Cathepsin B and its inhibitor stefin A in brain tumors

Cysteine protease cathepsin B (CatB) and its endogenous inhibitor stefin A (StA) play an important role in tumor progression. Increase of CatB express ion and lower levels of its inhibitors were associated with tumor malignanc y in brain tumors. In this study of 100 patients, CatB was localized by imm unostaining to both, tumor and endothelial cells of primary brain tissue. S ignificant correlation with poor prognosis was found by univariate Cox's re gression model. Intense overall immunostaining and immunostaining in endoth elial cells alone were prognostic for survival (p=0.003 in both). When comp aring CatB expression at mRNA level, we found considerable differences betw een center and periphery of a tumor as well as between different tumor samp les. StA mRNA was only detected in benign, but not in malignant tissues. We suggest that screening of cysteine-protease genes expression can be applie d in clinical prognosis of brain tumors.