Long noncoding RNA DLX6-AS1 promotes liver cancer by increasing the expression of WEE1 via targeting miR-424-5p

Expression of lncRNA DLX6-AS1 in patients with hepatic carcinoma and its prognostic value

Hepatic carcinoma (HCC) is one of the most common malignant tumors worldwide, and the prognosis of HCC patients is often poor. Long-chain non-coding RNA (lncRNA) distal-less homeobox 6 antisense 1 (DLX6-AS1) has been shown to be involved in the pathogenesis of various cancers. This study aims to investigate the expression of DLX6-AS1 in HCC patients and its prognostic value. The serum DLX6-AS1 was quantified using a reverse transcription-polymerase chain reaction (RT-PCR) assay in both HCC patients and healthy individuals, and the correlation of DLX6-AS1 with clinicopathological features of HCC patients, as well as the diagnostic and prognostic value of DLX6-AS1 for HCC patients, were analyzed. The results showed that the expression of serum DLX6-AS1 in HCC patients was significantly higher than that of healthy individuals (P < 0.05), and DLX6-AS1 was related to tumor differentiation, pathological staging, and lymph node metastasis (all P < 0.05). Patients with high DLX6-AS1 expression showed significantly higher mortality than those with low DLX6-AS1 expression, and the DLX6-AS1 expression in dead patients was significantly higher than that in living patients. Furthermore, the AUC of DLX6-AS1 for poor prognosis of HCC patients was larger than 0.8. The univariate analysis revealed that the poor prognosis of HCC patients was related to pathological staging, lymph node metastasis, differentiation, and DLX6-AS1 expression (all P < 0.05), and the Cox multivariate analysis revealed that pathological staging, lymph node metastasis, differentiation, and DLX6-AS1 expression were independent risk factors for poor prognosis of HCC patients (all P < 0.05). These findings suggest that DLX6-AS1 may be a promising target for diagnosis, treatment, and prognosis prediction of HCC patients.

Circulating RNA ZFR promotes hepatocellular carcinoma cell proliferation and epithelial-mesenchymal transition process through miR-624-3p/WEE1 axis

BACKGROUND

Hepatocellular carcinoma (HCC), the most common type of primary liver cancer, is the fourth leading cause of cancer-related deaths worldwide. Previous evidence shows that the expression of circulating RNA ZFR (circZFR) is upregulated in HCC tissues. However, the molecular mechanism of circZFR in HCC is unclear.

METHODS

Quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) was employed to detect the expression of circZFR, microRNA-624-3p (miR-624-3p) and WEE1 in HCC tissues and cells. RNase R assay and actinomycin D treatment assay were used to analyze the characteristics of circZFR. For functional analysis, the capacities of colony formation, cell proliferation, cell apoptosis, migration and invasion were assessed by colony formation assay, 5-ethynyl-2'-deoxyuridine (EdU) assay, flow cytometry assay and transwell assay. Western blot was used to examine the protein levels of WEE1 and epithelial-mesenchymal transition (EMT)-related proteins. The interactions between miR-624-3p and circZFR or WEE1 were validated by dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay. Xenograft models were established to determine the role of circZFR in vivo.

RESULTS

circZFR and WEE1 were upregulated, while miR-624-3p expression was reduced in HCC tissues and cells. circZFR could sponge miR-624-3p, and WEE1 was a downstream gene of miR-624-3p. Knockdown of circZFR significantly reduced the malignant behaviors of HCC and that co-transfection with miR-624-3p inhibitor restored this change. Overexpression of WEE1 abolished the inhibitory effect of miR-624-3p mimic on HCC cells. Mechanistically, circZFR acted as a competitive endogenous RNA (ceRNA) to regulate WEE1 expression by targeting miR-624-3p. Furthermore, in vivo studies have illustrated that circZFR knockdown inhibited tumor growth.

CONCLUSIONS

circZFR knockdown reduced HCC cell proliferation, migration and invasion and promoted apoptosis by regulating the miR-624-3p/WEE1 axis, suggesting that the circZFR/miR-624-3p/WEE1 axis might be a potential target for HCC treatment.

Crosstalk between long noncoding RNA and microRNA in Cancer

miRNAs and lncRNAs play a central role in cancer-associated gene regulations. The dysregulated expression of lncRNAs has been reported as a hallmark of cancer progression, acting as an independent prediction marker for an individual cancer patient. The interplay of miRNA and lncRNA decides the variation of tumorigenesis that could be mediated by acting as sponges for endogenous RNAs, regulating miRNA decay, mediating intra-chromosomal interactions, and modulating epigenetic components. This paper focuses on the influence of crosstalk between lncRNA and miRNA on cancer hallmarks such as epithelial-mesenchymal transition, hijacking cell death, metastasis, and invasion. Other cellular roles of crosstalks, such as neovascularization, vascular mimicry, and angiogenesis were also discussed. Additionally, we reviewed crosstalk mechanism with specific host immune responses and targeting interplay (between lncRNA and miRNA) in cancer diagnosis and management.

Synthetic and Medicinal Chemistry Approaches Toward WEE1 Kinase Inhibitors and Its Degraders

WEE1 is a checkpoint kinase critical for mitotic events, especially in cell maturation and DNA repair. Most cancer cells' progression and survival are linked with elevated levels of WEE1 kinase. Thus, WEE1 kinase has become a new promising druggable target. A few classes of WEE1 inhibitors are designed by rationale or structure-based techniques and optimization approaches to identify selective acting anticancer agents. The discovery of the WEE1 inhibitor AZD1775 further emphasized WEE1 as a promising anticancer target. Therefore, the current review provides a comprehensive data on medicinal chemistry, synthetic approaches, optimization methods, and the interaction profile of WEE1 kinase inhibitors. In addition, WEE1 PROTAC degraders and their synthetic procedures, including a list of noncoding RNAs necessary for regulation of WEE1, are also highlighted. From the standpoint of medicinal chemistry, the contents of this compilation serve as an exemplar for the further design, synthesis, and optimization of promising WEE1-targeted anticancer agents.

Making Sense of Antisense lncRNAs in Hepatocellular Carcinoma

Transcriptome complexity is emerging as an unprecedented and fascinating domain, especially by high-throughput sequencing technologies that have unveiled a plethora of new non-coding RNA biotypes. This review covers antisense long non-coding RNAs, i.e., lncRNAs transcribed from the opposite strand of other known genes, and their role in hepatocellular carcinoma (HCC). Several sense-antisense transcript pairs have been recently annotated, especially from mammalian genomes, and an understanding of their evolutionary sense and functional role for human health and diseases is only beginning. Antisense lncRNAs dysregulation is significantly involved in hepatocarcinogenesis, where they can act as oncogenes or oncosuppressors, thus playing a key role in tumor onset, progression, and chemoradiotherapy response, as deduced from many studies discussed here. Mechanistically, antisense lncRNAs regulate gene expression by exploiting various molecular mechanisms shared with other ncRNA molecules, and exploit special mechanisms on their corresponding sense gene due to sequence complementarity, thus exerting epigenetic, transcriptional, post-transcriptional, and translational controls. The next challenges will be piecing together the complex RNA regulatory networks driven by antisense lncRNAs and, ultimately, assigning them a function in physiological and pathological contexts, in addition to defining prospective novel therapeutic targets and innovative diagnostic tools.

Prognostic MicroRNA Fingerprints Predict Recurrence of Early-Stage Hepatocellular Carcinoma Following Hepatectomy

Purpose: This study aims to develop liquid biopsy assays for early HCC diagnosis and prognosis. Methods: Twenty-three microRNAs were first consolidated as a panel (HCCseek-23 panel) based on their reported functions in HCC development. Serum samples were collected from 103 early-stage HCC patients before and after hepatectomy. Quantitative PCR and machine learning random forest models were applied to develop diagnostic and prognostic models. Results: For HCC diagnosis, HCCseek-23 panel demonstrated 81% sensitivity and 83% specificity for identifying HCC in the early-stage; it showed 93% sensitivity for identifying alpha-fetoprotein (AFP)-negative HCC. For HCC prognosis, the differential expressions of 8 microRNAs (HCCseek-8 panel: miR-145, miR-148a, miR-150, miR-221, miR-223, miR-23a, miR-374a, and miR-424) were significantly associated with disease-free survival (DFS) (Log-rank test p-value = 0.001). Further model improvement using these HCCseek-8 panel in combination with serum biomarkers (i.e. AFP, ALT, and AST) demonstrated a significant association with DFS (Log-rank p-value = 0.011 and Cox proportional hazards analyses p-value = 0.002). Conclusion: To the best of our knowledge, this is the first report to integrate circulating miRNAs, AST, ALT, AFP, and machine learning for predicting DFS in early HCC patients undergoing hepatectomy. In this setting, HCCSeek-23 panel is a promising circulating microRNA assay for diagnosis, while HCCSeek-8 panel is promising for prognosis to identify early HCC recurrence.

