Long non-coding RNA FOXD2-AS1 aggravates nasopharyngeal carcinoma carcinogenesis by modulating miR-363-5p/S100A1 pathway

Role of microRNA-363 during tumor progression and invasion

Recent progresses in diagnostic and therapeutic methods have significantly improved prognosis in cancer patients. However, cancer is still considered as one of the main causes of human deaths in the world. Late diagnosis in advanced tumor stages can reduce the effectiveness of treatment methods and increase mortality rate of cancer patients. Therefore, investigating the molecular mechanisms of tumor progression can help to introduce the early diagnostic markers in these patients. MicroRNA (miRNAs) has an important role in regulation of pathophysiological cellular processes. Due to their high stability in body fluids, they are always used as the non-invasive markers in cancer patients. Since, miR-363 deregulation has been reported in a wide range of cancers, we discussed the role of miR-363 during tumor progression and metastasis. It has been reported that miR-363 has mainly a tumor suppressor function through the regulation of transcription factors, apoptosis, cell cycle, and structural proteins. MiR-363 also affected the tumor progression via regulation of various signaling pathways such as WNT, MAPK, TGF-β, NOTCH, and PI3K/AKT. Therefore, miR-363 can be introduced as a probable therapeutic target as well as a non-invasive diagnostic marker in cancer patients.

Upregulation of lnc-FOXD2-AS1, CDC45, and CDK1 in patients with primary non-M3 AML is associated with a worse prognosis

Acute myeloid leukemia (AML) is a heterogeneous hematologic malignancy with an unfavorable outcome. The present research aimed to identify novel biological targets for AML diagnosis and treatment. In this study, we performed an in-silico method to identify antisense RNAs (AS-RNAs) and their related co-expression genes. GSE68172 was selected from the AML database of the Gene Expression Omnibus and compared using the GEO2R tool to find DEGs. Antisense RNAs were selected from all the genes that had significant expression and a survival plot was drawn for them in the GEPIA database, FOXD2-AS1 was chosen for further investigation based on predetermined criteria (logFC ≥|1| and P < 0.05) and its noteworthy association between elevated expression level and a marked reduction in the overall survival (OS) in patients diagnosed with AML. The GEPIA database was utilized to investigate FOXD2-AS1-related co-expression and similar genes. The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis and gene ontology (GO) function analysis of the mentioned gene lists were performed using the DAVID database. The protein-protein interaction (PPI) network was then constructed using the STRING database. Hub genes were screened using Cytoscape software. Pearson correlation analysis was conducted using the GEPIA database to explore the relationship between FOXD2-AS1 and the hub genes. The transcription of the selected coding and non-coding genes, including FOXD2-AS1, CDC45, CDC20, CDK1, and CCNB1, was validated in 150 samples, including 100 primary AML non-M3 blood samples and 50 granulocyte colony stimulating factor (G-CSF)-mobilized healthy donors, using quantitative Real-Time PCR (qRT-PCR). qRT-PCR results displayed significant upregulation of lnc-FOXD2-AS1, CDC45, and CDK1 in primary AML non-M3 blood samples compared to healthy blood samples (P = 0.0032, P = 0.0078, and P = 0.0117, respectively). The expression levels of CDC20 and CCNB1 were not statistically different between the two sets of samples (P = 0.8315 and P = 0.2788, respectively). We identified that AML patients with upregulation of FOXD2-AS1, CDK1, and CDC45 had shorter overall survival (OS) and Relapse-free survival (RFS) compared those with low expression of FOXD2-AS1, CDK1, and CDC45. Furthermore, the receiver operating characteristic (ROC) curve showed the potential biomarkers of lnc -FOXD2-AS1, CDC45, and CDK1 in primary AML non-M3 blood samples. This research proposed that the dysregulation of lnc-FOXD2-AS1, CDC45, and CDK1 can contribute to both disease state and diagnosis as well as treatment. The present study proposes the future evolution of the functional role of lnc-FOXD2-AS1, CDC45, and CDK1 in AML development.

A review on the role of FOXD2-AS1 in human disorders

FOXD2 adjacent opposite strand RNA 1 (FOXD2-AS1) is a long non-coding RNA being transcribed from a locus on chromosome 1p33. This transcript has been found to be up-regulated in tumor samples of almost all types of malignancies in association with a significant increase in malignant features. FOXD2-AS1 can affect activity of PI3K/AKT, AKT/mTOR, Hippo/YAP, Notch, NRf2, Wnt/β-catenin, NF-ƙB and ERK/MAPK pathways. Furthermore, it can enhance stem cell properties in cancer cells and prompt epithelial-mesenchymal transition. It is also involved in induction of resistance to a variety of anticancer agents such as adriamycin, cisplatin, 5-fluorouracil, temozolomide and gemcitabine. This article summarizes the impact of FOXD2-AS1 in diverse human disorders.

Highly-expressed lncRNA FOXD2-AS1 in adipose mesenchymal stem cell derived exosomes affects HaCaT cells via regulating miR-185-5p/ROCK2 axis

The healing of skin wounds is a highly coordinated multi-step process that occurs after trauma including surgical incisions, thermal burns, and chronic ulcers. In this study, the authors investigated lncRNA FOXD2-AS1 function in adipose mesenchymal exosomes from ADMSCs that were successfully extracted. Highly expressed lncRNA FOXD2-AS1 in ADMSCs-exosomes accelerated HaCaT cell migration and proliferation. LncRNA FOXD2-AS1 negatively targeted miR-185-5p, and miR-185-5p negatively targeted ROCK2. Highly expressed lncRNA FOXD2-AS1 in ADMSCs-exosomes promoted HaCaT cell migration and proliferation via down-regulating miR-185-5p and further up-regulating ROCK2. In conclusion, LncRNA FOXD2-AS1 overexpression in ADMSCs derived exosomes might accelerate HaCaT cell migration and proliferation via modulating the miR-185-5p/ROCK2 axis.

Evaluation of lncRNA FOXD2-AS1 Expression as a Diagnostic Biomarker in Colorectal Cancer

Background

Colorectal cancer (CRC) is still considered one of the prevalent cancers worldwide. Investigation of potential biomarkers for early detection of CRC is essential for the effective management of patients using therapeutic strategies. Considering that, this study was aimed to examine the changes in lncRNA FOXD2-AS1 expression through colorectal tumorigenesis.

Methods

Fifty CRC tumor tissues and fifty adjacent normal tissue samples were prepared and involved in the current study. Total RNA was extracted from the samples and then reverse transcribed to complementary DNA. Next, the expression levels of lncRNA FOXD2-AS1 were evaluated using real-time PCR in CRC samples compared to normal ones. Also, receiver operating characteristic curve analysis was used to evaluate the diagnostic value of FOXD2-AS1 for CRC.

Results

The obtained results showed that the expression level of FOXD2-AS1 gene was significantly (p<0.0001) up-regulated in tumor tissues compared to normal marginal tissues. Also, a significant correlation was observed between higher the expression of FOXD2-AS1and the differentiation of tumor cells. Furthermore, ROC curve analysis estimated an AUC value of 0.59 for FOXD2-AS1, suggesting its potential as a diagnostic target.

Conclusion

Taken together, the current study implied that tissue-specific upregulation of lncRNA FOXD2-AS1 might be appropriate diagnostic biomarkers for CRC. Nonetheless, more studies are needed to validate these results and further illustrate FOXD2-AS1 function through colorectal tumorigenesis.

FOXD2-AS1 acts an oncogene in esophageal squamous cell carcinoma through sponging miR-204-3p

PURPOSE

A growing number of evidences has revealed that long non-coding RNAs (lncRNAs) have vital effect in the pathogenesis of esophageal squamous cell carcinoma (ESCC). In our work, we found that lncRNA FOXD2 adjacent opposite strand RNA 1 (FOXD2-AS1) was significantly increased in clinical ESCC samples and cell lines.

METHODS

The biological effect of FOXD2-AS1 on EC109 and KYSE150 cells showed that the low expression of FOXD2-AS1 inhibited the proliferation through CCK8 and colony formation assays, invasion by transwell chamber test, migration abilities by wound healing assay, and enhance apoptosis rates by flow cytometry assay.

RESULTS

Through bioinformatics analysis and luciferase reporter assays, microRNA (miR)-204-3p was proved to be a target of FOXD2-AS1. We further confirmed that FOXD2-AS1 was the upstream inhibitor of miR-204-3p and the down-regulation of miR-204-3p reversed the repressive effects of low expression of FOXD2-AS1 on ESCC progression. In addition, inhibition of FOXD2-AS1 effectively suppressed the tumor growth.

CONCLUSIONS

In general, our results suggested that FOXD2-AS1 may be of vital therapeutic importance for the treatment of ESCC patients.

