TiO2nanotubes promote osteogenic differentiation of human bone marrow stem cells via epigenetic regulation ofRMRP/DLEU2/EZH2 pathway

TiO2nanotubes (TNTs) significantly promote osteogenic differentiation and bone regeneration of cells. Nevertheless, the biological processes by which they promote osteogenesis are currently poorly understood. Long non-coding RNAs (lncRNAs) are essential for controlling osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs). Epigenetic chromatin modification is one of the pathways in which lncRNAs regulate osteogenic differentiation. Here, we reported that TNTs could upregulate lncRNARMRP, and inhibition of lncRNARMRPin human BMSCs (hBMSCs) grown on TNTs could decrease runt-related transcription factor 2 (RUNX2), alkaline phosphatase, osteopontin, and osteocalcin (OCN) expression. Furthermore, we discovered that inhibiting lncRNARMRPelevated the expression of lncRNADLEU2, and lncRNADLEU2knockdown promoted osteogenic differentiation in hBMSCs. RNA immunoprecipitation experiments showed that lncRNADLEU2could interact with EZH2 to induce H3K27 methylation in the promoter regions of RUNX2 and OCN, suppressing gene expression epigenetically. According to these results, lncRNARMRPis upregulated by TNTs to promote osteogenic differentiation throughDLEU2/EZH2-mediated epigenetic modifications.

Long noncoding RNA DLEU2 regulates the progression of Wilm's tumor via miR-539-3p/HOXB2 axis

BACKGROUND

Wilm's tumor is the most common renal cancer in the pediatric age group. Long noncoding RNAs (lncRNAs) are a kind of RNA transcripts longer than ∼200 nucleotides, which have been revealed to be involved in the progression of Wilm's tumor.

OBJECTIVE

The purpose of this study was to investigate the function and molecular mechanism of deleted in lymphocytic leukemia 2 (DLEU2) lncRNA in Wilm's tumor progression.

STUDY DESIGN

Quantitative real-time polymerase chain reaction (qRT-PCR) was used to detect the expression of DLEU2, miR-539-3p and HOXB2 mRNA in Wilm's tumor tissues and cells. Cell counting kit-8 assay, 5-ethynyl-2'-deoxyuridine (EdU) assay, colony formation assay, transwell assay, and flow cytometry were applied to explore the function of DLEU2 in Wilm's tumor cell malignant phenotypes and the regulatory mechanism among DLEU2, miR-539-3p and HOXB2 in Wilm's tumor cells. Western blot examined the protein levels of Bax, Bcl-2 and HOXB2. The relationship between miR-539-3p and DLEU2 or HOXB2 was verified by dual-luciferase reporter assay. Xenograft models of Wilm's tumor were established to study the role of DLEU2 in vivo.

RESULTS

DLEU2 and HOXB2 were significantly highly expressed in primary Wilm's tumor tissues and in vitro cell lines. Silencing of DLEU2 reduced the proliferation, migration and invasion of Wilm's tumor cells, and promoted cell apoptosis. MiR-539-3p was confirmed to be a target of DLEU2. DLEU2 silencing inhibited the malignant behaviors of Wilm's tumor cells by releasing miR-539-3p. In addition, HOXB2 was a target of miR-539-3p. Overexpression of HOXB2 partially restored the inhibitory effects of miR-539-3p on Wilm's tumor cell malignant behaviors. Animal experiments also confirmed the anti-tumor effects of DLEU2 silencing in vivo.

CONCLUSION

DLEU2 up-regulates the expression of HOXB2 by targetedly repressing miR-539-3p, thereby at least partially promoting the development of Wilm's tumor, these findings provided novel therapeutic targets for Wilm's tumor.

