Down-regulation of long non-coding RNA HOTAIR inhibits invasion and migration of oesophageal cancer cells via up-regulation of microRNA-204

The roles and mechanisms of the lncRNA-miRNA axis in the progression of esophageal cancer: a narrative review

BACKGROUND AND OBJECTIVE

Esophageal cancer is one of the most common malignant digestive tract tumors. Despite various treatment methods, the prognosis of patients remains unsatisfactory, largely due to an insufficient understanding of the mechanisms involved in the pathogenesis and progression of esophageal cancer. More than 98% of the nucleotide sequences in the human genome do not encode proteins, and their transcription products are noncoding RNAs (ncRNAs), mainly long noncoding RNAs (lncRNAs) and microRNAs (miRNAs). Experiments have shown that lncRNAs and miRNAs play crucial roles in the occurrence and progression of various human malignancies. These ncRNAs influence the progression of esophageal cancer through an intricate regulatory network. We herein summarized the roles and mechanisms of the lncRNA-miRNA axis in esophageal cancer cell proliferation, apoptosis, epithelial-mesenchymal transition (EMT), invasion and metastasis, drug resistance, radiotherapy resistance, and angiogenesis. This review provides a rationale for anticancer therapy that targets the lncRNA-miRNA axis in esophageal cancer.

METHODS

Related articles published in the PubMed database between 05/30/2008 to 09/10/2022 were identified using the following terms: "lncRNA AND miRNA AND esophageal cancer", "lncRNA AND miRNA AND cell proliferation", "lncRNA AND miRNA AND apoptosis", "lncRNA AND miRNA AND EMT", "lncRNA AND miRNA AND invasion and metastasis", "lncRNA AND miRNA AND drug resistance", and "lncRNA AND miRNA AND radiotherapy resistance". Published articles written in English available to readers were considered.

KEY CONTENT AND FINDINGS

We summarized the roles of the lncRNA-miRNA axis in the progression of esophageal cancer, including cell proliferation, apoptosis, EMT, invasion and metastasis, drug resistance, radio resistance, and other progressions, and determined that the lncRNA-miRNA axis may serve as a potential clinical treatment target for esophageal cancer.

CONCLUSIONS

The lncRNA-miRNA axis is closely related to the progression of esophageal cancer and may act as a potential biological target for the clinical treatment of patients with esophageal cancer.

MicroRNA-204-5p: A pivotal tumor suppressor

MicroRNAs (miRNAs) are a class of non-coding single-stranded RNA molecules with a length of approximately 18-25 nt nucleotides that regulate gene expression post-transcriptionally. MiR-204-5p originates from the sixth intron of the transient receptor potential cation channel subfamily M member 3 (TRPM3) gene. MiR-204-5p is frequently downregulated in various cancer types and is related to the clinicopathological characteristics and prognosis of cancer patients. So far, many studies have determined that miR-204-5p functions as a tumor suppressor for its extensive and powerful capacity to inhibit tumor proliferation, metastasis, autophagy, and chemoresistance in multiple cancer types. MiR-204-5p appears to be a promising prognostic biomarker and a therapeutic target for human cancers. This review summarized the latest advances on the role of miR-204-5p in human cancers.

The Emerging Role of Long Non-Coding RNAs in Esophageal Cancer: Functions in Tumorigenesis and Clinical Implications

Esophageal cancer (EC) is one of the most common malignancies of digestive tracts with poor five-year survival rate. Hence, it is very significant to further investigate the occurrence and development mechanism of esophageal cancer, find more effective biomarkers and promote early diagnosis and effective treatment. Long non-coding RNAs (lncRNAs) are generally defined as non-protein-coding RNAs with more than 200 nucleotides in length. Existing researches have shown that lncRNAs could act as sponges, guides, scaffolds, and signal molecules to influence the oncogene or tumor suppressor expressions at transcriptional, post-transcriptional, and protein levels in crucial cellular processes. Currently, the dysregulated lncRNAs are reported to involve in the pathogenesis and progression of EC. Importantly, targeting EC-related lncRNAs through genome editing, RNA interference and molecule drugs may be one of the most potential therapeutic methods for the future EC treatment. In this review, we summarized the biological functions and molecular mechanisms of lncRNAs, including oncogenic lncRNAs and tumor suppressor lncRNAs in EC. In addition, we generalized the excellent potential lncRNA candidates for diagnosis, prognosis and therapy in EC. Finally, we discussed the current challenges and opportunities of lncRNAs for EC.

