The rate of apoptosis varies in malignant tumors, and it can be involved in diminishing tumor size. Different protein-regulators of apoptosis, such as Bcl-2, BclX, and Bax have an influence on the rate of apoptosis in various tumors. In human renal diseases, such as the experimental model of acute renal failure, and many tumors, including Wilms' tumor, the expression of antiapoptotic members of Bcl-2 family is increased, while the expression of proapoptotic members is low.
Aim: The aim of our study was to investigate Bcl-X(S/L) protein expression in Wilms' tumor, to compare it with the expression in normal renal tissue, as well as to see if there is a correlation between Bcl-X(S/L) expression in Wilms' tumor with tumor stage, histological type, prognostic group, or response to preoperative chemotherapy.
Materials and methods: Twenty-eight cases of Wilms' tumor (two cases with metastasis) and two samples of normal kidney tissue were studied using streptavidin-biotin-complex technique. Bcl-X(S/L) expression levels were semiquantitatively scored.
Results: The expression of Bcl-X(S/L) was observed in the majority of cases (60.7%), more often in the blastemal than in the epithelial component of Wilms' tumor: 60.7% and 28.6%, respectively (p=0.02). There was a statistically significant inverse relationship between Bcl-X(S/L) expression and tumor stage (p=0.015). Bcl-X(S/L) was found less frequently in high-risk tumors then in tumors with good prognosis (p=0.02). Treated Wilms' tumors showed Bcl-X(S/L) expression more often than nontreated tumors, but the relationship was not statistically significant (p=0.08). Expression of Bcl-X(S/L) was detected in various histological types of Wilms' tumor, but there was no statistically significant association (p=0.82) except in cases with diffuse anaplasia (p=0.012), which were always negative. No Bcl-X(S/L) immunostaining was observed in two cases of metastasis or in one case of bilateral Wilms' tumor.
Conclusion: Our results suggest that the expression of Bcl-X(S/L) protein is associated with prognostic group, tumor stage, and presence of anaplasia.