The role of TGF-β-induced epithelial-mesenchymal transition (EMT) in cancer cell dissemination is well established, but the involvement of lncRNAs in TGF-β signaling is still unknown. In this study, we observed that the lncRNA-activated by TGF-β (lncRNA-ATB) was upregulated in hepatocellular carcinoma (HCC) metastases and associated with poor prognosis. lncRNA-ATB upregulated ZEB1 and ZEB2 by competitively binding the miR-200 family and then induced EMT and invasion. In addition, lncRNA-ATB promoted organ colonization of disseminated tumor cells by binding IL-11 mRNA, autocrine induction of IL-11, and triggering STAT3 signaling. Globally, lncRNA-ATB promotes the invasion-metastasis cascade. Thus, these findings suggest that lncRNA-ATB, a mediator of TGF-β signaling, could predispose HCC patients to metastases and may serve as a potential target for antimetastatic therapies.

These studies reveal an important role of METTL14 in tumor metastasis and provide a fresh view on m A modification in tumor progression. (Hepatology 2017;65:529-543).

In recent years, long noncoding RNAs (lncRNAs) have been shown to have critical regulatory roles in cancer biology. However, the contributions of lncRNAs to hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC) remain largely unknown. Differentially expressed lncRNAs between HBV-related HCC and paired peritumoral tissues were identified by microarray and validated using quantitative real-time polymerase chain reaction. Liver samples from patients with HBV-related HCC were analyzed for levels of a specific differentially expressed lncRNA High Expression In HCC (termed lncRNA-HEIH); data were compared with survival data using the Kaplan-Meier method and compared between groups by the log-rank test. The effects of lncRNA-HEIH were assessed by silencing and overexpressing the lncRNA in vitro and in vivo. The expression level of lncRNA-HEIH in HBV-related HCC is significantly associated with recurrence and is an independent prognostic factor for survival. We also found that lncRNA-HEIH plays a key role in G 0 /G 1 arrest, and further demonstrated that lncRNA-HEIH was associated with enhancer of zeste homolog 2 (EZH2) and that this association was required for the repression of EZH2 target genes. Conclusions: Together, these results indicate that lncRNA-HEIH is an oncogenic lncRNA that promotes tumor progression and leads us to propose that lncRNAs may serve as key regulatory hubs in HCC progression. (HEPATOLOGY 2011;54:1679-1689 H epatocellular carcinoma (HCC) is one of the most common human cancers worldwide, particularly in Southeast Asia and Africa. 1More than 70%-80% of HCC cases occur in high hepatitis B virus (HBV) endemic regions, and 50% of HCC cases worldwide are attributable to chronic infection with HBV. Unfortunately, the 5-year survival rate of HBV-related HCC patients remains poor, and approximately 600,000 HCC patients die each year, despite recent advances in surgical techniques and medical treatment.2 Although previous studies identified many aberrantly expressed protein-coding genes in HCC, novel molecular markers that can help in early diagnosis and risk assessment are still urgently needed. 3It is of paramount importance to understand the relationships between clinical symptoms and molecular changes in HCC for developing new diagnosis and treatment strategies for HCC and improving the prognosis of diagnosed patients. The human transcriptome comprises not only large numbers of protein-coding messenger RNAs (mRNAs), but also a large set of nonprotein coding Abbreviations:: CCK-8, Cell-Counting Kit-8 assay; ChIP, chromatin immunoprecipitation; cDNA, complementary DNA; 95% CI, 95% confidence interval; EZH2, enhancer of zeste homolog

