Fibronectin Type III Domain Containing 3B Research Articles

E2F1 promotes cell migration in hepatocellular carcinoma via FNDC3B.

FNDC3B (fibronectin type III domain containing 3B) is highly expressed in hepatocellular carcinoma (HCC) and other cancer types, and fusion genes involving FNDC3B have been identified in HCC and leukemia. Growing evidence suggests the significance of FNDC3B in tumorigenesis, particularly in cell migration and tumor metastasis. However, its regulatory mechanisms remain elusive. In this study, we employed bioinformatic, gene regulation, and protein-DNA interaction screening to investigate the transcription factors (TFs) involved in regulating FNDC3B. Initially, 338 candidate TFs were selected based on previous chromatin immunoprecipitation (ChIP)-seq experiments available in public domain databases. Through TF knockdown screening and ChIP coupled with Droplet Digital PCR assays, we identified that E2F1 (E2F transcription factor 1) is crucial for the activation of FNDC3B. Overexpression or knockdown of E2F1 significantly impacts the expression of FNDC3B. In conclusion, our study elucidated the mechanistic link between FNDC3B and E2F1. These findings contribute to a better understanding of FNDC3B in tumorigenesis and provide insights into potential therapeutic targets for cancer treatment.

Fibronectin Type III Domain Containing 3B as a Potential Prognostic and Therapeutic Biomarker for Glioblastoma.

Glioblastoma (GBM) is a representative malignant brain tumor characterized by a dismal prognosis, with survival rates of less than 2 years and high recurrence rates. Despite surgical resection and several alternative treatments, GBM remains a refractory disease due to its aggressive invasiveness and resistance to anticancer therapy. In this report, we explore the role of fibronectin type III domain containing 3B (FNDC3B) and its potential as a prognostic and therapeutic biomarker in GBM. GBM exhibited a significantly higher cancer-to-normal ratio compared to other organs, and patients with high FNDC3B expression had a poor prognosis (p < 0.01). In vitro studies revealed that silencing FNDC3B significantly reduced the expression of Survivin, an apoptosis inhibitor, and also reduced cell migration, invasion, extracellular matrix adhesion ability, and stem cell properties in GBM cells. Furthermore, we identified that FNDC3B regulates PTEN/PI3K/Akt signaling in GBM cells using MetaCore integrated pathway bioinformatics analysis and a proteome profiler phospho-kinase array with sequential western blot analysis. Collectively, our findings suggest FNDC3B as a potential biomarker for predicting GBM patient survival and for the development of treatment strategies for GBM.

BIOM-29. FIBRONECTIN TYPE III DOMAIN CONTAINING 3B AS PROGNOSTIC BIOMARKER AND REGULATORY TARGET FOR MALIGNANT BRAIN TUMOR

Abstract Malignant brain tumor (MBT) is an aggressive tumor with high drug-resistance and recurrence rates. Using ‘Oncopression’ big data analysis, we found that a fibronectin-related protein, fibronectin type III domain containing 3B (FNDC3B), was specifically overexpressed in brain tumor patients and conducted a pilot and mechanism study on the role of FNDC3B in MBT. We evaluated the functional significance of FNDC3B in MBT using FNDC3B specific siRNA and performing cell viability assay, real-time qPCR, Western blot, 3D-invasion assay, and wound healing assay. Furthermore, using proteome profiler human phospho-kinase arrays, we investigated the correlated signaling which activated while FNDC3B-mediated MBT cell progression. We found that down-regulation of FNDC3B decreased tumor cell proliferation, migratory and invasiveness properties as well as stemness phenotype which are hallmarks of cancer progression. Furthermore, we demonstrate that PI3K/AKT signaling pathways were involved mainly in FNDC3B-related tumor growth and mesenchymal phenotypes. Although follow-up studies are necessary, the results of this study suggest that FNDC3B is worth investigating as a novel alternative diagnostic and therapeutic target candidate for MBT.

Circ_0000285 regulates nasopharyngeal carcinoma progression through miR-1278/FNDC3B axis.