A diagnostic and prognostic value of blood-based circulating long non-coding RNAs in Thyroid, Pancreatic and Ovarian Cancer

Several studies have demonstrated the potential of circulating long non-coding RNAs (lncRNAs) as promising cancer biomarkers. Herein, we addressed the regulatory role of circulating lncRNAs and their potential value as diagnostic/prognostic markers for thyroid, pancreatic and ovarian cancers. Furthermore, we analyzed and measured the clinical implications and association of lncRNAs with sensitivity, specificity, and area under the ROC curve (AUC). Based on our meta-analysis, we found that GAS8-AS1 could discriminate thyroid cancer from non-cancer and other cancers with higher accuracy (AUC = 0.746; sensitivity = 61.70%, and specificity = 90.00%). Similarly, for ovarian cancer, lncRNA RP5-837J1.2 was found to have ideal diagnostic potential with critical clinical specifications of AUC = 0.996; sensitivity = 97.30% and specificity = 94.60%. Whereas we could not find any lncRNA having high diagnostic/prognostic efficiency in pancreatic cancer. We believe that lncRNAs mentioned above may explore clinical settings for the diagnosis and prognosis of cancer patients.

lncRNAs as Potential Targets in Small Cell Lung Cancer: MYC -dependent Regulation

BACKGROUND

Small Cell Lung Cancer (SCLC) is a highly aggressive malignancy. MYC family oncogenes are amplified and overexpressed in 20% of SCLCs, showing that MYC oncogenes and MYC regulated genes are strong candidates as therapeutic targets for SCLC. c-MYC plays a fundamental role in cancer stem cell properties and malignant transformation. Several targets have been identified by the activation/repression of MYC. Deregulated expression levels of lncRNAs have also been observed in many cancers.

OBJECTIVE

The aim of the present study is to investigate the lncRNA profiles which depend on MYC expression levels in SCLC.

METHODS

Firstly, we constructed lentiviral vectors for MYC overexpression/inhibition. MYC expression is suppressed by lentiviral shRNA vector in MYC amplified H82 and N417 cells, and overexpressed by lentiviral inducible overexpression vector in MYC non-amplified H345 cells. LncRNA cDNA is transcribed from total RNA samples, and 91 lncRNAs are evaluated by qRT-PCR.

RESULTS

We observed that N417, H82 and H345 cells require MYC for their growth. Besides, MYC is not only found to regulate the expressions of genes related to invasion, stem cell properties, apoptosis and cell cycle (p21, Bcl2, cyclinD1, Sox2, Aldh1a1, and N-Cadherin), but also found to regulate lncRNAs. With this respect, expressions of AK23948, ANRIL, E2F4AS, GAS5, MEG3, H19, L1PA16, SFMBT2, ZEB2NAT, HOTAIR, Sox2OT, PVT1, and BC200 were observed to be in parallel with MYC expression, whereas expressions of Malat1, PTENP1, Neat1, UCA1, SNHG3, and SNHG6 were inversely correlated.

CONCLUSION

Targeting MYC-regulated genes as a therapeutic strategy can be important for SCLC therapy. This study indicated the importance of identifying MYC-regulated lncRNAs and that these can be utilized to develop a therapeutic strategy for SCLC.

