Chen Yuk-Kwan, Hsue Shui-Sang, Lin Li-Min
Oral Pathology Department, School of Dentistry, Kaohsiung Medical University, Kaohsiung, Taiwan, ROC.
J Oral Pathol Med. 2002 Feb;31(2):82-6. doi: 10.1046/j.0904-2512.2001.00034.x.
Three isoforms of NO synthase (NOS) have been identified: endothelial NOS, neuronal NOS, and inducible NOS (iNOS). The enhanced expression of iNOS, at the protein level, has been reported previously in certain chemically induced oral carcinomas in hamster buccal-pouch mucosa, however, the corresponding expression of iNOS, at the mRNA level, has not yet been demonstrated. The purpose of the present study is to assess the iNOS mRNA expression level in 7,12-dimethylbenz[a]anthracene (DMBA)-induced hamster buccal-pouch carcinomas using a reverse transcription-polymerase chain reaction (RT-PCR).
Thirty-three outbred, young (six-weeks old), male, Syrian golden hamsters (Mesocricetus auratus) were randomly divided into one experimental group (13 animals) and two control groups (10 animals each). The pouches of a group of 13 animals of the experimental group were bilaterally painted with a 0.5% DMBA solution three times a week for 12 weeks. Each animal of one control group was similarly treated with mineral oil only, while the other control group of 10 animals remained untreated throughout the experiment.
Areas of dysplasia and squamous-cell carcinomas, with a 100% tumor incidence, developed for all of the DMBA-treated buccal pouches. The mineral oil-treated and untreated pouches had no obvious changes. A band of 499-bp, corresponding to iNOS mRNA, was present in all the DMBA-treated hamster buccal-pouch mucosa animals, but not in the untreated animals or the animals treated with mineral oil. Upon direct sequencing, this 499-bp band was confirmed to be part of the iNOS gene.
This study demonstrated that increased iNOS mRNA expression could contribute to the mechanism for experimentally induced oral carcinogenesis.
已鉴定出三种一氧化氮合酶（NOS）同工型：内皮型NOS、神经元型NOS和诱导型NOS（iNOS）。先前有报道称，在仓鼠颊囊黏膜中某些化学诱导的口腔癌中，iNOS在蛋白质水平上表达增强，然而，iNOS在mRNA水平上的相应表达尚未得到证实。本研究的目的是使用逆转录聚合酶链反应（RT-PCR）评估7,12-二甲基苯并[a]蒽（DMBA）诱导的仓鼠颊囊癌中iNOS mRNA的表达水平。
33只远交、年轻（6周龄）、雄性叙利亚金仓鼠（Mesocricetus auratus）被随机分为一个实验组（13只动物）和两个对照组（每组10只动物）。实验组的13只动物的颊囊每周双侧涂抹0.5% DMBA溶液3次，共12周。一个对照组的每只动物仅用矿物油进行类似处理，而另一个由10只动物组成的对照组在整个实验过程中未接受处理。
所有经DMBA处理的颊囊均出现发育异常和鳞状细胞癌区域，肿瘤发生率为100%。经矿物油处理和未处理的颊囊无明显变化。在所有经DMBA处理的仓鼠颊囊黏膜动物中均出现了一条对应于iNOS mRNA的499 bp条带，但在未处理的动物或经矿物油处理的动物中未出现。经直接测序，这条499 bp条带被确认为iNOS基因的一部分。
本研究表明，iNOS mRNA表达增加可能有助于实验性诱导口腔癌发生的机制。
