Selection and cloning of poly(rC)-binding protein 2 and Raf kinase inhibitor protein RNA activators of 2',5'-oligoadenylate synthetase from prostate cancer cells - RNA

Selection and cloning of poly(rC)-binding protein 2 and Raf kinase inhibitor protein RNA activators of 2',5'-oligoadenylate synthetase from prostate cancer cells
December 1, 2006
Ross J. Molinaro1,2, Babal Kant Jha2, Krishnamurthy Malathi2, Sooryanarayana Varambally3,4, Arul M. Chinnaiyan3,4 and Robert H. Silverman2,*
1 Department of Chemistry, Cleveland State University Euclid Avenue at East 24th Street, Cleveland, OH 44115, USA 2 Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic 9500 Euclid Avenue, Cleveland, OH 44195, USA 3 Department of Pathology, University of Michigan Medical School 1400 E Medical Center Drive, Ann Arbor, MI 48109, USA 4 Department of Urology, University of Michigan Medical School 1400 E Medical Center Drive, Ann Arbor, MI 48109, USA
Nucleic Acids Research
ABSTRACT
The antiviral and antitumor functions of RNase L are enabled by binding to the allosteric effectors 5'-phosphorylated, 2',5'-linked oligoadenylates (2-5A). 2-5A is produced by interferon-inducible 2',5'-oligoadenylate synthetases (OAS) upon activation by viral double-stranded RNA (dsRNA). Because mutations in RNase L have been implicated as risk factors for prostate cancer, we sought to determine if OAS activators are present in prostate cancer cells. We show that prostate cancer cell lines (PC3, LNCaP and DU145), but not normal prostate epithelial cells (PrEC), contain RNA fractions capable of binding to and activating OAS. To identify the RNA activators, we developed a cDNA cloning strategy based on stringent affinity of RNAs for OAS. We thus identified mRNAs for Raf kinase inhibitor protein (RKIP) and poly(rC)-binding protein 2 (PCBP2) that bind and potently activate OAS. In addition, human endogenous retrovirus (hERV) envelope RNAs were present in PC3 cells that bind and activate OAS. Analysis of several gene expression profiling studies indicated that PCBP2 RNA was consistently elevated in metastatic prostate cancer. Results suggest that OAS activation may occur in prostate cancer cells in vivo stimulated by cellular mRNAs for RKIP and PCBP2.
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