Long noncoding RNA FTX is associated with prognosis of glioma patients

RNA-Independent Regulatory Functions of lncRNA in Complex Disease

During the metagenomics era, high-throughput sequencing efforts both in mice and humans indicate that non-coding RNAs (ncRNAs) constitute a significant fraction of the transcribed genome. During the past decades, the regulatory role of these non-coding transcripts along with their interactions with other molecules have been extensively characterized. However, the study of long non-coding RNAs (lncRNAs), an ncRNA regulatory class with transcript lengths that exceed 200 nucleotides, revealed that certain non-coding transcripts are transcriptional "by-products", while their loci exert their downstream regulatory functions through RNA-independent mechanisms. Such mechanisms include, but are not limited to, chromatin interactions and complex promoter-enhancer competition schemes that involve the underlying ncRNA locus with or without its nascent transcription, mediating significant or even exclusive roles in the regulation of downstream target genes in mammals. Interestingly, such RNA-independent mechanisms often drive pathological manifestations, including oncogenesis. In this review, we summarize selective examples of lncRNAs that regulate target genes independently of their produced transcripts.

Emerging roles of long non-coding RNA FTX in human disorders

Long non-coding RNAs (lncRNAs) are involved the progression of cancerous and non-cancerous disorders via different mechanism. FTX (five prime to xist) is an evolutionarily conserved lncRNA that is located upstream of XIST and regulates its expression. FTX participates in progression of various malignancy including gastric cancer, glioma, ovarian cancer, pancreatic cancer, and retinoblastoma. Also, FTX can be involved in the pathogenesis of non-cancerous disorders such as endometriosis and stroke. FTX acts as competitive endogenous RNA (ceRNA) and via sponging various miRNAs, including miR-186, miR-200a-3p, miR-215-3p, and miR-153-3p to regulate the expression of their downstream target. FTX by targeting various signaling pathways including Wnt/β-catenin, PI3K/Akt, SOX4, PDK1/PKB/GSK-3β, TGF-β1, FOXA2, and PPARγ regulate molecular mechanism involved in various disorders. Dysregulation of FTX is associated with an increased risk of various disorders. Therefore, FTX and its downstream targets may be suitable biomarkers for the diagnosis and treatment of human malignancies. In this review, we summarized the emerging roles of FTX in human cancerous and non-cancerous cells.

Latest updates on cellular and molecular biomarkers of gliomas

Gliomas are the most common central nervous system malignancies, compromising almost 80% of all brain tumors and is associated with significant mortality. The classification of gliomas has shifted from basic histological perspective to one that is based on molecular biomarkers. Treatment of this type of tumors consists currently of surgery, chemotherapy and radiation therapy. During the past years, there was a limited development of effective glioma diagnostics and therapeutics due to multiple factors including the presence of blood-brain barrier and the heterogeneity of this type of tumors. Currently, it is necessary to highlight the advantage of molecular diagnosis of gliomas to develop patient targeted therapies based on multiple oncogenic pathway. In this review, we will evaluate the development of cellular and molecular biomarkers for the diagnosis of gliomas and the impact of these diagnostic tools for better tailored and targeted therapies.

Circular RNA circBFAR promotes glioblastoma progression by regulating a miR-548b/FoxM1 axis

Glioblastoma multiforme (GBM) is the most common and aggressive type of tumor of the primary nervous system. Treatment options for GBM include surgery, chemotherapy, and radiation therapy; however, the clinical outcomes are poor, with a high rate of recurrence. An increasing number of studies have shown that circular RNAs (circRNAs) serve important roles in several types of cancer. Gene Expression Omnibus (GEO) database was utilized to identify the differentially expressed circRNAs and their biological functions. Then, we detected the circular RNA bifunctional apoptosis regulator (circBFAR) was significantly increased in three GEO datasets. However, the role of circBFAR has not been reported in GBM. In this study, the expression of circBFAR was significantly increased both in GBM tissues or cell lines and was negatively correlated with overall survival in patients with GBM. Knockdown of circBFAR inhibited proliferation and invasion both in vitro and in vivo. Increased expression of circBFAR resulted in a reduction of miR-548b expression in glioma cells. A luciferase reporter and RIP assay indicated that miR-548b was a direct target of circBFAR, and miR-548b may negatively regulate the expression of FoxM1. Rescue experiments showed that overexpression of FoxM1 could counter the effect of circBFAR silencing on the proliferation and invasion of glioma cell lines. Moreover, we identified that circBFAR regulates FoxM1 by interacting with miR-548b in glioma cells. In conclusion, the present study demonstrated that a circBFAR/miR-548b/FoxM1 axis regulates the development of GBM and highlights potentially novel therapeutic targets for the treatment of GBM.