DLEU2 modulates proliferation, migration and invasion of platelet-derived growth factor-BB (PDGF-BB)-induced vascular smooth muscle cells (VSMCs) via miR-212-5p/YWHAZ axis

DLEU2 has been proved to act as an oncogene in a variety of cancers, but its role in cardiovascular diseases is dearth of research. Thus, this study mainly discussed the effect and possible mechanism of DLEU2 on platelet-derived growth factor-BB (PDGF-BB)-triggered vascular smooth muscle cell (VSMC) injury. To obtain authentic results, the expressions of target genes in atherosclerosis serum were determined by reverse transcription quantitative PCR (RT-qPCR) and the protein levels were evaluated by Western blot. PDGF-BB was used to simply simulate the biological characteristics of VSMCs in vitro. The effect of DLEU2 on the biological behavior of PDGF-BB-induced VSMCs was analyzed by gain- and loss-of-function assays. Bioinformatics analysis, dual luciferase reporter assay, and Pearson correlation method were conducted to determine the relationship between target genes. The role of DLEU2/miR-212-5p/ YWHAZ (tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein zeta) axis in PDGF-BB-induced VSMCs was verified by rescue experiments. As a result, DLEU2 and YWHAZ were up-regulated, and miR-212-5p was down-regulated in atherosclerosis serum. Overexpressed DLEU2 facilitated the biological behavior of PDGF-BB-induced VSMCs, whilst siDLEU2 did the opposite. Moreover, overexpressed DLEU2 promoted proliferating cell nuclear antigen (PCNA) expression but repressed α-smooth muscle actin (α-SMA) and Calponin expressions, while it also enhanced YWHAZ expression via suppressing miR-212-5p. MiR-212-5p mimic and siYWHAZ reversed the effects of overexpressed DLEU2 on above biological characteristics and protein expressions in PDGF-BB-induced VSMCs, while the regulatory effect of miR-212-5p mimic was partially offset by overexpressed YWHAZ. Collectively, DLEU2 modulates PDGF-BB-induced VSMC injury via miR-212-5p/YWHAZ axis in atherosclerosis.

Prognostic Value of Long Noncoding RNA DLEU2 and Its Relationship with Immune Infiltration in Kidney Renal Clear Cell Carcinoma and Liver Hepatocellular Carcinoma

Background

DLEU2 is a long noncoding RNA considered important in the progression of many cancers. However, correlations between DLEU2 and kidney renal clear cell carcinoma (KIRC) and liver hepatocellular carcinoma (LIHC) have rarely been reported.

Methods

We first analysed the expression of DLEU2 across cancers and the correlation between DLEU2 and the clinical features of KIRC and LIHC by using the “ggplot2” package in R and searched the Oncomine database and Timer website platform. We verified the expression of DLEU2 in the GEO dataset (GSE105261 and GSE45267). Receiver operating characteristic (ROC) curves were drawn using the “pROC” and “ggplot2” packages in R, and we constructed a DLEU2-based prognostic nomogram for KIRC and LIHC by using the “survival” and “rms” packages in R. Then, we analysed the correlation between DLEU2 expression and prognosis in R as well as the correlation between DLEU2 and immune cell infiltration in the TIMER database. Finally, we explored the causes of DLEU2 upregulation in the UCSC Xena and UALCAN databases.

Results

We found that DLEU2 was upregulated in many cancers, including KIRC and LIHC. Expression of DLEU2 is associated with tumour stage, grade, lymphatic metastasis, and distant metastasis in KIRC as well as alpha-fetoprotein (AFP), tumour stage, grade, lymphatic metastasis, and distant metastasis in LIHC. DLEU2 is an adverse factor for the prognosis of KIRC and LIHC. In addition, DLEU2 has moderate accuracy in diagnosing KIRC and LIHC and predicting their prognosis. Moreover, we found that expression of DLEU2 correlated positively with immune cell infiltration in KIRC and LIHC, and upregulation of DLEU2 in KIRC and LIHC suggests a poor prognosis based on immune cells analysis. Genetic and epigenetic analyses of DLEU2 indicate that copy number variations (CNVs) and methylation contribute to the upregulation of DLEU2.

Conclusion

The long noncoding RNA DLEU2 has the potential to predict the prognosis and immune infiltration of KIRC and LIHC.

Long non-coding RNA DLEU2 drives EMT and glycolysis in endometrial cancer through HK2 by competitively binding with miR-455 and by modulating the EZH2/miR-181a pathway

Background

Epithelial-to-mesenchymal transition (EMT) and aerobic glycolysis are fundamental processes implicated in cancer metastasis. Although increasing evidence demonstrates an association between EMT induction and enhanced aerobic glycolysis in human cancer, the mechanisms linking these two conditions in endometrial cancer (EC) cells remain poorly defined.

