Xuetao Cao

Scientific Reports 5: Article number: 10942; published online: 01 June 2015; updated: 23 February 2016 This Article contains typographical errors in Table 2 where ‘Week 2 (N = 32)’ was incorrectly given as ‘Week (N = 2)’.

Noncoding RNAs play important roles in cancer biology, providing potential targets for cancer intervention. As a new class of endogenous noncoding RNAs, circular RNAs (circRNAs) have been recently identified in cell development and function, and certain types of pathological responses, generally acting as a microRNA (miRNA) sponge to regulate gene expression. Identifying the deregulated circRNAs and their roles in cancer has attracted much attention. However, the expression profile and function of circRNAs in human hepatocellular carcinoma (HCC) remain to be investigated. Here, we analyzed the expression profile of human circRNAs in HCC tissues and identified circMTO1 (mitochondrial translation optimization 1 homologue; hsa_circRNA_0007874/hsa_circRNA_104135) as one circRNA significantly down-regulated in HCC tissues. HCC patients with low circMTO1 expression had shortened survival. By using a biotin-labeled circMTO1 probe to perform RNA in vivo precipitation in HCC cells, we identified miR-9 as the circMTO1-associated miRNA. Furthermore, silencing of circMTO1 in HCC could down-regulate p21, the target of oncogenic miR-9, resulting in the promotion of HCC cell proliferation and invasion. In addition, the tumor-promoting effect of circMTO1 silencing was blocked by miR9 inhibitor. Intratumoral administration of cholesterol-conjugated circMTO1 small interfering RNA promoted tumor growth in HCC-bearing mice in vivo. CONCLUSION: circMTO1 suppresses HCC progression by acting as the sponge of oncogenic miR-9 to promote p21 expression, suggesting that circMTO1 is a potential target in HCC treatment. The decrease of circMTO1 in HCC tissues may serve as a prognosis predictor for poor survival of patients. (Hepatology 2017;66:1151-1164).

Long noncoding RNAs (lncRNAs) play important roles in diverse biological processes; however, few have been identified that regulate immune cell differentiation and function. Here, we identified lnc-DC, which was exclusively expressed in human conventional dendritic cells (DCs). Knockdown of lnc-DC impaired DC differentiation from human monocytes in vitro and from mouse bone marrow cells in vivo and reduced capacity of DCs to stimulate T cell activation. lnc-DC mediated these effects by activating the transcription factor STAT3 (signal transducer and activator of transcription 3). lnc-DC bound directly to STAT3 in the cytoplasm, which promoted STAT3 phosphorylation on tyrosine-705 by preventing STAT3 binding to and dephosphorylation by SHP1. Our work identifies a lncRNA that regulates DC differentiation and also broadens the known mechanisms of lncRNA action.