Covalent binding of aflatoxin B1 to liver DNA in rats pretreated with ethanol

Summary Male Fischer F-344 rats were given ethanol in the drinking water and/or by single oral administration. Following this, the animals received p.o. 100 ng/kg of the hepatocarcinogen [³H]aflatoxin B₁ (AFB₁). 24 h later, the level of DNA-bound AFB₁ was determined in the liver and was found not to be affected by any type of ethanol pretreatment. A cocarcinogenic effect of ethanol in the liver is therefore unlikely to be due to an effect on the metabolic activation and inactivation processes governing the formation of DNA-binding AFB₁ metabolites.To whom correspondence should be addressed.Acknowledgment. We thank the European Science Foundation for the Toxicology Research Fellowship awarded to M.M.     

Is chlamydial heat shock protein 60 a risk factor for oncogenesis?

Heat shock protein 60 (HSP60) plays an important role in the protein folding of prokaryotic and eukaryotic cells. Most of the papers published on chlamydial HSP60 concern its role in immune response during infection. In the last decade, exposure to Chlamydia trachomatis has been consistently associated with the development of cervical and ovarian cancer. Moreover, it has been suggested that chlamydial HSP60 may have an anti-apoptotic effect during persistent infection. We hypothesize that the accumulation of exogenous chlamydial HSP60 in the cytoplasm of actively replicating eukaryotic cells may interfere with the regulation of the apoptotic pathway. The concomitant expression of viral oncoproteins and/or the presence of mutations may lead to the ability to survive apoptotic stimuli, loss of replicative senescence, uncontrolled proliferation and, finally neoplastic transformation.Received 15 August 2004; received after revision 1 October 2004; accepted 7 October 2004     

EB病毒及化学致癌物DNP对人胚鼻咽粘膜裸鼠移植的诱癌研究

用EBV,DNP及PMA分别或协同对人胚鼻咽粘膜裸鼠移植物进行诱癌研究,探讨上述因素在人实验性鼻咽癌发生中的作用。免疫荧光法检查证实,经B95-8上清液体外及体内转染的人胚鼻咽粘膜上皮表达EBNA。实验结果显示,实验各组均可见各种增生性改变,对照组仅见一般增生性病变。各诱癌组均可见癌前病变,组间无显著性差异。共出现癌8例(1)EBV组:原位癌1例。 (2)EBV+PMA组:早期浸润癌1例。(3)EBV+DNP组:原位癌及浸润癌各1例。(4)EBV+DNP+PMA组:浸润癌1例。 (5)DNP组:原位癌1例。(6)DNP+PMA组:原位癌及浸润癌各1例。结果提示EBV可能在人鼻咽上皮实验性癌变过程中起病因作用。本研究成功诱发了三例浸润癌,均系DAP与其它因素(PMA、EBV)协同作用,提示人鼻咽癌的发生可能与多种致癌因素的相互作用有关。     

TGF-β1在口腔扁平苔藓及鳞癌中的表达

目的:探讨TGF-β1在口腔扁平苔藓、鳞癌发病中的作用及口腔扁平苔藓的癌变机制。方法:应用免疫组化法,检测TGF-β1在口腔扁平苔藓、口腔鳞癌中的表达,并用半定量评估法定量,采用SPSS13.0统计软件对数据进行等级资料的非参数检验。结果:30例口腔扁平苔藓主要呈弱阳性表达,固有层淋巴细胞呈散在阳性;30例口腔鳞癌中13例呈阴性表达,其余多呈弱阳性,二者均与正常口腔黏膜强阳性相比表达明显下调(P<0.05)。但部分口腔癌呈强阳性表达,主要分布在癌的纤维间质中。结论:TGF-β1表达下调激活淋巴细胞导致口腔黏膜局部免疫功能紊乱是引起扁平苔藓发病的重要因素。TGF-β1表达的量和分布的变化促进口腔鳞癌的生长与侵袭,且与口腔扁平苔藓癌变有关。