Methods

We characterized the role and molecular mechanism of the glycolytic enzyme hexokinase 2 (HK2) in mediating EMT and glycolysis and investigated how long noncoding RNA DLEU2 contributes to the stimulation of EMT and glycolysis via upregulation of HK2 expression.

Results

HK2 was highly expressed in EC tissues, and its expression was associated with poor overall survival. Overexpression of HK2 effectively promoted EMT phenotypes and enhanced aerobic glycolysis in EC cells via activating FAK and its downstream ERK1/2 signaling. Moreover, microRNA-455 (miR-455) served as a tumor suppressor by directly interacting with HK2 mRNA and inhibiting its expression. Furthermore, DLEU2 displayed a significantly higher expression in EC tissues, and increased DLEU2 expression was correlated with worse overall survival. DLEU2 acted as an upstream activator for HK2-induced EMT and glycolysis in EC cells through two distinct mechanisms: (i) DLEU2 induced HK2 expression by competitively binding with miR-455, and (ii) DLEU2 also interacted with EZH2 to silence a direct inhibitor of HK2, miR-181a.

Conclusions

This study identified DLEU2 as an upstream activator of HK2-driven EMT and glycolysis in EC cells and provided significant mechanistic insights for the potential treatment of EC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-021-02018-1.

Long noncoding RNA DLEU2 drives the malignant behaviors of thyroid cancer through mediating the miR-205-5p/TNFAIP8 axis

OBJECTIVE

Considering the plight in thyroid cancer therapy, we aimed to find novel therapeutic targets from a molecular perspective.

METHODS

Quantitative real-time PCR (qRT-PCR) and Western blot assay were carried out to determine RNA and protein expression. Cell counting kit-8 (CCK8) assay, flow cytometry, transwell migration assay and aerobic glycolysis analysis were performed to analyze cell proliferation, apoptosis, migration and aerobic glycolysis of thyroid cancer cells. MiRcode and Starbase software were used to search the downstream genes of long noncoding RNA (lncRNA) deleted in lymphocytic leukemia 2 (DLEU2) and microRNA-205-5p (miR-205-5p), and the intermolecular combination was confirmed by dual-luciferase reporter assay. The in vivo role of DLEU2 in tumor growth was verified using the murine xenograft model.

RESULTS

DLEU2 and tumor necrosis factor-α-induced protein 8 (TNFAIP8) were highly expressed in thyroid cancer tissues and cell lines. DLEU2 and TNRAIP8 promoted the proliferation, migration and aerobic glycolysis and restrained the apoptosis of thyroid cancer cells. DLEU2/miR-205-5p/TNFAIP8 signaling axis was identified in thyroid cancer cells. TNFAIP8 overexpression largely rescued the malignant phenotypes in DLEU2-silenced thyroid cancer cells. DLEU2 positively regulated TNFAIP8 expression by acting as miR-205-5p sponge in thyroid cancer cells. DLEU2 silencing blocked the growth of xenograft tumors in vivo.

CONCLUSION

lncRNA DLEU2 exerted a pro-tumor role to promote proliferation, migration and aerobic glycolysis while repressing the apoptosis of thyroid cancer cells via miR-205-5p/TNFAIP8 axis.

LncRNA DLEU2 is activated by STAT1 and induces gastric cancer development via targeting miR-23b-3p/NOTCH2 axis and Notch signaling pathway

INTRODUCTION

Gastric cancer (GC) has severely affected the health of patients and caused high mortality around the world. Long non-coding RNAs (lncRNAs) have been validated to play significant roles in biological process of multiple cancers.

METHODS

Quantitative real-time PCR (RT-qPCR) and western blot analysis were conducted to evaluate the expression levels and protein levels of related genes in GC cells. Functional assays were implemented to explore the effect of deleted in lymphocytic leukemia 2 (DLEU2). The upstream and downstream mechanisms of DLEU2 were verified by mechanism investigations.

RESULTS

The expression of long non-coding RNA (lncRNA) DLEU2 was observably high in GC cells and tissues. DLEU2 silence depressed the capacities of proliferation, migration and invasion but promoted apoptosis in GC cells. Moreover, DLEU2 was activated by signal transducer and activator of transcription 1 (STAT1) and sequestered microRNA-23b-3p (miR-23b-3p) to modulate the expression of notch receptor 2 (NOTCH2), thereby stimulating Notch signaling pathway. More importantly, DLEU2 contributed to GC progression via targeting miR-23b-3p/NOTCH2 axis.

