IgG gene expression and its possible significance in prostate cancers.

Background: In spite of recent advances in treatment strategies, prostate cancer (PCa) remains the second leading cause of cancer death in men with its genetic and biologic behaviors still poorly understood. Recently, accumulating evidence indicates that cancer cells, as well as some normal cells can secret IgG. This study was designed to evaluate IgG gene expression and its possible significance in PCa tissue samples and cell lines.

Methods: IgG expression was assessed by immunohistochemistry, in situ hybridization, immunofluorescence, RT-PCR, and Western blot. The possible significance of IgG was evaluated on tissue array and cell lines. To assess cell viability and proliferation, MTS assay was carried out. Apoptosis was evaluated with propidium iodide and annexin-V staining.

Results: Expressions of IgG and its related genes were detected in cell lines. Abundant gene expressions of Igγ and Igκ chain were detected in PCa tissue samples, but not in normal prostate tissues. In addition, IgG expression was significantly higher in PCa tissues than in the benign prostate hyperplasia tissues (P < 0.001). Igγ expression was positively correlated to Gleason score and histological grade (P < 0.05). Furthermore, in vitro experiments showed that anti-human monoclonal IgG antibody suppressed cell proliferation and increased apoptosis in cultured PCa cells.

Conclusion: IgG gene expression in PCa is related to cell differentiation and clinical status. PCa cell produced IgG is involved in the biological behavior of this cancer and may serve as a useful marker for cancer cell differentiation and prognosis. Locally produced IgG could be a potential target for therapy.