Quantitative proteomics analysis revealed the potential role of lncRNA Ftx in cardiomyocytes.

OBJECTIVE: This study aims to decode the proteomic signature of cardiomyocytes in response to lncRNA Ftx knockdown and overexpression via proteomic analysis, and to study the biological role of lncRNA Ftx in cardiomyocytes.  METHODS: The expression level of the lncRNA Ftx in cardiomyocytes cultured in vitro was intervened, and the changes in protein levels in cardiomyocytes were quantitatively detected by liquid chromatography-mass spectrometry. The key molecules and pathways of the lncRNA-Ftx response were further examined by GO, KEGG, and protein interaction analysis. RESULTS: A total of 2828 proteins are quantified. With a 1.5-fold change threshold, 32 upregulated proteins and 49 downregulated proteins are identified in the lncRNA Ftx overexpression group, while 67 up-regulated proteins and 54 down-regulated proteins are identified in the lncRNA Ftx knockdown group. Functional clustering analysis of differential genes revealed that the lncRNA Ftx is involved in regulating cardiomyocyte apoptosis and ferroptosis and improving cellular energy metabolism. In addition, Hub genes such as ITGB1, HMGA2, STAT3, GSS, and LPCAT3 are regulated downstream by lncRNA Ftx. CONCLUSION: This study demonstrates that lncRNA Ftx plays a vital role in cardiomyocytes and may be involved in the occurrence and development of various myocardial diseases. It provides a potential target for clinical protection of the myocardium and reversal of myocardial fibrosis.

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 Colorectal Cancer Cells Migration and Invasion by miRNA-590-5p/RBPJ Axis.

Colorectal cancer (CRC) is one of the most lethal human cancers all over the world. Moreover, it ranks fourth for cancer-related deaths among males. Although many efforts have been made to cure CRC, the effect remains limited. It has been reported that lncRNA five prime to Xist (FTX) was upregulated in CRC. However, the mechanism by which lncRNA FTX regulates the progression of CRC remains largely unknown. In this study, qRT-PCR was performed to detect the expression of FTX, miR-590-5p and Recombination signal binding protein for immunoglobulin kappa J region (RBPJ) in CRC tissues or cells. Protein expression in cells was measured by western blot. MTT assay was used to test the cell viability. Moreover, transwell was performed to examine the cell migration and invasion. Luciferase report assay was performed to verify the relation between miR-590-5p and FTX or RBPJ. It was found that FTX was upregulated in CRC tissues and cells. Knockdown of FTX or overexpression of miR-590-5p can inhibit the proliferation, migration, and invasion of CRC cells. Besides, silencing of FTX could inhibit the expression of migration and invasion-related proteins in CRC cells. Meanwhile, miR-590-5p was the target of FTX, and RBPJ was the direct target of miR-590-5p. Inhibition of miR-590-5p could reverse the inhibitory effect of FTX on the progression of CRC. These findings suggested that knockdown of FTX could inhibit the tumorigenesis of CRC in vitro, which may serve as a potential novel strategy for treatment of CRC.

LncRNA FTX represses the progression of non-alcoholic fatty liver disease to hepatocellular carcinoma via regulating the M1/M2 polarization of Kupffer cells.

BACKGROUND: The effect of lncRNA FTX on non-alcoholic fatty liver disease (NAFLD) conversion to hepatocellular carcinoma (HCC) is unclear. METHODS: In our study, C57BL/6 mice was fed with high fat diet for obtaining NAFLD mouse model, and diethylnitrosamine induced the formation of HCC tumor. The expression of iNOS and CD206 in tissues were examined using immunohistochemistry. In addition, qRT-PCR was implemented to detect the expression of FTX and mRNAs. The percentage of M1 and M2 Kupffer cells (KCs) were determined using flow cytometry. The pathological change in liver tissues was displayed by H&E staining. Besides, immunofluorescence assay was performed to ensure the primary KCs through labeling F4/80. RESULTS: Here, we found that the expression of FTX and the ratio of M1/M2 KCs in liver tissues from NAFLD-transformed HCC (NAFLD-HCC) patients lower than in liver tissues from NAFLD patients. Subsequently, we revealed that the expression of FTX and M1/M2 KCs ratio were downregulated during NAFLD conversion to HCC. Importantly, increasing of FTX inhibited HCC tumor growth, improved liver damage and promoted M1 polarization of KCs during NAFLD conversion to HCC, while these effects of FTX were reversed by inactivating of KCs. Finally, in vitro experiments, our data indicated that FTX facilitated the M1 polarization of KCs. CONCLUSION: In conclusion, our results demonstrated that upregulation of FTX suppressed NAFLD conversion to HCC though promoting M1 polarization of KCs. Our findings presented a new regulatory mechanism for NAFLD conversion to HCC, and provided a new biomarker for inhibiting this conversion.

