Molecular functions and therapeutic applications of exosomal noncoding RNAs in cancer

Cancer: regulatory RNAs in tiny packages RNA molecules carried in small membrane-bound vesicles called exosomes, which are released naturally by some cells, are implicated in controlling the development of some cancers and may offer new approaches to treatment. Wen Wen Xu and colleagues at Jinan University in Guangzhou, China review the functions of small RNAs carried by exosomes in the development of cancer. They focus on a variety of 'noncoding' RNAs, which do not determine the manufacture of protein molecules but instead perform genetic regulatory functions. Some RNAs support the progression of specific cancers while some suppress other cancers. Their presence could perhaps be used to diagnose and predict the progress of particular cancers. The emerging research findings suggest exosomes might be used to treat cancer by delivering small regulatory RNA molecules into tumors, perhaps with other drugs. Cancer is one of the most difficult diseases in human society. Therefore, it is urgent for us to understand its pathogenesis and improve the cure rate. Exosomes are nanoscale membrane vesicles formed by a variety of cells through endocytosis. As a new means of intercellular information exchange, exosomes have attracted much attention. Noncoding RNAs exist in various cell compartments and participate in a variety of cellular reactions; in particular, they can be detected in exosomes bound to lipoproteins and free circulating molecules. Increasing evidence has suggested the potential roles of exosomal noncoding RNAs in the progression of tumors. Herein, we present a comprehensive update on the biological functions of exosomal noncoding RNAs in the development of cancer. Specifically, we mainly focus on the effects of exosomal noncoding RNAs, including microRNAs, circular RNAs, long noncoding RNAs, small nuclear RNAs, and small nucleolar RNAs, on tumor growth, metastasis, angiogenesis, and chemoresistance. Moreover, we outline the current clinical implications concerning exosomal noncoding RNAs in cancer treatment.