Diagnostic and therapeutic application of noncoding RNAsfor hepatocellular carcinoma

MicroRNAs （miRNAs） are small, noncoding RNA moleculesthat regulate gene expression posttranscriptionally,targeting thousands of messenger RNAs. Long noncodingRNAs （lncRNAs）, another class of noncodingRNAs, have been determined to be also involved intranscription regulation and translation of target genes.Since deregulated expression levels or functions ofmiRNAs and lncRNAs in hepatocellular carcinoma （HCC）are frequently observed, clinical use of noncodingRNAs for novel diagnostic and therapeutic applicationsin the management of HCCs is highly and emergentlyexpected. Here, we summarize recent findingsregarding deregulated miRNAs and lncRNAs for theirpotential clinical use as diagnostic and prognosticbiomarkers of HCC. Specifically, we emphasize thederegulated expression levels of such noncoding RNAsin patients＇ sera as noninvasive biomarkers, a field thatrequires urgent improvement in the clinical surveillanceof HCC. Since nucleotide-based strategies are beingapplied to clinical therapeutics, we further summarizeclinical and preclinical trials using oligonucleotidesinvolving the use of miRNAs and small interfering RNAsagainst HCC as novel therapeutics. Finally, we discusscurrent open questions, which must be clarified in thenear future for realistic clinical applications of thesenew strategies.