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•Circular RNAs in human HCC were identified using RNA-sequencing.•Circular RNA cSMARCA5 was downregulated in HCC and associated with poor prognosis.•Downregulation of cSMARCA5 in HCC ...was attributed to the upregulation of DHX9.•cSMARCA5 inhibited HCC growth and metastasis both in vitro and in vivo.•cSMARCA5 acted as the sponge of miR-17-3p and miR-181b-5p to upregulate TIMP3.
In recent years, circular RNAs (circRNAs) have been shown to have critical regulatory roles in cancer biology. However, the contributions of circRNAs to hepatocellular carcinoma (HCC) remain largely unknown.
cSMARCA5 (a circRNA derived from exons 15 and 16 of the SMARCA5 gene, hsa_circ_0001445) was identified by RNA-sequencing and validated by quantitative reverse transcription PCR. The role of cSMARCA5 in HCC progression was assessed both in vitro and in vivo. circRNAs in vivo precipitation, luciferase reporter assay, biotin-coupled microRNA capture and fluorescence in situ hybridization were conducted to evaluate the interaction between cSMARCA5 and miR-17-3p/miR-181b-5p.
The expression of cSMARCA5 was lower in HCC tissues, because of the regulation of DExH-Box Helicase 9, an abundant nuclear RNA helicase. The downregulation of cSMARCA5 in HCC was significantly correlated with aggressive characteristics and served as an independent risk factor for overall survival and recurrence-free survival in patients with HCC after hepatectomy. Our in vivo and in vitro data indicated that cSMARCA5 inhibits the proliferation and migration of HCC cells. Mechanistically, we found that cSMARCA5 could promote the expression of TIMP3, a well-known tumor suppressor, by sponging miR-17-3p and miR-181b-5p.
These results reveal an important role of cSMARCA5 in the growth and metastasis of HCC and provide a fresh perspective on circRNAs in HCC progression.
Herein, we studied the role of cSMARCA5, a circular RNA, in hepatocellular carcinoma. Our in vitro and in vivo data showed that cSMARCA5 inhibits the growth and migration of hepatocellular carcinoma cells, making it a potential therapeutic target.
N
-Methyladenosine (m
A) modification has been implicated in many biological processes. However, its role in cancer has not been well studied. Here, we demonstrate that m
A modifications are ...decreased in hepatocellular carcinoma, especially in metastatic hepatocellular carcinoma, and that methyltransferase-like 14 (METTL14) is the main factor involved in aberrant m
A modification. Moreover, METTL14 down-regulation acts as an adverse prognosis factor for recurrence-free survival of hepatocellular carcinoma and is significantly associated with tumor metastasis in vitro and in vivo. We confirm that METTL14 interacts with the microprocessor protein DGCR8 and positively modulates the primary microRNA 126 process in an m
A-dependent manner. Further experiments show that microRNA 126 inhibits the repressing effect of METTL14 in tumor metastasis.
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).
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. (Hepatology 2016;63:499–511)
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 up‐regulated 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)
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.
To explore whether plasma circular RNAs (circRNAs) can diagnose hepatitis B virus (HBV)‐related hepatocellular carcinoma (HCC), microarray and qPCR were used to identify plasma circRNAs that were ...increased in HBV‐related HCC patients compared to controls (including healthy controls, chronic hepatitis B and HBV‐related liver cirrhosis). A logistic regression model was constructed using a training set (n = 313) and then validated using another two independent sets (n = 306 and 526, respectively). Area under the receiver operating characteristic curve (AUC) was used to evaluate diagnostic accuracy. We identified a plasma circRNA panel (CircPanel) containing three circRNAs (hsa_circ_0000976, hsa_circ_0007750 and hsa_circ_0139897) that could detect HCC. CircPanel showed a higher accuracy than AFP (alpha‐fetoprotein) to distinguish individuals with HCC from controls in all three sets (AUC, 0.863 95% confidence interval, CI: 0.819–0.907 vs. 0.790 0.738–0.842, p = 0.036 in training set; 0.843 0.796–0.890 vs. 0.747 0.691–0.804, p = 0.011 in validation set 1 and 0.864 0.830–0.898 vs. 0.769 0.728–0.810, p < 0.001 in validation set 2). CircPanel also performed well in detecting Small‐HCC (solitary, ≤3 cm), AFP‐negative HCC and AFP‐negative Small‐HCC.
What's new?
To date, one limitation in the treatment of hepatocellular carcinoma (HCC) is the lack of serum biomarkers with satisfactory diagnostic accuracy. Here, the authors explored whether plasma circRNAs can be biomarkers to diagnose hepatitis B virus‐related HCC in 1155 participants from three hospitals in China. They identified a plasma circRNA panel (CircPanel, including hsa_circ_0000976, hsa_circ_0007750, and hsa_circ_0139897) that showed higher accuracy than the clinically‐used serum biomarker AFP in distinguishing individuals with HCC or Small‐HCC from controls and performed well in diagnosing AFP‐negative HCC and AFP‐negative Small‐HCC. Altogether, the findings point to CircPanel as a promising potential biomarker in HCC diagnosis.