Many protein-coding oncofetal genes are highly expressed in murine and human fetal liver and silenced in adult liver. The protein products of these hepatic oncofetal genes have been used as clinical markers for the recurrence of hepatocellular carcinoma (HCC) and as therapeutic targets for HCC. Herein we examined the expression profiles of long noncoding RNAs (lncRNAs) found in fetal and adult liver in mice. Many fetal hepatic lncRNAs were identified; one of these, lncRNA-mPvt1, is an oncofetal RNA that was found to promote cell proliferation, cell cycling, and the expression of stem cell-like properties of murine cells. Interestingly, we found that human lncRNA-hPVT1 was upregulated in HCC tissues and that patients with higher lncRNA-hPVT1 expression had a poor clinical prognosis. The protumorigenic effects of lncRNA-hPVT1 on cell proliferation, cell cycling, and stem cell-like properties of HCC cells were confirmed both in vitro and in vivo by gain-of-function and loss-of-function experiments. Moreover, mRNA expression profile data showed that lncRNA-hPVT1 up-regulated a series of cell cycle genes in SMMC-7721 cells. By RNA pulldown and mass spectrum experiments, we identified NOP2 as an RNA-binding protein that binds to lncRNA-hPVT1. We confirmed that lncRNA-hPVT1 up-regulated NOP2 by enhancing the stability of NOP2 proteins and that lncRNA-hPVT1 function depends on the presence of NOP2. Conclusion: Our study demonstrates that the expression of many lncRNAs is up-regulated in early liver development and that the fetal liver can be used to search for new diagnostic markers for HCC. LncRNA-hPVT1 promotes cell proliferation, cell cycling, and the acquisition of stem cell-like properties in HCC cells by stabilizing NOP2 protein. Regulation of the lncRNA-hPVT1/NOP2 pathway may have beneficial effects on the treatment of HCC. (HEPATOLOGY 2014;60:1278-1290

Although numerous long non-coding RNAs (lncRNAs) have been identified in mammals, many of their biological roles remain to be characterized. Early reports suggest that H19 contributes to carcinogenesis, including hepatocellular carcinoma (HCC). Examination of the Oncomine resource showed that most HCC cases express H19 at a level that is comparable with the liver, with a tendency toward lower expression. This is consistent with our previous microarray data and indicates a more complicated role of H19 in HCC that needs to be characterized. In this study, the expression level of H19 was assessed in different regions of HCC patients' liver samples. Loss- and gain-of-function studies on this lncRNA in the HCC cell lines, SMMC7721 and HCCLM3, were used to characterize its effects on gene expression and to assess its effect on HCC metastasis both in vitro and in vivo. In this study, we show that H19 was underexpressed in intratumoral HCC tissues (T), as compared with peritumoral tissues (L). Additionally, low T/L ratio of H19 predicted poor prognosis. H19 suppressed HCC progression metastasis and the expression of markers of epithelial-to-mesenchymal transition. Furthermore, H19 associated with the protein complex hnRNP U/PCAF/RNAPol II, activating miR-200 family by increasing histone acetylation. The results demonstrate that H19 can alter the miR-200 pathway, thus contributing to mesenchymal-to-epithelial transition and to the suppression of tumor metastasis. These data provide an explanation for the hitherto puzzling literature on the relationship between H19 and cancer, and could suggest the development of combination therapies that target H19 and the miR-200 family.

Understanding the roles of splicing factors and splicing events during tumorigenesis would open new avenues for targeted therapies. Here we identify an oncofetal splicing factor, MBNL3, which promotes tumorigenesis and indicates poor prognosis of hepatocellular carcinoma patients. MBNL3 knockdown almost completely abolishes hepatocellular carcinoma tumorigenesis. Transcriptomic analysis revealed that MBNL3 induces lncRNA-PXN-AS1 exon 4 inclusion. The transcript lacking exon 4 binds to coding sequences of PXN mRNA, causes dissociation of translation elongation factors from PXN mRNA, and thereby inhibits PXN mRNA translation. In contrast, the transcript containing exon 4 preferentially binds to the 3' untranslated region of PXN mRNA, protects PXN mRNA from microRNA-24-AGO2 complex-induced degradation, and thereby increases PXN expression. Through inducing exon 4 inclusion, MBNL3 upregulates PXN, which mediates the pro-tumorigenic roles of MBNL3. Collectively, these data demonstrate detailed mechanistic links between an oncofetal splicing factor, a splicing event and tumorigenesis, and establish splicing factors and splicing events as potential therapeutic targets.

