卵圆细胞的生物学特征及其与肝癌发生的关系

目的通过动态的方法观察卵圆细胞的主要生物学特征及其在肝癌发生过程中的演变规律,揭示卵圆细胞与肝癌发生之间的关系。方法构建实验性肝癌的大鼠诱癌模型,运用常规HE染色、免疫组织化学和爱新蓝染色等方法,动态观察卵圆细胞在肝癌发生过程中的演变规律和分子表达特征。结果随着诱癌时间延长,逐渐出现卵圆细胞的增生、癌前病变、胆管细胞癌和(或)肝细胞癌,各阶段卵圆细胞均表达OV-6、AFP和c-kit。结论原发性肝癌可能与卵圆细胞异常分化有关,卵圆细胞特征性表达为OV-6、AFP和c-kit。     

绿色荧光蛋白转基因小鼠诱导肝癌模型的建立

目的建立绿色荧光蛋白（green fluorescent protein,GFP）转基因小鼠肝癌模型,观察GFP蛋白在诱癌过程中荧光的变化。方法采用二乙基亚硝胺（diethylnitrosamine,DENA）／四氯化碳（CCk,乙醇／DENA诱导肝癌共20周,实验组50只和对照组10只均为GFP转基因小鼠。每周监测小鼠体重的变化;常规HE染色动态观察病理组织学;第4、12、16周处死小鼠取肝组织制作冷冻切片观察荧光表达,并以石蜡HE染色观察病理变化;第20周时处死小鼠取其肝肿物进行原代培养,观察肿瘤细胞中荧光表达和分布。结果实验组GFP转基因小鼠死亡15只,死亡率30％（15／50）。对照组10只小鼠未发生死亡。GFP转基因小鼠在诱癌的第4、12、16、20周依次出现肝炎,肝硬化、癌前病变和癌变等。荧光显微镜下观察到诱癌开始前、第4周、第12周和第16周肝脏组织的冷冻切片有GFP蛋白的表达,诱癌第20周肝肿物原代培养中肿瘤细胞的细胞质和细胞核中有GFP蛋白表达。结论本实验成功建立GFP转基因小鼠肝癌发生的动物模型,可动态观察肝癌细胞中GFP蛋白的表达。     

化学诱导小鼠肝癌模型中CD133的动态变化

目的:检测肝癌干细胞标志CD133在化学诱导C57BL/6J小鼠肝癌过程中各时期的动态变化.方法:通过化学法[二乙基亚硝胺(diethylnirtosamine,DEN)/四氯化碳(carbon tetrachloride,CC14)/乙醇]诱发50只C57BL/6J雄性小鼠肝癌,对照组为45只正常C57BL/6J雄性小鼠.观察小鼠成瘤情况和生长状态,对每2周定期处死小鼠获得的组织标本分别进行病理学切片观察,并采用实时荧光定量PCR、免疫组织化学法、蛋白质印迹法和FCM法分别检测CD133 mRNA和蛋白的表达情况.结果:化学诱导20周后,成功诱发出小鼠肝癌.实时荧光定量PCR和FCM检测结果显示,第8周后诱癌组小鼠肝组织中CD133的表达高于正常对照组,差异有统计学意义(P＜ 0.05或P＜0.001);随着诱癌时间的增加,CD133的表达量呈上升趋势,第16周时诱癌组CD133的表达明显高于前期诱癌组(P＜0.001).蛋白质印迹法检测结果显示,诱癌组CD133蛋白从第4周起出现弱表达,随着诱癌时间的递增,CD133蛋白表达量逐渐增多.免疫组织化学检测结果显示,诱癌组第8周CD133出现弱阳性,第16周出现中等阳性,第20周出现强阳性;而正常对照组无表达.结论:肝癌干细胞标志CD133参与了肝癌的发生、发展全过程,随着诱癌进展其表达量逐渐增加.     