Nasopharyngeal carcinoma (NPC) is cancer with high mortality and poor prognosis. Circular RNAs (circRNAs) have been identified in a wide variety of cancers. But the functional mechanism of circ_000285 in NPC remains unclear. To decipher the biological function and molecular mechanism of circ_000285 in NPC. Quantitative PCR (RT-qPCR) was applied for detecting the expression of circ_0000285, miR-1278, and FNDC3B. Western blot was used to measure the protein levels of Fibronectin type III domain containing 3B (FNDC3B), Bcl2 associated X (Bax), and B cell leukemia/lymphoma 2 (Bcl2). Cell proliferation, migration, and invasion were analyzed by colony formation, 5-ethynyl-2'-deoxyuridine (EdU), and transwell assays. Cell apoptosis was detected by flow cytometry assays. ELISA assay was used to analyze Caspase-3 activity. Bioinformatics was used to predict, and the target relationship between miR-1278 and circ_0000285 or FNDC3B was verified by luciferase reporter assay. Tumor xenograft models were established to examine how circ_0000285 functions during the mediation of NPC tumor growth in vivo. Increased circ_0000285 and FNDC3B expressions, and a decreased miR-1278 expression were observed in NPC tissues and cell lines. Knockdown of circ_0000285 inhibited NPC cell proliferation, migration, invasion, and while promoting NPC cell apoptosis in vitro. Circ_0000285 knockdown-mediated anti-tumor effects in NPC cells could be largely reversed by silencing of miR-1278 or overexpression of FNDC3B. Circ_0000285 could up-regulate FNDC3B expression by sponging miR-1278 in NPC cells. Knockdown of circ_0000285 could inhibit tumor growth in vivo. Circ_0000285 upregulates FNDC3B expression by adsorbing miR-1278 to promote NPC development.

Integrated machine learning methods identify FNDC3B as a potential prognostic biomarker and correlated with immune infiltrates in glioma.

BackgroundRecent discoveries have revealed that fibronectin type III domain containing 3B (FNDC3B) acts as an oncogene in various cancers; however, its role in glioma remains unclear.MethodsIn this study, we comprehensively investigated the expression, prognostic value, and immune significance of FNDC3B in glioma using several databases and a variety of machine learning algorithms. RNA expression data and clinical information of 529 patients from the Cancer Genome Atlas (TCGA) and 1319 patients from Chinese Glioma Genome Atlas (CGGA) databases were downloaded for further investigation. To evaluate whether FNDC3B expression can predict clinical prognosis of glioma, we constructed a clinical nomogram to estimate long-term survival probabilities. The predicted nomogram was validated by CGGA cohorts. Differentially expressed genes (DEGs) were detected by the Wilcoxon test based on the TCGA-LGG dataset and the weighted gene co-expression network analysis (WGCNA) was implemented to identify the significant module associated with the expression level of FNDC3B. Furthermore, we investigated the correlation between FNDC3B with cancer immune infiltrates using TISIDB, ESTIMATE, and CIBERSORTx.ResultsHigher FNDC3B expression displayed a remarkably worse overall survival and the expression level of FNDC3B was an independent prognostic indicator for patients with glioma. Based on TCGA LGG dataset, a co-expression network was established and the hub genes were identified. FNDC3B expression was positively correlated to the tumor-infiltrating lymphocytes and immune infiltration score, and high FNDC3B expression was accompanied by the increased expression of B7-H3, PD-L1, TIM-3, PD-1, and CTLA-4. Moreover, expression of FNDC3B was significantly associated with infiltrating levels of several types of immune cells and most of their gene markers in glioma.ConclusionThis study demonstrated that FNDC3B may be involved in the occurrence and development of glioma and can be regarded as a promising prognostic and immunotherapeutic biomarker for the treatment of glioma.

CircFNDC3B knockdown restrains the progression of oesophageal squamous cell carcinoma through miR-214-3p/CDC25A axis.