CONCLUSIONS

In summary, our research identified the STAT1/DLEU2/miR-23b-3p/NOTCH2/Notch axis in GC development, indicating that DLEU2 might function as a novel biomarker in GC.

Long noncoding RNA DLEU2 affects the proliferative and invasive ability of colorectal cancer cells

Emerging evidence indicates that long noncoding RNAs (lncRNAs) are closely associated with colorectal cancer (CRC) tumorigenesis. One example is lncRNA Deleted in Lymphocytic Leukemia 2 (DLEU2). However, how DLEU2 contributes to CRC is still poorly understood. This study sought to investigate the effects of DLEU2 on CRC pathogenesis, and the underlying mechanism involved. Using a quantitative real-time polymerase chain reaction (qRT-PCR) assay, we demonstrated that the expression levels of DLEU2 in 45 pairs of CRC tissues were higher than those in the corresponding normal colon mucosal tissues. In addition, CRC patients with high DLEU2 expression levels exhibited poor overall survival (OS) and recurrence-free survival (RFS), as determined by analyses and measurements from the GEO and GEPIA databases. When DLEU2 was silenced using short interfering RNA (siRNA) in CRC cell line, the results demonstrated that DLEU2 silencing suppressed CRC cell tumorigenesis in vitro, which was associated with decreased expression of cyclin dependent kinase 6(CDK6), ZEB1, and ZEB2 as well as enhancing the expression of Cyclin-dependent kinase inhibitor 1A (CDKN1A). Taken together, the results of this study suggested that DLEU2 may play critical roles in the progression of CRC and may serve as a prognostic biomarker for CRC.

Deleted in lymphocytic leukemia 2 (DLEU2): An lncRNA with dissimilar roles in different cancers

Deleted in lymphocytic leukemia 2" (DLEU2) is a long non-coding transcript with several splice variants. It has been identified through a comprehensive sequencing of a commonly deleted region in leukemia i.e. the 13q14 region. Afterwards, different investigations reported up-regulation of this long non-coding RNA in several types of cancers. Up-regulation of DLEU2 has been shown to determine poor survival in esophageal, pancreatic, laryngeal, renal, cervical and lung cancers. However, the diagnostic power of DLUE2 has only assessed in two studies; only one them exhibiting promising results. A limitation of most of studies is that they did not differentiate between transcript variants of this lncRNA. Therefore, it is not possible to attribute the observed functions to a certain alternate transcript. In this manuscript, we discuss the results of these studies in three different sections based on the type of experiments.

lncRNA DLEU2 acts as a miR-181a sponge to regulate SEPP1 and inhibit skeletal muscle differentiation and regeneration

Sarcopenia is a serious public health problem associated with the loss of muscle mass and function. The purpose of this study was to identify molecular markers and construct a ceRNA pathway as a significant predictor of sarcopenia. We designed a prediction model to select important differentially expressed mRNAs (DEMs), and constructed a sarcopenia associated ceRNA network. After correlation analysis of each element in the ceRNA network based on clinical samples and GTEX database, C2C12 mouse myoblasts were used as a model to verify the identified ceRNA pathways. A new model for predicting sarcopenia based on four molecular markers SEPP1, SV2A, GOT1, and GFOD1 was developed. The model was used to construct a ceRNA network and showed high accuracy. Correlation analysis showed that the expression levels of lncDLEU2, SEPP1, and miR-181a were closely associated with a high risk of sarcopenia. lncDLEU2 inhibits muscle differentiation and regeneration by acting as a miR-181a sponge regulating SEPP1 expression. In this study, a highly accurate prediction tool was developed to improve the prediction outcomes of sarcopenia. These findings suggest that the lncDLEU2-miR-181a-SEPP1 pathway inhibits muscle differentiation and regeneration. This pathway may be a new therapeutic target for the treatment of sarcopenia.