Overexpression of FOXD2-AS1 enhances proliferation and impairs differentiation of glioma stem cells by activating the NOTCH pathway via TAF-1

Emerging data have highlighted the importance of long noncoding RNAs (lncRNAs) in exerting critical biological functions and roles in different forms of brain cancer, including gliomas. In this study, we sought to investigate the role of lncRNA FOXD2 adjacent opposite strand RNA 1 (FOXD2-AS1) in glioma cells. First, we used sphere formation assay and flow cytometry to select U251 glioma stem cells (GSCs). Then, we quantified the expression of lncRNA FOXD2-AS1, TATA-box binding protein associated factor 1 (TAF-1) and NOTCH1 in glioma tissues and GSCs, as well as the expression of GSC stem markers, OCT4, SOX2, Nanog, Nestin and CD133 in GSCs. Colony formation assay, sphere formation assay, and flow cytometry were used to evaluate GSC stemness. Next, the correlations among lncRNA FOXD2-AS1, TAF-1 and NOTCH1 were investigated. LncRNA FOXD2-AS1, TAF-1 and NOTCH1 were found to be elevated in glioma tissues and GSCs, and silencing lncRNA FOXD2-AS1 inhibited stemness and proliferation, while promoting apoptosis and differentiation of GSCs. LncRNA FOXD2-AS1 overexpression also led to increased NOTCH1 by recruiting TAF-1 to the NOTCH1 promoter region, thereby promoting stemness and proliferation, while impairing cell apoptosis and differentiation. Mechanistically, lncRNA FOXD2-AS1 elevation promoted glioma in vivo by activating the NOTCH signalling pathway via TAF-1 upregulation. Taken together, the key findings of our investigation support the proposition that downregulation of lncRNA FOXD2-AS1 presents a viable and novel molecular candidate for improving glioma treatment.

The Interaction Between Non-Coding RNAs and Calcium Binding Proteins

Calcium binding proteins (CBP) are a group of proteins mediating the effects of calcium on cellular functions. These proteins can regulate calcium levels inside the cells and contribute in several cellular functions through transporting this ion across cell membranes or decoding related signals. Recent studies have shown that several non-coding RNAs interact with CBPs to affect their expression or activity. The interactions between these transcripts and CBPs have implications in the pathoetiology of human disorders, including both neoplastic and non-neoplastic conditions. In the current review, we describe the interactions between three classes of non-coding RNAs (long non-coding RNAs, circular RNAs, and microRNAs) and a number of CBPs, particularly CAB39, S100A1, S100A4, S100A7 and S100P. This kind of interaction has been verified in different pathological contexts such as drug-induced cardiotoxicity, osteoblasts cytotoxicity, acute lung injury, myocardial ischemia/reperfusion injury, proliferative diabetic retinopathy, glomerulonephritis, as well as a wide array of neoplastic conditions.

LINC00641 contributes to nasopharyngeal carcinoma cell malignancy through FOXD1 upregulation at the post-transcriptional level

Nasopharyngeal carcinoma (NPC) is a common tumor in the head and neck and is prevalent in China, especially in the southern regions. Molecular mechanisms have attracted much attention in NPC research. FOXD1 has been reported to be a tumor promoter in various cancers. The present study was designed to explore the function of FOXD1 in NPC cells. Functional analyses, including the trypan blue staining assay, EdU and JC-1 assay, and flow cytometry analysis, revealed that FOXD1 facilitated NPC cell proliferation and inhibited NPC cell apoptosis. Next, by means of "starBase" database and mechanism analyses, such as RIP assay, RNA pull-down assay and luciferase reporter assay, miR-378a-3p was found to target FOXD1 and negatively regulate FOXD1 expression in NPC cells. Moreover, miR-378a-3p plays a suppressive role in NPC cells. LINC00641 was identified as a sponge of miR-378a-3p and positively modulated FOXD1 expression in NPC cells. Finally, a series of rescue assays indicated that LINC00641 accelerated NPC cell proliferation and hindered NPC cell apoptosis through FOXD1 upregulation. In conclusion, the present study demonstrated an innovative ceRNA mechanism of LINC00641/miR-378a-3p/FOXD1 in NPC cells, which might provide new insights into NPC treatment.

MiR-363-5p modulates regulatory T cells through STAT4-HSPB1-Notch1 axis and is associated with the immunological abnormality in Graves' disease

MiRNAs are a class of small non-coding RNAs with ability to regulate function of Treg cells and are involved in many autoimmune diseases. Our previous study found that miR-363-5p expression was significantly upregulated in peripheral Treg cells of GD patients. Herein, we aimed to investigate its effect and mechanism on Treg cell dysfunction in GD patients. The results showed that miR-363-5p upregulation was significantly associated with the Treg cell dysfunction and inflammatory factors levels in GD patients. Transcriptome sequencing revealed that 883 genes were significantly regulated by miR-363-5p in Treg cells. These genes with significant differential expression were primarily involved in lymphocyte differentiation, immunity, as well as Notch1 and various interleukin signalling pathways. Moreover, miR-363-5p can regulate HSPB1 and Notch1 through the target gene STAT4, thereby regulating Notch1 signalling pathway and inhibiting Treg cells. The effects of miR-363-5p on Treg cell function and STAT4-HSPB1-Notch1 axis were also verified in GD patients. In conclusion, our results indicated that miR-363 could inhibit the proliferation, differentiation and function of Treg cells by regulating the STAT4-HSPB1-Notch1 axis through target gene STAT4. MiR-363-5p may play an important role in Treg cell dysfunction and immune tolerance abnormalities in GD patients.

miR‑4306 inhibits the malignant behaviors of colorectal cancer by regulating lncRNA FoxD2‑AS1

MicroRNA (miR)‑4306 and FoxD2‑adjacent opposite strand RNA 1 (FOXD2‑AS1) are cancer‑related genes involved in tumor progression. However, the potential functional roles of miR‑4306 and FoxD2‑AS1 in colorectal cancer (CRC) development remain unknown. The present study aimed to investigate the biological functions and the molecular mechanisms of miR‑4306 and FoxD2‑AS1 in CRC. Reverse transcription‑quantitative PCR analysis was performed to determine the expression levels of FoxD2‑AS1 and miR‑4306 in CRC tissues and cell lines. Functional experiments, including Cell Counting Kit‑8, colony formation, cell cycle assays and western blotting, were conducted to examine the effects of FoxD2‑AS1 and miR‑4306 on the malignant behaviors of CRC cells. In addition, the relationship between FoxD2‑AS1 and miR‑4306 was assessed using a dual‑luciferase reporter assay and Pearson's correlation analysis. Compared with normal samples and cells, FoxD2‑AS1 expression was increased and miR‑4306 expression was decreased in CRC tissues and cells. Functional experiments demonstrated that silencing FoxD2‑AS1 inhibited proliferation and induced cell arrest at G0/G1 phase in CRC cells, while the overexpression of FoxD2‑AS1 showed opposite results. Ki‑67 and proliferating cell nuclear antigen expression levels were decreased after transfection with small interfering RNA FoxD2‑AS1, but were increased after transfection with FoxD2‑AS1 overexpression plasmid. Furthermore, investigations into the underling mechanism revealed that FoxD2‑AS1 functioned as a molecular sponge of miR‑4306. The inhibitory effects of FoxD2‑AS1 silencing on CRC progression were reversed by miR‑4306 knockdown. Collectively, the present study demonstrated that FoxD2‑AS1 functioned as an oncogene in CRC progression, and that miR‑4306 could inhibit the malignant behaviors of CRC by regulating FoxD2‑AS1. Thus, the current study provided a promising therapeutic target for CRC treatment.

Moderate Prognostic Value of lncRNA FOXD2-AS1 in Gastric Cancer with Helicobacter pylori Infection

PURPOSE

Gastric cancer (GC) is one of the most frequent tumors worldwide and identification of a sensitive and specific prognostic biomarker is of great importance. Long non-coding RNAs (lncRNAs) play crucial roles in tumorigenesis of various malignancies. In the present study, we investigated lncRNA FOXD2-AS1 expression in gastric tumors and assessed its potential as a prognostic biomarker.

METHODS

A total of 95 tumor and corresponding adjacent non-tumor tissue specimens were collected from patients with GC from Imam Reza hospital, Tabriz, Iran. Total RNA was isolated and FOXD2-AS1 expression was measured using quantitative reverse transcriptase (qRT)-PCR.

RESULTS

FOXD2-AS1 was significantly upregulated in tumor samples as compared to non-tumor tissues (P < 0.0001). In addition, higher expression of FOXD2-AS1 was significantly associated with lymph node metastasis and Helicobacter pylori infection. The receiver operating characteristic (ROC) curve analysis revealed that FOXD2-AS1 might be served as a potential prognostic biomarker for GC.

CONCLUSION

FOXD2-AS1 is upregulated in gastric tumors and can be used as a valuable biomarker in the prognosis of patients with GC.

Identification of diagnostic and prognostic lncRNA biomarkers in oral squamous carcinoma by integrated analysis and machine learning

BACKGROUND

Patients with oral squamous carcinoma (OSCC) present difficulty in precise diagnosis and poor prognosis.

OBJECTIVE

We aimed to identify the diagnostic and prognostic indicators in OSCC and provide basis for molecular mechanism investigation of OSCC.

METHODS

We collected sequencing data and clinical data from TCGA database and screened the differentially expressed mRNAs (DEmRNAs) and lncRNAs (DElncRNAs) in OSCC. Machine learning and modeling were performed to identify the optimal diagnostic markers. In order to determine lncRNAs with prognostic value, survival analysis was performed through combing the expression profiles with the clinical data. Finally, co-expressed DEmRNAs of lncRNAs were identified by interacted network construction and functional annotated by GO and KEGG analysis.

