Prostate cancer is the second leading cancer in men world-wide. Due to its heterogeneous nature, a considerable amount of research effort has been dedicated in identifying effective clinical biomarkers with a focus on proteins, messenger RNA and microRNAs. However, there is limited data on the role and expression of long noncoding RNAs (lncRNAs) in prostate cancer exosomes.
Researchers from the University of Technology, Sydney have profiled four common prostate cancer cell lines and compared these to the normal PNT2 cells. Their array data suggested that lncRNAs are present in abundance in both healthy and prostate cancer exosomes. They normalized the data using quantile normalization and then filter the data by using a two-fold threshold. From this the dataset, they also identified 26 down-regulated and 19 upregulated lncRNAs which were common to these exosomes. Furthermore, these exosomal lncRNAs appeared to be enriched for miRNA seeds with a preference for miR-17, miR-18a, miR-20a, miR-93, miR-106b and the let-7 family members. With these observation, the resesarchers put forward the notion that lncRNAs can act as miRNA sponges and their specific enrichment in exosomes is an important step in prostate cancer carcinogenesis. The heat maps clearly showed the similarities and differences in the lncRNA expression between cancer exosomes/cells versus the normal exosomes/cells. Although there have been many studies using small ncRNAs for cancer diagnosis, with this dataset, it may be possible to discover potential exosomal lncRNAs which can be utilized for prostate cancer diagnosis.
A heatmap representing the differential lncRNA expression in the parental prostate cancer cell lineages and their exosomes. “red” indicates high relative expression and “blue” indicates low relative expression.