DLEU2: A Meaningful Long Noncoding RNA in Oncogenesis

BACKGROUND

Long non-coding RNA (lncRNA) with little or no coding ability has shown a variety of biological functions in cancer, including epigenetic regulation, DNA damage, regulation of microRNAs, and participation in signal transduction pathways. LncRNA can be used as an oncogene and tumor suppressor gene through transcriptional regulation in cancer. For example, the over-expressed lncRNA DLEU2 promotes the occurrence of laryngeal cancer, lung cancer, hepatocellular carcinoma, etc., and inhibits the progression of chronic lymphocytic leukemia. Deleted in Lymphocytic Leukemia 2 (DLEU2), as one of the long non-coding RNAs, was first found in chronic lymphoblastic leukemia and drawn into the progress of innumerable cancers. The molecular mechanism of DLEU2 in multiple tumors will be revealed.

METHODS

In this review, current studies on the biological functions and mechanisms of DLEU2 in tumors are summarized and analyzed; related researches are systematically retrieved and collected through PubMed.

RESULTS

DLEU2, a novel cancer-related lncRNA, has been demonstrated to be abnormally expressed in various malignant tumors, including leukemia, esophageal cancer, lung cancer, glioma, hepatocellular carcinoma, malignant pleural mesothelioma, bladder cancer, pancreatic cancer, pharynx and throat cancer, renal clear cell carcinoma, breast cancer, osteosarcoma. Besides, lncRNA DLEU2 has been shown to be involved in the process of proliferation, migration, invasion and inhibition of apoptosis of cancer cells.

CONCLUSION

Due to the biological functions and mechanisms involved in DLEU2, it may represent an available biomarker or potential therapeutic target in a variety of malignant tumors.

Knockdown of LncRNA DLEU2 Inhibits Cervical Cancer Progression via Targeting miR-128-3p

Objective

Cervical cancer is one of the most common female malignancies worldwide and represents a major global health challenge. The fast growth of tumor and high rates of metastasis still lead to a poor prognosis of cervical cancer patients. It is urgent to clarify the mechanism and identify predictive biomarkers for the treatment of cervical cancer. Long non-coding RNAs (LncRNAs) have been identified in cervical cancer and are related to malignant phenotypes of cervical cancer cells. However, the roles and mechanism of LncRNA deleted in lymphocytic leukemia (DLEU2) in the tumorigenesis and progression of cervical cancer remain unknown.

Materials and Methods

qPCR was performed to analyze the expression of DLEU2, Cyclin D1, CDK4, Bax, Bcl2 and mi-128-3p. Western blot was performed to detect the cell cycle hallmarks expression. CCK8 was used to examine cell proliferation. Cellular apoptosis was analyzed by Hoechst 33,258 staining and AV/PI staining with flow cytometry. Cell cycle was analyzed by flow cytometry. The xenograft model in nude mice was used to elucidate the function of DLEU2 in vivo. Bioinformatics analysis and luciferase reporter assay were proceeded to clarify whether miR-128-3p directly binds with lncRNA DLEU2. Pull‑down assay and RNA-binding protein immunoprecipitation assay were used for exploring the relationship between DLEU2 and miR-128-3p.

Results

We demonstrated that DLEU2 was upregulated in cervical cancer tumor tissues. Downregulation of DLEU2 inhibited cell proliferation, induced apoptosis and cell cycle arrest at G2/M phase of cervical cancer cells in vitro, and suppressed tumor growth in vivo. Further, LncRNA DLEU2 is one of the targets of miR-128-3p. miR-128-3p inhibitor abrogated the cell proliferation suppressed by knockdown of DLEU2, apoptosis induced by knockdown of DLEU2 and reversed the expression of cell cycle hallmarks regulated by knockdown of DLEU2.

Conclusion

Taken together, these results suggested knockdown of DLEU2 inhibited cervical cancer progression via targeting miR-128-3p.