大鼠肝癌发生期间细胞增殖与凋亡关系初探

探讨肝癌发生过程中细胞周期调控下细胞增殖与凋亡的关系。方法：以二乙基亚硝胺诱导的大鼠实验性肝癌为模型,以Ｋｉ－６７抗原和Ｓｕｂ－Ｇ１法分别作为细胞增殖和细胞凋亡定量分析方法。凋亡细胞比例与Ｋｉ－６７阳性细胞比例之比值为描述两者关系的客观指标。结果：除诱癌８周和２０周外,余各实验组的细胞凋亡数目对照组相比均存在明显差异。在肝硬变前期和肝硬变期Ａｐ与Ｋｉ基本呈正比关系。Ａｐ／Ｋｉ于诱癌２、１０、１８周     

β-catenin在小鼠化学肝癌形成过程中的动态变化

目的:检测β-catenin在化学诱导C57BL/6J小鼠肝癌过程中各时期的动态变化。方法:化学法[二乙基亚硝胺(diethylnirtosamine,DEN)/四氯化碳(carbon tetrachloride,CCl4)/乙醇]诱发50只C57BL/6J雄性小鼠肝癌,对照组为45只正常C57BL/6J雄性小鼠。观察小鼠成瘤情况和生长状态,对每2周定期处死小鼠获得的组织标本分别进行病理学切片观察,并采用荧光实时定量PCR、免疫组织化学法和蛋白质印迹法分别检测β-catenin mRNA和蛋白的表达情况。结果:化学诱导20周后,成功诱发小鼠肝癌。荧光实时定量PCR第4周起小鼠肝癌组织中β-catenin的表达高于正常对照组,差异有统计学意义(P<0.05)。随着诱癌时间的增加,β-catenin的表达量呈上升趋势,第18和20周时诱癌组β-catenin的表达明显高于前一诱癌组(P<0.05)。蛋白印记法及免疫组化检测发现诱癌组第4周起至第14周细胞核内β-catenin有表达,细胞质内的表达也较正常对照组多,细胞膜表达减弱,这期间诱癌组间细胞核和细胞浆内β-catenin表达无明显差异。第16周可发现细胞浆内的β-catenin蛋白表达较之前时间组降低,第20周降至最低。而第18周和第20周细胞核的β-catenin蛋白表达明显多于前面时间段,第20周最多。细胞膜无表达。结论:随着肝癌演变,细胞浆内的β-catenin蛋白有可能向细胞核内移位,致使细胞核内β-catenin蛋白更进一步累积,激活一系列靶基因,导致肝癌形成。β-catenin蛋白在细胞膜、细胞浆和细胞核中分布在正常肝脏组织、肝硬化、肝癌这一过程中均不相同,表明β-catenin与肝癌的发生发展有密切关系。     

肝癌干细胞表面标志物CK19在化学诱癌过程中的差异表达

目的检测CK19基因在化学诱发C57BL/6J小鼠肝癌过程中各阶段的表达差异。方法对50只C57BL/6J雄性小鼠通过化学法诱发肝癌,以50只正常C57BL/6J雄性小鼠为对照组。观察诱癌小鼠的生长状况,每4周处死一批小鼠获取组织标本进行病理学、荧光实时定量PCR(FQ-RT-PCR)法、Western blot等检测CK19基因及蛋白表达差异。结果在化学诱癌第16周后处死的小鼠出现明显的灰白色小结节,直径为2 mm大小,第20周时肝癌结节直径在5 ~25 mm之间,呈多发性。早期病理改变主要是肝细胞排列结构轻度紊乱,细胞轻度的异型增生。病理切片显示为中、高分化的肝癌细胞,可见瘤巨细胞和病理性核分裂,间质肝纤维组织增生,提示有肝硬化改变;RT-PCR,Western blot 结果显示,实验组小鼠在化学诱癌第16周开始CK19-mRNA表达升高,第20周时明显增强;荧光定量结果显示,CK19 mRNA在化学诱癌第4、8、12、16及20周的小鼠肝癌组织中的表达水平分别为(2.133±0.470)、(2.395±0.472)、(2.767±0.729)、(3.217±0.627)和(14.095±5.812),与同期对照组比较差异具有统计学意义（P<0.05）。结论肝癌干细胞标志物CK19参与了肝癌的发生发展,其表达量随诱癌时间的延长而逐渐增加,但其对肝癌发生发展的确切调控机制有待深入研究。     