Knockdown of long non-coding RNA CCAT2 suppresses growth and metastasis of esophageal squamous cell carcinoma by inhibiting the -catenin/WISP1 signaling pathway

Objective

Long non-coding RNA (lncRNA) colon cancer-associated transcript 2 (CCAT2) plays oncogenic roles in several cancers, including esophageal squamous cell carcinoma (ESCC). However, the specific mechanism of how CCAT2 influences ESCC tumorigenesis is still unknown.

Methods

Using RT-qPCR, the mRNA expression levels of CCAT2 in 33 paired ESCC and adjacent non-cancer tissues and cell lines were measured. Lentiviral vector sh-CCAT2 was designed and transfected into TE10 cells. CCK-8 and transwell assays were employed to detect the effects of CCAT2 knockdown on cell proliferation and invasion, respectively. RT-qPCR and western blots were used to detect the effects of CCAT2 knockdown.

Results

CCAT2 was overexpressed in ESCC tissues compared with corresponding adjacent tissues. CCAT2 knockdown could suppress cell proliferation and invasion in vitro. Furthermore, knockdown of CCAT2 could suppress the mRNA and protein levels of β-catenin and Wnt-induced-secreted-protein-1 (WISP1), as well as the mRNA levels of their downstream targets VEGF-A, MMP2, and ICAM-1. High expression of CCAT2 and WISP1 were associated with poor prognosis of ESCC patients.

Conclusions

In conclusion, a novel CCAT2/β-catenin/WISP1 axis was revealed in ESCC progression and may provide a promising therapeutic target against ESCC. CCAT2 and WISP1 are potential molecular biomarkers for predicting prognosis of ESCC.

Comprehensive In Silico Analysis of a Novel Serum Exosome-Derived Competitive Endogenous RNA Network for Constructing a Prognostic Model for Glioblastoma

Purpose

Glioblastoma (GBM) is one of the most aggressive brain tumors with high mortality, and tumor-derived exosomes provide new insight into the mechanisms of GBM tumorigenesis, metastasis and therapeutic resistance. We aimed to establish an exosome-derived competitive endogenous RNA (ceRNA) network for constructing a prognostic model for GBM.

Methods

We obtained the expression profiles of long noncoding RNAs (lncRNAs), miRNAs, and mRNAs from the GEO and TCGA databases and identified differentially expressed RNAs in GBM to construct a ceRNA network. By performing lasso and multivariate Cox regression analyses, we identified optimal prognosis-related differentially expressed lncRNAs (DElncRNAs) and generated a risk score model termed the exosomal lncRNA (exo-lncRNA) signature. The exo-lncRNA signature was subsequently validated in the CGGA GBM cohort. Finally, a novel prognostic nomogram was constructed based on the exo-lncRNA signature and clinicopathological parameters and validated in the CGGA external cohort. Based on the ceRNA hypothesis, oncocers were identified based on highly positive correlations between lncRNAs and mRNAs mediated by the same miRNAs. Furthermore, regression analyses were performed to assess correlations between the expression abundances of lncRNAs in tumors and exosomes.

Results

A total of 45 DElncRNAs, six DEmiRNAs, and 38 DEmRNAs were identified, and an exosome-derived ceRNA network was built. Three optimal prognostic-related DElncRNAs, HOTAIR (HR=0.341, P<0.001), SOX21-AS1 (HR=0.30, P<0.001), and STEAP3-AS1 (HR=2.47, P<0.001), were included to construct the exo-lncRNA signature, which was further proven to be an independent prognostic factor. The novel prognostic nomogram was constructed based on the exo-lncRNA signature, patient age, pharmacotherapy, radiotherapy, IDH mutation status, and MGMT promoter status, with a concordance index of 0.878. ROC and calibration plots both suggested that the nomogram had beneficial discrimination and predictive abilities. A total of 11 pairs of prognostic oncocers were identified. Regression analysis suggested excellent consistency of the expression abundance of the three exosomal lncRNAs between exosomes and tumor tissues.