RESULTS

A total of 1114 (345 up- and 769 down-regulated) DEmRNAs and 156 (86 up- and 70 down-regulated) DElncRNAs were obtained in OSCC. Following the machine learning and modeling, 15 lncRNAs were identified to be the optimal diagnostic indicators of OSCC. Among them, FOXD2.AS1 was significantly associated with survival rate of patients with OSCC. In addition, Focal adhesion and ECM-receptor interaction pathways were found to be involved in OSCC.

CONCLUSIONS

FOXD2.AS1 might be a prognostic marker for OSCC and our study may provide more information to the further study in OSCC.

The role of FOXD2-AS1 in cancer: a comprehensive study based on data mining and published articles

Background and aims: Long non-coding RNA (lncRNA) FOXD2 adjacent opposite strand RNA 1 (FOXD2-AS1) is aberrantly expressed in various cancers and associated with cancer progression. A comprehensive meta-analysis was performed based on published literature and data in the Gene Expression Omnibus database, and then the Cancer Genome Atlas (TCGA) dataset was used to assess the clinicopathological and prognostic value of FOXD2-AS1 in cancer patients.

Methods: Gene Expression Omnibus databases of microarray data and published articles were used for meta-analysis, and TCGA dataset was also explored using the GEPIA analysis program. Hazard ratios (HRs) and pooled odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the role of FOXD2-AS1 in cancers.

Results: This meta-analysis included 21 studies with 2391 patients and 25 GEO datasets with 3311 patients. The pooled HRs suggested that highly expressed FOXD2-AS1 expression was correlated with poor overall survival (OS) and disease-free survival (DFS). Similar results were obtained by analysis of TCGA data for 9502 patients. The pooled results also indicated that FOXD2-AS1 expression was associated with bigger tumor size and advanced TNM stage, but was not related to age, gender, differentiation and lymph node metastasis.

Conclusion: The present study demonstrated that FOXD2-AS1 is closely related to tumor size and TNM stage. Additionally, increased FOXD2-AS1 was a risk factor of OS and DFS in cancer patients, suggesting FOXD2-AS1 may be a potential biomarker in human cancers.

Long non-coding RNA FOXD2-AS1 promotes proliferation, migration and invasion of ovarian cancer cells via regulating the expression of miR-4492

The aim of the present study was to determine the role of long non-coding RNA (lncRNA) forkhead box D2 antisense 1 (FOXD2-AS1) in the development of ovarian cancer, investigate the underlying mechanisms and provide a potential diagnostic biomarker for ovarian cancer. A total of 39 ovarian cancer patients were included, and the ovarian cancer tissues and paracancer tissues were obtained. The ovarian cancer cell lines SKOV3 and OVCAR3 and the human ovarian normal epithelial cell line IOSE80 were cultured. The expression of lncRNA FOXD2-AS1 and miR-4492 was detected by reverse transcription-quantitative PCR. Small interfering RNA targeting FOXD2-AS1 (si-FOXD2-AS1), microRNA (miR)-4492 mimics, miR-4492 inhibitor and their corresponding controls were transfected into cells. The proliferation was detected with a Cell-Couting-Kit-8 assay, and migration and invasion were determined using Transwell assays. The mutual binding site of lncRNA FOXD2-AS1 and miR-4492 was predicted with the miRDB database and verified by a luciferase reporter assay. Finally, a rescue assay was performed. The results suggested that lncRNA FOXD2-AS1 was upregulated in ovarian cancer tissues and cell lines. si-FOXD2-AS1 was able to inhibit the proliferation, migration and invasion of ovarian cancer cells. lncRNA FOXD2-AS1 was confirmed to directly target miR-4492. The expression of lncRNA FOXD2-AS1 and miR-4492 exhibited a negative correlation. In a rescue experiment, miR-4492 inhibitor abrogated the effect of siFOXD2-AS1 in SKOV3 and OVCAR3 cell lines. In conclusion, lncRNA FOXD2-AS1 promotes the proliferation and invasion of ovarian cancer cells via regulating the expression of miR-4492. It may be a novel potential diagnostic biomarker and therapeutic target for ovarian cancer.

Long Noncoding RNAs in Gastrointestinal Cancer: Tumor Suppression Versus Tumor Promotion

Approximately 80% of the human genome harbors biochemical marks of active transcription that its majority transcribes to noncoding RNAs, namely long noncoding RNAs (lncRNAs). LncRNAs are heterogeneous RNA transcripts that regulate critical biological processes such as cell survival and death. They involve in the progression of different cancers by affecting transcriptional and post-transcriptional modifications as well as epigenetic control of numerous tumor suppressors and oncogenes. Recent findings show that aberrant expression of lncRNAs is associated with tumor initiation, progression, invasion, and overall survival of patients with gastrointestinal (GI) cancers. Some lncRNAs play as tumor suppressors in all GI cancers, but others play as tumor promoters. However, some other lncRNAs might function as a tumor suppressor in one GI cancer, but as a tumor promoter in another GI cancer type. This fact highlights possible context dependency of the expression patterns and roles of at least some lncRNAs in GI cancer development and progression. Here, we review the functional relation of lncRNAs involved in the development and progression of GI cancer by focusing on their roles as tumor suppressor and tumor promoter genes.

Long Non-Coding RNA FOXD2-AS1 Serves as a Potential Prognostic Biomarker for Patients With Cancer: A Meta-Analysis and Database Testing

BACKGROUND

The aim of this study is to summarize the current findings concerning the FOXD2-AS1 expression and cancer prognosis.

METHODS

The correlation intensity between FOXD2-AS1 expression and cancer prognosis was estimated using pooled hazard ratio (HRs) with 95% confidence intervals (CIs). GEPIA was used to assess disease-free survival (DFS), progression-free survival (PFS) and overall survival (OS) of cancer patients and differential FOXD2-AS1 expression in cancer and adjacent tissues.

RESULTS

A total of 11 studies including 2,177 patients with OS and 477 patients with DFS/PFS data were analyzed in evidence synthesis. Overall, the pooled analysis indicated that FOXD2-AS1 expression was significantly associated with OS (HR=1.51, 95%Cl: 1.26-1.81, P<0.001) and DFS (HR=1.66, 95%CI: 1.34-2.04, P<0.001). Subgroup analysis showed that high expression of FOXD2-AS1 was significant correlated with poor OS in the median (HR=1.51, 95%CI: 1.30-1.75, P<0.001) and normal group (HR=1.50, 95%CI: 1.09-2.05, 0.01) based on cut-off value, and high FOXD2-AS1 expression was significant linked with poor DFS in patients with digestive tract cancer (DTC) (HR=1.66, 95%CI: 1.34-2.04, P<0.001). Similarly, a significant correlation between increased FOXD2-AS1 expression and poor PFS with other cancers (HR=3.84, 95%CI 1.26-11.70, P=0.02) was found. In database testing, a highly significant correlation was observed between high expression of FOXD2-AS1 and poor OS (HR=1.9, P<0.001), but not DFS (HR=1.0, P=0.900).

CONCLUSIONS

Our findings indicated that FOXD2-AS1 may serve as a potential independent prognostic factor in cancer, especially in the Chinese population.

Long Noncoding RNA AFAP1-AS1 Is a Critical Regulator of Nasopharyngeal Carcinoma Tumorigenicity

Background

The long noncoding RNA actin filament associated protein 1 antisense RNA1 (AFAP1-AS1) is a critical player in various cancers. However, the clinical value and functional mechanisms of AFAP1-AS1 during the tumorigenicity of nasopharyngeal carcinoma (NPC) remain unclear. Here, we investigated the clinical application and potential molecular mechanisms of AFAP1-AS1 in NPC tumorigenesis and progression.

Methods

The expression level of AFAP1-AS1 was determined by qRT-PCR in 10 paired fresh human NPC tissues and adjacent normal tissues. RNAscope was performed on 100 paired paraffin-embedded NPC and adjacent nontumor specimens. The biological functions of AFAP1-AS1 were assessed by in vitro and in vivo functional experiments. RNA-protein pull-down assays were performed to detect and identify the AFAP1-AS1-interacting protein KAT2B. Protein-RNA immunoprecipitation (RIP) assays were conducted to examine the interaction of AFAP1-AS1 and KAT2B. Chromatin immunoprecipitation (ChIP) and luciferase analyses were utilized to identify the binding site of transcription intermediary factor 1 alpha (TIF1α) and H3K14ac on the RBM3 promoter.

Results

AFAP1-AS1 is upregulated in NPC and is a poor prognostic indicator for survival in NPC patients. AFAP1-AS1 was required for NPC proliferation in vitro and tumorigenicity in vivo. Mechanistic investigations suggested that AFAP1-AS1 binds to KAT2B and promotes acetyltransferase activation at two residues (E570/D610). KAT2B further promotes H3K14 acetylation and protein binding to the bromo domain of TIF1α. Consequently, TIF1α acts as a nuclear transcriptional coactivator of RBM3 transcription, leading to YAP mRNA stabilization and enhanced NPC tumorigenicity.

