Far Upstream Element-binding Protein 1 Research Articles

Circulating autoantibodies to alpha-enolase (ENO1) and far upstream element-binding protein 1 (FUBP1) are negative prognostic factors for pancreatic cancer patient survival

Pancreatic ductal adenocarcinoma (PDA) has a dismal prognosis due to a lack of early diagnostic markers and effective therapy. In PDA patients, the glycolytic enzyme and plasminogen receptor alpha-enolase (ENO1) and the transcription factor far upstream element-binding protein 1 (FUBP1) are upregulated and elicit the production of autoantibodies (aAb) that discriminate healthy subjects from PDA patients, with the latter mostly directed to post-translational phosphorylated isoforms. Here, the correlation of prognosis with circulating ENO1 and FUBP1aAb, and their protein tissue expression was analyzed in PDA patients. Circulating ENO1 and FUBP1 aAb was analyzed in two cohorts of PDA patients by ELISA (n = 470), while tissues expression was observed by immunohistochemistry (n = 45). Overall survival (OS) was estimated using the Kaplan–Meier method, while the Cox model was used to estimate the hazard ratios (HR) adjusted for the main prognostic factors. Logistic models were applied to assess associations between death and its risk indicators. All statistical analyses were performed with Stata version 15. Unlike ENO1 aAb, there was a significant correlation between FUBP1 aAb and FUBP1 expression in tumors (p = 0.0268). In addition, we found that high ENO1 (p = 0.016) and intermediate FUBP1 aAb levels (p = 0.013) were unfavorable prognostic factors. Notably, it was found that high anti-FUBP1 aAb level is a good prognostic marker for tail-body PDA (p = 0.016). Our results suggest that different levels of circulating aAb to ENO1 and FUBP1 predict a poor outcome in PDA patients and can be used to improve therapeutic strategies.

Icariin activates far upstream element binding protein 1 to regulate hypoxia-inducible factor-1α and hypoxia-inducible factor-2α signaling and benefits chondrocytes.

Icariin (ICA) is a typical flavonoid glycoside derived from epimedium plants. It has both anabolic and anti-catabolic effects to improve bone mineral density and reduce bone microstructural degradation. However, the effect and underlying mechanism of ICA on the proliferation and metabolism of chondrocyte and synthesis of extracellular matrix are still unclear. This study aimed to investigate the role and regulation of far upstream element binding protein 1 (FUBP1) in chondrocytes treated with ICA to maintain homeostasis and suppress inflammatory responses. In the study, the effect of ICA on chondrocytes with overexpressed or silenced FUBP1 was detected by the MTS and single-cell cloning methods. The expression of hypoxia-inducible factor-1/2α (HIF-1/2α), FUBP1, matrix metalloproteinase (MMP)9, SRY-box transcription factor 9 (SOX9), and type II collagen (Col2α) in ATDC5 cells, a mouse chondrogenic cell line, treated with ICA was evaluated by immunoblotting. Western blotting revealed 1 µM ICA to have the most significant effect on chondrocytes. Alcian blue staining and colony formation assays showed that the promoting effect of ICA was insignificant in FUBP1-knockdown cells (P > 0.05) but significantly enhanced in FUBP1-overexpressed cells (P < 0.05). Western blot results from FUBP1-knockdown cells treated with or without ICA showed no significant difference in the expression of FUBP1, HIF-1/2α, MMP9, SOX9, and Col2α proteins, whereas the same proteins showed increased expression in FUBP1-overexpressed chondrocytes; moreover, HIF-2α and MMP9 expression was significantly inhibited in FUBP1-knockdown chondrocytes (P < 0.05). In conclusion, as a bioactive monomer of traditional Chinese medicine, ICA is beneficial to chondrocytes.

Far upstream element-binding protein 1 confers lobaplatin resistance by transcriptionally activating PTGES and facilitating the arachidonic acid metabolic pathway in osteosarcoma.

