Elevated expression of angiogenin in prostate cancer and its precursors

Purpose: Angiogenin is a polypeptide involved in the formation and establishment of new blood vessels necessary for growth and metastasis of numerous malignant neoplasms, including prostatic adenocarcinoma. Antiangiogenin therapy inhibits the establishment, growth, and metastasis of prostatic adenocarcinoma in animal studies. In this study, we have investigated the expression of angiogenin in prostatic adenocarcinoma, high-grade prostatic intraepithelial neoplasia, and adjacent benign prostatic epithelium in a large cohort of prostatectomy specimens. Methods: We have studied the expression of angiogenin by immunohistochemistry in prostatic adenocarcinoma, high-grade prostatic intraepithelial neoplasia, and adjacent benign prostatic tissue in 107 human total prostatectomy specimens. Results: The percentage of cells staining positively for angiogenin in benign prostatic glandular epithelium (mean = 17%) was significantly less than for high-grade prostatic intraepithelial neoplasia (mean = 58%, P < 0.001) and prostatic adenocarcinoma (mean = 60%, P < 0.001). Compared with adjacent benign prostatic epithelium, the staining intensity was significantly greater in high-grade prostatic intraepithelial neoplasia (P < 0.001) and prostatic adenocarcinoma (P < 0.001). Furthermore, staining intensity has significantly stronger in prostatic adenocarcinoma versus high-grade prostatic intraepithelial neoplasia (P = 0.0023). However, there was no correlation of angiogenin expression with various clinical and pathologic variables examined, including age at surgery, Gleason scores, pathologic stage, tumor extent, angiolymphatic invasion, extraprostatic extension, seminal vesical invasion, lymph node metastasis, surgical margin status, presence of prostatic intraepithelial neoplasia, and perineural invasion. Conclusion: Angiogenin expression in prostatic tissue increases as prostatic epithelial cells evolve from a benign to an invasive phenotype. The increasing expression of prostatic adenocarcinoma in the progression from benign prostate to high-grade prostatic intraepithelial neoplasia and ultimately to prostatic adenocarcinoma are consistent with previous studies showing the influential role that angiogenin plays in the growth, invasion, and metastasis of prostatic adenocarcinoma and many other malignant tumors.