Conclusions

Our findings suggest that AFAP1-AS1 functions as an oncogenic biomarker and promotes NPC tumorigenicity through enhanced KAT2B acetyltransferase activation and YAP mRNA stabilization.

Long non‑coding RNA FOXD2‑AS1 regulates the tumorigenesis and progression of breast cancer via the S100 calcium binding protein A1/Hippo signaling pathway

Breast cancer is one of the most prevalent cancer types and is accompanied by a high incidence and mortality rate, severely threatening women's health globally. Long non‑coding RNA forkhead box D2 adjacent apposite strand RNA 1 (lncRNA FOXD2‑AS1) has been identified to function as an oncogene in human cancers; however, it has rarely been investigated in breast cancer. The aim of the present study was to investigate the role of FOXD2‑AS1 in breast cancer, and to clarify the underlying mechanisms. The expression of FOXD2‑AS1 in breast cancer cell lines was first quantified by reverse transcription‑quantitative PCR, and the biological function of FOXD2‑AS1 was then determined. Cellular proliferative ability was determined by Cell Counting kit‑8 assay, and wound healing and Transwell assays were conducted to assess the cell migratory and invasive ability. Corresponding protein expression levels were determined by western blot analysis. In addition, experimental animal models were established by the subcutaneous injection of MDA‑MB‑468 cells into the right axillary lymph nodes of BALB/c nude mice, and the effects of FOXD2‑AS1 on tumor growth were observed. The results indicated that FOXD2‑AS1 expression was upregulated in breast cancer cell lines, and that FOXD2‑AS1 downregulation significantly inhibited the proliferation, migration and invasiveness of MCF‑7 and MDA‑MB‑468 cells. S100 calcium binding protein A1 (S100A1) was also upregulated in breast cancer cell lines and was positively regulated by FOXD2‑AS1. Furthermore, the inhibition of S100A1 and the overexpression of the serine/threonine‑protein kinase, large tumor suppressor homolog 1 (LATS1), inhibited the FOXD2‑AS1‑induced cellular proliferation, migration and invasiveness in breast cancer. Experimental mouse models revealed that FOXD2‑AS1 downregulation significantly inhibited tumor growth, and that the levels of phosphorylated (p‑)YAP and p‑LATS1 were upregulated by FOXD2‑AS1 knockdown, indicating that the inhibition of FOXD2‑AS1 activated Hippo/yes‑associated protein signaling. On the whole, the findings of the present study suggest that the FOXD2‑AS1/S100A1/Hippo axis is involved in the tumorigenesis and progression of breast cancer. In the future, these may contribution to the identification of more effective breast cancer treatments.

Screening lncRNAs with diagnostic and prognostic value for human stomach adenocarcinoma based on machine learning and mRNA-lncRNA co-expression network analysis

BACKGROUND

Stomach adenocarcinoma (STAD), is one of the most lethal malignancies around the world. The aim of this study was to find the long noncoding RNAs (lncRNAs) acting as diagnostic and prognostic biomarker of STAD.

METHODS

Base on TCGA dataset, the differentially expressed mRNAs (DEmRNAs) and lncRNAs (DElncRNAs) were identified between STAD and normal tissue. The machine learning and survival analysis were performed to evaluate the potential diagnostic and prognostic value of lncRNAs for STAD. We also build the co-expression network and functional annotation. The expression of selected candidate mRNAs and lncRNAs were validated by Quantitative real-time polymerase chain reaction (qRT-PCR) and GSE27342 dataset. GSE27342 dataset were also to perform gene set enrichment analysis.

RESULTS

A total of 814 DEmRNAs and 106 DElncRNAs between STAD and normal tissue were obtained. FOXD2-AS1, LINC01235, and RP11-598F7.5 were defined as optimal diagnostic lncRNA biomarkers for STAD. The area under curve (AUC) of the decision tree model, random forests model, and support vector machine (SVM) model were 0.797, 0.981, and 0.983, and the specificity and sensitivity of the three model were 75.0% and 97.1%, 96.9% and 96%, and 96.9% and 97.1%, respectively. Among them, LINC01235 was not only an optimal diagnostic lncRNA biomarkers, but also related to survival time. The expression of three DEmRNAs (ESM1, WNT2, and COL10A1) and three optimal diagnostic lncRNAs biomarkers (FOXD2-AS1, RP11-598F7.5, and LINC01235) in qRT-PCR validation was were consistent with our integrated analysis. Except for FOXD2-AS1, ESM1, WNT2, COL10A1, and LINC01235 were upregulated in STAD, which was consistent with our integration results. Gene set enrichment analysis results indicated that DNA replication, Cell cycle, ECM-receptor interaction, and P53 signaling pathway were four significantly enriched pathways in STAD.

CONCLUSION

Our study identified three DElncRNAs as potential diagnostic biomarkers of STAD. Among them, LINC01235 also was a prognostic lncRNA biomarkers.

Long non-coding RNA FOXD2-AS1 promotes cell proliferation, metastasis and EMT in glioma by sponging miR-506-5p

Long non-coding RNA forkhead box D2 adjacent opposite strand RNA 1 (FOXD2-AS1) has emerged as a potential oncogene in several tumors. However, its biological function and potential regulatory mechanism in glioma have not been fully investigated to date. In the present study, RT-qPCR was conducted to detect the levels of FOXD2-AS1 and microRNA (miR)-506-5p, and western blot assays were performed to measure the expression of CDK2, cyclinE1, P21, matrix metalloproteinase (MMP)7, MMP9, N-cadherin, E-cadherin and vimentin in glioma cells. A luciferase reporter assay was performed to verify the direct targeting of miR-506-5p by FOXD2-AS1. Subsequently, cell viability was analyzed using the CCK-8 assay. Cell migration and invasion were analyzed using Transwell and wound healing assays, respectively. The results demonstrated that FOXD2-AS1 was significantly overexpressed in glioma cells, particularly in U251 cells. Knockdown of FOXD2-AS1 in glioma cells significantly inhibited cell proliferation, migration, invasion and epithelial–mesenchymal transition (EMT) and regulated the expression of CDK2, cyclinE1, P21, MMP7 and MMP9. Next, a possible mechanism for these results was explored, and it was observed that FOXD2-AS1 binds to and negatively regulates miR-506-5p, which is known to be a tumor-suppressor gene in certain human cancer types. Furthermore, overexpression of miR-506-5p significantly inhibited cell proliferation, migration, invasion and EMT, and these effects could be reversed by transfecting FOXD2-AS1 into the cells. In conclusion, our data suggested that FOXD2-AS1 contributed to glioma proliferation, metastasis and EMT via competitively binding to miR-506-5p. FOXD2-AS1 may be a promising target for therapy in patients with glioma.

Long Noncoding RNA DANCR Regulates Cell Proliferation by Stabilizing SOX2 mRNA in Nasopharyngeal Carcinoma

The long noncoding RNA DANCR (differentiation antagonizing non-protein coding RNA) displays aberrant expression in various cancers. However, its clinical value and functional mechanisms in nasopharyngeal carcinoma (NPC) remain poorly understood. We found that DANCR is dramatically up-regulated in human NPC, and that it is an indicator for poor survival prognosis. DANCR knockdown suppressed cell proliferation, colony formation in vitro, and tumorigenicity in vivo. Mechanistic analyses demonstrated that DANCR could bind to RNA-binding protein 3 (RBM3) protein and stabilize SOX2 mRNA, resulting in NPC cell proliferation. Our findings indicate that DANCR functions as an oncogene and a potential therapeutic target for NPC.

Long noncoding RNA FOXD2-AS1 aggravates hepatocellular carcinoma tumorigenesis by regulating the miR-206/MAP3K1 axis

LncRNAs play crucial roles in the development of various cancers including hepatocellular carcinoma (HCC). Nevertheless, the function of the long noncoding RNA (lncRNA) FOXD2‐AS1 in HCC is still poorly understood. In this study, we focused on the role of FOXD2‐AS1 in HCC. We found that FOXD2‐AS1 was significantly upregulated in HCC cells in comparison to normal human liver cells, LO2. In this study, we also demonstrated that miR‐206 expression was greatly reduced in HCC cells. Furthermore, the inhibition of FOXD2‐AS1 repressed HCC cell proliferation, enhanced cell apoptosis, and restrained cell invasion and migration. The knockdown of FOXD2‐AS1 elevated miR‐206 expression, and we validated an interaction between these RNAs. Additionally, miR‐206 mimics inhibited HCC development while miR‐206 mimics had the opposite effect. MAP kinase 1 (MAP3K1) was predicted to be a target of miR‐206. We discovered that FOXD2‐AS1 modulated MAP3K1 expression by sponging miR‐206 in MHCC‐97L and HepG2 cells. Finally, our in vivo experiments validated that the knockdown of FOXD2‐AS1 inhibited HCC progression by modulating the miR‐206/MAP3K1 axis. In conclusion, this work implies FOXD2‐AS1 accelerates HCC progression through sponging miR‐206 and regulating MAP3K1 expression.