Matrine induces hepatocellular carcinoma apoptosis and represses EMT and stemness through microRNA-299-3p/PGAM1 axis

This study explored the impacts of matrine on hepatocellular carcinoma (HCC) cell growth, metastasis, epithelial-mesenchymal transition (EMT), and stemness through regulating the microRNA (miR)-299-3p/phosphoglycerate mutase 1 (PGAM1) axis. The association between miR-299-3p expression with the prognosis of HCC patients was studied. miR-299-3p and PGAM1 sequences were transfected into matrine-treated HCC cells, and cell proliferation, invasion, apoptosis, and stemness were detected, as well as protein expression of EMT- and stemness-related makers. The targeting relationship between miR-299-3p and PGAM1 was identified. Matrine elevated miR-299-3p expression, repressed proliferation, invasion, and anti-apoptosis of HCC cells, and constrained EMT and stemness in vitro. PGAM1 was a target of miR-299-3p. Repression of PGAM1 rescued the effects of miR-299-3p downregulation on HCC cells. Matrine stimulates HCC cell apoptosis and represses the process of EMT and stemness through the miR-299-3p/PGAM1 axis.

Emerging roles and potential clinical applications of long non-coding RNAs in hepatocellular carcinoma

Hepatocellular carcinoma is one of the most common highly malignant tumors in humans, as well as the leading cause of cancer-related death worldwide. Growing evidence has indicated that lncRNAs are implicated in different molecular mechanisms, including interactions with DNA, RNA, or protein, so that to regulate the gene expression at epigenetic, transcriptional, or posttranscriptional level. Moreover, the mechanism of action of lncRNA is closely related to its subcellular localization. An increasing number of studies have certified that lncRNA plays a significant biological function in the occurrence and development of hepatocellular carcinoma, such as involving in cell proliferation, metastasis, apoptosis, ferroptosis, autophagy, and reprogramming of energy metabolism. As a result, lncRNA has great potential as a novel biomarker for diagnosis or therapeutics of hepatocellular carcinoma. In this review, we highlight the correlation between subcellular localization of lncRNA and its mechanism of action, discuss the biological roles of lncRNA and the latest research advances in hepatocellular carcinoma, and emphasize the potential of lncRNA as a therapeutic target for advanced patients of hepatocellular carcinoma.

Strategies of LncRNA DLX6-AS1 on Study and Therapeutics

Accumulating evidence has revealed the vital regulatory roles of lncRNA DLX6-AS1 in various tumors at pre-transcriptional, transcriptional, and post-transcriptional levels, which makes it a potential prognosis factor and therapeutic target. In addition, the presence of lncRNA DLX6-AS1 in the exosomes of peripheral blood of patients with tumors may also contribute to it being a possible cancer-related biomarker. However, most literature studies are devoted to studying the effect of lncRNA DLX6-AS1 as a sponging molecule of miRNAs, the research of which is likely to get stuck into a dilemma. Literature studies published already have demonstrated an exciting cell malignant phenotype inhibition with the knockdown of lncRNA DLX6-AS1 in various tumor cell lines. With the comprehensive development of delivery systems, high-throughput sequencing, and aptamers, the problems of finding novel research methods and exploring the therapeutic options which are based on lncRNA DLX6-AS1 in vivo could come into a period to deal with. This review aims to summarize the research statuses of lncRNA DLX6-AS1, discuss other study methodologies and therapeutic strategies on it, which might be of help to the deep learning of lncRNA DLX6-AS1 and its application from basic to clinical research.

Noncoding RNA-mediated macrophage and cancer cell crosstalk in hepatocellular carcinoma

The tumor microenvironment (TME) is a well-recognized system that plays an essential role in tumor initiation, development, and progression. Intense intercellular communication between tumor cells and other cells (especially macrophages) occurs in the TME and is mediated by cell-to-cell contact and/or soluble messengers. Emerging evidence indicates that noncoding RNAs (ncRNAs) are critical regulators of the relationship between cells within the TME. In this review, we provide an update on the regulation of ncRNAs (primarily micro RNAs [miRNAs], long ncRNAs [lncRNAs], and circular RNAs [circRNAs]) in the crosstalk between macrophages and tumor cells in hepatocellular carcinoma (HCC). These ncRNAs are derived from macrophages or tumor cells and act as oncogenes or tumor suppressors, contributing to tumor progression not only by regulating the physiological and pathological processes of tumor cells but also by controlling macrophage infiltration, activation, polarization, and function. Herein, we also explore the options available for clinical therapeutic strategies targeting crosstalk-related ncRNAs to treat HCC. A better understanding of the relationship between macrophages and tumor cells mediated by ncRNAs will uncover new diagnostic biomarkers and pharmacological targets in cancer.

Sequence Requirements for miR-424-5p Regulating and Function in Cancers

MiRNAs (microRNAs) are the most abundant family of small noncoding RNAs in mammalian cells. Increasing evidence shows that miRNAs are crucial regulators of individual development and cell homeostasis by controlling various biological processes. Therefore, miRNA dysfunction can lead to human diseases, especially in cancers with high morbidity and mortality worldwide. MiRNAs play different roles in these processes. In recent years, studies have found that miR-424-5p is closely related to the occurrence, development, prognosis and treatment of tumors. This review discusses how miR-424-5p plays a role in different kinds of cancers from different stages of tumors, including its roles in (i) promoting or inhibiting tumorigenesis, (ii) regulating tumor development in the tumor microenvironment and (iii) participating in cancer chemotherapy. This review provides a deep discussion of the latest findings on miR-424-5p and its importance in cancer, as well as a mechanistic analysis of the role of miR-424-5p in various tissues through target gene verification and pathway analysis.

Knockdown of long noncoding RNA HUMT inhibits the proliferation and metastasis by regulating miR-455-5p/LRP4 axis in hepatocellular carcinoma

The present study aimed at investigating the effects and mechanism of long noncoding RNA highly upregulated in metastatic triple-negative breast cancer lymph node (lncRNA HUMT) in hepatocellular carcinoma (HCC). Quantitative real-time polymerase chain reaction was used to assess the expression of HUMT, microRNA (miR)-455-5p, and low-density lipoprotein receptor-related protein 4 (LRP4) in HCC tissues. Colony forming and 5-ethynyl-2′-deoxyuridine assays were performed to assess cell proliferation. Transwell assay was performed to measure cell migration and invasion. Cell cycle distribution was assessed using flow cytometry. The protein expression of LRP4, proliferating cell nuclear antigen (PCNA), matrix metallopeptidase 2 (MMP-2), and MMP-9 was detected using western blot. Luciferase reporter assay and RNA immunoprecipitation assay was used to confirm the target association between miR-455-5p and HUMT or LRP4. In our study, the level of HUMT was enhanced in HCC tissues and cells. Cell proliferation, invasion, and migration in HCC cells were repressed by knockdown of HUMT, and knockdown of HUMT arrested cells in G1 phase and decreased the levels of PCNA, MMP-2, and MMP-9. MiR-455-5p was a target of HUMT. Lowexpression of miR-455-5p reversed the inhibitive influence on HCC cells induced by of HUMT silencing. LRP4 was a target of miR-455-5p and was negatively regulated by miR-455-5p. In addition, LRP4 expression was positively modified by HUMT, and LRP4 inhibited the inhibitory effects on HCC cells induced by HUMT silencing. In conclusion, HCC cell proliferation, invasion, and migration were restrained by knockdown of HUMT, which was related to the miR-455-5p/LRP4 axis.

DLX6-AS1: A Long Non-coding RNA With Oncogenic Features

Long non-coding RNAs (lncRNAs) are a heterogeneous group of ncRNAs with characteristic size of more than 200 nucleotides. An increasing number of lncRNAs have been found to be dysregulated in many human diseases particularly cancer. However, their role in carcinogenesis is not precisely understood. DLX6-AS1 is an lncRNAs which has been unveiled to be up-regulated in various number of cancers. In different cell studies, DLX6-AS1 has shown oncogenic role via promoting oncogenic phenotype of cancer cell lines. Increase in tumor cell proliferation, migration, invasion, and EMT while suppressing apoptosis in cancer cells are the effects of DLX6-AS1 in development and progression of cancer. In the majority of cell experiment, mediator miRNAs have been identified which are sponged and negatively regulated by DLX6-AS1, and they in turn regulate expression of a number of transcription factors, eventually affecting signaling pathways involved in carcinogenesis. These pathways form axes through which DLX6-AS1 promotes carcinogenicity of cancer cells. Xenograft animal studies, also have confirmed enhancing effect of DLX6-AS1 on tumor growth and metastasis. Clinical evaluations in cancerous patients have also shown increased expression of DLX6-AS1 in tumor tissues compared to healthy tissues. High DLX6-AS1 expression has shown positive association with advanced clinicopathological features in cancerous patients. Survival analyses have demonstrated correlation between high DLX6-AS1 expression and shorter survival. In cox regression analysis, DLX6-AS1 has been found as an independent prognostic factor for patients with various types of cancer.