Circular RNA (circRNAs) Fibronectin Type III Domain Containing 3B (FNDC3B) (circFNDC3B) has been revealed to be involved in the progression of oesophageal squamous cell carcinoma (ESCC). Hence, the potential regulatory network of circFNDC3B in ESCC was further investigated. Levels of genes and proteins were examined by qRT-PCR and Western blot. In vitro assays were performed using colony formation assay, 5-Ethynyl-2'-deoxyuridine (EdU) assay, flow cytometry, wound healing assay, and transwell assay. The target relationship between miR-214-3p and circFNDC3B or cell division cycle 25 homologue A (CDC25A) was verified by dual-luciferase reporter and RIP assays. In vivo assay was carried out using the xenograft nude mice model. CircFNDC3B was highly expressed in ESCC, and high circFNDC3B expression was tightly associated with poor prognosis in ESCC patients. Functionally, circFNDC3B knockdown not only suppressed ESCC cell growth, migration and invasion in vitro, but hindered ESCC tumour growth in vivo. Mechanistically, circFNDC3B acted as a sponge for miR-214-3p to up-regulate the expression of its target CDC25A. Rescue experiments showed that miR-214-3p inhibitor reversed the anticancer effects of circFNDC3B knockdown. Moreover, forced expression of miR-214-3p suppressed the malignant phenotypes mentioned above, while this condition was abolished by CDC25A overexpression. CircFNDC3B silencing restrains the tumorigenesis of oesophageal squamous cell carcinoma through miR-214-3p/CDC25A axis, which opens a new window to the development of novel therapeutic strategy for ESCC patients.

Long Non-Coding RNA DUXAP8 Acts as an Oncogene in Sinonasal Squamous Cell Carcinoma Through miR-584-5p/FNDC3B Pathway.

Sinonasal squamous cell carcinoma (SNSCC) is one of the least frequent carcinomas in the head and neck and accounts for 60% to 75% of sinonasal malignancies. The role of long non-coding RNAs (lncRNAs) in cancer development has drawn great attention over the years. The current study intended to assess the role and specific mechanism of lncRNA double homeobox A pseudogene 8 (DUXAP8) in SNSCC. Quantitative real-time PCR (qRT-PCR) analysis was implemented to assess the expression level of DUXAP8, microRNA-584-5p (miR-584-5p), and fibronectin type III domain containing 3B (FNDC3B). Proliferation assays included colony formation assay, Cell Counting Kit-8 (CCK-8) assay, and 5-ethynyl-2'-deoxyuridine (EdU) assay. Transwell assays were implemented to monitor cell migration and invasion. Cell apoptosis was evaluated via terminal deoxynucleotidyl transferase (TdT) dUTP nick-end labeling (TUNEL) and JC-1 experiments. Mechanism experiments included RNA pull-down assay, RNA binding protein immunoprecipitation (RIP) assay, and luciferase reporter assay. DUXAP8 is overexpressed in SNSCC cells. Functionally, DUXAP8 silencing suppresses the malignant progression of SNSCC. Furthermore, DUXAP8 up-regulates the expression of FNDC3B via sponging miR-584-5p. Rescue experiments demonstrated that DUXAP8 mediates the progression of SNSCC via up-regulating FNDC3B expression. In conclusion, DUXAP8 acts as an oncogene in SNSCC, which may be a new molecular marker for SNSCC.

Biomarkers for primary open-angle glaucoma progression

Glaucoma is a heterogeneous group of progressive optic neurodegenerative. Although most patients with primary open angle glaucoma (POAG) are stable for many years, certain subgroups of POAG patients could progress over time even with treatment. This study is to identify aqueous humor (AH) biomarkers that may be associated with disease progression in POAG patients. Gene differential expression study of prospectively collected AH from patients with stable or progressive POAG. Metagenomic deep sequencing (MDS) was performed on the aqueous fluid of 20 patients with stable POAG and 20 patients with progressive POAG. Differential gene expression analysis was performed to identify host transcriptome signatures. A total of 21 transcripts were differentially expressed between groups. Differential transcripts identified by MDS. Twenty transcripts were up-regulated and 1 transcript was down-regulated in progressive POAG patients compared to stable patients. Of those, 11 transcripts were eye-related, and 5 transcripts were related to glaucomatous phenotypes (Fibronectin type III domain containing 3B (FNDC3B), Clusterin (CLU), Proprotein convertase subtilisin/kexin type 6 (PCSK6), Cadherin EGF LAG seven-pass G-type receptor 1 (Celsr1), and Rho guanine nucleotide exchange factor 4 (ARHGEF4)). Biomarkers associated with POAG progression can be identified from aqueous fluid. Identification of the biomarkers may improve glaucoma surveillance for progressive POAG.

Hsa_circRNA_0001971 contributes to oral squamous cell carcinoma progression via miR-186-5p/Fibronectin type III domain containing 3B axis.