肝癌干细胞标志CD90在化学诱癌过程中的动态变化

目的检测CD90在化学诱导C57BL/6J小鼠肝癌过程中各时期的动态变化。方法实验组通过化学法诱导50只C57BL/6J雄性小鼠肝癌,对照组为50只正常C57BL/6J雄性小鼠。观察小鼠成瘤情况和生长状态。对每4周定期处死的小鼠组织标本进行病理学观察,应用RT-PCR和荧光实时定量PCR(FQ-RT-PCR)、Western印迹法技术检测100只小鼠肝组织及相应阶段正常肝组织CD90 mRNA及其蛋白表达情况。结果在化学诱癌第16周时,小鼠肝脏表面开始出现结节样变化,直径约2mm,呈灰白色,多发性。病理改变主要是肝细胞排列轻度紊乱,细胞轻度异型增生。第20周时肝癌结节直径在5～25mm之间,镜下为中、高分化的肝癌细胞;RT-PCR检测结果显示,实验组在16周以前CD90蛋白不表达。FQ-RT-PCR、Western blot检测结果显示,CD90 mRNA在化学诱癌16周以前,实验组与对照组比较差异无统计学意义(P>0.05),但在诱癌16周以后,CD90表达呈显著性增加,实验组与对照组比较,差异具有统计学意义(P<0.05)。结论肝癌干细胞标志物CD90在肝癌的发生、发展过程中,其蛋白表达随着诱癌时间的延长而逐渐增加,认为CD90对肝癌的发生、发展有一定的调控作用。     

PH+DENA+PB诱发的大鼠肝癌中间病变研究

本文选用健康SD大鼠160只,用PH+DENA+PB诱癌模型,即:在肝大部切除术(PH)后18-24hrs腹腔注射二乙基亚硝胺(DENA)10mg/kg进行启动,一周后饮水中加入0.05％的苯巴比妥(PB)进行促进,在1周和1、2、3、4、5、7和10月末分批股动脉放血处死动物,用H.E.染色、酶组化和免疫组化对照观察和体视学定量的方法,对该模型产生的肝癌中间病变的演变过程和转变灶、结节发生的时间、部位、性别差异进行了研究。     

细胞色素超家族基因在DEN诱发大鼠肝癌过程中的表达特征

[目的]探讨细胞色素基因在肝癌发生过程中表达的特征。[方法]对正常大鼠肝组织以及DEN诱癌后大鼠第4周、8周、16周、20周（肝癌形成）含肝癌组织Affymetrix Rat 230A GeneChip芯片所检测数据标准化处理后，进行差异分析。[结果]从芯片中共筛选出与细胞色素有关的基因81个，其中已知的细胞色素超家族成员58个，包括40个细胞色素P450（Cyp）基因家族成员和11个细胞色素C氧化酶（cytochrome c oxidase，Cox）基因家族成员，以及7个其它成员；其次，在整个DEN诱癌过程中，表达有显著性变化的细胞色素基因有19个，包括9个明显上调的基因和10个明显下调的基因。[结论]细胞色素、尤其是细胞色素P450家族成员可能在大鼠肝癌发生过程发挥重要作用，值得注意的是Cypla1、Cypla2、Cyp3a3、Cyp4bl和Cyp27bl等人类癌症相关基因．以及Cyp26al、Cyba和CoxVa等人类共有基因．变化显著．可能有助于对人类肝癌发生过程的研究及肝癌的诊治。     

