Lurie A G, Coghill J E, Rozenski D L
Department of Oral Diagnosis, School of Dental Medicine, University of Connecticut Health Center, Farmington 06032.
J Natl Cancer Inst. 1988 May 18;80(6):407-14. doi: 10.1093/jnci/80.6.407.
Studies examined the binding of radiolabeled 7,12-dimethylbenz[a]anthracene (DMBA) to epithelial DNA of hamster cheek pouch (HCP) maintained in organ explant culture. Adduct formation was studied as functions of [3H]DMBA dose, of the time after single [3H]DMBA applications, and of the route by which the DMBA was administered--either topically or in the culture media. Total DMBA-DNA adduct formation [total binding index (TBI)] was determined by DNA-bound 3H activity, and qualitative binding characteristics were further studied by high-pressure liquid chromatography. [3H]DMBA was applied either in the culture media at concentrations of 0.005-0.5 micrograms/ml or topically in mineral oil or ethanol in doses of 0.005-0.5 micrograms to each tissue fragment. Histopathologic changes in DMBA-treated HCP fragments included substantial aberrations in maturation of cornified and keratin layers and focal squamatization and dysplasia of the basal epithelium--considerable tissue necrosis was encountered in the high-DMBA-dose groups. Dose-response data were qualitatively similar among treatment types, with the greatest TBIs in topical ethanol groups and the lowest TBIs in culture medium groups. Kinetics of adduct formation and removal showed a rapid increase in TBIs to peak values at 24-72 hours followed by a biphasic decrease in TBIs, which leveled off at 7%-20% of peak values at 120-240 hours. Chromatographic analyses of selected samples at various times from all treatment groups showed three major peaks that are likely to be the same 1,2,3,4-tetrahydro-3,4-dihydroxy-1, 2-oxide-deoxyribonucleoside adducts observed in other rodent in vivo and cell culture systems. These results are consistent with those of other laboratories studying DMBA-DNA interactions and suggest that in vitro studies of DMBA-treated HCP explants are useful in studying the molecular nature of DMBA-DNA interactions in oral mucosal carcinogenesis.
多项研究检测了放射性标记的7,12-二甲基苯并[a]蒽（DMBA）与器官外植体培养中仓鼠颊囊（HCP）上皮DNA的结合情况。研究了加合物形成与[³H]DMBA剂量、单次应用[³H]DMBA后的时间以及DMBA给药途径（局部给药或加入培养基中）之间的关系。通过DNA结合的³H活性测定总DMBA-DNA加合物形成[总结合指数（TBI）]，并通过高压液相色谱进一步研究定性结合特征。[³H]DMBA以0.005 - 0.5微克/毫升的浓度加入培养基中，或以0.005 - 0.5微克的剂量局部滴加在矿物油或乙醇中，施加于每个组织片段。DMBA处理的HCP片段的组织病理学变化包括角质化和角质层成熟的显著异常，以及基底上皮的局灶性鳞状化生和发育异常——在高DMBA剂量组中出现了相当程度的组织坏死。不同处理类型之间的剂量反应数据在性质上相似，局部乙醇组的TBI最高，培养基组的TBI最低。加合物形成和去除的动力学显示，TBI在24 - 72小时迅速增加至峰值，随后呈双相下降，在120 - 240小时稳定在峰值的7% - 20%。对所有处理组不同时间的选定样本进行色谱分析，显示出三个主要峰，可能与在其他啮齿动物体内和细胞培养系统中观察到的1,2,3,4-四氢-3,4-二羟基-1,2-氧化物-脱氧核糖核苷加合物相同。这些结果与其他研究DMBA-DNA相互作用的实验室结果一致，表明对DMBA处理的HCP外植体进行体外研究有助于研究口腔黏膜致癌过程中DMBA-DNA相互作用的分子本质。