Mechanism of miR-424-5p promoter methylation in promoting epithelial-mesenchymal transition of hepatocellular carcinoma cells

The current study set out to clarify the role of miR-424-5p promoter methylation in epithelial mesenchymal transition (EMT) of hepatocellular carcinoma (HCC) cells. The findings of quantitative real-time-polymerase chain reaction and methylation-sensitive high-resolution melting assays elicited that miR-424-5p was poorly expressed in HCC tissues and cells while highly methylated. Meanwhile, upon demethylation, miR-424-5p expression levels were partly recovered in HCC cells. In addition, miR-424-5p upregulation reduced cell viability and elevated apoptosis of HCC cells, in parallel with increased N-cadherin and decreased E-cadherin levels. Dual-luciferase reporter assay further validated that miR-424-5p bound to the kinesin family member 2A (KIF2A), and miR-424-5p overexpression downregulated KIF2A. In addition, KIF2A overexpression reversed the miR-424-5p-driven changes in terms of cell viability, apoptosis and EMT-related protein levels. Furthermore, xenograft tumors were established via injection of Huh7 cells, followed by miR-424-5p overexpression in vivo, which inhabited KIF2A downregulation and attenuated tumor growth along with decreased Ki67 positive expression, diminished N-cadherin and elevated E-cadherin levels. Overall, our findings supported the conclusion that miR-424-5p promoter methylation reduced miR-424-5p expression and upregulated KIF2A, thereby promoting HCC EMT.

DLX6-AS1: a putative lncRNA candidate in multiple human cancers

Long non-coding RNAs (lncRNAs) have important roles in regulating the expression of genes and act as biomarkers in the initial development of different cancers. Increasing research studies have verified that dysregulation of lncRNAs occurs in various pathological processes including tumorigenesis and cancer progression. Among the different lncRNAs, DLX6-AS1 has been reported to act as an oncogene in the development and prognoses of different cancers, by affecting many different signalling pathways. This review summarises and analyses the recent research studies describing the biological functions of DLX6-AS1, its overall effect on signalling pathways and the molecular mechanisms underlying its action on the expression of genes in multiple human cancers. Our critical analysis suggests that different signalling pathways associated to this lncRNA may be used as a biomarker for diagnosis, or targets of treatment in cancers.

Long noncoding RNA NORAD acts as a ceRNA mediates gemcitabine resistance in bladder cancer by sponging miR-155-5p to regulate WEE1 expression

BACKGROUND

Increasing evidences have proved that long noncoding RNAs (lncRNAs) regulate the occurrence of bladder cancer (BC) and participate in various pathophysiology processes. However, little is unknown about the role of lncRNAs in drug resistance of BC cells. In this study, we explored the role of non-coding RNA activated by DNA damage (NORAD) in the gemcitabine (GEM) resistant of BC cells and explored its potential mechanism.

METHODS

Real-time quantitative PCR (RT-qPCR) was used to detect the expression of NORAD and miR-155-5p of BC cells. Cell counting kit-8 (CCK-8) and Western blot were used to detect cell inhibition rate and the expression of WEE1 G2 checkpoint kinase (WEE1), P-glycoprotein (P-gp) and multidrug resistance-associated protein 1 (MRP1). Flow cytometry detected cell cycle and apoptosis. Dual luciferase reporter gene assay and RNA immunoprecipitation (RIP) assay were used to confirm the targeting relationship between miR-155-5p, NORAD and WEE1. The xenograft model was used to observe the function of NORAD in vivo. immunohistochemistry (IHC) assay was used to detect the expression of WEE1, caspase-3 and Ki67 in tumor tissues.

RESULTS

NORAD highly expressed in GEM-resistant BC cell lines. Knockdown of NORAD significantly inhibited the proliferation of T24/GEM cells, the expression of drug-resistant proteins P-gp and MRP1, inhibit the G0/G1 phase of cells, and induce cell apoptosis. Knockdown of NORAD reversed the promotion effect of miR-155-5p on WEE1 expression and promoted the sensitivity of T24/GEM cells to GEM. In vivo, knockdown of NORAD inhibited the tumor growth, and enhanced the GEM-sensitivity in mice.

CONCLUSION

These data highlight the potential of NORAD acts as a therapeutic target for BC GEM resistance. It revealed the vital roles of NORAD/miR-155-5p/WEE1 axis in GEM resistant BC cells, providing a novel therapeutic strategy for BC.

DLX6-AS1 activated by H3K4me1 enhanced secondary cisplatin resistance of lung squamous cell carcinoma through modulating miR-181a-5p/miR-382-5p/CELF1 axis

Cisplatin (CDDP) based chemotherapy is widely used as the first-line strategy in treating non-small cell lung cancer (NSCLC), especially lung squamous cell carcinoma (LUSC). However, secondary cisplatin resistance majorly undermines the cisplatin efficacy leading to a worse prognosis. In this respect, we have identified the role of the DLX6-AS1/miR-181a-5p/miR-382-5p/CELF1 axis in regulating cisplatin resistance of LUSC. qRT-PCR and Western blot analysis were applied to detect gene expression. Transwell assay was used to evaluate the migration and invasion ability of LUSC cells. CCK-8 assay was used to investigate the IC50 of LUSC cells. Flow cytometry was used to test cell apoptosis rate. RNA pull-down and Dual luciferase reporter gene assay were performed to evaluate the crosstalk. DLX6-AS1 was aberrantly high expressed in LUSC tissues and cell lines, and negatively correlated with miR-181a-5p and miR-382-5p expression. DLX6-AS1 expression was enhanced by H3K4me1 in cisplatin resistant LUSC cells. Besides, DLX6-AS1 knockdown led to impaired IC50 of cisplatin resistant LUSC cells. Furthermore, DLX6-AS1 interacted with miR-181a-5p and miR-382-5p to regulate CELF1 expression and thereby mediated the cisplatin sensitivity of cisplatin resistant LUSC cells. DLX6-AS1 induced by H3K4me1 played an important role in promoting secondary cisplatin resistance of LUSC through regulating the miR-181a-5p/miR-382-5p/CELF1 axis. Therefore, targeting DLX6-AS1 might be a novel way of reversing secondary cisplatin resistance in LUSC.

Circ-RNF13, as an oncogene, regulates malignant progression of HBV-associated hepatocellular carcinoma cells and HBV infection through ceRNA pathway of circ-RNF13/miR-424-5p/TGIF2

Circular RNA RNF13 (circ-RNF13; ID: hsa_circ_0067717) is newly identified to be abnormally upregulated in hepatitis B virus (HBV)-associated hepatocellular carcinoma (HCC) patients. However, its role and mechanism remain to be further annotated. First of all, real-time quantitative PCR (RT-qPCR) was utilized to examine RNA expression, and circ-RNF13 was upregulated in HBV-infected human HCC tissues and HBV-expressing cells (Huh7-HBV and Hep3B-HBV), accompanied with TGFβ-induced factor homeobox 2 (TGIF2) upregulation and microRNA (miR)-424-5p downregulation. Loss-of-functional experiments were performed using MTS assay, colony formation assay, flow cytometry, enzyme-linked immunosorbent assay, transwell assay, and xenograft tumor model. As a result, blocking circ-RNF13 enhanced the apoptosis rate of Huh7-HBV and Hep3B-HBV cells, but inhibited cell proliferation, colony formation, migration, and invasion in vitro, along with suppressed tumor growth in vivo. Besides, RT-qPCR data showed that HBV DNA copies and levels of hepatitis B surface antigen (HBsAg) and hepatitis B e antigen (HBeAg) were diminished by circ-RNF13 knockdown in Huh7-HBV and Hep3B-HBV cells. Mechanistically, circ-RNF13 and TGIF2 could directly interacting with miR-424-5p according to dual-luciferase reporter assay, suggesting that circ-RNF13 and TGIF2 served as competing endogenous RNAs (ceRNAs) for miR-424-5p. Functionally, overexpressing miR-424-5p mimicked and silencing miR-424-5p counteracted the effects of circ-RNF13 depletion in HBV-expressing HCC cells in vitro; TGIF2 restoration partially abrogated the role of miR-424-5p upregulation. In conclusion, circ-RNF13 might sponge miR-424-5p to suppress HBV-associated HCC cells malignant progression and HBV infection by regulating TGIF2, providing a novel insight into the occurrence and treatment of HBV-associated HCC.

