Tissue samples from the breast cancer patients contained significantly higher levels of aromatic DNA adducts (mean +/- SEM: 97.4 +/- 23.4 x 109 nucleotides) than did samples obtained from the controls (mean +/- SEM: 23.5 +/- 6.9 x 109 nucleotides). A bulky benzo[a]pyrene (BP)-like adduct was detected in 41% of the cancer patients, but in none of the controls. The level of this adduct was extremely high in some patients (> 1/106). While 88% of the patients with a smoking history had smoking-specific DNA adducts in their breast tissues, the presence of BP-like adduct was not related to smoking history. The cancer patients also had a significantly higher level of lipid peroxidation-related DNA adducts than did controls. The level of these adducts correlated with the presence of the BP-like adduct. To further explore the origin of the BP-like adduct, we examined the level of polycyclic aromatic hydrocarbon (PAH)-DNA adducts and 8-hydroxyguanine (8-OH-G) in tissue sections obtained from 37 breast cancer patients using immunocytochemistry. We found that patients who had the BP-like adduct showed significantly greater immunostaining for PAH adducts than did those without the BP-like adduct (p = 0.04). In addition, we found that adipocytes tended to have greater immunostaining for the PAH adducts than did epithelial cells. On the other hand, epithelial cells tended to have a higher frequency and greater intensity of staining for 8-OH-G than did adipocytes. The detection of PAH adducts, lipid peroxidation-related DNA adducts, and 8-OH-G in normal breast tissues of breast cancer patients suggests that both exogenous and endogenous DNA-damaging factors may be involved in breast cancer. The exogenous source may involve the types of carcinogen exposure other than cigarette smoking, and the endogenous source may involve oxidative stress associated with normal metabolic activities.     

Lipid peroxidation and DNA adduct formation in lymphocytes of premenopausal women: Role of estrogen metabolites and fatty acid intake

A diet high in linoleic acid (an ω-6 PUFA) increased the formation of miscoding etheno (ε) - DNA adducts in WBC-DNA of women, but not in men (Nair et al., Cancer Epidemiol Biomark Prev 1997;6:597-601). This gender specificity could result from an interaction between ω-6 PUFA intake and estrogen catabolism, via redox-cycling of 4-hydroxyestradiol (4-OH-E(2) ) and subsequent lipid peroxidation (LPO). In this study, we investigated whether in premenopausal women LPO-derived adducts in WBC-DNA are affected by serum concentration of 2- and 4-hydroxyestradiol metabolites and by fatty acid intake. DNA extracted from buffy coat and plasma samples, both blindly coded from healthy women (N = 124, median age 40 year) participating in the EPIC-Heidelberg cohort study were analyzed. Three LPO-derived exocyclic DNA adducts, εdA, εdC and M(1) dG were quantified by immuno-enriched (32) P-postlabelling and estradiol metabolites by ultra-sensitive GC-mass spectrometry. Mean M(1) dG levels in WBC-DNA were distinctly higher than those of εdA and εdC, and all were positively and significantly interrelated. Serum levels of 4-OH-E(2) , but not of 2-OH-E(2) , metabolites were positively related to etheno DNA adduct formation. Positive correlations existed between M(1) dG levels and linoleic acid intake or the ratios of dietary linoleic acid/oleic acid and PUFA/MUFA. Aerobic incubation of 4-OH-E(2) , arachidonic acid and calf thymus DNA yielded two to threefold higher etheno DNA adduct levels when compared with assays containing 2-OH-E(2) instead. In conclusion, this study is the first to compare M(1) dG and etheno-DNA adducts and serum estradiol metabolites in human samples in the same subjects. Our results support a novel mechanistic link between estradiol catabolism, dietary ω-6 fatty acid intake and LPO-induced DNA damage supported by an in vitro model. Similar studies in human breast epithelial tissue and on amplification of DNA-damage in breast cancer patients are in progress.     

Detection of 1,N6-etheno-2'-deoxyadenosine and 3,N4-etheno-2'-deoxycytidine occurring endogenously in DNA

1,N6-Etheno-2'-deoxyadenosine (epsilon dA) and 3,N4-etheno-2'-deoxycytidine (epsilon dC) are DNA adducts formed by a number of genotoxic chemicals, including vinyl chloride. They are also formed endogenously in tissue DNA, probably from a reactive metabolite of lipid peroxidation. Both the qualitative and quantitative detection of endogenous adducts is important in order to place adduct formation by chemicals such as vinyl chloride in the context of this natural background level. Methods with sufficient sensitivity are therefore being developed to measure the natural background of epsilon dA and epsilon dC adducts. We have developed a high-performance liquid chromatography (HPLC)-32P-postlabelling method to measure epsilon dA and epsilon dC at alkylation frequencies of 1 adduct in 10(7)-10(8) nucleotides in 10-microgram samples of DNA. In HPLC-32P-postlabelling analysis of liver DNA from control Wistar rats, epsilon dA and epsilon dC were determined at levels of 1 adduct in 8.1 x 10(7) and 1 adduct in 1.8 x 10(7) nucleotides, respectively. The levels of epsilon dA and epsilon dC measured in liver DNA of animals exposed orally to five daily doses of 50 mg/kg body weight vinyl chloride were found by this method to be 1 adduct in 2.9 x 10(7) and 1 adduct in 1.4 x 10(7) nucleotides, respectively. In contrast, in a direct labelling study, radiolabelled epsilon dA and epsilon dC were not detected in liver DNA of rats exposed for 6 h by nose-only inhalation to [1,2-14C]vinyl chloride at up to 45 ppm v/v. Immunochemical procedures are also being developed for recognizing etheno adducts. Thus, a monoclonal antibody raised to protein conjugates of epsilon dC showed high selectivity in the recognition of this DNA adduct. When the antibody was immobilized on a solid support and used in an immunoenrichment procedure to purify epsilon dC from a large excess of normal nucleotides, one epsilon dC adduct from about 10(8) normal nucleotides could be resolved. Coupling the immunoaffinity enrichment procedure with capillary zone electrophoresis permitted the detection of approximately one epsilon dC adduct in 3 x 10(6) nucleotides.     

