Abstract 1464: Telomere DNA damage links benign prostatic hypertrophy, intraepithelial neoplasia, and prostate cancer

Telomere DNA damage has been demonstrated in benign prostatic hypertrophy (BPH), which is associated with prostate epithelial cell senescence. Telomere DNA damage is the most frequently observed genetic alteration in prostatic intraepithelial neoplasia, and is associated with poor clinical outcomes in prostate cancer. Gene expression database analysis revealed decreased TRF2 expression during malignant progression of the prostate gland. We reasoned that reduced TRF2 expression in prostate epithelium, by activating the telomere DNA damage response, would allow us to model both benign and malignant prostate disease. TRF2 expression was deleted in prostate epithelium using conditional null mutant mice. TRF2 expression in prostate glands and tumors was determined by quantitative reverse transcription polymerase chain reaction. Histopathology was analyzed by hematoxylin and eosin staining. Telomere DNA damage response was determined by 53BP1 localization at telomeres, and by ATM/Chk2/p53 western blotting. Androgen receptor, smooth muscle actin, keratin expression, and proliferation index were determined by immunohistochemistry. Cellular senescence was determined by histone H3K9me3 immunofluorescence microscopy. Apoptotic cells were determined by TUNEL analysis. Telomerase activity was determined by telomere repeat amplification protocol. Alternative lengthening of telomeres was determined by PML localization at telomeres and telomere circular DNA analysis. Genomic instability was determined by metaphase telomere fluorescence in situ hybridization. Sca1+/CD49f+ prostate cancer stem cells were sorted by flow cytometry and transplanted subcutaneously with urogenital sinus mesenchyme cells in Matrigel. Prostate glands with reduced epithelial TRF2 expression developed age- and p53-dependent hypertrophy, senescence, ductal dilation, and smooth muscle hyperplasia similar to human BPH. Prostate tumors with reduced TRF2 expression were classified as high grade androgen receptor negative luminal adenocarcinomas which exhibited decreased latency, increased proliferation, and distant metastases. Prostate cancer stem cells with reduced TRF2 expression were highly tumorigenic and maintained telomeres both by telomerase and alternative lengthening (ALT). Telomerase inhibition in prostate tumors with reduced TRF2 expression produced significant reduction in prostate tumor incidence by halting progression at intraepithelial neoplasia (PIN). These lesions were highly differentiated, exhibited low proliferation index, and high apoptotic cell fraction. Prostate tumors with reduced TRF2 expression and telomerase inhibition failed to metastasize and did not exhibit ALT. Our results demonstrate that the telomere DNA damage response links BPH, PIN, and prostate cancer and may be therapeutically manipulated to prevent prostate cancer progression. Citation Format: Jianchun Wu, David L. Crowe. Telomere DNA damage links benign prostatic hypertrophy, intraepithelial neoplasia, and prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1464.