LncRNA FTX Involves in the Nogo-66-Induced Inhibition of Neurite Outgrowth Through Regulating PDK1/PKB/GSK-3ß Pathway.

Nogo-66 can inhibit neurite outgrowth, while its regulation mechanisms have not been fully elucidated. Recent studies prove that lncRNAs are involved in neurite outgrowth. This study was aimed to investigate whether lncRNA FTX was involved in Nogo-66-induced inhibition of neurite outgrowth and explore the potential mechanism. The expression of relative genes was detected by qRT-PCR and western blot. The function of FTX was determined by overexpression and knockdown techniques. The interaction between FTX and PDK1 was evaluated by RIP and RNA pull-down assays. FTX expression was downregulated by Nogo-66 in PC12 cells. Nogo-66-induced inhibition of neurite outgrowth was relieved by FTX overexpression. FTX bound to PDK1 protein to disturb the interaction between PDK1 and E3 ubiquitin ligase RNF126, thereby blocked the ubiquitination degradation of PDK1 and elevated PDK1 protein level. Mechanically, FTX involved in the Nogo-66-induced inhibition of neurite outgrowth through the PDK1/PKB/GSK-3ß pathway. In SCI rats, FTX knockdown inhibited neurite outgrowth induced by the receptor antagonist of Nogo-66. The present results suggested that FTX took part in Nogo-66-inhibited neurite outgrowth, and FTX exerted its function through regulating PDK1/PKB/GSK-3ß pathway.

LncRNA FTX inhibits hippocampal neuron apoptosis by regulating miR-21-5p/SOX7 axis in a rat model of temporal lobe epilepsy.

Emerging evidence has shown that long noncoding RNA (LncRNA) is involved in the development of epileptogenesis. However, the expression profile and the biological function of FTX in epilepsy remains unclear. This study aimed to provide functional evidence and elucidate the molecular mechanisms by which the FTX affects status epilepticus (SE) induced hippocampal apoptosis. SE rat model was introduced by intraperitoneal injection of lithium chloride and pilocarpine. Our results showed that FTX is notably reduced in the hippocampus. Moreover, the in vivo overexpression of FTX inhibited SE-induced hippocampus neuron apoptosis. Mechanically, we found that FTX negatively regulated miR-21-5p expression by targeting its 3'UTR to regulate neuron apoptosis. Upregulation of miR-21-5p attenuates anti-apoptosis property of FTX overexpression by regulating SOX7 expression in epileptiform hippocampal neurons. Collectively, our study for the first time demonstrated the anti-apoptosis ability of FTX during epileptogenesis and uncovered a novel FTX-mediated mechanism in SE-induced neural apoptosis by targeting miR-21-5p/SOX7 axis, which provides a new target in developing lncRNA-based strategies to reduce SE-induced hippocampal neuron apoptosis.

Quantitative Proteomics Analysis Reveals the Potential Role of lncRNA FTX in Endothelial Cells.

OBJECTIVE: This study investigated the role of long non-coding RNAs (lncRNAs) FTX in vascular endothelial cells (ECs). METHODS: Transfection of FTX/Sh-FTX with lentivirus was used to construct gain and loss of function cell models in human umbilical vein endothelial cells (HUVECs). Liquid chromatography-mass spectrometry was used for quantitative proteomics analysis of differentially expressed proteins (DEPs). Gene Ontology, Kyoto Encyclopedia of Genes and Genomes, and protein interaction analysis were further conducted to investigate the key molecules and pathways that respond to lncRNA-FTX. RESULTS: In the proteomics analysis, 3308 quantifiable proteins were identified, 64 proteins were upregulated and 103 were downregulated when lncRNA FTX was overexpressed. Additionally, 100 proteins were upregulated and 147 were downregulated when lncRNA FTX was knocked down. Functional clustering analysis of DEPs demonstrated that lncRNA FTX was involved in multiple biological processes. Among them, the expression of complement 3 (C3), cartilage oligomeric matrix protein (COMP), faciogenital dysplasia 6 (FGD6), and tissue inhibitor of metalloproteinase 1 (TIMP1) was significantly upregulated when lncRNA FTX was knocked down, and significantly downregulated when lncRNA FTX was overexpressed. They are associated with inflammation, collagen deposition, angiogenesis, and regulation of liver stem cell differentiation, which may be associated with the occurrence and development of liver fibrosis. CONCLUSIONS: The study demonstrated that lncRNA FTX might play a potential role in ECs and contribute to the development of liver fibrosis. Thus, FTX may be a promising target for the prevention or reversal of liver fibrosis.