Conclusions

Exosomal lncRNAs may serve as promising prognostic predictors and therapeutic targets. The prognostic nomogram based on the exo-lncRNA signature might provide an intuitive method for individualized survival prediction and facilitate better treatment strategies.

CircNT5E promotes the proliferation and migration of bladder cancer via sponging miR-502-5p

Accumulating evidence suggest that circRNA RNAs (circRNAs) play important roles in tumor formation and development. circNT5E has been shown to be an oncogenic gene in several types of cancer, and the high expression of circNT5E lead to tumorigenesis and cancer progression. However, the precise role of circNT5E in bladder cancer (Bca) has not been characterized. In this study, we observed that circNT5E expression was augmented in Bca tissues compared with that in adjacent normal tissues, and its expression level was positively associated with larger tumor size and lower survival rate. Further experiments showed that suppression of circNT5E restrained the growth and metastasis of Bca cells in vitro. circNT5E was mainly distributed in the cytoplasm and it captured miR-502-5p to increase HOXC8 mRNA and protein expression. Moreover, decreased miR-502-5p obviously reversed the circNT5E silencing-mediated inhibition of Bca cell growth and migration. Thus, this study suggested that circNT5E may act as a pro-oncogene in the development and progression of Bca and it may become a useful tumor biomarker and promising therapeutic target for Bca treatment.

The HOTAIR lncRNA: A remarkable oncogenic promoter in human cancer metastasis

Long non-coding RNA (lncRNA) is a new type of non-coding RNA that has an important regulatory influence on several human diseases, including cancer metastasis. HOX antisense intergenic RNA (HOTAIR), a newly discovered lncRNA, has an important effect on tumour proliferation, migration and metastasis. HOTAIR regulates cell proliferation, changes gene expression, and promotes tumour cell invasion and migration. However, its molecular mechanism of action remains unknown. The present review summarizes the molecular mechanism and role of HOTAIR in tumour invasion and metastasis, discusses the association between HOTAIR and tumour metastasis through different pathways, such as the transforming growth factor β, Wnt/β-catenin, PI3K/AKT/MAPK and vascular endothelial growth factor pathways, emphasizes the function of HOTAIR in human malignant tumour metastasis and provides a foundation for its application in the diagnosis, prognosis and medical treatment of various tumours.

HOTAIR inhibits the proliferation of glioblastoma cells by targeting miR-219

BACKGROUND

To investigate the influences of HOX transcript antisense ribonucleic acid (HOTAIR) on the proliferation and apoptosis of glioblastoma cells by targeting micro RNA (miR)-219.

OBJECTIVE

With glioblastoma cell line U87 as the object, the changes in expression levels of HOTAIR and miR-219 in each group were detected via quantitative real-time polymerase chain reaction (qRT-PCR) after HOTAIR in U87 cell lines was knocked down using small interfering RNA (siRNA). Then the cell proliferation in each group was determined using Cell Counting Kit-8 (CCK-8) and colony formation assays. Flow cytometry was applied to detect the cell apoptosis, and Western blotting assay was adopted to measure the changes in protein levels of Cyclin D1 and Bcl-2-associated X protein (Bax). After miR-219 knockdown with siRNA, the changes in expression levels of HOTAIR and miR-219 in each group were examined through qRT-PCR, and the cell proliferation was tested by CCK-8 assay.

RESULTS

After interference inHOTAIR using siRNA, compared with those in control group, the RNA expression level of HOTAIR was decreased remarkably (p< 0.05), the RNA expression level of miR-219 was increased notably (p< 0.05), the cell proliferation rate was inhibited evidently (p< 0.05), the apoptosis rate was enhanced obviously (p< 0.05), the protein expression level of Cyclin D1 declined markedly (p< 0.05), and the protein expression level of Bax rose distinctly (p< 0.05) in HOTAIR-siRNA group. After miR-219 knockdown with siRNA, the cell proliferation rate was raised remarkably (p< 0.05), but there was no significant change in the RNA expression level of HOTAIR (p> 0.05).