BackgroundCircular RNAs (circRNAs) are closely associated with the progression of oral squamous cell carcinoma (OSCC). circRNA_0001971 has been proved to accelerate the OSCC development. Here, we aim to identify the new molecular mechanism of hsa_circRNA_0001971 (circRNA_0001971) in OSCC.MethodsThe levels of circRNA_0001971, miR‐186‐5p, and fibronectin type III domain containing 3B (FNDC3B) in tissues and cells were verified by qRT‐PCR or Western blotting. The interaction between circRNA_0001971, miR‐186‐5p, and FNDC3B was identified by bioinformatics analysis, luciferase assay, and RIP assay. The effect of circRNA_0001971/miR‐186‐5p/FNDC3B axis on OSCC cell proliferation, migration, and invasion by cell functional experiments including CCK8, wound healing, and transwell assays.ResultsOur study displayed that circRNA_0001971 and FNDC3B were elevated in OSCC, whereas miR‐186‐5p was declined in OSCC. Silencing circRNA_0001971 attenuated the malignancy of OSCC cells by suppressing proliferation, migration, and invasion. In OSCC cells, circRNA_0001971 sponged miR‐186‐5p to enhance FNDC3B. Due to the interaction between circRNA_0001971, miR‐186‐5p, and FNDC3B, FNDC3B overexpression relieved the negative function of silencing circRNA_0001971 in OSCC cells.ConclusionOverall, our study discovered that circRNA_0001971 was a tumor promoter in OSCC progression by targeting miR‐186‐5p/FNDC3B axis.

FNDC3B and BPGM Are Involved in Human Papillomavirus-Mediated Carcinogenesis of Cervical Cancer.

Human papillomavirus (HPV)-mediated cervical carcinogenesis is a multistep progressing from persistent infection, precancerous lesion to cervical cancer (CCa). Although molecular alterations driven by viral oncoproteins are necessary in cervical carcinogenesis, the key regulators behind the multistep process remain not well understood. It is pivotal to identify the key genes involved in the process for early diagnosis and treatment of this disease. Here we analyzed the mRNA expression profiles in cervical samples including normal, cervical intraepithelial neoplasia (CIN), and CCa. A co-expression network was constructed using weighted gene co-expression network analysis (WGCNA) to reveal the crucial modules in the dynamic process from HPV infection to CCa development. Furthermore, the differentially expressed genes (DEGs) that could distinguish all stages of progression of CCa were screened. The key genes involved in HPV-CCa were identified. It was found that the genes involved in DNA replication/repair and cell cycle were upregulated in CIN compared with normal control, and sustained in CCa, accompanied by substantial metabolic shifts. We found that upregulated fibronectin type III domain-containing 3B (FNDC3B) and downregulated bisphosphoglycerate mutase (BPGM) could differentiate all stages of CCa progression. In patients with CCa, a higher expression of FNDC3B or lower expression of BPGM was closely correlated with a shorter overall survival (OS) and disease-free survival (DFS). A receiver operating characteristic (ROC) analysis of CIN and CCa showed that FNDC3B had the highest sensitivity and specificity for predicting CCa development. Taken together, the current data showed that FNDC3B and BPGM were key genes involved in HPV-mediated transformation from normal epithelium to precancerous lesions and CCa.

LncRNA LINC00355 Acts as a Novel Biomarker and Promotes Glioma Biological Activities via the Regulation of miR-1225/FNDC3B.

Background Accumulating evidence has implicated long noncoding RNAs (lncRNAs) in glioma progression. Here, we aimed to explore the potential roles of a novel lncRNA, LINC00355, in glioma and to clarify the underlying mechanisms. Methods RT-PCR was used to examine the relative expressions of LINC00355 in glioma cell lines and specimen samples. The clinicopathological and prognostic significances of LINC00355 in glioma patients were statistically analyzed. To determine cell activities, CCK-8, clonogenic assays, flow cytometry, migration, and invasion assays were performed. Moreover, the potential mechanisms of LINC00355 were investigated by bioinformatics assays and luciferase reporter assays. Results LINC00355 expression was increased in glioma cell lines and specimens, and higher LINC00355 expression predicted advanced clinical progress and reduced overall survival and disease-free survival in glioma patients. Functionally, LINC00355 depletion promoted cell proliferation, invasion, and migration in glioma cells and induced apoptosis of glioma cells, whereas LINC00355 upregulation resulted in the opposite effects in vitro. Mechanistic assays revealed that LINC00355 as a sponge for miR-1225 repressed fibronectin type III domain-containing 3B (FNDC3B) expressions. Conclusion Our findings revealed the tumor-promotive roles of LINC00355 in the progression of glioma, indicating that LINC00355 exhibited ceRNA functions via modulating miR-1225/FNDC3B axis.