实验性大鼠肝癌形成过程中c—myc,Ha—ras,Ki—ras的表达特点及其生物意义

目的：通过动态观察ｃ－ｍｙｃ、Ｈａ－ｒａｓ和Ｋｉ－ｒａｓ在实验性大鼠肝癌形成过程中的表达变化，探讨上述原癌基因与肝癌发生的关系及其生物学意义。方法：用３＇－Ｍｅ－ＤＡＢ饲喂ＳＤ大鼠，分别于第４，６，８，１４和１７周处死大鼠，取其肝脏，石蜡包埋，并进行核酸原位杂交。结果：在诱癌全过程中，ｃ－ｍｙｃ和Ｈａ－ｒａｓ均为同步表达；在诱癌的早期即可检测到较多ｃ－ｍｙｃ和Ｈａ－ｒａｓ的阳性表达细胞，而Ｋｉ－ｒａｓ的细胞数则很少，且反应强度弱；而诱癌后期，各癌基因ｍＲＮＡ阳性表达细胞均减少；至第１７周，所有癌组织内均显示三种癌基因表达阴性，或仅见个别小癌巢内少数癌细胞呈弱阳性。而癌旁肝组织内却可见三种癌基因的大量表达。结论：ｃ－ｍｙｃ和Ｈａ－ｒａｓ被激活是肝癌发生过程中的早期事件，且二者之间具有协同作用，这种协同作用在肝癌的启动上可能具有重要意义；Ｋｉ－ｒａｓ的激活则发生较晚，可能与促进细胞恶性转化有关。     

Antigenic relationship between oval cells and a subpopulation of hepatic foci, nodules, and carcinomas induced by the "resistant hepatocyte" model system

Although proliferation of small ductular-like cells, designated oval cells, is often observed during the early stages of chemically induced hepatocarcinogenesis, their role during the carcinogenic process remains controversial. To investigate the possibility that oval cells may give rise to preneoplastic lesions that ultimately progress to hepatocellular carcinomas, we have carried out phenotypic analysis with a panel of monoclonal antibodies to determine if there is an antigenic relationship between oval cells and hepatic foci, nodules, and tumors induced by the resistant hepatocyte model system. In this model, rats are given a single dose (200 mg/kg) of diethylnitrosamine, followed by a brief exposure to 2-acetylaminofluorene and a partial hepatectomy. We found that approximately 10% of the early focal lesions observed 28 days after diethylnitrosamine expressed either one or both of the oval cell antigens designated OC.2 and OV-6. By 28 weeks after diethylnitrosamine, 16 of 16 hepatic nodules heterogeneously expressed OV-6 whereas 5-10% of the persistent nodules contained scattered small hepatocyte-like cells that expressed OC.2. Examination of resistant hepatocyte-induced primary hepatocellular carcinomas with an expanded panel of monoclonal antibodies demonstrated that most cells comprising 29 of 29 tumors expressed OV-6 and that 15-20% of the OV-6-positive tumors contained subpopulations of cells also expressing 3 additional oval cell antigens, OC.2, OC.3, and OV-1. All of the tumors examined expressed normal levels of the hepatocyte antigens, H.1 and HBD.1, and had dramatically reduced levels of H.2, H.4, and cell CAM 105 but showed elevated levels of the transferrin receptor, gamma-glutamyltranspeptidase, and the normal hepatocyte antigen, H.5. In conclusion, our findings demonstrate an antigenic relationship between oval cells and a subpopulation of hepatic foci, nodules, and tumors in the resistant hepatocyte model, suggesting that at least some primary tumors may be derived from oval cells in this model system.     

Persistence of the cholangiocellular and hepatocellular lesions observed in rats fed a choline-deficient/DL-ethionine-supplemented diet.

