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Purpose: Protein kinases are known to play a prominent role in oncogenic progression across multiple cancer subtypes, yet their role in prostate cancer progression remains underexplored. The purpose of this study was to identify kinases that drive prostate cancer progression. Experimental Design: To discover kinases that drive prostate cancer progression, we investigated the association between gene expression of all known kinases and longterm clinical outcomes in tumor samples from 545 patients with high-risk disease. We evaluated the impact of genetic and pharmacologic inhibition of the most significant kinase associated with metastatic progression in vitro and in vivo. Results: DNA-dependent protein kinase (DNAPK) was identified as the most significant kinase associated with metastatic progression in high-risk prostate cancer. Inhibition of DNAPK suppressed the growth of both AR-dependent and AR-independent prostate cancer cells. Gene set enrichment analysis nominated Wnt as the top pathway associated with DNAPK. We found that DNAPK interacts with the Wnt transcription factor LEF1 and is critical for LEF1-mediated transcription. Conclusions: Our data show that DNAPK drives prostate cancer progression through transcriptional regulation of Wnt signaling and is an attractive therapeutic target in aggressive prostate cancer.

Therapeutic radiation results in a cascade of cellular events culminating either in repair of DNA damage and cell survival, or failure to repair damage and cell death. Gene expression is partially under epigenetic control in the form of DNA methylation. We investigated whole genome DNA methylation profiles of MDA-MB-231 breast cancer cells following therapeutic radiation to determine genes and pathways that are differentially methylated. MDA-MB-231 cells were treated with a single dose of 0, 2, or 6 Gy and incubated at 1, 2 4, 8, 24, 48, and 72 hrs before obtaining DNA extracts. DNA was subjected to whole genome DNA methylation profile analysis using an Infinium BeadArray which has the ability to determine CpG methylation at 450,000 genomic sites and covering all genes. Compared to unirradiated cells, 2 and 6 Gy irradiated cells showed 419-1661 CpG sites with decreased methylation and 514-2657 CpG sites with increased methylation, depending on time and dose. The number of hypomethylated genes in 2 Gy irradiated cells increased over time while the number of hypermethylated genes decreased in the first 8 hrs and then increased to a maximum at 72 hrs. In 6 Gy irradiated cells, no pattern was detected, although there was overall more DNA methylation changes than in 2 Gy irradiated cells, indicated a dose effect. Gene ontology analysis using Genomatix Genome Analyzer showed significant changes in DNA repair, cell cycle, apoptosis, and cell survival pathway gene methylation. DNA repair genes were differentially methylated as early as 1 hr after irradiation and sustained through 72 hrs. Epigenetic changes persisted after DNA repair, as shown by gamma-H2AX immunofluorescence, had taken place. Cell cycle, cyclin-dependent kinase, and cyclin-dependent kinase inhibitor genes were differentially methylated 4-24 hrs post-irradiation, correlating with a G2 cell cycle arrest as determined by flow cytometry. These data suggest that epigenetic regulation in the form of DNA methylation is integrated with the cellular response to radiation. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4349. doi:1538-7445.AM2012-4349