Prognostic significance of long non-coding RNA five prime to XIST in various cancers

BACKGROUND

To observe the clinicopathological and prognostic value of long non-coding RNA five prime to X inactive specific transcript (lncFTX) in multiple tumors.

METHODS

Eligible studies for lncFTX were identified by searching PubMed, Embase, Web of Science and Cochrane Library databases from inception to December 01, 2020. Stata 12.0 software was used to calculate the odds ratio (OR)/hazard ratio (HR) and 95% confidence interval (95% CI). We used The Cancer Genome Atlas (TCGA) dataset to further investigate the differential expression and prognostic value of lncFTX.

RESULTS

We included 11 studies involving a total of 1633 patients. The results showed that the expression of lncFTX was positively associated with advanced TNM stage (III-IV versus I-II) (OR = 2.30, 95% CI: 1.74-3.03, P < 0.05), lymph nodes metastasis (OR = 3.01, 95% CI: 2.00-4.52, P < 0.05), distant metastasis (OR = 3.68, 95% CI: 2.13-6.34, P < 0.05), and cancer mortality (HR = 1.83, 95% CI: 1.20-2.81, P < 0.05). However, the expression of lncFTX was not associated with tumor differentiation (poor differentiation versus well or moderate differentiation) and vessel invasion of cancer. Subgroup analysis showed that the higher lncFTX expression was associated with shorter overall survival in cancer patients, regardless of the sample size and cancer type. No publication bias was found, and the sensitivity analysis results suggested that the main findings were robust. Elevated expression and prognostic significance of FTX were confirmed using TCGA dataset.

CONCLUSIONS

This study found that the expression of lncFTX was positively associated with advanced tumor node metastasis (TNM) stage, lymph nodes, distant metastasis and, cancer mortality, suggesting that lncFTX might be a potential prognostic biomarker for tumors.

LncRNA FTX promotes the malignant progression of colorectal cancer by regulating the miR-214-5p-JAG1 axis

Background

Long non-coding RNAs (lncRNAs) have recently been found to be vital regulators of various cancers, including colorectal cancer (CRC). It has been previously reported that the dysregulated expression of lncRNA Five prime to Xist (FTX) is involved in carcinogenesis. However, the role of lncRNA FTX in the progression of CRC is still unclear.

Methods

Fluorescence in situ hybridization (FISH) was used to detect the expression of lncRNA FTX and miR-214-5p in CRC tissues. Cell Counting Kit-8 assay, transwell assay, wound-healing assay, and proliferation assay were used to explore the function of lncRNA FTX in CRC cells. Quantitative real-time polymerase chain reaction (qRT-PCR), western blotting, and luciferase reporter assay were used to confirm the relationship between lncRNA FTX and miR-214-5p-jagged canonical Notch ligand 1 (JAG1). We further explored the role of lncRNA FTX in vivo using xenograft tumor assay.

Results

lncRNA FTX was found to be upregulated in CRC tissues by FISH. The downregulation of endogenous lncRNA FTX expression inhibited CRC cell proliferation, migration, and invasion. Mechanistically, lncRNA FTX sequestered miR-214-5p and thus released its repression on JAG1, driving the malignant progression of CRC.

Conclusions

These findings give rise to a new perspective, the lncRNA FTX-miR-214-5p-JAG1 regulatory axis, in exploring the cancer-promoting mechanism of lncRNA FTX in CRC.