LncRNA DLEU2 promotes tumour growth by sponging miR-337-3p in human osteosarcoma

According to statistics, abnormal regulation of lncRNAs pivotally influences multiple malignant tumours. DLEU2, as one of these lncRNAs, is detected to be related to growth and development of tumours. The molecular mechanisms of DLEU2 in osteosarcoma, however, are still unknown. QRT-PCR was adopted to analyse the correlations of clinicopathological features and prognosis of osteosarcoma cases with DLEU2. The influences of DLEU2 on cell migration and viability were evaluated independently by experiments in vitro and in vivo. Bioinformatics analysis, RNA immunoprecipitation (RIP) assay, and dual luciferase reporter gene assay confirmed the specific binding of DLEU2 to miR-337-3p. Moreover, rescue experiments were carried out to further evaluate the regulatory association between miR-337-3p expression and DLEU2. In osteosarcoma tissues and cells, DLEU2 expression level was raised remarkably in comparison with that in para-carcinoma normal tissues, and DLEU2 high expression had associations with poor prognosis, tumour stages, and TS of osteosarcoma cases. Cell migration ability and viability were blocked by DLEU2 knockdown but enhanced by ectopic DLEU2 expression in vitro and in vivo. Additionally, DLEU2 was found to sponge miR-337-3p and trigger the stimulating effect in osteosarcoma cells, which would be suppressed by miR-337-3p mimics. Furthermore, a negative correlation existed between miR-337-3p expression and DLEU2 in osteosarcoma tissues. This study manifests that DLEU2 sponges miR-337-3p to accelerate tumour growth and is confirmed to be a factor for poor prognosis of osteosarcoma cases. SIGNIFICANCE OF THE STUDY: LncRNA DLEU2 has been reported to be dysregulated in many tumours; however, the functions and underlying mechanism of DLEU2 in osteosarcoma pathogenesis are still unknown. This study is the first to demonstrate the roles of DLEU2 in osteosarcoma and revealed that DLEU2 may serve as a ceRNA to sponge miR-337-3p and then promote the progression of osteosarcoma, providing a potential therapeutic target for osteosarcoma.

LncRNA DLEU2 accelerates the tumorigenesis and invasion of non-small cell lung cancer by sponging miR-30a-5p

Long non‐coding RNAs (lncRNAs) have been reported to participate in the pathogenesis of non–small cell lung cancer (NSCLC). However, how lncRNA deleted in lymphocytic leukaemia 2 (DLEU2) contributes to NSCLC remains undocumented. The clinical significance of lncRNA DLEU2 and miR‐30a‐5p expression in NSCLC was analysed by using fluorescence in situ hybridization and TCGA cohorts. Gain‐ and loss‐of‐function experiments as well as a NSCLC tumour model were executed to determine the role of lncRNA DLEU2 in NSCLC. DLEU2‐sponged miR‐30a‐5p was verified by luciferase reporter, and RIP assays. Herein, the expression of lncRNA DLEU2 was elevated in NSCLC tissues, and its high expression or low expression of miR‐30a‐5p acted as an independent prognostic factor of poor survival and tumour recurrence in NSCLC. Silencing of lncRNA DLEU2 repressed the tumorigenesis and invasive potential of NSCLC, whereas re‐expression of lncRNA DLEU2 showed the opposite effects. Furthermore, lncRNA DLEU2 harboured a negative correlation with miR‐30a‐5p expression in NSCLC tissues and acted as a sponge of miR‐30a‐5p, which reversed the tumour‐promoting effects of lncRNA DLEU2 by targeting putative homeodomain transcription factor 2 in NSCLC. Altogether, lncRNA DLEU2 promoted the tumorigenesis and invasion of NSCLC by sponging miR‐30a‐5p.

Expression analysis of a panel of long non-coding RNAs (lncRNAs) revealed their potential as diagnostic biomarkers in bladder cancer

INTRODUCTION

Long non-coding RNAs (lncRNAs) have fundamental roles in cell migration, proliferation, invasion and metastasis.

METHODS

In the current study, we evaluated expression of a panel of lncRNAs in bladder cancer tissues, adjacent non-cancerous tissues (ANCTs) and normal bladder tissues to evaluate their diagnostic power.

RESULTS

PV1 was down-regulated in tumor tissues compared with both ANCTs and normal controls (Expression ratios of 0.48 and 0.14; P values of 0.4 and <0.001 respectively). HOTAIR, NEAT1, TUG1 and FAS-AS1 were significantly down-regulated in tumor tissues compared with normal controls (Expression ratios of 0.4, 0.68, 0.54 and 0.11; P values of 0.04, 0.02, 0.02 and <0.001 respectively).

CONCLUSION

Combination of transcript levels of seven lncRNAs improved both sensitivity and specificity values to 100%. The current study shows dysregulation of lncRNAs in bladder cancer and implies their role as diagnostic markers in this malignancy.