The emerging landscape of long non-coding RNAs in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common and aggressive cancers. HCC shows high prevalence and lethality caused by a variety of etiologic factors. However, the underlying mechanisms and the diagnostic markers identifying patients at risk in advance has not been entirely elucidated. Long non-coding RNAs (lncRNAs) are a subgroup of non-coding RNAs greater than 200 nucleotides in length with no protein-coding capability. With the progress in sequencing technologies and bioinformatic tools, the landscape of lncRNAs is being revealed. Numerous discoveries point out that lncRNAs participate in HCC carcinogenesis and metastasis through altering cell proliferation and invasion ability, apoptosis, and chemo- or radio-sensitivity. Moreover, lncRNA is easy to detect compared to the traditional diagnostic methods. This review summarizes the mechanisms of major lncRNAs in HCC discovered in recent years and lncRNAs as early diagnostic markers for HCC.

Research progress of DLX6-AS1 in human cancers

Long non-coding RNAs (lncRNAs) are a kind of translational-repressor RNAs composed of more than 200 nucleotides and formerly considered as "transcriptional noise". Recently studies have shown that lncRNAs could bind to multiple biomolecules such as DNA, transcription factors, RNA, chromatin complexes and proteins, and regulate target gene expression at multi-levels, thus playing an essential role in human tumors. DLX6-AS1, a recently discovered oncogenic lncRNA, is highly expressed in various human tumors, including lung cancer, liver cancer and pancreatic cancer. This paper mainly reviewed the regulatory mechanism of DLX6-AS1 as a competitive endogenous RNA (ceRNA) in tumor cell proliferation, cell apoptosis, angiogenesis, epithelial-mesenchymal transformation, chemotherapy resistance and metabolic changes. Furthermore, the translational value of DLX6-AS1 in cancer was also elucidated, which suggested its potential as a diagnostic or prognostic biomarker in cancer. In summary, this present article not only makes an in-depth analysis of the expression changes and carcinogenic mechanism of DLX6-AS1 in various human cancers, but also provides a new breakthrough for the diagnosis and treatment of cancers.

The crosstalk network of XIST/miR-424-5p/OGT mediates RAF1 glycosylation and participates in the progression of liver cancer

BACKGROUND

Liver cancer is a major public health concern, but the mechanistic actions of biomarkers contributing to liver cancer remain to be determined. In this study, we aimed to investigate the regulatory cascade of microRNA-424-5p (miR-424-5p), X-inactive-specific transcript (XIST) and O-GlcNAc transferase (OGT) in liver cancer.

METHODS

Differentially expressed miRNAs and target genes related to liver cancer were predicted by bioinformatics analyses, and their expression was determined in liver tissues of patients with liver cancer and liver cancer cells. The RNA immunoprecipitation (RIP), RNA pull-down and dual luciferase reporter assay were used to examine the binding affinity among XIST and miR-424-5p and OGT. Then, gain- and loss-of-function assays were conducted to evaluate the effects of the XIST/miR-424-5p/OGT axis on malignant phenotypes. A nude mouse model of liver cancer was further established for in vivo substantiation.

RESULTS

XIST and OGT were up-regulated in liver cancer tissues and cells, responsible for poor prognosis in patients with liver cancer, while miR-424-5p was down-regulated. XIST competitively bound to miR-424-5p to increase OGT expression. XIST silencing inhibited malignant phenotypes of liver cancer cells, while miR-424-5p down-regulation negated its effect. miR-424-5p suppressed RAF1 glycosylation by negatively regulating OGT expression and promoted its ubiquitination/degradation. Furthermore, XIST knockdown inhibited tumour growth and metastasis in nude mice, while ectopic OGT reversed its effect.

CONCLUSION

These results reveal a novel mechanism by which the interaction of XIST/miR-424-5p/OGT participates in the malignancy and metastasis of liver cancer.

DLX6-AS1: An Indispensable Cancer-related Long Non-coding RNA

BACKGROUND

There is increasing evidence that lncRNA, a type of transcript that is over 200 nucleotides in length and may serve as oncogenes or suppressor genes, is implicated in the pathophysiology of human diseases. In particular, tumorigenesis and progress are closely correlated with its abnormal expression. In addition, it may become a promising target for many oncology biotherapies. Abnormal DLX6-AS1 expression affects different cellular processes such as proliferation, aggression and metastasis. This review aims to probe into the pathophysiological functions and molecular mechanisms of DLX6-AS1 in various cancers.

METHODS

By retrieving the literature, this review summarizes the biological function and mechanism of LncRNA DLX6-AS1 in tumor occurrence.

RESULTS

The lncRNA DLX6-AS1 is a new tumor-related RNA that has recently been found to be aberrantly expressed in diverse cancers, such as pancreatic cancer, osteosarcoma, non-small cell lung cancer, gastric carcinoma, glioma, hepatocellular cancer, colorectal carcinoma, renal carcinoma, esophageal squamous cell cancer, ovarian cancer, Ewing sarcoma, cervical cancer, breast cancer, thyroid cancer, neuroblastoma, pulmonary adenocarcinoma, nasopharyngeal carcinoma, squamous laryngeal cancer and bladder cancer, etc. Meanwhile, it is identified that DLX6-AS1 regulates the aggression, translocation and proliferation of diverse cancers.

CONCLUSION

LncRNA DLX6-AS1 may be viable markers in tumors or a potential therapeutic target for multiple tumors.

Identification and Validation of Immune-Related lncRNA Signature as a Prognostic Model for Skin Cutaneous Melanoma

Purpose

Skin cutaneous melanoma (SKCM) is the most aggressive skin cancer that results in high morbidity and mortality rate worldwide. Immune-related long non-coding RNAs (IRlncRs) play an important role in regulating gene expression in tumors. Therefore, in this study, we aimed to identify IRlncRs signature that could predict prognosis and therapeutic targets for melanoma irrespective of the gene expression levels.

Methods

RNA-sequencing data were obtained from The Cancer Genome Atlas (TCGA). IRlncRs were identified using co-expression analysis and recognized using univariate analysis. The impact of IRlncRs on survival was analyzed using a modified least absolute shrinkage and selection operator (Lasso) regression model. A 1-year survival receiver operating characteristic curve was constructed, and the area under the curve was calculated to identify the optimal cut-off point to distinguish between high and low-risk groups in patients with SKCM. Furthermore, integrative analysis was performed to identify the impact of clinicopathological features, chemotherapeutic treatment, tumor-infiltrating immune cells, and mutant genes on survival.

Results

A total of 28 IRlncRs significantly associated with survival were identified. Seventeen IRlncRs pairs were used to build a survival risk model that could be used to distinguish between low and high-risk groups. The high-risk group was negatively associated with tumor-infiltrating immune cells and had a higher half inhibitory centration for chemotherapeutic agents such as cisplatin and vinblastine. Additionally, the high-risk group had a positive correlation with the expression of specific mutant genes such as BRAF and KIT.

Conclusion

Our findings demonstrate that some IRlncRs have a significant correlation with survival and therapeutic targets for SKCM patients and may provide new insight into the clinical diagnosis and treatment strategies for SKCM patients.

Exosomal DLX6-AS1 from hepatocellular carcinoma cells induces M2 macrophage polarization to promote migration and invasion in hepatocellular carcinoma through microRNA-15a-5p/CXCL17 axis

Background

Hepatocellular carcinoma (HCC) cells-secreted exosomes (exo) could stimulate M2 macrophage polarization and promote HCC progression, but the related mechanism of long non-coding RNA distal-less homeobox 6 antisense 1 (DLX6-AS1) with HCC-exo-mediated M2 macrophage polarization is largely ambiguous. Thereafter, this research was started to unearth the role of DLX6-AS1 in HCC-exo in HCC through M2 macrophage polarization and microRNA (miR)-15a-5p/C-X-C motif chemokine ligand 17 (CXCL17) axis.

Methods

DLX6-AS1, miR-15a-5p and CXCL17 expression in HCC tissues and cells were tested. Exosomes were isolated from HCC cells with overexpressed DLX6-AS1 and co-cultured with M2 macrophages. MiR-15a-5p/CXCL17 down-regulation assays were performed in macrophages. The treated M2 macrophages were co-cultured with HCC cells, after which cell migration, invasion and epithelial mesenchymal transition were examined. The targeting relationships between DLX6-AS1 and miR-15a-5p, and between miR-15a-5p and CXCL17 were explored. In vivo experiment was conducted to detect the effect of exosomal DLX6-AS1-induced M2 macrophage polarization on HCC metastasis.

Results

Promoted DLX6-AS1 and CXCL17 and reduced miR-15a-5p exhibited in HCC. HCC-exo induced M2 macrophage polarization to accelerate migration, invasion and epithelial mesenchymal transition in HCC, which was further enhanced by up-regulated DLX6-AS1 but impaired by silenced DLX6-AS1. Inhibition of miR-15a-5p promoted M2 macrophage polarization to stimulate the invasion and metastasis of HCC while that of CXCL17 had the opposite effects. DLX6-AS1 mediated miR-15a-5p to target CXCL17. DLX6-AS1 from HCC-exo promoted metastasis in the lung by inducing M2 macrophage polarization in vivo.