Drug resistance is a major obstacle in cancer treatment and recurrence prevention and leads to poor outcomes in patients suffering from osteosarcoma. Clarification of the mechanism of drug resistance and exploration of effective strategies to overcome this obstacle could lead to clinical benefits for these patients. The expression of far upstream element-binding protein 1 (FUBP1) was found to be markedly elevated in osteosarcoma cell lines and clinical specimens compared with osteoblast cells and normal bone specimens. High expression of FUBP1 was correlated with a more aggressive phenotype and a poor prognosis in osteosarcoma patients. We found that overexpression of FUBP1 confers lobaplatin resistance, whereas the inhibition of FUBP1 sensitizes osteosarcoma cells to lobaplatin-induced cytotoxicity both in vivo and in vitro. Chromatin immunoprecipitation-seq and RNA-seq were performed to explore the potential mechanism. It was revealed that FUBP1 could regulate the transcription of prostaglandin E synthase (PTGES) and subsequently activate the arachidonic acid (AA) metabolic pathway, which leads to resistance to lobaplatin. Our investigation provides evidence that FUBP1 is a potential therapeutic target for osteosarcoma patients. Targeting FUBP1, its downstream target PTGES and the AA metabolic pathway may be promising strategies for sensitizing chemoresistant osteosarcoma cells to lobaplatin.

The NR_109/FUBP1/c-Myc axis regulates TAM polarization and remodels the tumor microenvironment to promote cancer development

BackgroundTumor-associated macrophages (TAMs) are a major component of the tumor microenvironment (TME) and exert an important role in tumor progression. Due to the heterogeneity and plasticity of TAMs, modulating the...

A circular RNA, circPTPN14, increases MYC transcription by interacting with FUBP1 and exacerbates renal fibrosis.

Fibrosis is a relentlessly progressive and irreversible cause of organ damage, as in chronic kidney disease (CKD), but its underlying mechanisms remain elusive. We found that a circular RNA, circPTPN14, is highly expressed in human kidneys with biopsy-proved chronic interstitial fibrosis, mouse kidneys subjected to ischemia/reperfusion (IR) or unilateral ureteral obstruction (UUO), and TGFβ1-stimulated renal tubule epithelial cells (TECs). The intrarenal injection of circPTPN14 shRNA alleviated the progression of fibrosis in kidneys subjected to IR or UUO. Knockdown of circPTPN14 in TECs inhibited TGFβ1-induced expression of profibrotic genes, whereas overexpressing circPTPN14 increased the profibrotic effect of TGFβ1. The profibrotic action of circPTPN14 was ascribed to an increase in MYC transcription. The binding of circPTPN14 to the KH3 and KH4 domains of far upstream element (FUSE) binding protein 1 (FUBP1) enhanced the interaction between FUBP1 and FUSE domain, which was required for the initiation of MYC transcription. In human kidneys (n = 30) with biopsy-proved chronic interstitial fibrosis, the expression of circPTPN14 positively correlated with MYC expression. Taken together these studies show a novel mechanism in the pathogenesis of renal fibrosis, mediated by circPTPN14, which can be a target in the diagnosis and treatment of CKD.

Discovery of Anthranilic Acid Derivatives as Difluoromethylornithine Adjunct Agents That Inhibit Far Upstream Element Binding Protein 1 (FUBP1) Function.

Polyamine biosynthesis is regulated by ornithine decarboxylase (ODC), which is transcriptionally activated by c-Myc. A large library was screened to find molecules that potentiate the ODC inhibitor, difluoromethylornithine (DFMO). Anthranilic acid derivatives were identified as DFMO adjunct agents. Further studies identified the far upstream binding protein 1 (FUBP1) as the target of lead compound 9. FUBP1 is a single-stranded DNA/RNA binding protein and a master controller of specific genes including c-Myc and p21. We showed that 9 does not inhibit 3H-spermidine uptake yet works synergistically with DFMO to limit cell growth in the presence of exogenous spermidine. Compound 9 was also shown to inhibit the KH4 FUBP1-FUSE interaction in a gel shift assay, bind to FUBP1 in a ChIP assay, reduce both c-Myc mRNA and protein expression, increase p21 mRNA and protein expression, and deplete intracellular polyamines. This promising hit opens the door to new FUBP1 inhibitors with increased potency.

FBP1 knockdown decreases ovarian cancer formation and cisplatin resistance through EZH2-mediated H3K27me3.

Worldwide, ovarian cancer (OC) is the seventh common cancer and the second most common cause of cancer death in women. Due to high rates of relapse, there is an urgent need for the identification of new targets for OC treatment. The far-upstream element binding protein 1 (FBP1) and enhancer of zeste homolog 2 (EZH2) are emerging proto-oncogenes that regulate cell proliferation and metastasis. In the present study, Oncomine data analysis demonstrated that FBP1 was closely associated with the development of OC, and The Cancer Genome Atlas (TCGA) data analysis indicated that there was a positive correlation between FBP1 and EZH2 in ovarian tissues. Moreover, we found that FBP1 knockdown suppressed tumor formation in nude mice and cisplatin resistance of OC cells, but the role of FBP1 in the cisplatin resistance of OC cells remained unclear. In addition, we verified physical binding between FBP1 and EZH2 in OC cells, and we demonstrated that FBP1 knockdown enhanced cisplatin cytotoxicity in OC cells and down-regulated EZH2 expression and trimethylation of H3K27. These results suggested that FBP1 increases cisplatin resistance of OC cells by up-regulating EZH2/H3K27me3. Thus, FBP1 is a prospective novel target for the development of OC treatment.

