The Expression Of Apoptosis-related Gene Bcl-2,bax And Caspase-3 Protein In CIN And Cervical Carcinoma

A loss of balance between proliferation and apoptosis leads to tumor formation. Normal cervical epithelium becomes dysplastic before potentially developing into carcinoma. This study was conducted to delineate the role of apoptosis- related proteins in various stages of development in cervical neoplasia. Both regulator and effector proteins were examined.MethodsThe expression of apoptosis - related proteins, including Bcl-2, Bax and Caspase -3,was evaluated in 17 normal squamous epithelium, 21 low - grade cervical intraepithelial neoplasias ( GIN - L) , 19 high- grade cervical intraepithelial neoplasias ( CIN - H) , and 22 cervical squamous cell carcinomas, was analyzed on paraffin sections using immunohisto-chemistry. Specimens showing cytosolic immunoreactivity in 10% or more of the neoplastic cells were considered immunopositive.ResultsSeventy nine subjects were studied. All three apoptotic regulators examined were positive in a proportion of these neoplasms. There is no expression of the three proteins in normal epithelium. The expression of bcl - 2 was significantly higher in CIN - H than in CIN - L ( P < 0. 05 ). The expression of bcl - 2, Bax, Caspase 3 was reduced in cervical carcinoma compared to CIN - H ( P < 0.05).ConclusionsThere is an increase in expression of bcl - 2 in GIN - H compared to GIN -L and the increase is thought to be related to the increased proliferative activity in dysplastic cells. The reduction of bcl -2 Bax, Caspase 3 expression in carcinoma indicates that the apoptotic mechanism has become defective in the process of malignant transformation. Most of the dysplasdc and neoplastic cervical epithelial cells appeared incapable of entering terminal differentiation and complete it by apoptosis, possibly due to their failure to express or activate apoptosis executing enzymes.