The hepatitis B virus X protein (HBx) has been implicated as an oncogene in both epigenetic modifications and genetic regulation during hepatocarcinogenesis, but the underlying mechanisms are not ...entirely clear. Long noncoding RNAs (lncRNAs), which regulate gene expression with little or no protein‐coding capacity, are involved in diverse biological processes and in carcinogenesis. We asked whether HBx could promote hepatocellular carcinoma (HCC) by regulating the expression of lncRNAs. In this study we investigated the alteration in expression of lncRNAs induced by HBx using microarrays and real‐time quantitative polymerase chain reaction (PCR). Our results indicate that HBx transgenic mice have a specific profile of liver lncRNAs compared with wildtype mice. We identified an lncRNA, down‐regulated expression by HBx (termed lncRNA‐Dreh), which can inhibit HCC growth and metastasis in vitro and in vivo, act as a tumor suppressor in the development of hepatitis B virus (HBV)‐HCC. LncRNA‐Dreh could combine with the intermediate filament protein vimentin and repress its expression, and thus further change the normal cytoskeleton structure to inhibit tumor metastasis. We also identified a human ortholog RNA of Dreh (hDREH) and found that its expression level was frequently down‐regulated in HBV‐related HCC tissues in comparison with the adjacent noncancerous hepatic tissues, and its decrement significantly correlated with poor survival of HCC patients. Conclusion: These findings support a role of lncRNA‐Dreh in tumor suppression and survival prediction in HCC patients. This discovery contributes to a better understanding of the importance of the deregulated lncRNAs by HBx in HCC and provides a rationale for the potential development of lncRNA‐based targeted approaches for the treatment of HBV‐related HCC. (HEPATOLOGY 2013)
Recently, long noncoding RNAs (lncRNAs) were found to be dysregulated in a variety of tumors. However, it remains unknown how and through what molecular mechanisms the expression of lncRNAs is ...controlled. In this study, we found that the lncRNA Low Expression in Tumor (lncRNA-LET) was generally downregulated in hepatocellular carcinomas, colorectal cancers, and squamous-cell lung carcinomas. We demonstrated that hypoxia-induced histone deacetylase 3 repressed lncRNA-LET by reducing the histone acetylation-mediated modulation of the lncRNA-LET promoter region. Interestingly, the downregulation of lncRNA-LET was found to be a key step in the stabilization of nuclear factor 90 protein, which leads to hypoxia-induced cancer cell invasion. Moreover, the relationship among hypoxia, histone acetylation disorder, low lncRNA-LET expression level, and metastasis was found in clinical hepatocellular carcinoma samples. These results advance our understanding of the role of lncRNA-LET as a regulator of hypoxia signaling and offer new avenues for therapeutic intervention against cancer progression.
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► There is low expression of lncRNA-LET in various tumor tissues ► Hypoxia-induced low expression of lncRNA-LET occurred through histone deacetylase 3 ► The lncRNA-LET is bound to NF90, which increases NF90 degradation by the proteasome ► Low lncRNA-LET expression contributes to hypoxia-induced cell invasion
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 G0/G1 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
Background and Aims
HBV‐pgRNA (pregenomic RNA) has been proposed for predicting the response of nucleos(t)ide analogue (NA) treatment, guiding discontinuation of NA therapy and monitoring the ...emergence of viral mutations. However, the contributions of HBV‐pgRNA to HCC remain open for study.
Approach and Results
Double‐center cohorts of serum samples with undetectable serum HBV‐DNA (below the lower limit of detection) were obtained from long‐term NA‐treated (≥48 weeks) HBV‐related HCC patients. The correlation between serum pgRNA concentration and the prognosis of HCC were analyzed. The role pgRNA played in HCC development was assessed both in vitro and in vivo. Our findings revealed that for patients who underwent long‐term NA therapy with undetectable serum HBV‐DNA, patients with high serum pgRNA expression had a poorer overall survival rate and higher cumulative recurrence rate after hepatectomy. Experiments demonstrated that pgRNA promotes proliferation, stemness, and tumorigenicity of HCC cells. Mechanistically, we found that pgRNA could up‐regulate the expression of insulin‐like growth factor 2 mRNA‐binding protein 3 (IGF2BP3), a well‐proven oncoprotein, at the posttranscriptional level. Furthermore, interferon (IFN)‐α‐2a could degrade the stability of pgRNA through increasing its N6‐methyladenosine (m6A) RNA modification. Collectively, our findings uncover that serum pgRNA could serve as a potential biomarker for predicting the prognosis and recurrence of HCC in patients who received long‐term NA therapy with undetectable serum HBV‐DNA; and the pgRNA‐IGF2BP3 axis plays an important role in the development of HBV‐related HCC. Moreover, IFN‐α‐2a could reduce the stability of pgRNA by increasing its m6A RNA modification level, thereby suppressing the development of HBV‐related HCC.
Conclusions
In conclusion, our studies reveal a significance and mechanism of HBV‐pgRNA in increasing stemness features and offer a potential prognostic marker and a therapeutic target for HBV‐related HCC.
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