Smoking-related DNA adducts in human gastric cancers.

DNA was extracted from the tumour tissue of 26 patients (18 smokers, 8 non-smokers) undergoing surgery for gastric cancer, and analyzed for the presence of DNA adducts by the 32P-post-labelling method. Adducts were detected in all samples tested, and adduct levels ranged from 2 adducts/10(8) nucleotides to 60 adducts/10(8) nucleotides. In male subjects, adduct levels were significantly greater in the DNA of smokers than in that of non-smokers. These results support epidemiological data suggesting that smoking is a risk factor for gastric cancer.     

Determination of malondialdehyde-induced DNA damage in human tissues using an immunoslot blot assay

Malondialdehyde (MDA) is a product of lipid peroxidation and prostaglandin biosynthesis. It is mutagenic and carcinogenic and the major adduct formed by reaction with DNA, a highly fluorescent pyrimidopurinone (M1-dG), has been detected in healthy human liver and leukocyte DNA. Analytical methods used so far for the detection of M1- dG have not been applied to a large number of individuals or variety of samples. Often, only a few microg of DNA from human tissues are available for analysis and a very sensitive assay is needed in order to detect background levels of M1-dG in very small amounts of DNA. In this paper, the development of an immunoslot blot (ISB) assay for the measurement of MI-dG in 1 microg of DNA is described. The limit of detection of the assay is 2.5 adducts per 10(8) bases. A series of human samples were analysed and levels of 5.6-9.5 (n = 8) and 3.1-64.3 (n = 42) of M1-dG per 10(8) normal bases were detected in white blood cell and gastric biopsy DNA, respectively. Results on four human samples were compared with those obtained using an HPLC/32P-post- labelling (HPLC/PPL) method previously developed and indicated a high correlation between M1-dG levels measured by the two assays. The advantages of ISB over other assays including HPLC/PPL, such as the possibility of analysing 1 microg DNA/sample and the fact that it is less time-consuming and laborious, means that it can be more easily used for routine analysis of a large number of samples in biomonitoring studies.      

32P-postlabelling with high-performance liquid chromatography for analysis of abundant DNA adducts in human tissues

Abundant complex DNA adducts can be detected in human tissues by a combined 32P-postlabelling and high-performance liquid chromatography (HPLC) method. The HPLC profiles reveal a panorama of nuclease P1-resistant human adducts, which are not among the known human DNA adducts and are suspected of being endogenous. Lipid peroxidation-induced DNA adducts and I-compounds are two possible candidates for these adducts. Therefore, we performed two experiments: one was to identify chromatographically the lipid peroxidation-induced adducts among other human adducts with two acrolein- and crotonaldehyde-derived propano adduct standards (Acr-dG3 and Cro-dG1&2) and a structurally unknown adduct (Cro-DNA) derived from crotonaldehyde-treated DNA; and the other was to analyse the adducts in breast tissue from patients with breast cancer and from controls and to compare their behaviour with that of I-compounds in cancerous tissues. In the first experiment, Acr-dG3 and Cro-dG1 were detected in three human lung tissues, at levels ranging from 3.4 to 8.9 (x 10(-8)) and from not detectable to 2.9 (x 10(-8)), respectively. Acr-dG3 and Cro-DNA were detected in three human colon tissues, at levels of 0.2-0.4 (x 10(-8)) and 1.2-3.4 (x 10(-8)), respectively. In the second experiment, adjacent and tumorous breast tissues from 15 patients with breast cancer (of an average age of 33.4 years) and normal breast tissue from 18 controls (of an average age of 57.3) were analysed for the abundant complex adducts. The total adduct levels in the adjacent and tumorous tissues were lower than in the normal tissues (with medians of 8.0, 11.8 and 13.3 (x 10(-7)), respectively). Significant differences in the adduct levels between adjacent or tumorous tissues and normal tissues were observed in three HPLC peaks, and age was significantly associated with three peaks. These results are consistent with our speculation that the abundant adducts are comprised of lipid peroxidation-induced adducts and human homologues of I-compounds.     

Detection of DNA-adducts in normal and tumorous human prostate biopsies by p-32 postlabeling

Prostate cancer is the most commonly diagnosed cancer in men and the second leading cause of male cancer deaths in the United States. Several risk factors have been identified for prostate cancer, including increased serum testosterone levels, dietary fat intake, and ethnicity. In attempts to detect DNA damage in prostate tissue, we examined in a pilot study 18 pairs (36 samples) of normal and tumorous tissue biopsies from patients ages 50-76 years. DNA was isolated from frozen tissue by solvent extractions with DNA yield ranging from 392-1925 mu g/g tissue (mean 849 +/- 339 mu g/g). Analysis of the DNA by the nuclease P1-mediated P-32-postlabeling assay revealed the presence of multiple adducts in all DNA samples, irrespective of whether the tissue was normal or tumorous. Adduct levels generally ranged from 1-34 (mean 8 +/- 8) per 10(9) nucleotides for normal tissue and 3-37 (mean 11 +/- 9) per 10(9) nucleotides for tumorous tissue. Our data suggest (i) accumulation of DNA adducts in both normal and tumorous tissues; (ii) chromatographic similarity of certain adducts; and (iii) on an average, somewhat higher adduct levels in tumorous than normal tissue. Due to the small sample size examined, it remains to be determined if these DNA adducts were related to any of the risk factors.