Conclusion

DLX6-AS1 from HCC-exo regulates CXCL17 by competitively binding to miR-15a-5p to induce M2 macrophage polarization, thus promoting HCC migration, invasion and EMT.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-021-01973-z.

DLX6-AS1 accelerates cell proliferation through regulating miR-497-5p/SNCG pathway in prostate cancer

Prostate cancer (PCa) has become the second leading cause of cancer-related mortality in males worldwide. Although the long noncoding RNA DLX6-AS1 has been recognized to be an oncogene in multiple cancers, the biological function and regulatory mechanism of DLX6-AS1 in prostate cancer are still obscure. In the present study, we observed that DLX6-AS1 was significantly upregulated in PCa tissues and cells. Knockdown of DLX6-AS1 inhibited PCa progression by suppressing cell proliferation and accelerating cell apoptosis. Molecular mechanism exploration indicated that DLX6-AS1 acted as a sponge for miR-497-5p and synuclein gamma (SNCG) was a downstream target gene of miR-497-5p. In addition, there was a negative correlation between DLX6-AS1 and miR-497-5p in PCa tissues. Rescue assays showed that SNCG overexpression could partially recover DLX6-AS1 knockdown-mediated inhibition of progression in PCa. Furthermore, xenograft tumor model was established to determine the role of DLX6-AS1 in PCa tumor growth and the results suggested that DLX6-AS1 could facilitate tumor growth by regulating SNCG in vivo. In conclusion, our study investigated the biological function and underlying mechanism of DLX6-AS1 in PCa and validated that DLX6-AS1 functioned as an oncogene through miR-497-5p/SNCG axis.

DLX6-AS1 is a potential biomarker and therapeutic target in cancer initiation and progression

Long noncoding RNAs (lncRNAs) are involved in multiple functions such as the regulation of cellular homeostasis. They play prominent roles in the pathogenesis of human cancer, and contribute to every hallmark of cancer. The novel cancer-related lncRNA DLX6 antisense RNA 1 (DLX6-AS1) plays an essential regulatory role in enhancing and initiating carcinogenesis and tumor progression. This progression is due to the aberrant regulation of downstream factors in vitro as well as in vivo. DLX6-AS1 is significantly dysregulated in various cancers. DLX6-AS1 functions in tumor initiation and progression are regulated at the epigenetic, transcription, and posttranscriptional regulation levels. DLX6-AS1 functions as an oncogene, binding to miRNA targeting sites competing endogenous RNAs and causing the upregulation of downstream tumor-related genes and carcinogenesis. The regulation and detailed molecular mechanisms of DLX6-AS1 and its potential role in malignancies are comprehensively described in this paper. DLX6-AS1 has the potential to become a novel biomarker and therapeutic target for cancer.

Dual relationship between long non-coding RNAs and STAT3 signaling in different cancers: New insight to proliferation and metastasis

Uncontrolled growth and metastasis of cancer cells is an increasing challenge for overcoming cancer, and improving survival of patients. Complicated signaling networks account for proliferation and invasion of cancer cells that need to be elucidated for providing effective cancer therapy, and minimizing their malignancy. Long non-coding RNAs (lncRNAs) are RNA molecules with a length of more than 200 nucleotides. They participate in cellular events, and their dysregulation in a common phenomenon in different cancers. Noteworthy, lncRNAs can regulate different molecular pathways, and signal transducer and activator of transcription 3 (STAT3) is one of them. STAT3 is a tumor-promoting factors in cancers due to its role in cancer proliferation (cell cycle progression and apoptosis inhibition) and metastasis (EMT induction). LncRNAs can function as upstream mediators of STAT3 pathway, reducing/enhancing its expression. This dual relationship is of importance in affecting proliferation and metastasis of cancer cells. The response of cancer cells to therapy such as chemotherapy and radiotherapy is regulated by lncRNA/STAT3 axis. Tumor-promoting lncRNAs including NEAT1, SNHG3 and H19 induces STAT3 expression, while tumor-suppressing lncRNAs such as MEG3, PTCSC3 and NKILA down-regulate STAT3 expression. Noteworthy, upstream mediators of STAT3 such as microRNAs can be regulated by lncRNAs. These complicated signaling networks are mechanistically described in the current review.

Promising long noncoding RNA DLX6-AS1 in malignant tumors

Although its diagnosis and treatment have greatly improved in recent decades, cancer remains the major cause of death worldwide. Thus, there is an urgent need to find novel biomarkers and therapeutic targets to improve efficiency of diagnosis and treatment of patients with cancer. Long noncoding RNAs (lncRNAs), a new class of noncoding RNAs (ncRNAs), have been found to play a salient role in human tumorigenesis and progression. Distal-less homeobox 6 antisense RNA 1 (DLX6-AS1) is a novel lncRNA with aberrant expression in various cancers tissues and cell lines compared with nontumor tissues and normal cell lines. Importantly, DLX6-AS1 is closely associated with tumor cell proliferation, apoptosis, invasion, and migration. Patients with high DLX6-AS1 expression often had poorer prognosis than those with low expression. The oncogenicity of DLX6-AS1 mainly (indirectly or indirectly) interacts with targeting genes, and then regulates downstream genes and signaling pathways. Together with the findings of animal model studies, these data suggest that DLX6-AS1 may serve as a feasible predictor or therapeutic target in different cancers. Herein, we summarize the main findings concerning the function and molecular mechanisms of DLX6-AS1 to identify a molecular basis for future clinical application.

The microRNA-424/503 cluster: A master regulator of tumorigenesis and tumor progression with paradoxical roles in cancer

MicroRNAs (miRNAs) are a group of non-coding RNAs that play a crucial role in post-transcriptional gene regulation and act as indispensable mediators in several critical biological processes, including tumorigenesis, tissue homeostasis, and regeneration. MiR-424 and miR-503 are intragenic miRNAs that are clustered on human chromosome Xq26.3. Previous studies have reported that both miRNAs are dysregulated and play crucial but paradoxical roles in tumor initiation and progression, involving different target genes and molecular pathways. Moreover, these two miRNAs are concomitantly expressed in several cancer cells, indicating a coordinating function as a cluster. In this review, the roles and regulatory mechanisms of miR-424, miR-503, and miR-424/503 cluster are summarized in different types of cancers.

lncRNA HAND2-AS1 Inhibits Liver Cancer Cell Proliferation and Migration by Upregulating SOCS5 to Inactivate the JAK-STAT Pathway

Objective: lncRNA HAND2 antisense RNA 1 (HAND2-AS1) is consistently well recognized to suppress multiple tumors, while its function was uncertified in liver cancer. Materials and Methods: qRT-PCR analysis and TCGA database discovered the expression in liver cancer. CCK-8 and Transwell migration assay demonstrated the impact of HAND2-AS1 on cell proliferation and migration. Bioinformatic analysis and luciferase reporter assay were utilized to monitor the binding between HAND2-AS1 or SOCS5 mRNA and miR-3118. The function of SOCS5 on inactivating the JAK-STAT pathway was confirmed through Western blot assays. Rescue experiments unmasked that HAND2-AS1-mediated SOCS5 affected cell proliferation and migration through the JAK-STAT pathway in liver cancer. Results: The authors discovered the downregulated HAND2-AS1 in liver cancer cells. HAND2-AS1 augmentation apparently impaired the capacity of liver cancer viability, proliferation, and migration. Cytoplasmic HAND2-AS1 directly bound to miR-3118 and released SOCS5, leading to upregulation of SOCS5. Next, the negative regulator role of SOCS5 in the adjusting JAK-STAT pathway was reconfirmed in this study. Conclusions: HAND2-AS1 enhanced inactivation of the JAK-STAT pathway through sponging miR-3118 and facilitating SOCS5 to retard cell proliferation and migration in liver cancer.

Long Noncoding RNA HEIH Promotes Proliferation, Migration and Invasion of Retinoblastoma Cells Through miR-194-5p/WEE1 Axis

Background

Abnormally expressed long noncoding RNA (lncRNA) high expression in hepatocellular carcinoma (HEIH) has been implicated in many types of human cancer, and plays crucial roles in tumor development and progression. However, little is known about its function in retinoblastoma.

Methods

qRT-PCR was used to determine the expression levels of HEIH, miR-194-5p and WEE1 in retinoblastoma tissues and cell lines. The trypan blue exclusion method, colony formation assay, wound-healing assay and transwell invasion assay were performed to evaluate the effects of HEIH, miR-194-5p and WEE1 on cell proliferation, migration and invasion. Bioinformatics analysis, dual-luciferase reporter assay and Western blot were employed to investigate the regulatory relationship among HEIH, miR-194-5p and WEE1.