Male outbred Sprague-Dawley rats were fed a choline-deficient diet containing 0.10% DL-ethionine (CDE) for 4, 6, 10, 14 or 22 weeks followed by a standard diet for up to 59 weeks. Liver sections were histochemically analyzed for the following parameters: basophilia, glycogen content and the activities of glycogen synthase (SYN), glycogen phosphorylase (PHO), glucose-6-phosphatase (G6PASE), glucose-6-phosphate dehydrogenase (G6PDH), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), glycerin-3-phosphate dehydrogenase (G3PDH), 'malic enzyme' (MDH), alkaline phosphatase (ALKPASE) and gamma-glutamyltranspeptidase (GGT). The stop experiments revealed that many of the oval cells proliferating during the first 4-6 weeks may undergo necrotic changes and disappear with time, whereas cholangiofibroses appearing in animals fed CDE for at least 10 weeks are persistent lesions. The sequence of lesions seen in this study, leading from persistent oval cells through cholangiofibroses to cholangiofibromas, strongly suggests that the oval cells are the precursor cells of cholangiocellular tumors. The proliferating oval cells and the hepatic foci consisting of clear and acidophilic or mixed cell populations were always spatially separated and no transitions between oval and parenchymal cells were observed. These results argue against a precursor-product relationship between oval and parenchymal cells. Both proliferating and persistent oval cells, cholangiofibroses and cholangiofibromas showed a strong staining for G6PDH, GAPDH, G3PDH, MDH, ALKPASE and GGT; low PHO, SYN and G6PASE activities were also detected in these lesions. Persistent glycogen-storage foci, which developed in all rats fed CDE for 4-14 weeks followed by a normal lab chow for over a year, had increased PHO, G6PDH, MDH, ALKPASE and GGT activities, while SYN, GAPDH and G3PDH activities remained unaltered and G6PASE activity decreased. Mixed cell foci appearing in animals fed CDE for 22 weeks followed by a normal lab chow for 59 weeks had strongly increased G6PDH, GAPDH, G3PDH, MDH, ALKPASE and GGT activities as well as decreased G6PASE activity. These results indicate that the characteristic metabolic pattern of preneoplastic hepatic foci is independent of the further administration of the carcinogenic diet. The shift from glycogen metabolism to glycolysis and the pentose phosphate pathway occurring during the later stages of CDE-induced hepatocarcinogenesis is an autogenous process apparently directing the disturbed carbohydrate metabolism towards alternative metabolic pathways. A similar metabolic shift also seems to take place during cholangiocarcinogenesis.     

3′-Me-DAB诱导大鼠肝癌发生过程中p53及相关基因mRNA的定量分析

背景与目的:有关肝癌中 p53基因突变及 p53蛋白表达异常已有报道 , 但其在 mRNA水平上的变化尚不清楚 . 为了解在肝癌发生、发展和预后过程中 p53、谷胱甘肽转硫酶 P( glutathione S-transferase P,GST-P) 、甲胎蛋白 ( α -fetoprotein,AFP) 和白蛋白 mRNA水平的变化 , 本研究定量分析癌前病变和癌灶中 GST-P、 AFP和白蛋白 mRNA的量 . 方法:在 3′ -甲基 -4-二甲胺偶氮苯 (3′ -methyl-4-dimethylaminoazobenzene,3′ -Me-DAB)诱发 F344大鼠肝癌过程中 , 用激光捕获显微取样仪 (LCM)准确获得大鼠肝脏中微小癌灶或癌前病变组织后 , 采用 LightCyclerTM V3 System 实时 (real-time)RT-PCR定量分析这些病灶组织中 mRNA水平 . 结果:在实验的第 6、 12和24周,癌前病变组织中p53mRNA量均显著高于正常组织(P≤0.001)。从第6周到第24周,癌前病变组织中p53mRNA逐渐降低(P<0.01)。癌组织中p53mRNA含量高于正常组织,低于同期癌前病变组织(P=0.028和0.0136)。第24周的癌前病变组织或癌组织中细胞核呈p53强染色。各实验期,癌前病变中GST-PmRNA量明显高于正常组织和癌组织(P<0.001)。癌组织中AFPmRNA的表达量显著高于癌前病变组织和正常组织(P<0.001),白蛋白mRNA的表达量显著低于这两种组织(P<0.01)。GST-P和AFP分别在癌前病变组织和癌组织中呈灶状强表达。结论：GST-P和AFPmRNA分别在癌前病灶组织和癌组织中强表达,是这些病变组织的重要标志物。p53mRNA在早期肝癌前病变和癌灶中显示高水平的表达,而较晚期p53蛋白升高。     

Different lineages of chemically induced hepatocellular carcinoma in rats defined by monoclonal antibodies