BackgroundRecent evidences showed that long noncoding RNAs (lncRNAs) are frequently dysregulated and play important roles in various cancers. Clear cell renal cell carcinoma (ccRCC) is one of the leading cause of cancer-related death, largely due to the metastasis of ccRCC. However, the clinical significances and roles of lncRNAs in metastatic ccRCC are still unknown.MethodslncRNA expression microarray analysis was performed to search the dysregulated lncRNA in metastatic ccRCC. quantitative real-time PCR was performed to measure the expression of lncRNAs in human ccRCC samples. Gain-of-function and loss-of-function experiments were performed to investigate the biological roles of lncRNAs on ccRCC cell proliferation, migration, invasion and in vivo metastasis. RNA pull-down, RNA immunoprecipitation, chromatin immunoprecipitation, and western blot were performed to explore the molecular mechanisms underlying the functions of lncRNAs.ResultsThe microarray analysis identified a novel lncRNA termed metastatic renal cell carcinoma-associated transcript 1 (MRCCAT1), which is highly expressed in metastatic ccRCC tissues and associated with the metastatic properties of ccRCC. Multivariate Cox regression analysis revealed that MRCCAT1 is an independent prognostic factor for ccRCC patients. Overexpression of MRCCAT1 promotes ccRCC cells proliferation, migration, and invasion. Depletion of MRCCAT1 inhibites ccRCC cells proliferation, migration, and invasion in vitro, and ccRCC metastasis in vivo. Mechanistically, MRCCAT1 represses NPR3 transcription by recruiting PRC2 to NPR3 promoter, and subsequently activates p38-MAPK signaling pathway.ConclusionsMRCCAT1 is a critical lncRNA that promotes ccRCC metastasis via inhibiting NPR3 and activating p38-MAPK signaling. Our results imply that MRCCAT1 could serve as a prognostic biomarker and therapeutic target for ccRCC.Electronic supplementary materialThe online version of this article (doi:10.1186/s12943-017-0681-0) contains supplementary material, which is available to authorized users.

In recent years, long noncoding RNAs (lncRNAs) have been investigated as a new class of regulators of biological function. A recent study reported that lncRNAs control cell proliferation in hepatocellular carcinoma (HCC). However, the role of lncRNAs in liver regeneration and the overall mechanisms remain largely unknown. To address this issue, we carried out a genome-wide lncRNA microarray analysis during liver regeneration in mice after 2/3 partial hepatectomy (PH) at various timepoints. The results revealed differential expression of a subset of lncRNAs, notably a specific differentially expressed lncRNA associated with Wnt/b-catenin signaling during liver regeneration (an lncRNA associated with liver regeneration, termed lncRNA-LALR1). The functions of lncRNA-LALR1 were assessed by silencing and overexpressing this lncRNA in vitro and in vivo. We found that lncRNA-LALR1 enhanced hepatocyte proliferation by promoting progression of the cell cycle in vitro. Furthermore, we showed that lncRNA-LALR1 accelerated mouse hepatocyte proliferation and cell cycle progression during liver regeneration in vivo. Mechanistically, we discovered that lncRNA-LALR1 facilitated cyclin D1 expression through activation of Wnt/b-catenin signaling by way of suppression of Axin1. In addition, lncRNA-LALR1 inhibited the expression of Axin1 mainly by recruiting CTCF to the AXIN1 promoter region. We also identified a human ortholog RNA of lncRNA-LALR1 (lncRNA-hLALR1) and found that it was expressed in human liver tissues. Conclusion: lncRNA-LALR1 promotes cell cycle progression and accelerates hepatocyte proliferation during liver regeneration by activating Wnt/b-catenin signaling. Pharmacological intervention targeting lncRNA-LALR1 may be therapeutically beneficial in liver failure and liver transplantation by inducing liver regeneration. (HEPATOLOGY 2013;58:739-751)