Silencing of DLEU2 suppresses pancreatic cancer cell proliferation and invasion by upregulating microRNA-455

Long noncoding RNA (lncRNA) DLEU2 has been shown to be dysregulated in several type of tumor. However, the potential biological roles and molecular mechanisms of DLEU2 in pancreatic cancer (PC) progression are poorly understood. In this study, we found that the DLEU2 level was substantially upregulated in PC tissues and PC cell lines, and significantly associated with poor clinical outcomes in PC patients. Overexpression of DLEU2 significantly induced PC cell proliferation and invasion, whereas knockdown of DLEU2 impaired cell proliferation and invasion in vitro. Furthermore, bioinformatics analysis, luciferase reporter assay, and RNA immunoprecipitation assay revealed that DLEU2 directly bond to microRNA‐455 (miR‐455) and functioned as an endogenous sponge for miR‐455, which could remarkably suppress cell growth and invasion. We also determined that SMAD2 was a direct target of miR‐455, and the restoration of SMAD2 rescued cell growth and invasion that were reduced by DLEU2 knockdown or miR‐455 overexpression. In addition, low miR‐455 expression and high SMAD2 expression was correlated with poor patient survival. These results indicate that DLEU2 is an important promoter of PC development, and targeting the DLEU2/miR‐455/SMAD2 pathway could be a promising therapeutic approach in the treatment of PC.

Upregulated long-non-coding RNA DLEU2 exon 9 expression was an independent indicator of unfavorable overall survival in patients with esophageal adenocarcinoma

In this study, we aimed to explore the expression profiles of some known functional lncRNAs in esophageal adenocarcinoma (EAD) and to screening the potential prognostic makers, using data from The Cancer Genome Atlas (TCGA)-esophageal carcinoma (ESCA). Results showed that DLEU2 is a high potential OS related marker among 73 functional lncRNAs. DLEU2 and its intronic miR-15a and miR-16-1 expression were significantly upregulated in EAD compared with adjacent normal tissues. However, miR-15a and miR-16-1 expression were only weakly correlated with DLEU2 expression. Univariate and multivariate analysis confirmed that DLEU2 expression, but not miR-15a or miR-16-1 expression is an independent prognostic marker in terms of OS (HR:1.688, 95%CI: 1.085-2.627, p = 0.020) in EAD patients. The exon 9 of DLEU2 is very strongly co-expressed with DLEU2 (Pearson's r = 0.96) and showed better predictive value than total DLEU2 expression in predicting the OS of EAD patients. Multivariate analysis confirmed its independent prognostic value (HR:1.970, 95%CI: 1.266-3.067, p = 0.003), after adjustment of histologic grade, pathological stages and the presence of residual tumor. By checking the methylation status of DLEU2 gene, we excluded the possibility of the influence of two CpG sites near the DLEU2 exon 9 locus on its expression. In addition, although copy number alterations (CNAs) were observed DLEU2 gene, heterozygous loss (-1), low-level copy gain (+1) and high-level amplification (+2) had no significant association with DLEU2 transcription. Based on these findings, we infer that DLEU2 exon 9 expression might serve as a valuable biomarker of unfavorable OS in EAD patients.

Integrative Analysis of Dysregulated lncRNA-Associated ceRNA Network Reveals Functional lncRNAs in Gastric Cancer

Mounting evidence suggests that long noncoding RNAs (lncRNAs) play important roles in the regulation of gene expression by acting as competing endogenous RNA (ceRNA). However, the regulatory mechanisms of lncRNA as ceRNA in gastric cancer (GC) are not fully understood. Here, we first constructed a dysregulated lncRNA-associated ceRNA network by integrating analysis of gene expression profiles of lncRNAs, microRNAs (miRNAs), and messenger RNAs (mRNAs). Then, we determined three lncRNAs (RP5-1120P11, DLEU2, and DDX11-AS1) as hub lncRNAs, in which associated ceRNA subnetworks were involved in cell cycle-related processes and cancer-related pathways. Furthermore, we confirmed that the two lncRNAs (DLEU2 and DDX11-AS1) were significantly upregulated in GC tissues, promote GC cell proliferation, and negatively regulate miRNA expression, respectively. The hub lncRNAs (DLEU2 and DDX11-AS1) could have oncogenic functions, and act as potential ceRNAs to sponge miRNA. Our findings not only provide novel insights on ceRNA regulation in GC, but can also provide opportunities for the functional characterization of lncRNAs in future studies.