CONCLUSION

HOTAIR can repress the proliferation and promote the apoptosis of glioblastoma cells by targeting miR-219.

The emerging role of long noncoding RNAs in esophageal carcinoma: from underlying mechanisms to clinical implications

Long noncoding RNAs (lncRNAs), a type of transcriptional product more than 200 nucleotides in length, have emerged as crucial regulators in human cancers. Accumulating data have recently indicated relationships between lncRNAs and esophageal carcinoma (EC). Of note, lncRNAs act as decoys/sponges, scaffolds, guides, and signals to regulate the expression of oncogenes or tumor suppressors at epigenetic, post-transcriptional, and protein levels, through which they exert their unique EC-driving or EC-suppressive functions. Moreover, the features of EC-related lncRNAs have been gradually exploited for developing novel diagnostic and therapeutic strategies in clinical scenarios. LncRNAs have the potential to be used as diagnostic and prognostic indicators individually or in combination with other clinical variables. Beyond these, although the time is not yet ripe, therapeutically targeting EC-related lncRNAs via gene editing, antisense oligonucleotides, RNA interference, and small molecules is likely one of the most promising therapeutic strategies for the next generation of cancer treatment. Herein, we focus on summarizing EC-driving/suppressive lncRNAs, as well as discussing their different features regarding expression profiles, modes of action, and oncological effects. Moreover, we further discuss current challenges and future developing possibilities of capitalizing on lncRNAs for EC early diagnosis and treatment.

Roles of the HOX Proteins in Cancer Invasion and Metastasis

Invasion and metastasis correspond to the foremost cause of cancer-related death, and the molecular networks behind these two processes are extremely complex and dependent on the intra- and extracellular conditions along with the prime of the premetastatic niche. Currently, several studies suggest an association between the levels of HOX genes expression and cancer cell invasion and metastasis, which favour the formation of novel tumour masses. The deregulation of HOX genes by HMGA2/TET1 signalling and the regulatory effect of noncoding RNAs generated by the HOX loci can also promote invasion and metastasis, interfering with the expression of HOX genes or other genes relevant to these processes. In this review, we present five molecular mechanisms of HOX deregulation by which the HOX clusters products may affect invasion and metastatic processes in solid tumours.

MicroRNA-148a-3p inhibits cancer progression and is a novel screening biomarker for gastric cancer

PURPOSE

Dysregulation of miR-148a-3p in gastric cancer was reported. However, the diagnostic potential and biological function of miR-148a-3p in gastric cancer progression is not fully studied.

METHODS

Bioinformatics analysis and RT-qPCR assay were performed to analyze the expression of miR-148a-3p in gastric cancer tissues and plasma of gastric cancer patients. Receiver operating characteristic curve analysis was performed to analyze the diagnostic value of miR-148a-3p. In vitro proliferation, apoptosis, migration, invasion, sphere formation assay and Western blotting assay were performed to evaluate the biological function of miR-148a-3p in gastric cancer progression.

RESULTS

miR-148a-3p was significantly down-regulated in both gastric cancer patients' tissue and plasma samples. Plasma miR-148a-3p showed promising efficacy for gastric cancer diagnosis. Overexpression of miR-148a-3p could inhibit the proliferative phenotype, metastatic phenotype, and cancer stem-like properties of gastric cancer cells.

CONCLUSIONS

miR-148a-3p inhibits cancer progression and is a novel diagnostic biomarker for gastric cancer.

OIP5-AS1/miR-137/ZNF217 Axis Promotes Malignant Behaviors in Epithelial Ovarian Cancer

Background

Long non-coding RNAs (lncRNAs) have been reported to play crucial regulatory roles in cellular activities and are associated with the carcinogenesis of various diseases. OIP5-AS1, as a novel lncRNA, function in epithelial ovarian cancer (EOC) still remains unclear.

Material and Methods

qRT-PCR and Western blot analyses were performed to measure relevant expression, as needed. A series of functional experiments were performed to determine the role of OIP5-AS1 in EOC cells. Luciferase report, RNA pull down and RIP assays were performed to testify the interaction between relevant RNAs.

