Prostein expression is highly restricted to normal and malignant prostate tissues

BACKGROUND Prostein is a recently described molecule expressed at the mRNA level in a prostate‐specific manner. A murine monoclonal antibody was developed, characterized, and used to evaluate the expression of prostein protein in prostatic, other normal tissue and tumor samples. METHODS The murine anti‐prostein monoclonal antibody 10E3‐G4‐D3 was generated using recombinant prostein. ELISA, FACS, and Western analyzes were used to characterize 10E3‐G4‐D3. Immunohistochemistry was used to characterize the expression of prostein in tissues. RESULTS 10E3‐G4‐D3 specifically recognizes a linear intracellular epitope of prostein. IHC analysis demonstrates that prostein is expressed in the vast majority of normal and malignant prostatic tissues, regardless of grade and metastatic status. No protein expression is detected in a panel of approximately 4,700 normal and malignant tissue samples representing the great majority of essential tissues and tumors. CONCLUSIONS Prostein is exquisitely specific for prostate tissues, indicating a potential clinical utility of 10E3‐G4‐D3 as a diagnostic biomarker, and support the use of prostein as a novel target for development of prostein‐specific antibody and T‐cell based therapeutic strategies for prostate cancer. © 2004 Wiley‐Liss, Inc.