Abstract 2712: Heterogeneous nuclear ribonucleoprotein H1 confers transcription and transactivation of androgen receptor: Implications for prostate cancer progression in African American men

Caucasian American (CA) and other ethnic minority groups. The causes of this ethnic disparity in clinical manifestation and outcome of the disease are not well understood. Here we identified, by employing a combined approach of laser capture microdissected (LCM), suppressive subtractive hybridization (SSH), and custom race-based CaP cDNA microarray on fresh specimens, selective expression of heterogeneous nuclear ribonucleoprotein H1 (hnRNPH1) in prostate tumor cells of AA men in comparison to CA men. An ethnicity-based tissue microarray (TMA) analysis revealed selective nuclear accumulation of hnRNPH1 in tumor cells compared to adjacent normal epithelium and benign prostatic hyperplasia (BPH). We also show that hnRNPH1 up-regulates transcription, physically interact with, and confers hormone-dependent (HD) and independent (HI) transactivation of androgen receptor (AR) in CaP cells. Further, our reporter, ChIP, and EMSA analyses demonstrate hnRNPH1 binds to androgen response elements (AREs) on promoter and enhancer element of PSA gene and the ligand binding domain-encoding exons D, E and H of the AR gene, suggesting it acts as a coactivator of AR in CaP cells. Interestingly, siRNA silencing of hnRNPH1caused growth arrest and enhanced cytotoxicty of Bicalutamide in AR-expressing CaP cells. These findings support a model in which hnRNP H1 is an exclusive auxiliary factor for AR to elicit androgen-specific transcriptional regulation of androgen-regulated genes and drug resistance. Given heterogeneity of CaP and that AR is implicated in androgen independent progression of CaP, the results demonstrate a previously uncharacterized mechanism for AR-hnRNPH1 axis in disease progression and hormone refractory via enhancing HD and HI mediated transcription and transactivation of AR in a subset of prostate tumor cells in AA men. The results not only reveal racial differences in the biology of CaP, but also provide, for the first time, a new frontier for the development of diagnostic, preventive, and/or targeted therapeutic strategies to circumvent disease progression in AA men. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2712.