Liver-specific lncRNAs associated with liver cancers

Abstract

Long non-coding RNAs (lncRNAs) are transcripts with a length more than 200 nt, which do not encode proteins and act just as RNA molecules. In general, lncRNAs have much more distinct tissue specificity than proteins, as they usually realize more peculiar regulatory functions. Their expression levels are often altered in a response to stress conditions, metabolic changes, development of different diseases, and carcinogenesis. Cancer-associated lncRNAs are widely considered as perspective and useful biomarkers. Thus, development of clinical tests, which include tissue-specific and cancer-specific lncRNAs, might significantly contribute to cancer diagnostics and/or prognosis of the disease. A number of lncRNAs is known to be dysregulated in liver tumors and considered as probable biomarkers. However, most of them are rather universally well-known lncRNAs associated with various cancers. In the present review, we aimed to shed light on other lncRNAs with preferential expression in liver and/or liver tumors, for example, LINC01554, LINC01093, LINC01348, LINC02428, FAM99B, etc. We summarized recent discoveries unveiling their dysregulation in liver malignancies and related cellular mechanisms in which they are involved and considered their significance as probable liver cancer biomarkers.

Keywords: biomarkers; hepatocellular carcinoma; liver cancer; long noncoding RNA.

Fig. 1

Median gene‐level expression [log₂(TPM+1)] of described lncRNAs in different human tissues/cell types according to the open access dataset (GTEx_Analysis_v10_RNASeQCv2.4.2_gene _median_tpm.gct.gz) downloaded from GTEx Portal (www.gtexportal.org, [28]).

Fig. 2

Median gene‐level expression [log₂(TPM+1)] of described lncRNAs in different liver diseases and conditions in comparison to normal GTEx data and bulk adjacent liver tissues (Adj. normal) according to the open access dataset (Hsa_mRNA_lncRNA_anno.txt) downloaded from GepLiver atlas (http://www.gepliver.org/#/download, [31]). Abbreviations: ALD, alcoholic liver disease; CCA, cholangiocarcinoma; HBL, hepatoblastoma; HCC, hepatocellular carcinoma; NAFLD, nonalcoholic fatty liver disease; сHCC‐CCA: combined HCC‐CCA.