Study Of Apoptosis And The Expression Of Bcl-2, Bax In Oral Submucous Fibrosis And Cancerization Of Oral Submucous Fibrosis

Objective: To investigate the apoptosis and the expression of apoptosis-associated proteins Bcl-2 and Bax in oral submucous fibrosis and cancerization of oral submucous fibrosis, so as to discuss the pathological mechanism of OSF.Methods: The apoptosis and the expression of Bcl-2 and Bax were obsevered in 45 cases of OSF, 10 cases of cancerization of OSF and 10 cases of normal oral mucosa by TUNEL and immunohistochemistry. The percentage of apoptotic cells labeled by the TUNEL method was estimated as an apoptotic index(AI). The rate of positive reaction were observed and counted blindly,and the staining intensity were judged by staining score.Results: 1. TUNEL was positive in normal oral mucosa,the positive staining could been mostly seen in stratum granulosum and strayum spinosum. The AI was significant increased in cancerization of OSF,the differences between cancerization of OSF and all stages of OSF and normal oral mucosa was significant(P<0.05). No significant differences was found in AI between early, medium-term stages of OSF and normal oral mucosa(P>0.05).2. Bcl-2 protein was detected negative or weakly positive in normal oral mucosa, which confined to basal membrane, but a upgrade increase of expression could be found in early stage of OSF, and enhanced with the aggravation of pathological grades. The expression in cancerization of OSF was higher than early, medium-term stages of OSF and normal oral mucosa(P<0.05),but no significant differences was found with advanced stage of OSF. No statistically significant differences were found between normal oral mucosa and early,medium-term stage of OSF(P>0.05).3. Bax immunostaining was seen slight throughout the thickness of the normal oral mucosa, but Bax expression was declined in early stage of OSF. The differences between early,medium-term stages of OSF and cancerization of OSF was statistically significant (P<0.05). The expression of Bax increased at advanced stage of OSF compared with early and medium-term stages of OSF(P<0.05).No significant differences were found between normal oral mucosa and early and medium-term stages of OSF(P>0.05).Conclusions: 1. Apoptotic cell death in epithelium was increased at advanced stage of OSF, indicates excessive apoptosis occurs may contribute to epithelial atrophy.2. The upgrade expression of Bcl-2 protein in cancerization of OSF, it was supposed that may act as an important role in the cancerization of OSF by allowing escape from apoptosis.3. Overexpression of Bax was contributed to the apoptosis in advanced stage of OSF, and related to the apoptosis in cancerization of OSF.