Abnormal Expression And Clinical Significance Of Cathepsins In Patients With Meningiomas

Objective: Meningiomas are benign neoplasmas that derive from coverings of the brain. Approximately 10% of benign tumors progress into atypical, malignant tumors. At present, there isn' t a reliable clinical and histological marker that can evaluate its pathological classification and prognosis all the better. The aim of this study was to evaluate the clinical applicable significance of cathepsins B and L and their inhibitors in distinguishing malignant from benign forms of meningiomas. Methods: Using immunohistochemical analysis, we detected the levels of cathepsins B, cathepsin L and their endogenous cysteine proteinase inhibitors stefin A and cystatin C in specimens of 76 meningiomas which were re-classified by experienced pathologist. Results: Of the 76 meningiomas studied, 57 were benign meningiomas, 11 were atypical meningiomas, and 8 were malignant meningiomas. A high immunohistochemical score (4~6) for cathepsin B was more frequent in atypical meningiomas and malignant meningiomas than in benign meningiomas ( x 2=6.24,P<0.05; x 2=6.28,P<0.05). No statistical difference in immunohistochemical staining of cathepsin B was found between atypical meningiomas and malignant meningiomas(x2=0.15,P>0.05). Higher expression of cathepsin L was found in malignant meningiomas as compared with benign meningiomas ( x 2=4.15,P<0.05), but it was no statistical difference in atypical meningiomas as compared with benign meningiomas( x2 = 0.55,P>0.05). Differences in immunostaining were observed according to tumor location and invasion and non invasion, We demonstrated that convexity and parasagittal meningiomas expressed higher immunohistochemical score(4-6) of cathepsin B than did basal meningiomas( x 2=4.43,P<0.05; x 2=8.70,P<0.01).Invasive meningiomas expressed higher immunohistochemical score(4-6) of cathepsin B than did non invasive meningiomas ( x2=11.80, P<0.01; x2=5.61, P<0.05 ) . The immunohistochemical staining of cathepsin L expressed similarly. No immunostaining for stefin A and cystatin C was detected in any of the tumors. Conclusions: The present data suggest that the levels of cathepsin B and cathepsin L antigens are significantly higher in maligment meningiomas. Therefore, they will become an important marker which can distinguish benign meningiomas from malignant meningiomas. Specifically, cathepsin B could more be to become a new valuable marker to distinguish benign meningiomas from malignant and atypical meningiomas.