Results

We found that HEIH was up-regulated in retinoblastoma tissues and cell lines. Furthermore, high level of HEIH was associated with TNM stage, optic nerve invasion and choroidal invasion of patients with retinoblastoma. Functional studies showed that HEIH knockdown significantly suppressed retinoblastoma cell proliferation, migration and invasion. Mechanistically, HEIH promoted retinoblastoma progression by serving as a sponge of miR-194-5p to regulate WEE1 expression.

Conclusion

Our work suggests that HEIH acts as an oncogenic lncRNA to promote retinoblastoma proliferation and metastasis, providing a new insight into the retinoblastoma treatment.

MiR-424-5p regulates cell cycle and inhibits proliferation of hepatocellular carcinoma cells by targeting E2F7

Objective

This study aims to explore the mechanism of the miR-424-5p/E2F7 axis in hepatocellular carcinoma (HCC) and provide new ideas for targeted therapy of HCC.

Methods

Bioinformatics analysis was used to identify the target differentially expressed miRNA in HCC and predict its target gene. qRT-PCR was employed to verify the expression of miR-424-5p and E2F7 mRNA in HCC cells. Western blot was performed to detect the effect of miR-424-5p ectopic expression on the protein expression of E2F7. CCK-8 was used to detect proliferative activity of HCC cells and flow cytometry was carried out for analyzing cell cycle distribution. Dual luciferase reporter assay was conducted to verify the direct targeting relationship between miR-424-5p and E2F7.

Results

We observed that miR-424-5p was down-regulated in HCC cells. CCK-8 showed that overexpression of miR-424-5p inhibited cell proliferation, and flow cytometry showed that miR-424-5p could block cells in G0/G1 phase. E2F7 was up-regulated in HCC cells, and E2F7 overexpression could facilitate the proliferative ability of HCC cells and promote the cell cycle progressing from G0/G1 to S phase. Furthermore, dual-luciferase reporter assay indicated that miR-424-5p could directly down-regulate E2F7 expression. Analysis on cell function demonstrated that miR-424-5p inhibited the proliferation of HCC cells and blocked cell cycle at G0/G1 phase by targeting E2F7.

Conclusion

Our results proved that E2F7 was a direct target of miR-424-5p, and miR-424-5p could regulate cell cycle and further inhibit the proliferation of HCC cells by targeting E2F7.

lncRNA CTBP1-AS2 promotes proliferation and migration of glioma by modulating miR-370-3p-Wnt7a-mediated epithelial-mesenchymal transition

Glioma is one of the most common and aggressive malignant primary brain tumors, with a poor 5-year survival rate. The long noncoding RNA (lncRNA) CTBP1-AS2 has been shown to be correlated with the prognosis of cancer, but the role of CTBP1-AS2 in glioma and its concrete mechanism is fully unknown. The clinical data and tissues of glioma patients were analyzed. Cell viability and migration assays were performed. Western blotting and qRT-PCR were adopted for investigation of target protein expressions. Double luciferase assay was used to investigate the interaction between different elements. The lncRNA CTBP1-AS2 had increased expression profiles in tumor tissues, which is associated with poor prognosis. In detail, CTBP1-AS2 knockdown decreased proliferation and migration phenotypes in both U87-MG and LN229 cells. Moreover, CTBP1-AS2 knockdown suppressed the key epithelial-mesenchymal transition (EMT) markers by downregulating Wnt7a-mediated signaling. Furthermore, miR-370-3p functioned as a link that could be absorbed by CTBP1-AS2, thus regulating Wnt7a expression. Lastly, the CTBP1-AS2-miR-370-3p-Wnt7a axis modulated EMT in glioma cells in vitro and in vivo. This study provides new insights that a novel lncRNA, CTBP1-AS2, regulates EMT of glioma by modulating the miR-370-3p-Wnt7a axis.

Crosstalk between long non-coding RNA DLX6-AS1, microRNAs and signaling pathways: A pivotal molecular mechanism in human cancers

Long non-coding RNAs (lncRNAs) are a type of non-protein coding RNA, which have been found to play multiple roles in various molecular and cellular processes by epigenetic regulation of gene expression at post transcriptional levels. LncRNAs may act either as an oncogene or as a tumor suppressor gene in different cancers. Aberrant expression and dysregulation of lncRNAs has been correlated with cancer development and tumor growth via several different signaling pathways. Therefore, lncRNAs could serve as diagnostic biomarkers and as therapeutic targetes in many human cancers. Previous studies have reported that dysregulated expression of the lncRNA called DLX6-AS1 in various cancer types, such as lung, colorectal, bladder, ovarian, hepatocellular, pancreatic and gastric. DLX6-AS1 plays an important role in tumorigenesis by affecting cell proliferation, migration, invasion, EMT, and apoptosis. DLX6-AS1 exerts these regulatory effects by interfering with various microRNA axes and signaling pathways including, Wnt/βcatenin, Notch, P13/AKT/mTOR, and STAT3. This review focuses on the possible mechanisms by which DLX6-AS1 regulates tumor initiation and progression. Accordingly, DLX6-AS1 may act as a novel potential biomarker for cancer diagnosis or therapy in future.

Role of miRNA-424 in Cancers

microRNA (miRNA) is an important part of non-coding RNA that regulates gene expression at a posttranscriptional level. miRNA has gained increasing interest in recent years, both in research and clinical fields. miRNAs have been found to play an important role in various diseases, particularly cancer. Aberrant miR-424 expression is found in several tumors where they can function as either oncogenes or tumor-suppressor genes. Meanwhile, miR-424 is also affected by the reorganization of many other non-coding RNAs such as lncRNA and cirRNA. Several studies have found that miR-424 participates in proliferation, differentiation, apoptosis, invasion, angiogenesis, and drug resistance, and plays an important role in the tumorigenesis and progression of tumors. This review will focus on the recent progress of research on miR-424 in tumors.

Identification of Potential Diagnostic and Prognostic Pseudogenes in Hepatocellular Carcinoma Based on Pseudogene-miRNA-mRNA Competitive Network

Background

It is widely known that hepatocellular carcinoma (HCC) has high rates of morbidity and mortality. A large number of studies have indicated that pseudogenes have an important effect on the carcinogenesis of HCC. Pseudogenes can play a role through the ceRNA network. There have been numerous studies on lncRNA-miRNA-mRNA and circRNA-miRNA-mRNA networks. However, the pseudogene-miRNA-mRNA network in HCC has rarely been researched or reported on.

Material/Methods

The Cancer Genome Atlas (TCGA) database was researched and differences between selected genes were studied. A pseudogene-miRNA-mRNA network was then constructed and clustering of pseudogenes was studied. The diagnostic value of the selected pseudogenes, their functions, and pathways were investigated using available databases to understand their possible pathogenic mechanism in HCC. The protein-protein interaction network of target genes was found and the top 10 hub genes were identified. Expression of hub genes in HCC tissues was then detected by RT-qPCR.

Results

By analyzing the gene difference and clinical data of HCC, we constructed a ceRNA network composed of 4 pseudogenes, 8 miRNAs, and 30 mRNAs. The pseudogenes AP000769.1, KRT16P1, KRT16P3, and RPLP0P2 were all correlated with the diagnosis and prognosis of HCC. Functional analyses through the Kyoto Encyclopedia of Genes and Genomes and the Gene Ontology databases indicated that pseudogenes can affect the physiological process of HCC through the p53 pathway. The top 10 hub genes identified were all highly expressed in HCC tissues and affected the patient survival rate.

Conclusions

In this study, 4 pseudogenes related to the diagnosis and prognosis of liver cancer were found through the construction of a ceRNA network. These 4 pseudogenes might constitute new therapeutic targets for liver cancer patients.

Long Noncoding RNA DLX6-AS1 Regulates the Growth and Aggressiveness of Colorectal Cancer Cells Via Mediating miR-26a/EZH2 Axis

Objective: To understand the regulation of long noncoding RNA DLX6-AS1-mediated miR-26a/EZH2 axis in the growth of colorectal cancer (CRC) cells. Methods: The expression of DLX6-AS1, miR-26a, and EZH2 was detected in CRC tissues by quantitative reverse transcription-polymerase chain reaction. The CRC HT-29 cell line was selected for transfection and subjected to observe the growth by MTT and colony formation assays, cell cycle by flow cytometry, and migration and invasion by wound healing and Transwell assays, respectively. Finally, the expression of cycle- and metastasis-related proteins was detected by western blotting. Results: DLX6-AS1 and EZH2 were increased, with a decreased miR-26a in CRC tissues, showing significant negative correlations between DLX6-AS1 and miR-26a, and between miR-26a and EZH2. CRC patients at advanced stage or with lymphatic metastasis had higher DLX6-AS1 expression. Dual-luciferase reporter gene assay uncovered the targeting correlations between DLX6-AS1 and miR-26a, or miR-26a and EZH2. After transfection of DLX6-AS1 siRNA or EZH2 siRNA, the growth and metastasis of CRC cells were suppressed, arresting the cells in G0/G1 phase, with a magnificent reduction in the ratio of cells in S phase or G2/M phase; meanwhile, Cyclin D1, Vimentin, and MMP9 expressions decreased evidently, whereas E-cadherin expression was upregulated. Changes above were fully reversed after transfection of miR-26a inhibitor, whereas si-EZH2 transfection abolished the positive role of miR-26a inhibitor on growth of CRC cells. Conclusion: Silencing DLX6-AS1 may block the malignant features of CRC cells by inhibiting the expression of EZH2 through upregulation of miR-26a. Thus, it is critical to the development and progression of CRC.

