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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.

Unlabelled: Tumor cells with stemness (stem-cell) features contribute to initiation and progression of hepatocellular carcinoma (HCC), but involvement of long noncoding RNAs (lncRNAs) remains largely unclear. Genome-wide analyses were applied to identify tumor-associated lncRNA-DANCR. DANCR expression level and prognostic values of DANCR were assayed in two HCC cohorts (China and Korea, n = 135 and 223). Artificial modulation of DANCR (down- and overexpression) was done to explore the role of DANCR in tumorigenesis and colonization, and tumor-bearing mice were used to determine therapeutic effects. We found that lncRNA-DANCR is overexpressed in stem-like HCC cells, and this can serve as a prognostic biomarker for HCC patients. Experiments showed that DANCR markedly increased stemness features of HCC cells to promote tumorigenesis and intra-/extrahepatic tumor colonization. Conversely, DANCR knockdown attenuated the stem-cell properties and in vivo interference with DANCR action led to decreased tumor cell vitality, tumor shrinkage, and improved mouse survival. Additionally, we found that the role of DANCR relied largely on an association with, and regulation of, CTNNB1. Association of DANCR with CTNNB1 blocked the repressing effect of microRNA (miR)-214, miR-320a, and miR-199a on CTNNB1. This observation was confirmed in vivo, suggesting a novel mechanism of tumorigenesis involving lncRNAs, messenger RNAs, and microRNAs., Conclusions: These studies reveal a significance and mechanism of DANCR action in increasing stemness features and offer a potential prognostic marker and a therapeutic target for HCC., (© 2015 by the American Association for the Study of Liver Diseases.)

About 61-72% of transcribed regions possess long noncoding RNAs in antisense orientation (Antisense long noncoding RNAs, aslncRNAs). However, the function of aslncRNAs in HCC remains unclear. We found numerous aslncRNAs were deregulated and might be involved in regulatory gene-net of HCC. The PCNA-AS1, antisense to PCNA, is significantly up-regulated in HCC and could promote tumor growth in vitro and in vivo. The effects of PCNA-AS1 rely on regulation of PCNA via forming RNA hybridization to increase PCNA mRNA stability. We concluded that aslncRNAs might act as upstream regulators in HCC and PCNA-AS1 could serve as a novel therapeutic target., (Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.)

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., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Unlabelled: Survival of patients with hepatocellular carcinoma (HCC) remains poor, which is largely attributed to active angiogenesis. However, the mechanisms underlying angiogenesis in HCC remain to be discovered. In this study, we found that long noncoding RNA associated with microvascular invasion in HCC (lncRNA MVIH) (lncRNA associated with microvascular invasion in HCC) was generally overexpressed in HCC. In a cohort of 215 HCC patients, the overexpression of MVIH was associated with frequent microvascular invasion (P = 0.016) and a higher tumor node metastasis stage (P = 0.009) as well as decreased recurrence-free survival (RFS) (P < 0.001) and overall survival (P = 0.007). Moreover, the up-regulation of MVIH served as an independent risk factor to predict poor RFS. We also found that MVIH could promote tumor growth and intrahepatic metastasis by activating angiogenesis in mouse models. Subsequent investigations indicated that MVIH could activate tumor-inducing angiogenesis by inhibiting the secretion of phosphoglycerate kinase 1 (PGK1). Additionally, in 65 HCC samples, MVIH expression was inversely correlated with the serum level of PGK1 and positively correlated with the microvessel density., Conclusion: Deregulation of lncRNA MVIH is a predictor for poor RFS of HCC patients after hepatectomy and could be utilized as a potential target for new adjuvant therapies against active angiogenesis., (Copyright © 2012 American Association for the Study of Liver Diseases.)