Results

We found that OIP5-AS1 was significantly overexpressed in EOC. Knockdown of OIP5-AS1 inhibited cell proliferation, migration, invasion and epithelial–mesenchymal transition (EMT) process, yet facilitated apoptosis in vitro. OIP5-AS1 functioned as a competing endogenous RNA (ceRNA) to elevate ZNF217 expression through sponging miR-137. Furthermore, miR-137 inhibition and ZNF217 upregulation can reverse the effects of silencing OIP5-AS1 on the cellular activities of ovarian cancer cells. Also, depleted OIP5-AS1 hindered tumor growth and metastasis in vivo.

Conclusion

OIP5-AS1 regulated ovarian cancer progression via modulating miR-137/ZNF217 signaling, suggesting that targeting OIP5-AS1 could be conducive to EOC clinical treatment.

LncRNA HOTAIR induces sunitinib resistance in renal cancer by acting as a competing endogenous RNA to regulate autophagy of renal cells

Background

Cell autophagy has been proposed to be involved in drug resistance therapy. However, how the long non-coding RNA (lncRNA) reduces risks of drug resistance in renal cancer (RC) cells needs a thorough inquiry. This study was assigned to probe the effect and mechanism of HOTAIR on sunitinib resistance of RC.

Methods

Clinical RC tissues and para-carcinoma tissues were obtained to detect the expressions of miR-17-5p, HOTAIR and Beclin1. Sunitinib-resistant cells (786-O-R and ACHN-R) were constructed using parental RC cells (786-O and ACHN). The resistance of 786-O-R and ACHN-R cells to sunitinib was examined. Western blot and qRT-PCR were assayed to obtain the expressions of miR-17-5p, HOTAIR and Beclin1. The effects of HOTAIR knockdown or miR-17-5p overexpression/knockdown on cell autophagy and sunitinib resistance were measured by MDC staining, immunofluorescence and Western blot. The sensitivity of RC cells to sunitinib and change in cell clone formation after sunitinib treatment were assessed by CCK-8 assay and colony formation assay, respectively. The relationships among HOTAIR, miR-17-5p and Beclin1 were verified by dual-luciferase reporter gene and RIP assay. The role of HOTAIR knockdown in sunitinib resistance was verified in nude mice.

Results

HOTAIR expression in sunitinib-resistant cells is higher than that in parental cells. Knockdown of HOTAIR in sunitinib-resistant cells lead to refrained sunitinib resistance and cell autophagy both in vivo and in vitro. Activation of autophagy could raise resistance to sunitinib in RC cells, while inhibition of autophagy could improve the sensitivity of sunitinib-resistant cells to sunitinib. HOTAIR could compete with miR-17-5p to regulate Beclin1 expression. Knockdown of miR-17-5p in parental cells increases cell resistant to sunitinib, and overexpression of miR-17-5p in sunitinib-resistant cells increases cell sensitive to sunitinib.

Conclusion

HOTAIR negatively targets miR-17-5p to activate Beclin1-mediated cell autophagy, thereby enhancing sunitinib resistance in RC cells.

Medulloblastoma malignant biological behaviors are associated with HOTAIR/miR-483-3p/CDK4 axis

BACKGROUND

Medulloblastoma is the most common malignant brain tumor in children. Although the 5-year survival rate is high, patients with relapsed medulloblastoma have a guarded prognosis. HOX transcript antisense RNA (HOTAIR) has been proved to be related to the metastasis of various tumors. Therefore, the molecular mechanism of HOTAIR in medulloblastoma cells was investigated in this study.