Silence of FOXD2-AS1 inhibited the proliferation and invasion of esophagus cells by regulating miR-145-5p/CDK6 axis

This study aimed to investigate the function of long non-coding RNA FOXD2 adjacent opposite strand RNA 1 (lncRNA FOXD2-AS1) during the progression of esophagus cancer (EC) and explore its underlying molecular mechanisms. The level of FOXD2-AS1 in EC tissues and paracancerous tissues was detected by using RT-qPCR; ROC curve was used to evaluate the diagnostic value of FOXD2-AS1 for EC. In addition, CCK8 assay and immunofluorescence staining assay were used to detect the proliferation of Eca-109 and TE-1 cells. To investigate the function of FOXD2-AS1 on cell apoptosis and cell cycle, flow cytometry was performed. To detect the invasion ability of EC cells, transwell invasion assay was performed. Starbase3.0 and Targetscan were used to predict the target genes of FOXD2-AS1 and miR-145-5p, and protein expressions were detected with western blot. We found FOXD2-AS1 was significantly upregulated in EC tissues compared with adjacent normal tissues, which was positively correlated with clinicopathological parameters of patients with EC. Downregulation of FOXD2-AS1 inhibited the proliferation and invasion by inducing apoptosis of EC cells. Moreover, FOXD2-AS1 may regulate the expression of CDK6 by targeting miR-145-3p. Meanwhile, silencing of FOXD2-AS1 caused G1 phase arrest of EC cells by reducing the expression of CDK6. In conclusion, silening FOXD2-AS1 significantly inhibited the proliferation and invasion of EC cells by regulating the miR-145-5p/CDK6 axis. Therefore, FOXD2-AS1 might be used as diagnostic biomarker and therapeutic target for EC.

FoxD2-AS1 promotes glioma progression by regulating miR-185-5P/HMGA2 axis and PI3K/AKT signaling pathway

BACKGROUND/AIMS

The present study was aimed at exploring the role of long noncoding RNA (lncRNA) FOXD2-AS1 in the development and progression of glioma and the underlying mechanism of FOXD2-AS1/miR-185-5p/HMGA2 network in glioma via regulation of PI3K/Akt signaling pathway.

METHODS

Microarray analysis was used for preliminary screening for candidate lncRNAs and mRNAs in glioma tissues. qRT-PCR and Western blot were used to determine the expression of FOXD2-AS1. The potential effects of FOXD2-AS1 on the viability, mobility and apoptosis of glioma cells were evaluated using MTT assay, Transwell assays and flow cytometry. The xenograft tumor model was performed to examine the influence of the lncRNA FOXD2-AS1/miR-185-5p/HMGA2 network on the biological functions of glioma cells. Luciferase assay and immunoprecipitation assay were examined to dissect molecular mechanisms.

RESULTS

LncRNA FOXD2-AS1 was overexpressed in human glioma, and upregulated FOXD2-AS11 expression indicated higher WHO grade (p < 0.05). MiR-185-5p was downregulated, whereas HMGA2 was upregulated in glioma tissues in comparison with para-carcinoma tissues. FOXD2-AS1 could regulate the expression of HMGA2 via miR-185-5p. Knockdown of FOXD2-AS1 significantly inhibited proliferation and metastatic potential of glioma cells, whereas endogenous expression FOXD2-AS1 inhibited the glioma cell activity through targeting HMGA2.

CONCLUSIONS

lncRNA FOXD2-AS1 acted as a sponge of miR-185-5p and influenced the PI3K/Akt signaling pathway through regulating HMGA2. LncRNA FOXD2-AS1 modulated HMGA2 and PI3K/Akt downstream signaling through sponging miR-185-5p, thereby promoting tumorigenesis and progression of glioma.

lncRNA MCM3AP-AS1 promotes the development of oral squamous cell carcinoma by inhibiting miR-363-5p

The aim of the present study was to study the mechanism of the long non-coding (lnc)RNA MCM3AP-AS1 in the development of oral squamous cell carcinoma (OSCC). Patients with OSCC (n=36) volunteered to join the study, and their tumor/normal tissues were collected. MCM3AP-AS1 and microRNA (miR)-363-5p expression in tissues and cells was determined by reverse transcription-quantitative (RT-q)PCR. Following transfection, a CCK-8 assay and Transwell experiments were conducted to explore the effects of MCM3AP-AS1 on OSCC cell proliferation, migration and invasion. The interaction between MCM3AP-AS1 and miR-363-5p was detected by luciferase reporter gene assay. RT-qPCR analysis demonstrated significantly higher MCM3AP-AS1 expression in tumor tissues or OSCC cells compared with normal tissues or human oral keratinocytes cells (P<0.05). A high MCM3AP-AS1 level was associated with poor prognosis in OSCC patients (P<0.05 or P<0.01). Compared to the small interfering (si)-negative control (NC) group, OSCC cells of si-MCM3AP-AS1 group exhibited markedly lower optical density (at 450 nm) value and relative migration and invasion (P<0.05). miR-363-5p was directly inhibited by MCM3AP-AS1. OSCC cells of si-MCM3AP-AS1 + inhibitor-NC group exhibited clearly lower relative proliferation, migration and invasion compared with cells of si-NC + inhibitor-NC group and si-MCM3AP-AS1 + miR-363-5p inhibitor group (P<0.05). MCM3AP-AS1 promoted OSCC cells proliferation, migration and invasion by inhibiting miR-363-5p.

Long non-coding RNA AC023794.4-201 exerts a tumor-suppressive function in laryngeal squamous cell cancer and may serve as a potential prognostic biomarker

After the expression level of lncRNA AC023794.4-201 was upregulated in 2 laryngeal squamous cell carcinoma (LSCC) cell lines (AMC-HN-8 and TU-212) and LSCC xenografts, the biological function of lncRNA AC023794.4-201 in LSCC was further investigated using in vitro and in vivo experiments, such as cell function experiments and nude mice transplantation. In our previous study, it was demonstrated that the expression level of the long non-coding RNA (lncRNA) AC023794.4-201 were decreased in laryngeal squamous cell carcinoma, particularly in cases of LSCC with lymphatic metastasis. Moreover, low expression levels of AC023794.4-201 were revealed to be an adverse prognostic factor for patients with LSCC. In the present study, lentiviruses were used to overexpress AC023794.4-201 before a series of cell function assays were performed and a xenograft nude mouse model was constructed, in order to further investigate the functions of AC023794.4-201 in LSCC. AC023794.4-201 inhibited the proliferation and the cloning capacity of LSCC cells compared with the negative control group as indicated by real-time cell analysis and the plate colony formation assay. Flow cytometry and transwell migration assays demonstrated that AC023794.4-201 inhibited the migration, induced cell cycle arrest and increased the apoptotic rate of LSCC cells. The results of the in vivo studies demonstrated that AC023794.4-201 significantly inhibited the growth of LSCC xenografts, and promoted apoptosis. In conclusion, the findings of the present study suggested that AC023794.4-201 may exert tumor-suppressive functions in the progression of LSCC and may serve as a potential prognostic biomarker for LSCC.

Development of a nine-lncRNA signature as a novel prognostic marker of estrogen receptor-negative breast cancer

Long non-coding RNAs (lncRNAs) have been demonstrated to be aberrantly expressed in several types of tumor, and dysregulated lncRNAs are suggested to play a prognostic role in breast cancer (BC). Estrogen receptor (ER) status is a prognostic factor in patients with ER-negative BC, which is associated with poor prognosis. Thus, the present study developed a prognostic lncRNA signature specifically for ER-negative BC, in order to predict the risk of post-surgery relapse and improve patient prognosis. A gene expression profile containing 1,631 lncRNAs was obtained by investigating and integrating publicly available cohorts of BC. Subsequently, a nine-lncRNA signature was developed and validated in two independent cohorts via the Cox regression model. Using the nine-lncRNA signature, patients in the discovery cohort were divided into high- and low-risk groups, with significantly different disease-free survival [DFS; hazard ratio (HR)=2.718, 95% confidence interval (CI)=2.115-3.494, P<0.0001]. Receiver operating characteristic curve analyses demonstrated that the area under the curve reached 0.908. Similar results were obtained in the two independent cohorts (HR=1.499, 95% CI=0.950-2.365, P=0.04; HR=1.262, 95% CI=1.056-1.510, P=0.01), respectively. Furthermore, the nine lncRNAs were demonstrated to play important roles in the cell invasion and metastasis of different types of tumor. The differentially expressed genes (DEGs) identified between the high- and low-risk groups were consistently high in the discovery and validation cohorts. Functional analysis indicated that these DEGs, as well as genes co-expressed with the nine lncRNAs, were involved in cancer-associated signaling pathways, all of which provide further evidence for the predictive ability of the nine-lncRNA signature. Overall, the present study developed a novel prognostic biomarker for ER-negative BC.