Mechanism of LncRNA FTX regulates nephroblastoma progression through MiR-215-5p/PI3K/AKT axis.

BACKGROUND: Nephroblastoma, also more commonly known as Wilms tumor (WT), is a common childhood malignancy that connects tumorigenesis and organ development in the kidney. OBJECTIVE: The current study focused on the effect of lncRNA FTX in nephroblastoma. STUDY DESIGN: Expression of lncRNA FTX in nephroblastoma tissues and cells was determined. The expression location of lncRNA FTX was detected by FISH. The binding of lncRNA FTX and miR-215-5p with Ago2 was verified by RIP. Following gain- and loss-of-function approaches, the crucial role of lncRNA FTX and miR-215-5p in nephroblastoma cell functions was measured with the involvement of the PI3K/AKT pathway. RESULTS: LncRNA FTX was elevated and miR-215-5p was declined in nephroblastoma. Silencing of lncRNA FTX or mimic of miR-215-5p inhibited the malignant properties of nephroblastoma cells. LncRNA FTX was localized in the cytoplasm and might bind miR-215-5p. LncRNA FTX promoted the malignant features of nephroblastoma cells by inhibiting miR-215-5p through activating of the PI3K/AKT pathway. CONCLUSIONS: LncRNA FTX is capable of accelerating nephroblastoma development in vitro by reducing miR-215-5p through activating of the PI3K/AKT pathway, indicating LncRNA FTX may possibly a future target for the diagnosis and treatment of nephroblastoma. SUMMARY FIGURE.

LncRNA FTX Inhibits Ferroptosis of Hippocampal Neurons Displaying Epileptiform Discharges In vitro Through the miR-142-5p/GABPB1 Axis.

Epilepsy is a disabling and drug-refractory neurological disorder. Long non-coding RNAs (lncRNAs) play a vital role in neuronal function and central nervous system development. This study aimed to explore the regulatory mechanism of lncRNA five prime to Xist (FTX) in cell ferroptosis following epilepsy to provide a theoretical foundation for epilepsy management. Hippocampal neurons were isolated from brain tissues of healthy male SD rats, and an in vitro cell model of epilepsy was established using magnesium-free (MGF) induction. Patch-clamp technique was used to determine the action potentials of neurons. Neuronal viability and apoptosis were assessed by CCK-8 assay and flow cytometry. Levels of FTX, miR-142-5p, and GABPB1 were determined by RT-qPCR and Western blot, respectively. The cellular location of FTX was predicted and validated by RNA immunoprecipitation. Dual-luciferase assay verified targeting relationships among FTX, miR-142-5p, and GAPBP1. Levels of ferroptosis indicators and ferroptosis-related proteins were measured using Western blot and corresponding kits. Neuronal ferroptosis and apoptosis increased after MGF induction, and FTX was weakly-expressed in MGF-induced neurons. FTX overexpression attenuated ferroptosis and apoptosis of MGF-induced neurons. miR-142-5p was upregulated after MGF induction and downregulated after FTX overexpression, and FTX targeted miR-142-5p. miR-142-5p overexpression partially negated the inhibitory action of FTX overexpression on ferroptosis of MGF-induced neurons. FTX regulated GABPB1 expression by targeting miR-142-5p. In conclusion, FTX overexpression mitigated ferroptosis of MGF-induced neurons through the miR-142-5p/GABPB1 axis. In conclusion, lncRNA FTX inhibited ferroptosis of MGF-induced rat hippocampal neurons via the miR-142-5p/GABPB1 axis.

Biological role of long non-coding RNA FTX in cancer progression.

Long non-coding RNAs (LncRNAs) are involved in several types of cancer and participate actively in tumorigenesis and disease progression. LncRNA FTX is the transcription product of the FTX gene located at the X-inactivation center (Xic). LncRNA FTX has been shown to regulate cancer cell proliferation, migration, and aberrant metabolism, as well as increase tumor growth and metastasis in vivo. Herein, we summarized currently available research on the interaction between LncRNA FTX and associated molecules and signaling pathways in malignant tumors to better understand the biological roles of LncRNA FTX in cancer progression.