Isoflurane upregulates microRNA-9-3p to protect rats from hepatic ischemia-reperfusion injury through inhibiting fibronectin type III domain containing 3B

ABSTRACT Isoflurane has been studied in ischemia-reperfusion injury, while the regulatory mechanism by which isoflurane regulates microRNA(miR)-9-3p in hepatic ischemia/reperfusion injury (HIRI) via targeting fibronectin type III domain containing 3B (FNDC3B) remains seldom investigated. This study aims to determine the role of miR-9-3p in HIRI progression under the treatment of isoflurane. Rat HIRI models were established and treated with isoflurane. MiR-9-3p was altered to assess its role in inflammation, oxidative stress, transaminases, pathology, and hepatocyte apoptosis in HIRI rat liver tissues. Expression of miR-9-3p and FNDC3B in rat liver tissues was determined, and the targeting relationship between miR-9-3p and FNDC3B was confirmed using bioinformatic prediction and dual luciferase reporter gene assay. MiR-9-3p was downregulated, whereas FNDC3B was upregulated in HIRI rat liver tissues. Isoflurane treatment upregulated miR-9-3p and attenuated pathological changes, inflammation, oxidative stress, transaminases, and hepatocyte apoptosis in HIRI rat liver tissues. MiR-9-3p upregulation further strengthened the effect of isoflurane on HIRI, while miR-9-3p downregulation suppressed the therapeutic role of isoflurane. FNDC3B was confirmed as a target gene of miR-9-3p. Isoflurane upregulates miR-9-3p to protect rats from HIRI by inhibiting FNDC3VB. Our research may provide novel targets for HIRI treatment.

CircSOS2 promotes cervical squamous cell carcinoma by regulation of proliferation, cell cycle, apoptosis, migration, invasion, and glycolysis by targeting miR-543/FNDC3B axis

BackgroundCervical squamous cell carcinoma (SCC) is a common subtype of cervical cancer. Circular RNAs (circRNAs) have been demonstrated as vital regulators in gene regulation and malignant tumor progression. Therefore, the precise role of circular RNA salt overly-sensitive 2 (circSOS2) was investigated in SCC. MethodsThe relative expression levels of circSOS2, microRNA-543 (miR-543), and Fibronectin type III domain containing 3B (FNDC3B) were determined by real-time quantitative polymerase chain reaction (RT-qPCR) and Western blot assays. The correlation between percent survival times of SCC patients and circSOS2 level was presented by Kaplan-Meier Plotter analysis. The cell proliferation was measured by MTT and colony-forming assays. Flow cytometry assay was used to assess apoptosis and cell cycle distribution. The migration and invasion were measured by transwell assay. The glycolysis was analyzed by extracellular acidification rate (ECAR) assay, Glucose Assay Kit, and Lactate Assay Kit. The interaction relationship between miR-543 and circSOS2 or FNDC3B was analyzed by dual-luciferase reporter, RNA immunoprecipitation (RIP), and RNA pull-down assays. A xenograft experiment was established to clarify the functional role of circSOS2 inhibition in viv. ResultsCircSOS2 was highly expressed in SCC tissues and cells; besides, its expression level was closely associated with poor prognosis. Loss-of-functional experiments revealed that suppression of circSOS2 repressed proliferation, cell cycle process, migration, invasion, and glycolysis while induced apoptosis in SCC cells, which was overturned by inhibition of miR-543. In addition, miR-543 was downregulated and negatively correlated with circSOS2 expression in SCC tissues. We also found that overexpression of miR-543 impeded proliferation, cell cycle process, migration, invasion, and glycolysis while induced apoptosis in SCC cells by targeting FNDC3B. The silencing of circSOS2 impeded tumorigenesis in vivo. ConclusionCircSOS2 conferred an oncogenic function in SCC by regulation of proliferation, cell cycle, apoptosis, migration, invasion, and glycolysis of SCC cells, which was contributed to its interactions with miR-543 and FNDC3B.

