誘發性一氧化氮合成?於人類口腔上皮癌前期病灶及鱗狀上皮細胞癌與DMBA誘發倉鼠頰囊袋鱗狀上皮細胞癌之免疫組織化學及反轉錄聚合?連鎖反應之研究

Nitric oxide (NO) plays a key role in the processes of inflammation and carcinogenesis. Three isoforms of nitric oxide synthase (NOS) have been identified: endothelial NOS (eNOS), neuronal NOS (nNOS), and inducible NOS (iNOS). To date, most cancer studies are concerned with iNOS. The role of iNOS in the oral carcinogenesis remains to be elucidated. The purpose of the present study is to investigate the immunohistochemical and mRNA expression of iNOS in human oral premalignant & malignant epithelial lesions and DMBA-induced hamster buccal carcinomas. Thirty-three outbred adult young (six weeks old) male Syrian golden hamsters were randomly divided into three groups: DMBA (0.5%) painted group（n=13）, mineral oil-treated group（n=10）, and untreated group（n=10）. Surgical human oral specimens with the following histological diagnoses were collected: mild (n=10), moderate and severe (n=10) dysplasia; submucous fibrosis (n=10); verrucous hyperplasia (n=10), verrucous carcinoma (n=10); squamous cell carcinoma (well-differentiated, n=10; moderate-differentiated and poor-differentiated, n=10); normal oral mucosa (n=5). Cytoplasmic and nuclear stainings were observed in both human oral premalignant & malignant epithelial lesions and DMBA-induced hamster buccal carcinomas. Inducible NOS staining was not demonstrated in the human normal oral mucosa, in the untreated or mineral-oil treated hamster pouches. On the other hand, iNOS mRNA expression was demonstrated in all the DMBA-induced carcinomas as well as in the majority of human oral premalignant and malignant epithelial lesions. No iNOS mRNA was detected in the untreated, mineral-oil treated pouches and the human normal oral mucosa. These findings suggested that iNOS may play an important role in the oral carcinogenesis.