Long non-coding RNAs (lncRNAs) form the largest transcript class in the human transcriptome. These lncRNA are expressed not only in the cells, but they are also present in the cell-derived extracellular vesicles such as exosomes. The function of these lncRNAs in cancer biology is not entirely clear, but they appear to be modulators of gene expression.
In this study, researchers from the University of Technology, Sydney characterized the expression of lncRNAs in several prostate cancer exosomes and their parental cell lines. They show that certain lncRNAs are enriched in cancer exosomes with the overall expression signatures varying across cell lines. These exosomal lncRNAs are themselves enriched for miRNA seeds with a preference for let-7 family members as well as miR-17, miR-18a, miR-20a, miR-93 and miR-106b. The enrichment of miRNA seed regions in exosomal lncRNAs is matched with a concomitant high expression of the same miRNA. In addition, the exosomal lncRNAs also showed an over representation of RNA binding protein binding motifs. The two most common motifs belonged to ELAVL1 and RBMX. Given the enrichment of miRNA and RBP sites on exosomal lncRNAs, their interplay may suggest a possible function in prostate cancer carcinogenesis.
(A) Venn diagram showing the common exosomal lncRNAs between the PC3, DU145, LNCaP and VCaP prostate cancer cell lines. (B) Heat map showing the expression of exosomal lncRNAs in prostate cancer cells and a normal cell line (PNT2). Red denotes high expression and aqua denotes reduced expression of the lncRNAs.