Long non-coding RNA DLX6-AS1 regulates neuroblastoma progression by targeting YAP1 via miR-497-5p

AIMS

The lncRNA distal-less homeobox 6 antisense 1 (DLX6-AS1) has been reported to be an oncogenic lncRNA in diverse malignant cancers; however, whether it has oncogenic role in neuroblastoma(NB) remain largely unknown. This study explored the expression status, function and potential mechanism of DLX6-AS1 in NB.

MAIN METHOD

In the current study, a total of 70 human NB tissues and matched adjacent non-tumor tissues were collected. Quantitative PCR (qPCR) was performed to study the expression differences of DLX6-AS1 in tissues and NB cell lines. Proliferation, migration, invasion and EMT status of transfected NB cells were evaluated by WST-1 assay, colony formation unit assay, Transwell assay and qPCR, respectively. The interaction between DLX6-AS1 and its potential targets was confirmed by luciferase reporter assay. Xenograft models were established to evaluate tumor proliferation in vivo.

KEY FINDING

We found that the expression of DLX6-AS1 was significantly increased in both NB tissues and cell lines, and elevated DLX6AS1 expression was positively correlated with advanced stage and poor survival. Proliferation rate, migration and invasion ability, as well as EMT process of NB cells was inhibited after DLX6-AS1 knockdown, meanwhile, the tumor growth in vivo was impaired after DLX6-AS1 inhibition. Further analysis showed that DLX6-AS1 regulates the expression of YAP1 by sponging miR-497-5p. DLX6-AS1 directly interacts with miR-497-5p and reduces the binding of miR-497-5p to YAP1 3'UTR, thus inhibiting the degradation of YAP1 by miR-497-5p.

SIGNIFICANCE

This work demonstrates that DLX6-AS1 partially enhances the proliferation, migration and invasion abilities of NB cells through the miR-497-5p/YAP1 pathway, DLX6-AS1 might act as a promising therapeutic target for NB.

DLX6-AS1/miR-204-5p/OCT1 positive feedback loop promotes tumor progression and epithelial-mesenchymal transition in gastric cancer

BACKGROUND

Accumulating evidence indicates that long non-coding RNAs (lncRNAs) participate in progression of gastric cancer (GC). Nevertheless, the function and expression level of DLX6-AS1 in GC remain unknown.

METHODS

We explored the sequencing data of DLX6-AS1 downloaded from The Cancer Genome Atlas. The expression of DLX6-AS1, miR-204-5p and OCT1 in 56 GC patients and GC cell lines was quantified by qRT-PCR and western blotting. Furthermore, we performed in vitro functional assays to assess proliferation, invasion and migration of GC cells by knockdown of DLX6-AS1. The expression level of epithelial-mesenchymal transition (EMT)-related genes was also determined by qRT-PCR and western blotting. Actin remodeling was detected by F-actin phalloidin staining. The luciferase reporter assay and chromatin immunoprecipitation assay was utilized to confirm the bioinformatic prediction. The function of the DLX6-AS1/miR-204-5p/OCT1 axis in GC proliferation was clarified by rescue assays.

RESULTS

We first demonstrated that DLX6-AS1 was upregulated in GC tissues and cell lines and was associated with T3/T4 invasion, distant metastasis and poor clinical prognosis. Further functional analysis showed that downregulation of DLX6-AS1 inhibited GC cell proliferation, migration, invasion and EMT in vitro. Mechanistic investigation indicated that DLX6-AS1 acted as a cancer-promoting competing endogenous RNA (ceRNA) by binding miR-204-5p and upregulating OCT1. Moreover, the transcription factor OCT1 was confirmed to enhance DLX6-AS1 expression by targeting the promoter region.

CONCLUSIONS

This study revealed that OCT1-induced DLX6-AS1 promoted GC progression and the EMT via the miR-204-5p/OCT1 axis, suggesting that this lncRNA might be a promising prognostic biomarker and therapeutic target for GC.

LncRNA MEG3 promotes melanoma growth, metastasis and formation through modulating miR-21/E-cadherin axis

Background

Melanoma is the most aggressive type of skin cancer with high mortality rate and poor prognosis. lncRNA MEG3, a tumor suppressor, is closely related to the development of various cancers. However, the role of lncRNA MEG3 in melanoma has seldom been studied.

Methods

RT-PCR was used to examine the expressions of lncRNA MEG3 and E-cadherin in melanoma patients and cell lines. Then, the biological functions of lncRNA MEG3 and E-cadherin were demonstrated by transfecting lncRNA MEG3-siRNA, lncRNA MEG3-overexpression, E-cadherin-siRNA and E-cadherin-overexpression plasmids in melanoma cell lines. Moreover, CCK8 assay and colony formation assay were utilized to assess the cell proliferation; Transwell assay was performed to evaluate the cell invasive ability; and tumor xenografts in nude mice were applied to test the tumor generation. Additionally, the target interactions among lncRNA MEG3, miR-21 and E-cadherin were determined by dual luciferase reporter assay. Finally, RT-PCR and WB were further conducted to verify the regulatory roles among lncRNA MEG3, miR-21 and E-cadherin.

Results

The clinical data showed that lncRNA MEG3 and E-cadherin expressions were both declined in carcinoma tissues as compared with their para-carcinoma tissues. Moreover, lncRNA MEG3 and E-cadherin expressions in B16 cells were also higher than those in A375 and A2058 cells. Subsequently, based on the differently expressed lncRNA MEG3 and E-cadherin in these human melanoma cell lines, we chose B16, A375 and A2058 cells for the following experiments. The results demonstrated that lncRNA MEG3 could suppress the tumor growth, tumor metastasis and formation; and meanwhile E-cadherin had the same effects on tumor growth, tumor metastasis and formation. Furthermore, the analysis of Kaplan–Meier curves also confirmed that there was a positive correlation between lncRNA MEG3 and E-cadherin. Ultimately, dual luciferase assays were further used to verify that lncRNA MEG3 could directly target miR-21 which could directly target E-cadherin in turn. Additionally, the data of RT-PCR and WB revealed that knockdown of lncRNA MEG3 in B16 cells inhibited miR-21 expression and promoted E-cadherin expression, but overexpression of lncRNA MEG3 in A375 and A2058 cells presented completely opposite results.

Conclusion

Our findings indicated that lncRNA MEG3 might inhibit the tumor growth, tumor metastasis and formation of melanoma by modulating miR-21/E-cadherin axis.

LncRNA DLX6-AS1 Contributes to Epithelial-Mesenchymal Transition and Cisplatin Resistance in Triple-negative Breast Cancer via Modulating Mir-199b-5p/Paxillin Axis

Triple-negative breast cancer (TNBC) is one of the most aggressive cancer types with high recurrence, metastasis, and drug resistance. Recent studies report that long noncoding RNAs (lncRNAs)-mediated competing endogenous RNAs (ceRNA) play an important role in tumorigenesis and drug resistance of TNBC. Although elevated lncRNA DLX6 antisense RNA 1 (DLX6-AS1) has been observed to promote carcinogenesis in various cancers, the role in TNBC remained unclear. In this study, expression levels of DLX6-AS1 were increased in TNBC tissues and cell lines when compared with normal tissues or breast fibroblast cells which were determined by quantitative real-time PCR (RT-qPCR). Then, CCK-8 assay, cell colony formation assay and western blot were performed in CAL-51 cells transfected with siRNAs of DLX6-AS1 or MDA-MB-231 cells transfected with DLX6-AS1 over expression plasmids. Knock down of DLX6-AS1 inhibited cell proliferation, epithelial-mesenchymal transition (EMT), decreased expression levels of BCL2 apoptosis regulator (Bcl-2), Snail family transcriptional repressor 1 (Snail) as well as N-cadherin and decreased expression levels of cleaved caspase-3, γ-catenin as well as E-cadherin, while up regulation of DLX6-AS1 had the opposite effect. Besides, knockdown of DLX6-AS1 in CAL-51 cells or up regulation of DLX6-AS1 in MDA-MB-231 cells also decreased or increased cisplatin resistance of those cells analyzed by MTT assay. Moreover, by using dual luciferase reporter assay, RNA immunoprecipitation and RNA pull down assay, a ceRNA which was consisted by lncRNA DLX6-AS1, microRNA-199b-5p (miR-199b-5p) and paxillin (PXN) was identified. And DLX6-AS1 function through miR-199b-5p/PXN in TNBC cells. Finally, results of xenograft experiments using nude mice showed that DLX6-AS1 regulated cell proliferation, EMT and cisplatin resistance by miR-199b-5p/PXN axis in vivo. In brief, DLX6-AS1 promoted cell proliferation, EMT, and cisplatin resistance through miR-199b-5p/PXN signaling in TNBC in vitro and in vivo.

