Non-vesicular extracellular RNA: A potential drug target to intervene cell-cell communication

The importance of non-vesicular extracellular RNA in the mammalian system is becoming increasingly apparent. Non-vesicular extracellular RNA is defined as RNA molecules not included in a lipid bilayer such as exosomes. Because non-vesicular extracellular RNA is not protected from RNases and is therefore rapidly degraded, they were not easily captured by conventional biofluid analyses. Recent publications showed that some non-vesicular extracellular RNAs are relatively stable in biofluids or tissue culture media, and they have unique biological functions. Major RNAs (rRNA, mRNA, and tRNA) and other non-cording RNAs play important roles in transcription or translation in the cell. In contrast, non-vesicular extracellular RNA has functions related to intercellular communication rather than protein synthesis. This review discusses the basics of non-vesicular extracellular RNA, including its definition, purification, receptors, and future prospects as a drug target.