초록
The proto-oncogene bcl-2 confers a survival advantage to cells by blocking programmed cell death (apoptosis). Overexpression of bcl-2 probably plays a role in tumorigenesis, and the expression of the bcl-2 protein has been investigated in many kinds of tumors. An increased expression of nitric oxide synthetase(NOS) has been observed in human colon cancer cell lines as well as in human gynecological, breast, and CNS tumors. However there have been only a few reports on the expression of bcl-2 and $NOS_2$ in oral white lesions and cancer. The aim of this study was to investigate the relationship between the expression of Bcl-2 and $NOS_2$ and several pathological parameters such as histological types and layers. We reported desregulation of bcl-2 and $NOS_2$ expression during progression from oral white lesion, lichen planus and leukoplakia to squamous cell carcinoma. The obtained results were as follows: 1. Immunohistochemical analysis with monoclonal antibodies to bcl-2 oncoprotein and $NOS_2$ in formalin-fixed paraffin-embedded tissue sections revealed that bcl-2 expression is restricted to the basal cell layer and $NOS_2$ was mild expressed only in subepithelial inflammatory cells in normal human mucosa. There wasn't specific finding of those in lichen planus and leukoplakia. 2. Bcl-2 immunoreactivity in severe epithelial dysplasia or CIS occurs throughout the epithelium, $NOS_2$ reactivity in most superficial layer were noted. 3. In well-differentiated squamous cell carcinomas, mostly bcl-2 was overexpressed. In moderated and poor squamous cell carcinomas, the expression of $NOS_2$ was increased and that of bcl-2 was decreased. 4. The immunoreactivity of bcl-2 was 12.5% of normal mucosa, 30% of leukoplakia, 44% of lichen planus and 67% of carcinoma in situ. In carcinoma, those were 43%, 50% and 67% according to differentiation, respectively. 5. The immunoreactivity of $NOS_2$ was 25% of normal mucosa, 70% of leukoplakia, 78% of lichen planus and 100% of carcinoma in situ and epithelial dysplasia. In carcinoma, those were higher in moderated(100%) and poor(83%) squamous cell carcinomas than in well differentiated type(71%). 6. The expression of bcl-2 and $NOS_2$ by Western blot was increased highly in lichen planus and leukoplakia. Therefore, the expression of bcl-2 was increased in the white and precancerous lesions and that was decreased by differentiation of carcinoma. However, $NOS_2$ immunoreactivity in carcinoma in situ was lower than those in moderated and poor squamous cell. These findings suggest that the interaction of bcl-2 and $NOS_2$ may be roled importantly in growth and development of carcinoma.
(Department of Oral Pathology, School of Dentistry, Wonkwang University)