Long and small noncoding circulating RNAs of human blood

Noncoding RNAs have emerged as potent regulators of gene expression both within cells and in extracellular fluids such as lymph and blood plasma. The aim of this study was to document the profile of extracellular RNAs normally circulating in blood of healthy individuals and to identify changes in circulating RNAs of cancer patients. For this, we obtained blood from healthy donors and patients with non-small cell lung cancer, thyroid cancer and osteosarcoma. We performed profound high throughput sequencing of whole blood plasma RNAs as well as RNAs of blood plasma fractions enriched with circulating membrane vesicles. Bioinformatics analysis of sequencing data allowed to describe the variety of circulating house keeping rRNAs and tRNAs, messenger RNAs, regulatory snRNAs, snoRNAs, scaRNAs, small cytoplasmic RNAs, microRNAs and the set of long noncoding RNAs. The results let us estimate the impact of different cells, tissues and organs on formation of blood circulating extracellular transcriptome with prominent contribution of platelets. Circulating long noncoding RNAs include both cytoplasmic (e.g. GAS5) and nuclear (MALAT1) species involved in vital cellular process and malignant transformation. In order to understand functions of circulating RNAs we synthetized the set of their artificial analogs and expressing vectors. Cultured cancer and non-transformed human cells were transfected with artificial analogs of circulating RNAs or DNA constructs and differential gene expression analysis was performed. We determined that analogs of circulating small and long noncoding RNAs activate innate immune system and induce specific gene expression alterations typical for specific class of RNA. Taken together our data provide basis for developing novel diagnostic and gene targeted therapeutic approaches.

This work was supported by Russian Science Foundation Grant RSF # 16–14- 10284 and Russian State funded budget project of ICBFM SB RAS # АААА-А17-117020210024-8