METHODS

HOTAIR was stably silenced in medulloblastoma cells (Daoy and D341). Cell proliferation and apoptosis were detected by 5'-Bromo-2'-deoxyuridine (BrdU) staining, Hoechst 33342 staining, immunohistochemical (IHC), Terminal-deoxynucleotidyl transferase-mediated nick end labeling (TUNEL) and flow cytometry, respectively. The targeted relationship between HOTAIR/Cyclin-dependent kinase 4 (CDK4) and miR-483-3p were predicted by bioinformatics and confirmed by luciferase reporter assay. Balb/C nude mice were inoculated with shRNA-HOTAIR transfected Daoy cells.

RESULTS

We found that the down-regulation of HOTAIR inhibited proliferation and induced apoptosis. Sh-RNA-HOTAIR also inhibited the expression of CKD4. The CDK4 dependent increase of cell proliferation and decrease of cell apoptosis were reversed by shRNA-HOTAIR. Finally, a xenograft model of medulloblastoma in nude mice was built, and the effect of shRNA-HOTAIR on the growth of tumors was analyzed by RT-PCR, immunofluorescence staining, and TUNEL staining. The data suggested interference of HOTAIR inhibited the growth, tumor weight, cell proliferation, and promoted cell apoptosis.

CONCLUSIONS

Our study altogether demonstrated HOTAIR influence cell proliferation and apoptosis by regulation of miR-483-3p and CDK4 in medulloblastoma cells. HOTAIR can be used as a candidate for potential applications in the treatment of medulloblastoma.

LncRNA linc00460 sponges miR-1224-5p to promote esophageal cancer metastatic potential and epithelial-mesenchymal transition

BACKGROUND

Increasing studies highlight the crucial role of long non-coding RNAs (lncRNAs) in carcinogenesis of various human cancer types, including esophageal cancer (ESCA). Long intergenic non-coding RNA 00460 (Linc00460), a novel oncogenic lncRNA, has been reported to accelerate ESCA cell growth. This study aimed to investigate the role and possible regulatory mechanism of linc00460 in ESCA metastasis.

METHODS

Bioinformatics analysis and quantitative real time polymerase chain reaction (qRT-PCR) were used to detect linc00460 expression in ESCA. Wound healing assay, Transwell assay and Western blot were utilized to examine migration, invasion and epithelial-mesenchymal transition (EMT) of ESCA cells. The direct binding effect between linc00460 and microRNA-1224-5p (miR-1224-5p) was evaluated by the dual luciferase reporter assay.

RESULTS

In this study, we discovered that lncRNA linc00460 was obviously over-expressed in ESCA, both in tissues and cell lines. Down-regulation of linc00460 significantly suppressed the metastatic potential (including cell migration and invasion) and EMT of ESCA cells. In addition, miR-1224-5p, a potential tumor suppressor, was negatively correlated with linc00460 in ESCA. Linc00460 and miR-1224-5p could bind directly in ESCA cells. Inhibition of miR-1224-5p partially abrogated the effects of linc00460 decrease on metastatic potential and EMT of ESCA cells.

CONCLUSIONS

Taken together, linc00460 may function as a molecular sponge to adsorb miR-1224-5p, thereby promoting ESCA metastasis and EMT. Our findings suggest that linc00460/miR-1224-5p is a possible clinical target for ESCA.

Long noncoding RNA LINC00324 promotes retinoblastoma progression by acting as a competing endogenous RNA for microRNA-769-5p, thereby increasing STAT3 expression

Long intergenic non–protein-coding RNA 324 (LINC00324) is abnormally expressed in multiple human cancer types and plays an important role in cancer initiation and progression. This study showed that LINC00324 was expressed at higher levels in retinoblastoma (RB) tumors and cell lines than in control samples. Increased LINC00324 expression closely correlated with the TNM stage, optic nerve invasion, and shorter overall survival among patients with RB. The knockdown of LINC00324 decreased RB cell proliferation, colony formation, migration, and invasion, and promoted apoptosis and cell cycle arrest in vitro as well as hindered tumor growth in vivo. With respect to the mechanism, LINC00324 acted as a competing endogenous RNA for microRNA-769-5p (miR-769-5p) in RB cells. The mRNA of signal transducer and activator of transcription 3 (STAT3) was identified as a direct target of miR-769-5p in RB cells. Rescue experiments indicated that restoration of STAT3 expression attenuated the tumor-suppressive actions of miR-769-5p in RB cells. Downregulation of miR-769-5p or restoration of STAT3 almost completely reversed the effects of LINC00324 knockdown on RB cells. Our findings describe a novel RB-related LINC00324–miR-769-5p–STAT3 axis that is implicated in the malignancy of RB in vitro and in vivo. This study may point to innovative therapeutic targets in RB.