Different lineages of hepatocellular carcinoma (HCC) were identified by the application of selected monoclonal antibodies to the study of the sequential histopathological changes which occurred during two regimens of chemical carcinogenesis in the rat. One regimen, that of Solt-Farber, caused prominent oval cell proliferation and large multiple neoplastic nodules, and the other regimen, continuous administration of diethylnitrosamine, produced minimal oval cell proliferation and a few small nodules. However, both regimens produce HCC in most exposed rats. Three monoclonal antibodies to liver cells, OV-6, H-4, and T-6, were selected on the basis of different tissue staining. OV-6 stains the cytoskeleton of bile duct cells, oval cells, and HCC but not that of hepatocytes. H-4 stains the cytoplasm of hepatocytes but of not hepatomas. T-6 stains the cytoskeleton of HCC only. In the Solt-Farber model, the monoclonal antibodies identified groups of hepatocytes within the persistent neoplastic nodules which had acquired the OV-6 epitope and had lost the H-4 epitope. HCC derived from this regimen had the same staining pattern, suggesting that the OV-6 positive H-4 negative hepatocytes were the precursors of the HCC. The presence within the nodules of oval cells, atypical duct structures, cells intermediate between duct cells and hepatocytes, and nodular hepatocytes all containing the OV-6 epitope raises the possibility that any of these cell types could serve as the precursor of the OV-6 positive hepatocytes that arose within the nodule. In the continuous diethylnitrosamine regimen a different staining pattern was seen. T-6 positive hepatocytes first appeared in periportal areas by the 5th week. These cells increased in numbers during the later weeks and with rare exceptions neither acquired the OV-6 epitope nor completely lost the H-4 epitope. Most HCC derived by the continuous diethylnitrosamine regimen were T-6 positive and OV-6 negative, suggesting a direct lineage from the periportal T-6 positive hepatocytes. These findings indicate that the lineage and phenotype of chemically induced HCC may vary with the carcinogenic regimen used and that HCC which arise in nodules may originate from cell types other than typical nodular cells.     

Hepatic oval cell response to the choline-deficient, ethionine supplemented model of murine liver injury is attenuated by the administration of a cyclo-oxygenase 2 inhibitor

Oval cell proliferation precedes neoplasia in many rodent modelsof hepatocellular carcinoma and prevention of this proliferativeresponse can reduce the risk of subsequent carcinoma. This studyaimed to determine whether a selective cyclo-oxygenase-2 (COX-2)inhibitor, SC-236, affects (i) the oval cell response to liverinjury in a mouse model of hepatocarcinogenesis and (ii) anoval cell line. Four-week-old mice were fed either normal chowor a choline deficient, ethionine supplemented (CDE) diet inthe presence or absence of SC-236. Liver histology and ovalcell numbers were determined after 2, 4, 12 and 52 weeks oftreatment. Oval cells were scored using morphological criteriaand positive immuno-staining for the M₂-isozyme of pyruvatekinase (M2PK) or A6. An immortalized oval cell line (PIL-2)was used to study the in vitro effects of SC-236 on oval cellproliferation, apoptosis and Akt phosphorylation. The percentageof M2PK-positive oval cells and COX-2-positive cells was reducedby 80% and 45%, respectively, in CDE-fed mice receiving SC-236compared with CDE-fed animals not receiving SC-236. Some M2PK-positiveoval cells were also COX-2 positive. The percentage of A6-positivecells was not affected by SC-236 administration to CDE-fed mice.Administration of SC-236 increased apoptosis as evidenced bya 73% increase in the number of TUNEL-positive cells at 2 weeksin CDE-fed mice. Primary oval cells and PIL-2 cells expressedCOX-2. In vitro treatment of PIL-2 cells with SC-236 resultedin a dose-dependent preferential death of A6-negative cells.Administration of 25 and 50 µM Prostaglandin E₂ partiallyattenuated SC-236 induced cell death by 25%. In vitro oval celldeath was associated with apoptosis and a 70% reduction in Aktphosphorylation. These results suggest that the SC-236 inducedreduction of M2PK-positive oval cell numbers may be due to COX-2dependent inhibition of Akt phosphorylation and induction ofapoptosis.     