The lncRNA DLX6-AS1 promoted cell proliferation, invasion, migration and epithelial-to-mesenchymal transition in bladder cancer via modulating Wnt/β-catenin signaling pathway

Background

Bladder cancer is the most common human urological malignancies with poor prognosis, and the pathophysiology of bladder cancer involves multi-linkages of regulatory networks in the bladder cancer cells. Recently, the long noncoding RNAs (lncRNAs) have been extensively studied for their role on bladder cancer progression. In this study, we evaluated the expression of DLX6 Antisense RNA 1 (DLX6-AS1) in the cancerous bladder tissues and studied the possible mechanisms of DLX6-AS1 in regulating bladder cancer progression.

Methods

Gene expression was determined by qRT-PCR; protein expression levels were evaluated by western blot assay; in vitro functional assays were used to determine cell proliferation, invasion and migration; nude mice were used to establish the tumor xenograft model.

Results

Our results showed the up-regulation of DLX6-AS1 in cancerous bladder cancer tissues and bladder cell lines, and high expression of DLX6-AS1 was correlated with advance TNM stage, lymphatic node metastasis and distant metastasis. The in vitro experimental data showed that DLX6-AS1 overexpression promoted bladder cancer cell growth, proliferation, invasion, migration and epithelial-to-mesenchymal transition (EMT); while DLX6-AS1 inhibition exerted tumor suppressive actions on bladder cancer cells. Further results showed that DLX6-AS1 overexpression increased the activity of Wnt/β-catenin signaling, and the oncogenic role of DLX6-AS1 in bladder cancer cells was abolished by the presence of XAV939. On the other hand, DLX6-AS1 knockdown suppressed the activity of Wnt/β-catenin signaling, and the tumor-suppressive effects of DLX6-AS1 knockdown partially attenuated by lithium chloride and SB-216763 pretreatment. The in vivo tumor growth study showed that DLX6-AS1 knockdown suppressed tumor growth of T24 cells and suppressed EMT and Wnt/β-catenin signaling in the tumor tissues.

Conclusion

Collectively, the present study for the first time identified the up-regulation of DLX6-AS1 in clinical bladder cancer tissues and in bladder cancer cell lines. The results from in vitro and in vivo assays implied that DLX6-AS1 exerted enhanced effects on bladder cancer cell proliferation, invasion and migration partly via modulating EMT and the activity of Wnt/β-catenin signaling pathway.

Exosomal long non-coding RNA DLX6-AS1 as a potential diagnostic biomarker for non-small cell lung cancer

Distal-less homeobox 6 antisense RNA 1 (DLX6-AS1) is upregulated in various solid tumors and serves a critical role in the tumorigenesis of cancer. However, to the best of our knowledge, the expression of circulating DLX6-AS1 and its role in the diagnosis of non-small cell lung cancer (NSCLC) have not been previously clarified. The aim of the present study was to investigate the expression and clinical significance of circulating DLX6-AS1 using reverse transcription-quantitative PCR in serum and exosomes derived from patients with NSCLC and healthy donors. The diagnostic value of circulating DLX6-AS1 was identified by receiver operating characteristic curve (ROC) analysis. First, it was revealed that the expression levels of DLX6-AS1 were significantly increased in tumor tissues compared with in adjacent normal tissues. In addition, DLX6-AS1 was highly expressed in NSCLC cell lines compared with in BEAS-2B cells. DLX6-AS1-knockdown inhibited cell proliferation and migration in vitro. It was subsequently demonstrated that the serum DLX6-AS1 level was significantly higher in patients with NSCLC compared with in healthy controls. Additionally, the higher DLX6-AS1 expression was associated with advanced disease stage, positive lymph node metastasis and poor tumor differentiation of NSCLC. ROC analysis demonstrated that the sensitivity and specificity of DLX6-AS1 were higher than those of CYFRA21-1, which is a serum marker for NSCLC. Finally, exosomal DLX6-AS1 expression was increased in patients with NSCLC compared with in healthy controls. The present data implied that circulating DLX6-AS1 was mainly incorporated into exosomes, providing a novel potential diagnostic marker for NSCLC.

Long non-coding RNA DSCAM-AS1 accelerates the progression of hepatocellular carcinoma via sponging miR-338-3p

Aberrant expression of long non-coding RNA DSCAM-AS1 (Down Syndrome Cell Adhesion Molecule antisense) has been observed in several cancers. However, the expression status, biological function and underling mechanism of DSCAM-AS1 in hepatocellular carcinoma (HCC) remain unclear. The expression of DSCAM-AS1 was detected in HCC tissues and serum from both HCC patients and healthy controls. MTS, wound healing and transwell invasion assays were used to examine the effects of DSCAM-AS1 on cell proliferation, migration, and invasion in HCC cells, respectively. MicroRNAs (miRNAs) targeted DSCAM-AS1 was predicated by Starbase2.0 and identified using luciferase reporter and RNA immunoprecipitation assays. The xenograft mice were established to examine the effect DSCAM-AS1 on tumor growth in vivo. We found that DSCAM-AS1 was up-regulated in HCC tissues relative to adjacent non-tumor tissues. Serum levels of DSCAM-AS1 were higher in HCC patients than that in healthy controls. Increased DSCAM-AS1 was associated with poor prognosis. Knockdown of DSCAM-AS1 significantly inhibited HCC cell proliferation, migration and invasion. Moreover, miR-338-3p was confirmed as a direct target of DSCAM-AS1 in HCC cells. The miR-338-3p inhibitor could partially reverse the inhibitory effect of DSCAM-AS1 depletion in HCC cells. DSCAM-AS1 positively regulated CyclinD1 and smoothened (SMO) expression (two targets of miR-338-3p) in HCC cells. Moreover, tumor growth was tremendously retarded in nude mice received injection of SMCC-7721 cells transfected with sh-DSCAM-AS1. Taken together, the present work suggested that DSCAM-AS1 functioned as an oncogenic lncRNA that promoted HCC progression by sponging miR-338-3p.

Long noncoding RNA DLX6-AS1 promotes liver cancer by increasing the expression of WEE1 via targeting miR-424-5p

Long noncoding RNAs (lncRNAs) played an important role in tumorigenesis and development of hepatocellular carcinoma (HCC). In this study, we first demonstrated that lncRNA DLX6 antisense RNA 1 (DLX6‐AS1) was upregulated in cancer tissues and cells lines compared with normal adjacent and cell line. Knock‐down DLX6‐AS1 by transfection with small interfering RNA (siRNA) suppressed cell proliferation, migration, and invasion of HCC cells. Cell cycle analysis showed that cells transfected with siRNA were arrested in G0/G1 phase. Then, we performed dual‐luciferase reporter assay and RNA immunoprecipitation (RIP) assay to show that DLX6‐AS1 could bind with miR‐424‐5p. And cotransfection inhibitor of miR‐424‐5p with siRNA of DLX6‐AS1 could abolish the inhibitory effect of siRNA of DLX6‐AS1 on cell proliferation, migration, and invasion. Moreover, we further demonstrated that the oncogene WEE1 G2 checkpoint kinase (WEE1) was the target of miR‐424‐5p and expression levels of WEE1 were positive correlation with that of DLX6‐AS1. Taken together, these results suggested that upregulated DLX6‐AS1 promoted cell proliferation, migration, and invasion of HCC through increasing expression of WEE1 via targeting miR‐424‐5p.

Long noncoding RNA DLX6-AS1 targets miR-124-3p/CDK4 to accelerate Ewing's sarcoma

Ewing's sarcoma is one of leading cause of malignancy occurred in the children and adolescents worldwide. Given the emerging critical role of long noncoding RNA (lncRNA) in the human cancer, as well as Ewing's sarcoma, we aim to identify the biological role of DLX6-AS1 in the tumorigenesis. Results unveil that DLX6-AS1 expression was increased in the tissue sample and cells. Functionally, the silencing of DLX6-AS1 could repress the proliferation and accelerate the apoptosis of Ewing's sarcoma cells. Mechanically, DLX6-AS1 functioned as the sponge of miR-124-3p, and then miR-124-3p targeted the 3'-UTR of CDK4 mRNA, forming the DLX6-AS1/miR-124-3p/CDK4 regulatory pathway. In conclusion, the critical role of DLX6-AS1 might unveil a potential therapeutic target for Ewing's sarcoma.