FUBP1 promotes the proliferation of lung squamous carcinoma cells and regulates tumor immunity through PD-L1.

Lung cancer is a common malignancy. Non-small cell lung cancer (NSCLC) is divided into lung squamous cancer (LUSC), large cell carcinoma, and adenocarcinoma. More than 85% of lung cancer cases are NSCLC patients. Further exploration of the pathogenesis of lung cancer is of great significance. In this study, functions of far upstream element-binding protein 1 (FUBP1) on the proliferation and tumor immunity of LUSC cells were evaluated. The Cancer Genome Atlas (TCGA) database, Western blot analysis, and immunohistochemistry (IHC) analysis were used to examine the overexpression levels of FUBP1 in LUSC and paracancerous tissues, LUSC cell line, and human normal lung cell line. Then, Western blot assay was employed to validate the transfection efficiency of FUBP1 knockdown in SK-MES-1 cells. Cell counting kit-8 and colony formation assays were used to detect the viability and proliferation of SK-MES-1 cells. Transwell assay was used to examine the migrative and invasive abilities of SK-MES-1 cells. Finally, the xenograft tumor mice model was applied to explore the role of FUBP1 in vivo. IHC assay was used to determine the expression levels FUBP1, PD-L1, and Ki-67. Flow cytometry technology was employed to detect the proportion of CD4+ and CD8+ cells in short sequence negative control (sh-NC) and sh-FUBP1 groups. Collectively, the results first indicated that FUBP1 was up-regulated in LUSC tissues and cells. It was also demonstrated that knockdown of FUBP1 suppressed cell migration, invasion, and proliferation in lung squamous carcinoma cells. Finally, knockdown of FUBP1 regulated tumor immunity in vivo. This research suggested that FUBP1 promotes the proliferation of LUSC cells and regulates tumor immunity through programmed death-ligand 1 (PD-L1).

Far upstream element -binding protein 1 (FUBP1) participates in the malignant process and glycolysis of colon cancer cells by combining with c-Myc

ABSTRACT Human distal upstream element (Fuse) binding protein 1 (FUBP1) is a transcriptional regulator of c-Myc and represents an important prognostic marker in many cancers. Therefore, the present study aimed to investigate whether FUBP1 could combine with c-Myc to participate in the progression of colon cancer. Detection of FUBP1 expression was done through reverse transcription-quantitative PCR (RT-qPCR), and the combination of FUBP1 and c-Myc was detected by immunoprecipitation assay. Cell counting kit (CCK)-8, colony formation, transwell and wound healing were applied for assessing the ability of cells to proliferate, migrate, and invade; glycolysis and lactic acid detection kits were used to detect glucose uptake and lactic acid content, while western blotting was adopted to detect the protein expression of glycolysis-related genes. FUBP1 expression was elevated in HCT116 cells relative to other colon cancer cell lines, and silencing FUBP1 could inhibit the ability of HCT116 cells to proliferate, migrate, invade and glycolysis, and enhance its apoptosis. In addition, the results of immunoprecipitation experiments showed that FUBP1 could bind to c-Myc. c-Myc overexpression reversed the inhibitory effects of FUBP1 knockdown on the ability of HCT116 cells to proliferate, migrate, invade and glycolysis. The results indicated that FUBP1 could participate in the deterioration process of colon cancer cells by combining with c-Myc, and it has clinical significance for understanding the key role of FUBP1 in tumor genesis.

Effect of RNA Interference Inhibiting the Expression of the FUBP1 Gene on Biological Function of Gastric Cancer Cell Line SGC7901.