LncRNA FTX Regulates Angiogenesis Through miR-342-3p/SPI1 Axis in Stroke.

BACKGROUND: Long non-coding RNAs (lnc-RNAs) and microRNAs (miRNAs) play key roles in the development of stroke. However, the role of lncRNA FTX in stroke is limited known. METHODS: Real-time polymerase chain reaction (real-time PCR) assays were used to measure the expression of lncRNA FTX, miR-342-3p and SPI1. Western blot assays were employed to examine SPI1 protein expression. The cell viability was measured by CCk8 assay. Cell migration was detected by wound healing assays and transwell assays. Angiogenesis was evaluated by matrigel tube formation assays. The interaction between lncRNA FTX, miR-342-3p and SPI1 was confirmed by site-directed mutagenesis and luciferase assays. RESULTS: The expression of lncRNA FTX was down-regulated in blood sample from stroke patients, MAO mice tissues and OGD/R treated BMECs. Overexpression of lncRNA FTX could increase the cell viability, migration and angiogenesis in OGD/R treated BMECs. LncRNA FTX could act as a ceRNA for miR-342-3p. Furthermore, miR-342-3p inhibition increased migration and angiogenesis in OGD/R-induced BMECs. Dual-luciferase reporter assay verified that SPI1 was a target of miR-342-3p. CONCLUSION: In summary, lncRNA FTX enhanced the angiogenesis in stroke by acting as a sponge of miR-342-3p to regulate the expression of SPI1 level.

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.

The Function of LncRNA FTX in Several Common Cancers.

BACKGROUND: LncRNA is a kind of non-coding RNA and its research is more popular in recent years, which has more than 200 nucleotides. It plays a significant part in various biological functions, including chromosome modification, genome modification, transcriptional activation, transcriptional interference, and other processes. FTX, at the center of the X chromosome inactivation and it has been shown that lncRNA FTX regulates cancer cells' development, migration, and invasion in many studies. METHODS: Relevant literature was collected through the PubMed system search and is summarized in this article. RESULTS: LncRNA FTX abnormally increased in tumor cells, such as liver cancer, stomach cancer, leukemia, renal cell carcinoma, colorectal cancer, glioma, osteosarcoma, etc. However, the expression level decreased in temporal lobe epilepsy, liver cirrhosis, heart failure, etc. Conclusion: FTX may be an important regulatory factor and a potential therapeutic target in cancers.

The lncRNA Ftx/miR-382-5p/Nrg1 axis improves the inflammation response of microglia and spinal cord injury repair.

During spinal cord injury (SCI), a quick and sustained decline of Neuregulin-1 (Nrg1) has been observed, exerting a significant positive effect in modulating the proliferation of astrocytes and the formation of glial scars within the damaged spinal cord. In this study, we revealed the abnormal downregulation of lncRNA Ftx and Nrg1 and upregulation of miR-382-5p after SCI, which contributed to the inflammatory response in microglial cells and affected SCI repair. Ftx overexpression was significantly reduced, and Ftx knockdown further promoted LPS effects on the inflammatory factors, indicating that lncRNA Ftx might affect the microglial inflammatory response. miR-382-5p targeted both lncRNA Ftx and Nrg1, and lncRNA Ftx competed with Nrg1 for miR-382-5p binding to act as a ceRNA, therefore counteracting miR-382-5p-mediated inhibition of Nrg1. miR-382-5p overexpression was significantly enhanced, and Nrg1 overexpression attenuated LPS effects on inflammatory factors within the microglia. Under LPS stimulation, the effects of Ftx overexpression were significantly reversed by overexpression of miR-382-5p, and the effects of miR-382-5p overexpression were significantly reversed by Nrg1 overexpression. In summary, the lncRNA Ftx/miR-382-5p/Nrg1 axis improves the inflammation response of the microglia, which might improve SCI repair.

Quantitative Proteomics Analysis Revealed the Potential Role of lncRNA Ftx in Promoting Gastric Cancer Progression.