FoxD2-AS1 is a prognostic factor in glioma and promotes temozolomide resistance in a O6-methylguanine-DNA methyltransferase-dependent manner

Glioma is the most common brain tumor with a dismal prognosis. While temozolomide (TMZ) based chemotherapy significantly improves survival in glioma patients, resistance against this compound commonly leads to glioma treatment failure. Overexpression of long-noncoding RNA (LncRNA) FoxD2 adjacent opposite strand RNA 1 (FoxD2-AS1) was identified to promote glioma development, but the role in TMZ resistance remains unclear. In this paper, we found that FoxD2-AS1 was overexpressed in recurrent glioma, high FoxD2-AS1 expression was significantly correlated with poor patient outcome. Methylation of O⁶-methylguanine-DNA methyltransferase (MGMT) is significantly less frequent in high FoxD2-AS1 expression patients. Knockdown of FoxD2-AS1 decreased the proliferation, metastatic ability of glioma cells and promote the sensitivity to TMZ in glioma cells. Furthermore, knockdown of FoxD2-AS1 induced hypermethylation of the promoter region of MGMT. Our data suggested that FoxD2-AS1 is a clinical relevance LncRNA and mediates TMZ resistance by regulating the methylation status of the MGMT promoter region.

Overexpression of the Long Noncoding RNA FOXD2-AS1 Promotes Cisplatin Resistance in Esophageal Squamous Cell Carcinoma Through the miR-195/Akt/mTOR Axis

Emerging evidence has demonstrated that long noncoding RNAs (lncRNAs) mediate the development of esophageal squamous cell carcinoma (ESCC) via various pathophysiological pathways. This study explored the impact of the lncRNA FOXD2-AS1 on cisplatin resistance in ESCC and its possible mechanisms. Upregulation of FOXD2-AS was detected in patients with ESCC and ESCC cells that are resistant to cisplatin. In an in vitro assay, knockdown of FOXD2-AS1 noticeably inhibited cell invasion and growth, triggered cell death, and repressed the stimulation of the Akt/mTOR axis in cisplatin-resistant ESCC cells (TE-1/DDP). Conversely, the overexpression of FOXD2-AS1 remarkably increased cell invasion and growth, repressed cell death, and triggered the stimulation of the Akt/mTOR axis in TE-1/DDP cells. These findings, along with bioinformatics and validation tests, showed that FOXD2-AS1 targeted miR-195 by acting as a competing endogenous RNA. FOXD2-AS1/miR-195/Akt/mTOR axis plays a crucial role in resistance to cisplatin in ESCC cells, offering an innovative strategy to treat ESCC.

LncRNA FOXD3-AS1 promotes proliferation, invasion and migration of cutaneous malignant melanoma via regulating miR-325/MAP3K2

PURPOSE

The aim was to study the mechanism of LncRNA FOXD3-AS1 in cutaneous melanoma.

METHODS

FOXD3-AS1 levels in 47 pairs of melanoma samples were detected. We used qRT-PCR to detect FOXD3-AS1, miR-325 and MAP3K2 expression in different staging samples and cutaneous melanoma cell lines. We used Kaplan-Meier curve to analyze survival rate in patients with FOXD3-AS1 high and low expression. Sh-FOXD3-AS1, miR-325, miR-325 inhibitor and oeMAP3K2 were transfected. The proliferation of A375 and SK-MEL-1 was detected by CCK8 and EdU labeling assay and cell clone formation assay. Dual luciferase reporter assay and pull down assay was used to confirm the binding site of FOXD3-AS1, miR-325 and MAP3K2. Flow cytometry was applied to detect the effect of lncRNA on cell cycle. The migration and invasion ability were detected by transwell assay.

RESULTS

LncRNA FOXD3-AS1 highly expressed in cutaneous melanoma cells and tissues. Patients with highly expressed LncRNA FOXD3-AS1 were always with shorter overall survival time. When LncRNA FOXD3-AS1 was knockdown, proliferation, invasion and migration of cutaneous malignant melanoma, and tumor weight was inhibited, and cell cycle was arrested. LncRNA FOXD3-AS1 negatively regulated the expression of miR-325, and then improved the level of MAP3K2. MiR-325 was with similarly effects on above biological process, and MAP3K2 overexpression could rescue the influence of sh-FOXD3-AS1. Tumor volume and weight were measured to confirm the effect of sh-FOXD3-AS1 in vivo.

CONCLUSION

LncRNA FOXD3-AS1 could promote proliferation, invasion and migration of cutaneous malignant melanoma via regulating miR-325/MAP3K2 axis.

lncRNA FOXD2-AS1 confers cisplatin resistance of non-small-cell lung cancer via regulation of miR185-5p-SIX1 axis

Background: Chemoresistance is a major obstacle for chemotherapy failure in non-small-cell lung cancer (NSCLC). lncRNAs are a class of pivotal regulators in various cancers, and the lncRNA FOXD2-AS1 is implicated in the progression of NSCLC. However, it is still unclear whether it regulates chemosensitivity. Methods: Expression levels of FOXD2-AS1, miR185-5p, and SIX1 mRNA were identified by reverse-transcription qPCR. CCK8 assay was performed to assess cell proliferation and chemosensitivity of cisplatin-resistant A549/DDP and H1299/DDP cells. Colony-forming assay was utilized to detect colony numbers. Cell migration and invasion ability were measured by transwell assay. The protein levels of LRP, Pgp, MRP1, and SIX1 were examined by Western blot assay. The correlation between FOXD2-AS1 and miR185-5p or miR185-5p and SIX1 were validated by bioinformatic, dual-luciferase, and RNA immunoprecipitation assays. Tumor xenografts were constructed to confirm the function and mechanism of FOXD2-AS1 in chemosensitivity of DDP-resistant NSCLC. Results: FOXD2-AS1 and SIX1 were upregulated and miR185-5p downregulated in DDP-resistant NSCLC. Absence of FOXD2-AS1 enhanced drug sensitivity of A549/DDP and H1299/DDP cells, reflected by the reduced colony formation, cell proliferation, migration, invasion, and drug resistance-associated protein expression. FOXD2-AS1 acted as a molecular sponge for miR185-5p and relieved the binding of miR185-5p and its target gene SIX1, leading to the derepression of SIX1 in A549/DDP and H1299/DDP cells. Rescue experiments validated the functional interaction among FOXD2-AS1, miR185-5p, and SIX1. Moreover, FOXD2-AS1 interference receded the growth of DDP-resistant NSCLC tumors in vivo. Conclusion: FOXD2-AS1/miR185-5p/SIX1 regulates the progression and chemosensitivity of DDP-resistant NSCLC, suggesting a potential therapeutic target for cisplatin-resistant NSCLC patients.

Long noncoding RNA FOXD2-AS1 promotes glioma cell cycle progression and proliferation through the FOXD2-AS1/miR-31/CDK1 pathway

Long noncoding RNAs (lncRNAs) are vital mediators involved in cancer progression. Previous studies confirmed that FOXD2 adjacent opposite strand RNA 1 (FOXD2-AS1) is upregulated in tumor diseases. The potential influence of FOXD2-AS1 in glioma progression, however, remains unknown. In this paper, FOXD2-AS1 was found to be upregulated in glioma tissues. Its level was linked with glioma stage. Moreover, glioma patients expressing high level of FOXD2-AS1 suffered worse prognosis. Biological functions of FOXD2-AS1 in glioma cells were analyzed through integrative bioinformatics and TCGA RNA sequencing data analysis. Pathway enrichment analysis uncovered that FOXD2-AS1 was mainly linked with cell cycle regulation in both low-grade glioma and glioblastoma. Further experiments demonstrated that silence of FOXD2-AS1 inhibited proliferation, arrested cell cycle and downregulated cyclin-dependent kinase 1 (CDK1) in human glioma cells. Dual-luciferase reporter assay confirmed that FOXD2-AS1 upregulated CDK1 by sponging miR-31. Rescue assays were performed and confirmed the regulatory loop FOXD2-AS1/miR-31/CDK1 in glioma. Collectively, our results indicated that the FOXD2-AS1/miR-31/CDK1 axis influenced glioma progression, providing a potential new target for glioma patients.

Prognostic value of long non-coding RNA FOXD2-AS1 expression in patients with solid tumors

BACKGROUND

Although increasing evidence has revealed that FOXD2-AS1 overexpression exists in various solid tumors, the value of FOXD2-AS1 as a prognostic marker in such cancers remains uncertain. Accordingly, the present research aimed to assess the association of FOXD2-AS1 with cancer prognosis and predict the biological function of FOXD2-AS1.

METHODS

We systematically retrieved PubMed, PMC, Web of Science, EMBASE and Wiley Online Library databases for eligible articles published up to December 2018. Pooled hazard ratios (HRs) and odds ratios (ORs) with 95% confidence intervals (95%CIs) were calculated to evaluate the correlation of FOXD2-AS1 expression with overall survival (OS), disease free survival (DFS) and clinicopathological characteristics. We also used five Gene Expression Omnibus (GEO) datasets from breast cancer patients to explore the relationship between FOXD2-AS1 expression and prognosis. Finally, we validated FOXD2-AS1 expression in various carcinomas and predicted its biological function based on the public databases.