Dissimilar Appearances Are Deceptive-Common microRNAs and Therapeutic Strategies in Liver Cancer and Melanoma

In this review, we summarize the current knowledge on miRNAs as therapeutic targets in two cancer types that were frequently described to be driven by miRNAs—melanoma and hepatocellular carcinoma (HCC). By focusing on common microRNAs and associated pathways in these—at first sight—dissimilar cancer types, we aim at revealing similar molecular mechanisms that are evolved in microRNA-biology to drive cancer progression. Thereby, we also want to outlay potential novel therapeutic strategies. After providing a brief introduction to general miRNA biology and basic information about HCC and melanoma, this review depicts prominent examples of potent oncomiRs and tumor-suppressor miRNAs, which have been proven to drive diverse cancer types including melanoma and HCC. To develop and apply miRNA-based therapeutics for cancer treatment in the future, it is essential to understand how miRNA dysregulation evolves during malignant transformation. Therefore, we highlight important aspects such as genetic alterations, miRNA editing and transcriptional regulation based on concrete examples. Furthermore, we expand our illustration by focusing on miRNA-associated proteins as well as other regulators of miRNAs which could also provide therapeutic targets. Finally, design and delivery strategies of miRNA-associated therapeutic agents as well as potential drawbacks are discussed to address the question of how miRNAs might contribute to cancer therapy in the future.

Down-regulation of long non-coding RNA HOTAIR inhibits invasion and migration of oesophageal cancer cells via up-regulation of microRNA-204

Oesophageal cancer is a progressive tumour with high mortality. However, therapies aimed at treating oesophageal cancer remain relatively limited. Accumulating studies have highlighted long non‐coding RNA (lncRNA) HOX transcript antisense RNA (HOTAIR), microRNA‐204 (miR‐204) and homeobox C8 (HOXC8) in the progression of oesophageal cancer. Herein, we tried to demonstrate the function of HOTAIR, miR‐204 and HOXC8 in oesophageal cancer and their relationship. Differentially expressed genes involved in oesophageal cancer were identified. The endogenous expression of HOTAIR and miR‐204 in oesophageal cancer cell lines was altered to elucidate their effects and to identify the interaction among HOTAIR, miR‐204 and HOXC8. We also explored the underlying regulatory mechanisms of HOTAIR and miR‐204 with siRNA against HOTAIR, miR‐204 mimic or miR‐204 inhibitor. Cell proliferation, migration, invasion and apoptosis were subsequently detected. Xenograft in nude mice was induced to evaluate tumourigenicity. miR‐204 was down‐regulated, while HOTAIR and HOXC8 were up‐regulated in the oesophageal cancer tissues. HOTAIR could competitively bind to miR‐204 and miR‐204 could further target HOXC8. The oesophageal cancer cells treated with si‐HOTAIR or miR‐204 mimic exhibited decreased expression levels of HOXC8, Vimentin and MMP‐9, but increased E‐cadherin level. Silenced HOTAIR or elevated miR‐204 inhibited proliferation, migration and invasion, along with stimulated apoptosis of oesophageal cancer cells. In summary, our results show that lncRNA HOTAIR could specifically bind to miR‐204 as a competing endogenous RNA and regulate miR‐204 and HOXC8. Hence, down‐regulation of HOTAIR could inhibit progression of oesophageal cancer, indicating a novel target for oesophageal cancer treatment.