PURPOSE: The molecular pathogenesis of gastric cancer is still ambiguous till now. Here, it is demonstrated that long noncoding RNA (lncRNA) Ftx acts as a novel tumor promotor of gastric cancer and a potent regulator of hexokinase-2 (HK2). EXPERIMENTAL DESIGN: The role of lncRNA Ftx is detected in the loss and gain-of-function models of gastric cancer cells. Tandem mass tags combined with multidimensional LC and MS analyses are performed to decipher comparative proteomic profiles of gastric cancer cells in response to lncRNA Ftx knockdown and overexpression. Real-time roteomics-clinical applications (PCR) and western blot are used to validate the proteomic data. RESULTS: A total of 5124 proteins are quantified and indicated in diverse biological functions and metabolic related signaling pathways. Interestingly, HK2, which is downregulated when lncRNA Ftx is deleted and upregulated while lncRNA Ftx is overexpressed, is further validated in gastric cancer cells. CONCLUSIONS AND CLINICAL RELEVANCE: The present study suggests lncRNA Ftx promotes gastric cancer progression by upregulating HK2, which provides a new perspective for the mechanism of gastric cancer progression, and thus identifies potential therapeutic targets for gastric cancer.

LncRNA FTX Promotes Proliferation and Invasion of Gastric Cancer via miR-144/ZFX Axis.

BACKGROUND: Long non-coding RNAs are important regulators in cancer cell tumorigenesis. We have demonstrated in a prior study that lncRNA FTX is dysregulated in gastric cancer (GC). In this study, we aim to report gastric cancer-related lncRNA FTX as a main regulator in GC development and progression. METHODS: In vitro and in vivo assays of FTX alterations have been performed to reveal a complex integrated phenotype affecting cell growth, migration, and invasion. lncRNA FTX expression levels in gastric cancer cells and normal cells were measured by RT-PCR. Luciferase reporter assays, Western blotting, and many immune, microscopy technologies were utilized to investigate the expressions of FTX- related proteins and RNAs. The functional role of FTX in cell growth, migration, and invasion were observed in vitro and in vivo. RESULTS: We explored the underlying mechanisms of FTX in GC development, and the microRNAs' relationship with FTX. We found that FTX promoted cell proliferation, migration, and invasion, as well as tumor growth, and this effect could latterly be attenuated by miR-144. ZFX attenuated the effects of FTX/miR-144 axis by sponging with miR-144. CONCLUSION: In summary, the above results support a model in which the FTX/miR-144/ZFX act as important effectors in GC tumorigenesis and progression, indicating new therapeutic methods in GC.

Long non-coding RNA Ftx promotes osteosarcoma progression via the epithelial to mesenchymal transition mechanism and is associated with poor prognosis in patients with osteosarcoma.

OBJECTIVE: Long non-coding RNA Ftx (lncRNA Ftx) is involved in a variety of cancers. However, the association between lncRNA Ftx and osteosarcoma is still unclear. In this study, we investigated the correlation between lncRNA Ftx and osteosarcoma, and the regulative effect of Ftx on the migration and invasion of osteosarcoma cells, as well as its molecular mechanism. METHODS: Expression levels of lncRNA Ftx in osteosarcoma tissues and adjacent non-tumor corresponding tissues (ANCTs) were detected using quantitative real-time PCR (qRT-PCR). Differences in patient survival were determined by the Kaplan-Meier method and a log-rank test. The Cox regression analysis was used for univariate and multivariate analyses of prognostic values. Human osteosarcoma cell lines Saos2 and HOS were transfected with the pcDNA-Ftx constructs. The scratch wound healing assay and Transwell assay were used to assess cell migration and invasion capability, respectively. Western blot analysis was conducted to investigate the expression of mesenchymal and epithelial markers. RESULTS: The results showed that the lncRNA Ftx group was higher in osteosarcoma tissues compared with the ANCTs group. Expression of lncRNA Ftx was correlated with the clinical stage and distant metastasis (P<0.05). The overall survival rate was lower in the high lncRNA Ftx group than in the low lncRNA Ftx group (log-rank test, P<0.05). Multivariate analysis revealed that in osteosarcoma patients, higher lncRNA MEG3, advanced clinical stage, and distant metastasis were all independent predictors of overall survival. Cell research showed that transfection of lncRNA Ftx significantly promoted the migration and invasion ability of osteosarcoma cells. In addition, E-cadherin was decreased, while N-cadherin and Snail-1 were increased, at both the protein and mRNA levels. Pre-treatment with Snail-1 siRNA abrogated the promotion effect of Ftx on the migration and invasion of osteosarcoma cells. CONCLUSIONS: Increased expression of lncRNA Ftx could not only be a biomarker for progression and prognosis of osteosarcoma, but also could regulate the development of osteosarcoma via the epithelial to mesenchymal transition (EMT) mechanism.