A Study Into the Expression of the Tumor Suppressor Gene p53 and the Oncogene bcl-2 in Human Breast Cancer

In this study, the protein expression of the mutant tumor suppressor gene p53, and oncogene bcl-2 was evaluated in 50 female breast cancer patients using two different techniques, ELISA and western blotting, the relation between these two techniques in relation to protein expression was detected, and the correlations between the expression of these two proteins and the different prognostic parameters of cancer breast were studied. The mean value of bcl-2 in breast cancer patients was statistically significantly higher than those of normal healthy controls using both ELISA and western blotting techniques. A significant positive correlation was found between bcl-2and both the tumor size and the stage of the tumor which signifies its important role as a prognostic factor in breast cancer. Also over-expression of mutant p53 was detected using both ELISA and western blotting techniques when compared to the normal healthy controls. The only statistically significant correlation between mutant p53 expression and the different prognostic parameters of breast cancer was found to be between p53 the stage of the tumor. When taking predictive cut off levels of bcl-2 at 75U/ml, and mutant p53 at 2.16U/ml, bcl-2 showed the highest sensitivity, specificity and diagnostic accuracy of (88%, 90%, and 90%) respectively, while mutant P53 showed its highest sensitivity, specificity and diagnostic accuracy (80%, 100%, and 85.7%) at the chosen cut offs. When done in either abnormal and both abnormal double combinations with the same cut offs, the sensitivity, specificity and diagnostic accuracy in the either abnormal combination have improved than either parameter singly, (92%, 100% and 94.29%) respectively, while in both abnormal combination the sensitivity, specificity, and diagnostic accuracy are (64%, 90% and 71.43) respectively. When studying the correlation between the 2 techniques (ELISA western blotting) used in determination of bcl-2 and P53 expression in breast cancer patients, all samples which showed over-expression for mutant P53 and bcl-2 using ELISA technique, also demonstrated over-expression using western blotting technique. The percent of positive expression for the mutant P53 and the bcl-2 proteins were higher (76%) and (88%) respectively using western blotting technique when compared to ELISA technique (70%) and (80%) respectively. The results of both techniques were statistically significantly correlated for both P53 and bcl-2. Although western blotting technique has a higher sensitivity compared to ELISA, it has many disadvantages as cost, reproducibility , time consumption and the requirement for high skills.