Evaluation of p53 and Bcl-2 oncoprotein expression in precancerous lesionsof the oral cavity

The oral cavity is continually exposed to various traumas due to the effect of thermal, mechanical and chemical stimuli, which when accompanied by inf lammatory states may promote the growth of neoplastic changes. Numerous stu dies have revealed a correlation between the expression of p53 and Bcl-2 pr oteins and the progression of neoplastic disease. It cannot be excluded tha t these proteins act as biomarkers of a neoplastic transformation threateni ng in precancerous states (including leukoplakia) or the already existing n eoplastic transformation (e.g. in oral squamous cell carcinoma). The aim of the study was to evaluate the expression of p53 and Bcl-2 protei ns in the proliferating epithelium in relation to leukoplakia degree ad wit h regard to the lesions accompanied and not accompanied by squamous cell ca rcinomas. Fifty-five cases of proliferating changes in the oral epithelium (leukoplak ia) were investigated. Group I contained 20 leukoplakias not accompanied by oral squamous cell carcinomas. Groups II, III and IV included 35 cases of changes in the vicinity of carcinomas on the lower lip (group II), in the f ront 2/3 of the tongue (group III) and in the oral floor (group TV). Staini ng was performed according to the immunohistochemical method with the use o f monoclonal antibodies against human p53 protein (DAKO No M7001) and Bcl-2 (DAKO No M0887). A higher expression of p53 protein (54%) was found in leu koplakia changes coexisting with squamous cell carcinomas, compared with th e non-accompanied ones (p53-45%). The results indicate a correlation betwee n epithelial dysplasia degree and p53 and Bcl-2 protein expression - severe dysplasia occurred with an increase in the expression of both proteins. Le ukoplakias situated in the vicinity of squamous cell carcinomas showed high er expression of p53 and Bcl-2 compared with the non-accompanied alteration s. A correlation was also revealed between the location and p53 and Bcl-2 p rotein expression degree in the non-accompanied changes; no such correlatio ns were found in proliferating epithelial changes adjacent to neoplastic tu mors.