Abstract LB-87: Analysis of JAZF1 loss-of-function reveals its role in regulation of genes relevant for prostate cancer
Authors: Gharwan Helen , Jones Tamara , Tang Wei , Ambs Stefan , Prokunina Ludmilla , Caplen Natasha 
Published: May 2015

Genome-wide association studies (GWAS) have mapped one of the prostate cancer susceptibility regions to a single nucleotide polymorphism (SNP) rs10486567 within intron 2 of the gene that encodes JAZF1, a putative transcriptional co-factor. In order to translate GWAS findings into clinically relevant information that will ultimately enable us to improve the management of prostate cancer it is essential to identify the biological role of the susceptibility variant in cells and tissues. To date, only a few studies address the biological function of JAZF1 and none in prostate cancer. To investigate the function of JAZF1 we generated expression profiles of several prostate cancer cell lines, in which JAZF1 was silenced. We conducted RNA-Seq of two metastatic prostate cancer cell lines, LNCaP and DU145, in which siRNA-mediated RNAi had been employed to induce JAZF1 loss-of-function (LOF). For this study, three different JAZF1 siRNAs were used, along with a siRNA (siNeg) serving as control for transfection-related changes in gene expression. Approximately 1,500 genes were identified as deregulated in both cell lines. Computational analysis of these genes showed enrichment for genes associated with prostate cancer (p=2.4x10-6, Ingenuity Pathway Analysis), including MAP2K4 and MET. These two genes were up-regulated following JAZF1 LOF in both cell lines, consistent with JAZF1's putative role as a transcriptional repressor. Among the genes down-regulated following siRNA silencing of JAZF1was ID1. ID1 is a negative transcriptional regulator that functions as part of the mitotic checkpoint machinery. One of ID1's target genes is the cell-cycle inhibitor p21. In JAZF1-silenced DU145 cells we observed a decrease in ID1 mRNA expression that was correlated with an increase in CDKN1A expression, the gene encoding p21; an observation confirmed at a protein level. Examination of publically available prostate cancer gene expression data indicated a correlation between JAZF1 and ID1 expression (p&lt;0.001). To further analyze the putative regulation of ID1 by JAZF1, and thus p21, we used lentivirus-mediated delivery of JAZF1-shRNAs to stably transduce DU145 cells,, OPCN-1 non-tumorigenic cells, and a non-metastatic prostate tumor epithelium cell line, OPCT-1. Under conditions of long-term JAZF1 LOF we observed increased ID1 expression as measured by Western Blot analysis and concurrent decreases in, p21 protein levels in all three-cell lines. Although this result appears contradictory to our initial observation of siRNA-mediated JAZF1 silencing, this difference may reflect cell line and temporal specific activity of JAZF1 as a transcriptional activator or repressor of ID1 expression. These findings are consistent though with JAZF1 functioning as a regulator of ID1, a protein reported to be over-expressed in prostate cancer that is associated with cancer cell proliferation and metastasis formation through activation of various oncogenic pathways.

Citation Format: Helen Gharwan, Tamara Jones, Wei Tang, Stefan Ambs, Ludmilla Prokunina, Natasha Caplen. Analysis of JAZF1 loss-of-function reveals its role in regulation of genes relevant for 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 LB-87. doi:10.1158/1538-7445.AM2014-LB-87