A FTH1 gene:pseudogene:miRNA network regulates tumorigenesis in prostate cancer

Pseudogenes, non-coding homologs of protein-coding genes, were once considered non-functional evolutional relics. Recent studies have shown that pseudogene transcripts can regulate their parental transcripts by sequestering shared microRNAs, thus acting as competing endogenous RNAs (ceRNAs). In this study, we utilize an unbiased screen to identify the ferritin heavy chain 1 (FTH1) transcript and multiple FTH1 pseudogenes as targets of several oncogenic miRNAs in prostate cancer. We characterize the critical role of this FTH1 gene:pseudogene:microRNA network in regulating tumorigenesis in prostate cancer, and show that impairing microRNA binding and subsequent ceRNA crosstalk results in complete phenotype rescue. Our results also demonstrate that pseudogenes are able to regulate intracellular iron levels, which are crucial for multiple physiological and pathophysiological processes. In summary, we describe a novel and extensive gene:pseudogene ceRNA network comprising multiple microRNAs and multiple pseudogenes derived from a single parental gene, which regulates iron storage and tumorigenesis in prostate cancer. Biotinylated microRNA-638 and microRNA-17 pulldown was performed using human prostate cancer cell line DU145 with two non-targeting controls (NC1 and NC2). DU145 cells with non-targeting controls (NC1 and NC2) or microRNA-638 mimic overexpression were used for RNA extraction and hybridization on Affymetrix microarrays.