Expression And Significance Of BAK,BIM And MCL-1 In Middle Ear Cholesteatoma

Objective: To investigate the expression of proapoptotic proteins BAK,BIM and antiapoptotic protein MCL-1 in middle ear cholesteatoma and the apoptosis status of cholesteatoma epithelium,and to explore its influences on bone destruction in cholesteatoma.Methods:Immunohistochemistry was used to detect the expression of BAK,BIM and MCL-1 proteins in 40 cases of middle ear cholesteatoma and 19 cases of normal external auditory canal.27 cases of middle ear cholesteatoma and 18 cases of normal external auditory canal were detected by terminal deoxynucleotidyl transferase-mediated d UTP nick-end-labeling(Tunel)method;middle ear cholesteatoma was divided into the severe bone destruction group and mild bone destruction group according to the degree of bone destruction.The BAK,BIM,and MCL-1 proteins were counted in the the severe bone destruction group(21 cases)and the mild bone destruction group(19 cases).Distribution of apoptotic cells in the severe bone destruction group(12 cases)and mild bone destruction group(15 cases)in Tunel staining.Pearson correlation analysis was used to examine the correlation between BAK,BIM and MCL-1 proteins.Results:The mean optical densities of BAK in the cholesteatoma group and the control group were 0.153±0.074 and 0.082±0.027,respectively,and the difference was statistically significant(P<0.01).The average optical density of BIM in the cholesteatoma group and the control group were 0.153±0.082 and 0.104±0.059 respectively,the difference was statistically significant(P=0.024);the mean optical density of MCL-1 in the cholesteatoma group and the control group were 0.237±0.080,0.125±0.026,respectively,the difference was statistically significant(P<0.01).The mean optical densities of MCL-1 in the severe bone destruction group and the mild bone destruction group were 0.213±0.092 and 0.263±0.055,respectively,and the difference was statistically significant(P=0.045);The mean optical densities of BAK in the the severe bone destruction group and the mild bone destruction group were 0.139±0.064 and 0.168±0.083,respectively,and the difference was not statistically significant(P=0.218).The average optical densities of BIM in the the severe bone destruction group and the mild bone destruction group were 0.147±0.095 and 0.159±0.067,respectively,and the difference was not statistically significant(P=0.661). apoptotic index were 0.471±0.146 and 0.100±0.030 in the cholesteatoma group and the control group,respectively,the difference was statistically significant(P<0.01);the apoptotic index in the the severe bone destruction group and the mild bone destruction group were 0.525±0.173 and 0.427±0.108,respectively,and the difference was not statistically significant(P=0.086);there was a positive correlation between BAK and MCL-1 in cholesteatoma epithelium(r=0.484,P<0.01),and there was a positive correlation between BIM and MCL-1(r= 0.466,P<0.01),there was a positive correlation between BAK and BIM(r=0.995,P<0.01).Conclusion : The abnormal expression of BAK,BIM and MCL-1 in middle ear cholesteatoma may be associated with high apoptosis of cholesteatoma epithelium,and MCL-1 may be involved in bone destruction of cholesteatoma.