RESULTS

A total of 13 studies with 2502 tumor patients were included. The pooled HRs demonstrated that FOXD2-AS1 overexpression was significantly associated with unfavorable OS (HR = 1.39, 95%CI: 1.23-1.57, p < 0.001) and DFS (HR = 2.24, 95%CI: 1.55-3.23, p < 0.001) in tumor patients. The pooled ORs indicated that FOXD2-AS1 upregulation was related to large tumor size (OR = 1.53, 95%CI: 1.26-1.85, p < 0.001), deep invasion depth (OR = 1.99, 95%CI: 1.53-2.58, p < 0.001), distant metastasis (OR = 2.03, 95%CI: 1.69-2.43, p < 0.001) and advanced TNM stage (OR = 1.35, 95%CI: 1.06-1.72, p = 0.0150), but not to lymph node metastasis nor differentiation. Moreover, a similar pooled result for the OS of breast cancer patients was obtained (HR = 1.55, 95%CI: 1.14-2.11, p = 0.0052) by analyzing GEO data. Finally, elevated FOXD2-AS1 expression in various solid tumor tissues was verified based on The Cancer Genome Atlas (TCGA) data. Further functional prediction demonstrated that FOXD2-AS1 may participate in some cancer-related pathways.

CONCLUSION

Elevated FOXD2-AS1 expression was associated with poor survival in patients with solid tumors and may serve as a potential prognostic biomarker for a variety of cancers.

Long noncoding RNA PXN-AS1-L promotes the malignancy of nasopharyngeal carcinoma cells via upregulation of SAPCD2

Accumulating evidences highlight the critical roles of long noncoding RNAs (lncRNAs) in a variety of cancers. LncRNA PXN‐AS1‐L was previously shown to exert oncogenic roles in hepatocellular carcinoma. However, the expression, role, and molecular mechanism of PXN‐AS1‐L in nasopharyngeal carcinoma (NPC) malignancy remain unknown. Here, we determined that PXN‐AS1‐L is upregulated in NPC tissues and cell lines. Increased expression of PXN‐AS1‐L predicts worse prognosis of NPC patients. PXN‐AS1‐L overexpression promotes NPC cell proliferation, migration, and invasion in vitro, and NPC tumor growth in vivo. PXN‐AS1‐L silencing suppresses NPC cell proliferation, migration, and invasion in vitro. Mechanistically, PXN‐AS1‐L directly interacts with SAPCD2 mRNA 3′‐untranslated region, prevents the binding of microRNAs‐AGO silencing complex to SAPCD2 mRNA, and upregulates the mRNA and protein level of SAPCD2. SAPCD2 is also increased in NPC tissues. The expression of SAPCD2 is significantly positively associated with that of PXN‐AS1‐L in NPC tissues. Gain‐of‐function and loss‐of‐function experiments demonstrated that SAPCD2 also promotes NPC cell proliferation, migration, and invasion. Furthermore, depletion of SAPCD2 significantly reverses the roles of PXN‐AS1‐L in promoting NPC cell proliferation, migration, and invasion in vitro, and NPC tumor growth in vivo. In conclusion, lncRNA PXN‐AS1‐L is upregulated in NPC and promoted NPC malignancy by upregulating SAPCD2 via direct RNA‐RNA interaction.

LncRNA SOX2-OT regulates proliferation and metastasis of nasopharyngeal carcinoma cells through miR-146b-5p/HNRNPA2B1 pathway

Nasopharyngeal carcinoma (NPC) is an aggressive malignancy with a high mortality on account of its frequent metastasis and poor prognosis. An extensive body of investigations has proven that long noncoding RNAs are implicated in a variety of biological processes. Although SOX2-OT has been reported to play an oncogenic role in osteosarcoma, the mechanism of SOX2-OT-driven NPC progression is still obscure. The aim of this study was to elucidate the biological function of SOX2-OT and the related possible mechanism in NPC. In our study, SOX2-OT was notably elevated in NPC samples and cells. Further, a high expression level of SOX2-OT was correlated with poor clinical outcomes of NPC. Results from loss-of-function experiments suggested that knockdown of SOX2-OT repressed cell proliferation, arrested cell cycle, facilitated cell apoptosis, and inhibited cell metastasis of NPC. To further investigate the molecular mechanism of SOX2-OT, miR-146b-5p was found to directly bind to SOX2-OT, which mediated the role of SOX2-OT in NPC tumorigenesis. In addition, HNRNPA2B1 was a target of miR-146b-5p and SOX2-OT modulated the expression of HNRNPA2B1 through competitively binding to miR-146b-5p. At last, we discovered that SOX2-OT regulated NPC progression by targeting miR-146b-5p/HNRNPA2B1 pathway, which may provide more innovative targets for the treatment of patients with NPC.

FOXD2-AS1 correlates with the malignant status and regulates cell proliferation, migration, and invasion in cutaneous melanoma

Long noncoding RNA (lncRNA) FOXD2 adjacent opposite strand RNA 1 (FOXD2-AS1) has been shown to be dysregulated in several types of human cancer. However, the role of FOXD2-AS1 in cutaneous melanoma was still unclear. In our study, FOXD2-AS1 expression has been found to be upregulated in cutaneous melanoma tissue specimens and cell lines compared with that in normal tissue specimens and normal human epidermal melanocyte, respectively. Furthermore, high expression of FOXD2-AS1 was obviously correlated with deep Breslow thickness, present ulceration, high Clark level and distant metastasis in cutaneous melanoma patients. However, there were no statistical associations between FOXD2-AS1 expression and cutaneous melanoma patients' disease-free survival and overall survival. The results of loss-of-function study showed that inhibition of FOXD2-AS1 suppresses cutaneous melanoma cell proliferation, migration and invasion through regulating phospho-Akt expression. In conclusion, FOXD2-AS1 is associated with clinical progression in cutaneous melanoma patients, and functions as oncogenic lncRNA in cutaneous melanoma cells.

EGR1-induced upregulation of lncRNA FOXD2-AS1 promotes the progression of hepatocellular carcinoma via epigenetically silencing DKK1 and activating Wnt/β-catenin signaling pathway

Long non-coding RNAs (lncRNAs) are regarded as a group of biomarkers in the initiation and development of various cancers, including hepatocellular carcinoma (HCC). LncRNA FOXD2-AS1 has been studied in human colorectal cancer and glioma as an oncogene. However, the function and mechanism of lncRNA FOXD2-AS1 in hepatocellular carcinoma are marked. In this study, we found that high expression of FOXD2-AS1 predicted poor prognosis of HCC patients in the TCGA database. The dysregulation of FOXD2-AS1 was determined in HCC tissues and cell lines by qRT-PCR. Functionally, silenced FOXD2-AS1 efficiently suppressed HCC progression by regulating cell proliferation, apoptosis, migration and epithelial-mesenchymal transition (EMT). Mechanistically, FOXD2-AS1 was found to be activated by the transcription factor EGR1. Furthermore, FOXD2-AS1 could activate the Wnt/β-catenin signaling pathway. The mechanism contributed to the interaction between FOXD2-AS1 and Wnt/β-catenin signaling pathway was analyzed. It was uncovered that FOXD2-AS1 enhanced the activity of Wnt/β-catenin signaling pathway by epigenetically silencing the inhibitor of Wnt/β-catenin signaling pathway (DKK1). Rescue assays demonstrated that DKK1 and Wnt/β-catenin signaling pathway involved in FOXD2-AS1-mediated HCC progression. In conclusion, our study demonstrated that EGR1-induced upregulation of lncRNA FOXD2-AS1 promotes the progression of hepatocellular carcinoma via epigenetically silencing DKK1 and activating Wnt/β-catenin signaling pathway.

Oncogenicity of lncRNA FOXD2-AS1 and its molecular mechanisms in human cancers

OBJECTIVES

Long non-coding RNAs (lncRNAs) are a group of noncoding RNAs with length larger than 200 nucleotides. LncRNAs have limited or no protein-coding capacity because of lack of obvious open reading frame. An increasing number of researches have shown that lncRNAs participate in the complex regulation network of cancer and play an important role in tumourigenesis and progression such as proliferation, migration and invasion. LncRNA FOXD2 adjacent opposite strand RNA 1 (FOXD2-AS1), located on chromosome 1p33 and with a transcript length of 2527 nucleotides, is a novel cancer-related lncRNA. FOXD2-AS1 was recently found to exhibit aberrant expression in various malignancies, including gastric, lung, bladder, colorectal, nasopharyngeal, esophageal, hepatocellular, thyroid and skin cancer, and its deregulation might be related to survival and prognosis of cancer patients. Pertinent to clinical practice, FOXD2-AS1 might act as a feasible biomarker or therapeutic target in human cancers. In this paper, we made a summary on the current findings concerning the biological functions and molecular mechanisms of FOXD2-AS1 in tumor progression.

MATERIALS AND METHODS

In this paper, we summarized and figured out recent studies about the expression and molecular biological mechanisms of FOXD2-AS1 in tumor progression. Existing relevant studies were obtained through a systematic search from PubMed, Embase, BioMedNet, GEO database and Cochrane Library.

RESULTS

FOXD2-AS1 was a valuable tumor-associated lncRNA. Its expression level was up-regulation in various malignancies, including gastric, lung, bladder, colorectal, nasopharyngeal, esophageal, hepatocellular, thyroid and skin cancer. In addition, the aberrant expressions of FOXD2-AS1 have shown to contribute to proliferation, migration and invasion of cancer cells, and its deregulation is related to carcinogensis, overall survival, disease free survival, prognosis and tumor progression.