Circ_0006948 Contributes to Cell Growth, Migration, Invasion and Epithelial-Mesenchymal Transition in Esophageal Carcinoma.

Circular RNAs (circRNAs) can act as promoters or inhibitors in cancer progression. Has_circ_0006948 (circ_0006948) was reported to aggravate the malignant behaviors of esophageal carcinoma (EC). This study focused on investigating the molecular mechanism of circ_0006948 in EC progression. The quantitative real-time polymerase chain reaction was performed to detect the expression of circ_0006948, microRNA-4262 (miR-4262) and fibronectin type III domain containing 3B (FNDC3B). Cell growth analysis was conducted by Cell Counting Kit-8 and colony formation assays. Cell migration and invasion were assessed by transwell assay. Epithelial-mesenchymal transition (EMT)-associated proteins and FNDC3B protein expression were assayed using western blot. Dual-luciferase reporter and RNA pull-down assays were performed to validate the target combination. Xenograft tumor assay was used for investigating the role of circ_0006948 in vivo. Circ_0006948 was upregulated in EC tissues and cells. Downregulating the expression of circ_0006948 or FNDC3B repressed cell growth, migration, invasion and EMT in EC cells. Target analysis indicated that miR-4262 was a target for circ_0006948 and FNDC3B was a downstream gene for miR-4262. Moreover, circ_0006948 could affect the expression of FNDC3B via sponging miR-4262. The effects of si-circ_0006948#1 on EC cells were partly restored by miR-4262 inhibition or FNDC3B overexpression. In addition, circ_0006948 also facilitated EC tumorigenesis in vivo by targeting the miR-4262/FNDC3B axis. Taken together, circ_0006948 functioned as an oncogenic factor in EC by the miR-4262-mediated FNDC3B expression regulation.

FNDC3B 3'-UTR shortening escapes from microRNA-mediated gene repression and promotes nasopharyngeal carcinoma progression.

Alternative polyadenylation (APA), which induces shortening of the 3′‐UTR, is emerging as an important feature in cancer development and progression. Nevertheless, the effects and mechanisms of APA‐induced 3′‐UTR shortening in nasopharyngeal carcinoma (NPC) remain largely unclear. Fibronectin type III domain containing 3B (FNDC3B) tended to use proximal polyadenylation site and produce shorter 3′‐UTR according to our previous sequencing study. Herein, we found that FNDC3B with shorter 3′‐UTR could escape from miRNA‐mediated gene repression, and caused its increased expression in NPC. Knocking down of FNDC3B inhibited NPC cell proliferation, migration, invasion, and metastasis in vitro and in vivo. Overexpression of FNDC3B, especially those with shorter 3′‐UTR, promoted NPC progression. Furthermore, the mechanism study revealed that FNDC3B could bind to and stabilize myosin heavy chain 9 (MYH9) to activate the Wnt/β‐catenin signaling pathway. In addition, MYH9 could reverse the inhibitory effects of FNDC3B knockdown in NPC. Altogether, our results suggested that the 3′‐UTR shortening of FNDC3B mRNA mediated its overexpression in NPC and promoted NPC progression by targeting MYH9. This newly identified FNDC3B‐MYH9‐Wnt/β‐catenin axis could represent potential targets for individualized treatment in NPC.

FNDC3B, Targeted by miR-125a-5p and miR-217, Promotes the Proliferation and Invasion of Colorectal Cancer Cells via PI3K/mTOR Signaling.