Upregulation of FTX expression is associated with a poor prognosis and contributes to the progression of thyroid cancer

The dysregulated expression of long non-coding RNA FTX transcript X inactive specific transcript regulator (FTX) has been reported to be involved in the tumorigenesis of multiple cancer types. However, to the best our knowledge, its function and clinical value in thyroid cancer remain unclear. The present study aimed to determine the potential role of FTX in the development and progression of thyroid cancer. Reverse transcription-quantitative PCR analysis revealed that the expression levels of FTX were upregulated in thyroid cancer tissues and cell lines compared with those in normal tissues and cell lines, respectively. Survival analysis demonstrated that patients with upregulated FTX expression had a lower survival rate. Functional experiments revealed that the knockdown of FTX inhibited proliferation, cell cycle progression, migration and invasion, and induced apoptosis in thyroid cancer cells, while FTX overexpression accelerated proliferation, migration and invasion, and alleviated apoptosis in thyroid cancer cells. In addition, FTX knockdown significantly inhibited tumor growth in vivo. Furthermore, in thyroid cancer cells, FTX was identified to positively regulate the expression levels of TGF-β1, which is known to play an important regulatory role in tumor metastasis. In conclusion, the findings of the present study suggested that FTX may accelerate thyroid cancer progression via regulation of cellular activities, including cell proliferation, migration, invasion and apoptosis. Thus, FTX may represent a potential biomarker for the diagnosis, treatment and prognosis of thyroid cancer.

Long non-coding RNA FTX predicts a poor prognosis of human cancers: a meta-analysis

Background: Several studies have assessed the relationship between long non-coding RNA five prime to Xist (FTX) expression, clinicopathological features, and survival outcomes in patients with cancer with conflicting results. This meta-analysis synthesized existing data to clarify the association between FTX with cancer prognosis.

Methods: PubMed, Embase, Cochrane library, Web of Science, Chinese CNKI, and the Chinese WanFang databases were used to search for relevant studies. The role of FTX in cancers was evaluated by pooled odds ratios (ORs) and hazard ratios (HRs) with 95% confidence intervals (CIs).

Results: Eleven studies comprising 1210 participants including colorectal cancer (CRC), hepatocellular carcinoma (HCC), gastric cancer (GC), renal cell carcinoma (RCC), osteosarcoma (OSC), and glioma were enrolled in this analysis. The meta-analysis showed that high FTX expression was significantly associated with several clinicopathological characteristics, including lymph node metastasis in patients with CRC, GC, HCC, and RCC, distant metastasis in patients with CRC, GC, HCC, and OSC, larger tumor size in patients with CRC, GC, HCC, RCC, and OSC, and subsequently TNM/clinical stage in patients with CRC, GC, HCC, OSC, and glioma. The pooled results from the survival analysis revealed a significant correlation between high FTX expression and shorter OS in patients with HCC, CRC, GC, OSC, and glioma. Further, FTX overexpression could be an independent predictive marker for shorter OS in patients with CRC, HCC, OSC, and glioma.

Conclusions: FTX may be a potential oncogene, with high FTX expression being associated with a poorer prognosis in patients with CRC, HCC, OSC, and glioma.

Long noncoding RNA FTX is associated with prognosis of glioma patients

Background

Long noncoding RNAs play influential roles in the progression of many types of human malignancies. The present study aimed to explore the prognostic value of long noncoding RNA FTX (FTX) on patients with glioma.

Methods

FTX expression in glioma specimens and matched adjacent non‐neoplasm specimens was examined by a quantitative real‐time polymerase chain reaction assay. Furthermore, assays of the relationships between FTX expression and clinicopathologic characteristics of patients with glioma were also performed. Kaplan–Meier methods were applied for the assays of the overall survival (OS) and progression‐free survival (PFS) of patients and Cox regression assays were used to analyze the clinical value of FTX used as a possible biomarker.

Results

FTX levels were significantly up‐regulated in glioma specimens compared to the paired non‐neoplasm specimens (p < 0.01). Furthermore, high FTX expression in neoplasm tissues was dramatically associated with World Health Organization grade (p = 0.001) and Karnofsky Performance Score (p = 0.009). Kaplan–Meier assays with 187 patients revealed that patients with high level of FTX expression displayed poorer OS (p = 0.002) and PFS (p = 0.000). Subsequently, multivariable Cox regression analysis identified FTX expression as an independent prognostic factor of unfavorable survivals in glioma (OS: p = 0.001; PFS: p = 0.002).

Conclusions

These findings indicated that FTX may be a novel predictor for prognostic assessment of glioma patients. However, studies conducted with larger numbers of patients are essential to confirm our findings.