Opa-Interacting Protein 5 Expression in Human Glioma Tissues IsEssential to the Biological Function of U251 Human Malignant GliomaCells

摘要

Opa-interacting protein 5 (OIP5) is a member of the cancer-testis antigen (CTA)family that elicits a spontaneous antitumor immune response. The failure ofcurrent immunotherapies for glioma has prompted the search for novel biomarkersthat may be utilized as therapeutic targets. This study aimed to investigatewhether OIP5 serves as a target for malignant glioma immunotherapy. Gliomaspecimens from 53 adult patients were evaluated for OIP5 expression byimmunohistochemical (IHC) staining, and the correlation of OIP5 expression withWorld Health Organization (WHO) tumor grade was analyzed. Endogenous expressionof OIP5 in glioma cell lines was determined via real-time polymerase chainreaction (RT-PCR). Using lentiviral siOIP5, the effect of OIP5 gene knockdown onproliferation, cell cycle, and apoptosis in U251 glioma cells was studied. Theresults show that OIP5 is overexpressed in glioma tissues and is correlated withWHO tumor grade (P < 0.001). However, OIP5 proteinexpression is barely detectable in normal adult brain tissues. MTT assays andanalysis using the Celigo Imaging Cytometry System reveal that the silencing ofOIP5 inhibits U251 cell growth. Cell cycle assays and Annexin V staining showthat OIP5 silencing disrupts the balance of the cell cycle and increases U251cell death. These results indicate that OIP5 is upregulated in malignant gliomaspecimens but barely detected in normal brain tissues. OIP5 knockdown inhibitsthe biological function of glioma cells, reinforcing that OIP5 may serve as animmunotherapeutic target for malignant glioma.