BackgroundFibronectin type III domain containing 3B (FNDC3B) acts as an oncogene in various cancers, and abnormal expression of FNDC3B has been found in colorectal cancer (CRC). Our study aimed to illustrate the role of FNDC3B in CRC development.MethodsThrough RT-qPCR and western blotting assays, the mRNA and protein expressions of target genes were measured. CCK-8 and MTT methods were used to detect cell proliferation. Invasion ability was determined using Transwell assay. TargetScan platform and luciferase reporter gene assay were performed to predict and validate the bindings between FNDC3B and miR-125a-5p or miR-217. Besides, the expression correlation was measured by Pearson’s Correlation analysis.ResultsWe found that FNDC3B was significantly upregulated in CRC tissues and tumor cell lines, and high expression of FNDC3B predicted a poor survival outcome. The bindings between FNDC3B and miR-125a-5p and miR-217 were respectively at the motifs of CUCAGGG and AUGCAGU. MiR-125a-5p and miR-217 were downregulated in CRC tissues, and both were negatively correlated with FNDC3B expression. Subsequently, the downregulated miR-125a-5p and miR-217 were confirmed as contributors FNDC3B upregulation in CRC. A loss-of-function assay demonstrated that FNDC3B knockdown inhibited the proliferation of CRC cells, while FNDC3B overexpression promoted the proliferation and invasion of tumor cells. Besides, we validated that PI3K/mTOR signaling was involved in the regulation of FNDC3B on the proliferation and invasion of CRC cells.ConclusionGenerally, our findings demonstrated that FNDC3B facilitated cell proliferation and invasion via PI3K/mTOR signaling, and further promoted CRC progression. The novel miR-125a-5p/FNDC3B and miR-217/FNDC3B axes might be new targets for CRC prognosis and therapy.

Novel lncRNA XLOC_032768 protects against renal tubular epithelial cells apoptosis in renal ischemia–reperfusion injury by regulating FNDC3B/TGF-β1

Renal ischemia–reperfusion injury is a leading cause of acute kidney injury, but its underlying mechanism remains poorly understood and effective therapies are still lacking. Here, we identified lncRNA XLOC_032768 as a novel target in renal ischemia–reperfusion injury by analyzing differentially expressed genes of the transcriptome data. PCR results show that XLOC_032768 was markedly downregulated in the kidney during renal ischemia–reperfusion in mice and in cultured kidney cells during hypoxia. Upon induction in vitro, XLOC_032768 overexpression repressed the expression of fibronectin type III domain containing 3B (FNDC3B) and tubular epithelial cells apoptosis. Administration of XLOC_032768 preserved FNDC3B expression and attenuated renal tubular epithelial cells apoptosis, resulting in protection against kidney injury in mice. Knockdown of FNDC3B markedly reduced the expression of TGF-β1 and apoptosis of renal tubular cells. Thus, XLOC_032768/FNDC3B/TGF-β1signaling pathway in ischemia–reperfusion injury may be targeted for therapy.

FNDC3B is associated with ER stress and poor prognosis in cervical cancer.

Currently, the occurrence and mortality rate of cervical cancer is high, particularly in low-to-middle-income countries. Therefore, the development of novel diagnostic and treatment strategies for cervical cancer is urgently required. The aim of the present study was to assess the prognostic significance of fibronectin type III domain containing 3B (FNDC3B) expression in patients with cervical cancer and to determine the underlying mechanism of FNDC3 in tumor development. Analysis of the ONCOMINE database revealed that FNDC3B was significantly upregulated in cervical cancer tissue compared with normal tissue. Additionally, FNDC3B expression data and the clinical characteristics of patients with cervical cancer were obtained from the cBioPortal database. Correlations between FNDC3B expression and overall survival were subsequently investigated. The results revealed that increased FNDC3B expression was significantly correlated with a lower overall survival in patients with cervical cancer. A co-expression network was subsequently constructed to elucidate the function of FNDC3B in cervical cancer. Co-expression genes for FNDC3B were obtained from the cBioPortal database and were subjected to Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses. The results demonstrated that the genes were enriched in pathways associated with migration, invasion, endoplasmic reticulum (ER) stress and the unfolded protein response (UPR). Furthermore, immunofluorescence results obtained from the Human Protein Atlas revealed that the FNDC3B protein was localized to the ER. The results revealed that upregulated FNDC3B expression may be a biomarker for poor prognosis for patients with cervical cancer. Additionally, the results revealed that FNDC3B may serve an oncogenic role in cancer development via ER stress, UPR, cell migration and invasion. However, further studies are required to determine the exact molecular mechanism of FNDC3B in the development of cervical cancer and to assess its potential as a novel therapeutic target for the treatment of this disease.

Overexpression of fibronectin type III domain containing 3B is correlated with epithelial-mesenchymal transition and predicts poor prognosis in lung adenocarcinoma.