CONCLUSIONS

LncRNA FOXD2-AS1 is an oncogene and probably represents a feasible biomarker or therapeutic target in human cancers.

Long non‑coding RNA FOXD2‑AS1/miR‑150‑5p/PFN2 axis regulates breast cancer malignancy and tumorigenesis

Breast cancer (BC) is a common cancer and leading cause of cancer‑associated mortality in women. Abnormal expression of long non‑coding RNA FOXD2 adjacent opposite strand RNA 1 (FOXD2‑AS1) was associated with the development of a number of tumors. However, whether FOXD2‑AS1 is dysregulated in BC and its underlying mechanisms remain unclear. In the present study, it was identified that FOXD2‑AS1 expression was upregulated in BC tissue, cell lines and sphere subpopulation. Additionally, the abnormal upregulation of FOXD2‑AS1 predicted poor prognosis in patients with BC. Furthermore, downregulation of FOXD2‑AS1 decreased cell proliferation, and migratory and invasive abilities in BC cells, and decreased the growth of transplanted tumors in vivo. Downregulation of FOXD2‑AS1 decreased the percentage of CD44 antigen+/signal transducer CD24- in breast cancer stem cell (BCSC) cells, and decreased the expression of numerous stem factors, including Nanog, octamer‑binding transcription factor 4 (Oct4), and sex determining region Y‑box 2 (SOX2), and inhibited the epithelial‑mesenchymal transition process. FOXD2‑AS1 was identified to be primarily located in the cytoplasm. Using bioinformatics analysis, a reporter gene assay and reverse transcription‑polymerase chain reaction assays, it was demonstrated that microRNA (miR)‑150‑5p was able to bind directly with the 3'‑untranslated region of FOXD2‑AS1 and PFN2 mRNA. miR‑150‑5p mimics decreased the cell proliferation, migration and invasion of BC cells. FOXD2‑AS1 knockdown significantly inhibited the miR‑150‑5p inhibitor‑induced increase in Nanog, Oct4 and SOX2 expression. The miR‑150‑5p inhibitor‑induced increase in N‑cadherin, and decrease in E‑cadherin and vimentin was inhibited by FOXD2‑AS1 knockdown. Profilin 2 (PFN2) expression was significantly upregulated in BC tissues. Additionally, the abnormal upregulation of PFN2 was associated with poor prognosis in patients with BC. FOXD2‑AS1 and PFN2 expression was positively correlated. Collectively, the present results demonstrated the role of the FOXD2‑AS1/miR‑150‑5p/PFN2 axis in the development of BC, and provides novel targets for the treatment of BC, and potential biomarkers for diagnosis and prognosis of BC.

Long noncoding RNA FOXD2-AS1 promotes glioma malignancy and tumorigenesis via targeting miR-185-5p/CCND2 axis

Glioma is the most aggressive malignant tumor in the adult central nervous system. Abnormal long noncoding RNA (lncRNA) FOXD2-AS1 expression was associated with tumor development. However, the possible role of FOXD2-AS1 in the progression of glioma is not known. In the present study, we used in vitro and in vivo assays to investigate the effect of abnormal expression of FOXD2-AS1 on glioma progression and to explore the mechanisms. FOXD2-AS1 was upregulated in glioma tissue, cells, and sphere subpopulation. Upregulation of FOXD2-AS1 was correlated with poor prognosis of glioma. Downregulation of FOXD2-AS1 decreased cell proliferation, migration, invasion, stemness, and epithelial-mesenchymal transition (EMT) in glioma cells and inhibited tumor growth in transplanted tumor. We also revealed that FOXD2-AS1 was mainly located in cytoplasm and microRNA (miR)-185-5p both targeted FOXD2-AS1 and CCND2 messenger RNA (mRNA) 3'-untranslated region (3'-UTR). miR-185-5p was downregulated in glioma tissue, cells, and sphere subpopulation. Downregulation of miR-185-5p was closely correlated with poor prognosis of glioma patients. In addition, miR-185-5p mimics decreased cell proliferation, migration, invasion, stemness, and EMT in glioma cells. CCND2 was upregulated in glioma tissue, cells, and sphere subpopulation. Upregulation of CCND2 was closely correlated with poor prognosis of glioma patients. CCND2 knockdown decreased cell proliferation, migration, invasion, and EMT in glioma cells. In glioma tissues, CCND2 expression was negatively associated with miR-185-5p, but positively correlated with FOXD2-AS1. FOXD2-AS1 knockdown and miR-185-5p mimics decreased CCND2 expression. Inhibition of miR-185-5p suppressed FOXD2-AS1 knockdown-induced decrease of CCND2 expression. Overexpression of CCND2 suppressed FOXD2-AS1 knockdown-induced inhibition of glioma malignancy. Taken together, our findings highlight the FOXD2-AS1/miR-185-5p/CCND2 axis in the glioma development.

LINC00210 as a miR-328-5p sponge promotes nasopharyngeal carcinoma tumorigenesis by activating NOTCH3 pathway

As a kind of essential regulators, long noncoding RNAs (lncRNAs) have attracted a lot of attention in recent years. Nevertheless, the function of lncRNA in nasopharyngeal carcinoma (NPC) remains poorly understood. In the present study, we explained the role and mechanism of LINC00210 in NPC progression. We found that LINC00210 expression was up-regulated in NPC samples. Besides, its overexpression was positively correlated with NPC metastasis while predicting poor prognosis. Based on functional experiments, we revealed that LINC00210 contributed to NPC cell proliferation and invasion in vitro, and promotes tumor growth in vivo. Mechanistically, we identified that LINC00210 was located in the cytoplasm of NPC cells and served as the miR-328-5p sponge. Furthermore, we showed that miR-328-5p targets the 3′ untranslated region (3′-UTR) of NOTCH3. Through inhibiting miR-328-5p activity, LINC00210 promoted NOTCH3 expression in NPC, leading to activation of NOTCH3 signaling pathway. In conclusion, our study indicates LINC00210 promotes NPC progression through modulating proliferation and invasion.

Long non-coding RNA LINC01503 promotes colorectal cancer cell proliferation and invasion by regulating miR-4492/FOXK1 signaling

Increasing evidence indicates that long non-coding RNAs (lncRNAs) are closely associated with the progression of human cancer, including colorectal cancer (CRC). A previous study suggested that lncRNA LINC01503 promotes squamous cell carcinoma progression. However, the function of LINC01503 in CRC has remained elusive. The present study indicated that LINC01503 was significantly upregulated in CRC tissues compared with that in adjacent normal tissues as detected by reverse transcription-quantitative polymerase chain reaction. It was demonstrated that knockdown of long intergenic non-protein coding RNA (LINC)01503 markedly inhibited the proliferation and invasion of CRC cells, whereas overexpression of LINC01503 had the opposite effects, as indicated by Cell Counting kit-8 and Transwell assays. Mechanistically, it was revealed that LINC01503 serves as a sponge for microRNA (miR)-4492, which targets forkhead box K1 (FOXK1) in CRC cells. In addition, luciferase reporter assays demonstrated the direct binding of miR-4492 mimics to LINC01503 and to a sequence in the 3'-untranslated region of FOXK1. Furthermore, it was demonstrated that overexpression of LINC01503 reduced the availability of miR-4492 in CRC cells. Furthermore, miR-4492 mimics inhibited FOXK1 expression, while simultaneous overexpression of LINC01503 abolished this effect. Finally, it was demonstrated that restoration of FOXK1 abolished the inhibitory effect of LINC01503 knockdown on CRC cell proliferation and invasion. Taken together, the present results suggested that LINC01503 promotes CRC progression via acting as a competing endogenous RNA for miR-4492/FOXK1.

LncRNA FOXD2-AS1 regulates chondrocyte proliferation in osteoarthritis by acting as a sponge of miR-206 to modulate CCND1 expression

Recently, accumulating evidence demonstrated that the long non-coding RNAs (lncRNAs) play important roles in osteoarthritis (OA) progression. However, the role of lncRNA FOXD2-AS1 on OA is still unclear. In the present study, qRT-PCR showed that expression of FOXD2-AS1 and Cyclin D1 (CCND1) was upregulated in OA cartilage tissues, while miR-206 expression was significantly decreased. CCK-8 and colony formation assays showed that FOXD2-AS1 could promote chondrocytes viability. Flow cytometry analysis showed that FOXD2-AS1 inhibition arrested chondrocytes in G0/G1 phase and induced cells apoptosis. Furthermore, luciferase reporter assay and RIP assay showed that FOXD2-AS1 could function as a sponge of miR-206. Rescue assays showed that miR-206 inhibitors reversed the effects of FOXD2-AS1 suppression on chondrocytes viability. In addition, we identified that CCND1 acted as a direct target of miR-206. FOXD2-AS1 suppression could inhibit CCND1 expression in chondrocytes, while miR-206 inhibitors reversed CCND1 expression. Moreover, rescue assays indicated that CCND1 overexpression reversed the effects of FOXD2-AS1 suppression on chondrocytes viability. Taken together, these data indicated that FOXD2-AS1 could promote the growth of chondrocytes by targeting miR-206/CCND1 axis.