Fumonisin B1-induced hepatocellular and cholangiocellular tumors in male Fischer 344 rats: potentiating effects of 2-acetylaminofluorene on oval cell proliferation and neoplastic development in a discontinued feeding study

Fumonisin B1 (FB1) is a naturally occurring mycotoxin produced by Fusarium verticillioides. Dietary exposure to FB1 has been linked to human cancer in certain parts of the world, and treatment with FB1 causes oval cell proliferation and liver tumors in rats. To study the potential role of oval (liver progenitor) cells in the cellular pathogenesis of FB1-induced liver tumors, we gave male F344 rats prolonged treatment with FB1 for 25 weeks, followed by return to control diet until 50 weeks ('stop study'). The time course of FB1-induced liver lesions was followed by examination of serial liver biopsies at set time intervals and post-mortem liver tissue at the end of the study. The effects of different FB1 treatment regimens (5 versus 25 weeks), as well as the modulating effect of 2-acetylaminofluorene (2-AAF), on the kinetics of oval cell proliferation and development of liver tumors were compared. Prolonged treatment with FB1 in normal diet caused persistent oval cell proliferation and generation of both hepatic adenomas and cholangiofibromas (CFs). These liver lesions occurred in the setting of chronic toxic hepatitis and liver fibrosis/cirrhosis, similar to that seen in human hepatocarcinogenesis. Some adenomas and CFs were dysplastic, and one post-mortem liver contained a hepatocellular carcinoma. OV-6+ oval cells were noted in close relation to proliferative neoplastic liver lesions, and some of these lesions expressed OV-6, suggesting that all these cell types were derived from a common progenitor cell. 2-AAF enhanced the size of FB1-induced glutathione S-transferase pi+ hepatocellular lesions and the incidence of CFs in post-mortem liver specimens, but this was not statistically significant. In conclusion, this study supports the involvement of dietary FB1 in liver carcinogenesis in male F344 rats. Oval cells may be the source of both the hepatocellular and cholangiocellular tumors induced by prolonged treatment with FB1. 2-AAF appears to have an enhancing effect on FB1-induced liver tumors, presumably due to its potent inhibitory effects on hepatocyte regeneration.     

Ethanol interactions with a choline-deficient,ethionine-supplemented feeding regime potentiate pre-neoplastic cellular alterations in rat liver

To examine the effect of ethanol on hepatocarcinogenesis induced by a choline-deficient, ethionine-supplemented (CDE) diet, rats were fed either an ethanol-supplemented diet or ethanol-free, isocaloric diet for 2 months, followed by a CDE diet or control diet for up to 8 months. Changes to cellular composition and pattern of gene expression in the liver were determined at 0 and 3 days, and 1, 2 and 3 weeks after commencing the CDE diet, using histological/immunochemical techniques and northern analysis. Oval cells in the liver were identified morphologically and by expression of pi-glutathione S-transferase (pi-GST), alpha-fetoprotein (AFP) and the embryonic isoform of pyruvate kinase (M2-PK). Oval cell numbers and changes in the pattern of gene expression induced by the CDE diet were accelerated by pre-treatment with ethanol. At all stages, the proportion of oval cells in the test group exceeded that in controls. After 1 week, oval cells had spread sufficiently from the periportal region to be observed pericentrally in test animals and by 3 weeks, extensive formation of ductal structures was apparent, which were absent in controls. Additionally, M2-PK and AFP mRNA were detected earlier, and in greater abundance in animals pre-treated with ethanol. After 8 months of CDE treatment, one or two small hepatic foci (<10 hepatocytes), strongly positive for pi-GST, were detected in the liver of ethanol-pre-treated animals. These foci were absent in CDE-treated animals; however, animals pre-treated with ethanol followed by chronic CDE treatment showed increased size (>40 hepatocytes) and numbers of foci, correlating with the extent of liver damage and varying from 5 to 50% of the liver section. Our data suggest that ethanol pre-treatment potentiates the short-term effects of the CDE diet by enhancing oval cell proliferation, while chronic CDE administration enhances the appearance of pre-malignant hepatic foci that are observed with ethanol pre-treatment alone.