Exosomal lncRNAs as new players in cell-to-cell communication.

Neoplastic cells use various intercellular communication mechanisms in order to adapt to the local microenvironment, manipulate the immune system, and facilitate metastasis. Exosomes release is a new mechanism of cell-to-cell communication. These nanovesicles enclose various types of molecules including lipids, proteins, DNA, messenger RNA (mRNA) and non-coding RNAs [microRNA and long non-coding RNA (lncRNA)]. lncRNAs are over 200 nt long transcripts, that exhibit no coding potential, but are crucial regulators of physiological processes and are deregulated in cancer. In this review, we will discuss the role of exosomal lncRNAs in cancer, which is an incipient research field that could bring new insights to the vast domain of intercellular communication. Exosomal lncRNAs seem to be promising biomarkers for any type of cancer. The exact role of exosomal lncRNAs is not fully revealed. Several studies show that cancer derived exosomal lncRNAs are functional and can transmit to neighboring cells different phenotypic patterns, like drug resistance and increased angiogenesis. We further discuss the mechanistic function of exosomal lncRNAs, and hypothesize that the crowded exosomal content can be a suitable place of RNA species crosstalk. Finally, we assume that lncRNAs could be a loading vehicle for miRNAs, mRNAs and other complex molecules into the exosome but future studies are required to confirm these hypotheses.