Fibronectin (FN) type III domain containing 3B (FNDC3B), a member of the FN family, regulates the invasion and metastasis of cells in numerous tumor types. However, the mechanisms through which FNDC3B regulates carcinogenesis in lung adenocarcinoma (LADC) tissues have remained elusive. The present study revealed that the protein levels of FNDC3B and vimentin were significantly elevated in LADC tissues compared with those in normal lung tissues. By contrast, the expression of E-cadherin was decreased in LADC tissues compared with that in normal lung tissues. Furthermore, the aberrant expression of FNDC3B and epithelial-mesenchymal transition (EMT) markers was significantly associated with histological differentiation, lymph node metastasis and tumor-nodes-metastasis stage. Kaplan-Meier analysis indicated that a high expression of FNDC3B may be associated with poor overall survival of patients with LADC. In addition, overexpression of FNDC3B promoted the protein expression of EMT-associated genes in the A549 lung adenocarcinoma cell line. In conclusion, the present results support the notion that FNDC3B acts as an oncogene in LADC; it may serve a pivotal role in the development and progression of LADC and may participate in the regulation of the EMT.

Abstract 1506: Characterization of fibronectin type III domain containing 3B (FNDC3B) as a novel fusion partner of retinoic acid receptor alpha in granulocytic differentiation

Abstract Acute promyelocytic leukemia (APL) is characterized by the promyelocytic leukemia-retinoic acid receptor alpha (PML-RARA) fusion. Recently, we identified fibronectin type III domain containing 3B (FNDC3B) as a novel RARA fusion partner resulting from the t(3;17)(q26;q21) translocation in a variant APL patient. Unlike other RARA fusion partners, FNDC3B appears as the only partner involved in granulocytic differentiation but the molecular mechanisms underlying its actions remain to be characterized. FNDC3B mRNA expression in normal and malignant hematopoietic cells was determined by quantitative RT-PCR. Transcriptional control of FNDC3B was studied by reporter gene assays, site-directed mutagenesis and chromatin immunoprecipitation (ChIP) assays. FNDC3B-regulated pathways were identified by transcriptome analyses. Using BloodSpot, we observed that FNDC3B expression was progressively up-regulated as human hematopoietic stem cells (HSCs) differentiate along the granulocytic lineage, with the highest level in terminally differentiated polymorphonuclear cells. Concordantly, we demonstrated lower expression of FNDC3B in human cord blood CD34+ HSCs than HL-60 promyelocytes. The specific involvement of FNDC3B in granulocytic differentiation was further suggested by higher FNDC3B expression and promoter activity in human promyelocytic than monocytic cell lines. Mutational analyses indicated that two putative CCAAT-enhancer binding protein epsilon (CEBPE) and one Sp1 binding sites were critical for FNDC3B promoter activity in HL-60 cells. The specific association of CEBPE and Sp1 with the FNDC3B promoter could be confirmed by ChIP assays. Knockdown of CEBPE in HL60 cells by small interfering RNA (siRNA) reduced FNDC3B expression and promoter activity. Furthermore, we observed a strong positive correlation between CEBPE and FNDC3B expression in the Cancer Genome Atlas (TCGA)-acute myeloid leukemia (AML) dataset (n=173, r=0.66, P&amp;lt;0.0001). Collectively, these findings indicate CEBPE, which is critical in terminal granulopoiesis, as an important factor controlling FNDC3B transcription in granulocytic cells. Using RNA-seq, we found that FNDC3B knockdown in NB4 promyelocytes was associated with preferential downregulation of genes encoding granule and endoplasmic reticulum (ER) structural/functional proteins. Concordantly, DAVID functional annotation of genes that are positively correlated with FNDC3B in the TCGA-AML cohort revealed enrichment of Gene Ontology terms related to ER functions. Together, these findings suggest that FNDC3B mediates its functions primarily by targeting the ER/granule pathway, which is important for granulocytic maturation. In summary, our data indicate FNDC3B as a novel CEBPE target in the myeloid transcriptional hierarchy and may provide new clues in abnormal granulopoiesis. Citation Format: Zhe Wand, Chi Keung Cheng, Terry Wong, Kin Mang Lau, Thomas S.k. Wan, Kam Tong Leung, Margaret Heung-Ling Ng. Characterization of fibronectin type III domain containing 3B (FNDC3B) as a novel fusion partner of retinoic acid receptor alpha in granulocytic differentiation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1506.