Identification of a novel lncRNA induced by the nephrotoxin ochratoxin A and expressed in human renal tumor tissue.

Long non-coding RNAs represent a fraction of the transcriptome that is being increasingly recognized. For most of them no function has been allocated so far. Here, we describe the nature and function of a novel non-protein-coding transcript, named WISP1-AS1, discovered in human renal proximal tubule cells exposed to the carcinogenic nephrotoxin ochratoxin A. WISP1-AS1 overlaps parts of the fourth intron and fifth exon of the Wnt1-inducible signaling pathway protein 1 (WISP1) gene. The transcript is 2922 nucleotides long, transcribed in antisense direction and predominantly localized in the nucleus. WISP1-AS1 is expressed in all 20 samples of a human tissue RNA panel with the highest expression levels detected in uterus, kidney and adrenal gland. Its expression was confirmed in primary tissues of human kidneys. In addition, WISP1-AS1 is expressed at higher levels in renal cell carcinoma (RCC) cell lines compared to primary proximal tubule cells as well as in RCC lesions than in the adjacent healthy control tissue from the same patient. Using specific gapmer antisense oligonucleotides to prevent its upregulation, we show that WISP1-AS1 (1) does not influence the mRNA expression of WISP1, (2) affects transcriptional regulation by Egr-1 and E2F as revealed by RNA-sequencing, enrichment analysis and reporter assays, and (3) modulates the apoptosis-necrosis balance. In summary, WISP1-AS1 is a novel lncRNA with modulatory transcriptional function and the potential to alter the cellular phenotype in situations of stress or oncogenic transformation. However, its precise mode of action and impact on cellular functions require further investigations.