Abstract 454: TET2 alterations facilitate progression of metastatic prostate cancer

Abstract

Abstract Metastatic prostate cancer (mPCa) is a highly lethal disease and molecular markers identifying disease subtypes and/or therapeutic targets are needed. We sequenced the exomes of five metastatic tumors and healthy kidney tissue from an index patient with castration resistant mPCa to identify lesions associated with disease progression and metastasis. A somatic missense TET2 alteration predicted to be deleterious to the protein was observed at the metastatic stage of disease. We sequenced TET2 in additional mPCa tumors and PCa cell lines and detected somatic missense alterations, frequent LOH, and a frameshift truncation in PCa cell line, DU-145, derived from a mPCa brain tumor. We also observed complex combinations of frequent and rare germline missense SNPs, which may contribute to a previously described association of TET2 with PCa risk by GWAS. In this study, we confirm transcription factor binding to TET2 alleles associated with disease by GWAS. We examine TET2 binding partners in prostate cells by affinity purification, mass spectrometry, and forward and reverse immunoprecipitation. We confirmed a protein complex containing TET2, OGT, and two transcriptional co-activators/splicing factors implicated in receptor-mediated gene expression. Functional analysis shows TET2 loss alters expression of a unique set of genes, increases cell proliferation, and therefore is a driver of PCa. TET2 loss may facilitate progression to castration resistant mPCa and appears to define a subset of cases with metastatic disease. Citation Format: Michael L. Nickerson, Sudipto Das, Hong Lou, Hongchuan Li, Sevilay Turan, Kate Im, Stephen Anderson, Thorkell Andresson, Michael Dean. TET2 alterations facilitate progression of metastatic prostate cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 454. doi:10.1158/1538-7445.AM2014-454