Kaplan I, Hochstadt T, Dayan D
Department of Oral Pathology and Oral Medicine The Maurice and Gabriela Goldschleger School of Dental Medicine Tel Aviv University, Tel Aviv ISRAEL.
Med Oral. 2002 Nov-Dec;7(5):336-43.
Saliva has been suggested to have a protective role against carcinogens in the oral cavity in animals. Water-soluble 4NQO is a suitable carcinogen to use in examining the role of saliva in oral cancer. The purpose of this study was to follow the changes induced by the carcinogen at the molecular level, as well as the effect of lack of saliva on these changes.
Topical application to the palate of a 0.5% 4NQO solution dissolved in glycol was used for 4 months to induce malignant transformation in a desalivated rat model. Histomorphometric analysis of proliferating cell nuclear antigen (PCNA), a cell cycle regulator and a proliferation marker, was performed.
Manifestation of PCNA significantly increased as the observed histologic changes progressed from hyperkeratosis, to mild or moderate dysplasia, severe dysplasia and squamous cell carcinoma. Differences in manifestation of PCNA among the diagnostic groups was significant (p< 0.05). In the desalivated group, PCNA expression was significantly higher than in control and normal groups, in both tongue and palate after 2 and 4 months (p< 0.05).
An unknown component of saliva has a temporary anti-carcinogenic protective effect, which can both delay and decrease the level of proliferation induced by the carcinogen 4NQO. The specific salivary component and the mechanism by which this protective effect is rendered are yet to be discovered.
在动物实验中，唾液被认为对口腔中的致癌物具有保护作用。水溶性4NQO是一种适用于研究唾液在口腔癌中作用的致癌物。本研究的目的是追踪致癌物在分子水平上引起的变化，以及缺乏唾液对这些变化的影响。
采用将0.5% 4NQO溶液溶解于乙二醇中局部涂抹于大鼠腭部的方法，持续4个月，以在去唾液大鼠模型中诱导恶性转化。对增殖细胞核抗原（PCNA）进行组织形态计量分析，PCNA是一种细胞周期调节因子和增殖标志物。
随着观察到的组织学变化从角化过度发展到轻度或中度发育异常、重度发育异常和鳞状细胞癌，PCNA的表达显著增加。各诊断组之间PCNA表达的差异具有统计学意义（p<0.05）。在去唾液组中，2个月和4个月后，舌和腭部的PCNA表达均显著高于对照组和正常组（p<0.05）。
唾液中的一种未知成分具有暂时的抗癌保护作用，它既可以延迟致癌物4NQO诱导的增殖水平，又可以降低该水平。这种保护作用的具体唾液成分和作用机制尚待发现。