The research aimed to observe the effect of gene silencing on the proliferation, migration, cell cycle, apoptosis, and other biological functions of human gastric cancer cells with RNA interference inhibiting the expression of the far upstream element-binding protein 1 (FUBP1) in the gastric cancer cell line SGC7901. The shRNA lentivirus vector of the target gene FUBP1 was constructed to transfect the gastric cancer cell line SGC7901. The qRT-PCR and western blot assays were used to detect the expression levels of FUBP1 mRNA and protein in the gastric cancer cells. The CCK-8 assay was used to detect the proliferation of gastric cancer cells. The cell scratch assay and the transwell assays were used to detect the migration of gastric cancer cells. Flow cytometry was used to detect cell cycle distribution and apoptosis. The shRNA lentiviral vector of FUBP1 was successfully transfected into the gastric cancer cell line SGC7901, and could effectively reduce the expression of mRNA and protein of FUBP1. The silencing of FUBP1 could inhibit the gastric cancer cell proliferation and affect the distribution of the cell cycle, resulting in S-phase arrest and cell growth inhibition. However, FUBP1 silencing has no significant effect on cell apoptosis and migration. The expression of FUBP1 can be inhibited specifically and effectively by RNA interference technology, which can significantly affect the biological function of the gastric cancer cell line SGC7901.

Long non-coding RNA KRT8P41/miR-193a-3p/FUBP1 axis modulates the proliferation and invasion of chordoma cells

Chordomas are low-grade malignancies accounting for 1–4% of primary bone malignancies. Moreover, local recurrences increase the rate of metastasis. Our previous study identified the far upstream element (FUSE)-binding protein 1 (FUBP1) as a biomarker and potential therapeutic target for chordoma. In this study, lncRNA KRT8P41 was identified as a lncRNA positively correlated with FUBP1. In chordoma patients, higher lncRNA KRT8P41 expression was correlated with a poorer prognosis. LncRNA KRT8P41 silencing significantly inhibited chordoma cell proliferation and invasion. miR-193a was negatively correlated with lncRNA KRT8P41 and FUBP1; lncRNA KRT8P41 inhibited miR-193a expression, and miR-193a inhibited FUBP1 expression. Furthermore, miR-193a directly bound to lncRNA KRT8P41 and FUBP1 and lncRNA KRT8P41 competed with FUBP1 for miR-193a binding and relieved miR-193a-mediated FUBP1 inhibition. LncRNA KRT8P41 silencing inhibited, whereas miR-193a inhibition promoted chordoma cell proliferation and invasion; the inhibition of miR-193a attenuated the roles of lncRNA KRT8P41. Within chordoma tissues, the expression of miR-193a was decreased, and the expression of FUBP1 increased compared to normal control tissues. LncRNA KRT8P41 exhibited a positive correlation with FUBP1 and a negative correlation with miR-193a in vivo. Therefore, it was concluded that lncRNA KRT8P41, miR-193a-3p, and FUBP1 form a lncRNA-miRNA-mRNA axis, modulating the proliferation and invasion of chordoma cells.

FUBP1 promotes colorectal cancer stemness and metastasis via DVL1-mediated activation of Wnt/β-catenin signaling.

Distant metastasis is, unfortunately, the leading cause of death in colorectal cancer (CRC). Approximately 50% of CRC patients develop liver metastases, while 10–30% of patients develop pulmonary metastases. The occurrence of metastasis is considered to be almost exclusively driven by cancer stem cells (CSCs) formation. However, the key molecules that confer the transformation to stem cells in CRC, and subsequent metastasis, remain unclear. Far upstream element‐binding protein 1 (FUBP1), a transcriptional regulator of c‐Myc, was screened in CSCs of CRC by mass spectrometry and was examined by immunohistochemistry in a cohort of CRC tissues. FUBP1 was upregulated in 85% of KRAS‐mutant and 25% of wild‐type CRC patients. Further, whether in KRAS‐mutant or wild‐type patients, elevated FUBP1 was positively correlated with CRC lymph node metastasis and clinical stage, and negatively associated with overall survival. Overexpression of FUBP1 significantly enhanced CRC cell migration, invasion, tumor sphere formation, and CD133 and ALDH1 expression in vitro, and tumorigenicity in vivo. Mechanistically, FUBP1 promoted the initiation of CSCs by activating Wnt/β‐catenin signaling via directly binding to the promoter of DVL1, a potent activator of β‐catenin. Knockdown of DVL1 significantly inhibited the transformation to stem cells in, as well as the tumorigenicity of, CRC. Activation of Wnt/β‐catenin signaling by DVL1 increased pluripotent transcription factors, including c‐Myc, NANOG, and SOX2. Moreover, FUBP1 was upregulated at the post‐transcriptional level. Elevated FUBP1 levels in KRAS wild‐type CRC patients is due to the decrease in Smurf2, which promotes ubiquitin‐mediated degradation of FUBP1. In contrast, FUBP1 was upregulated in KRAS‐mutant patients through both inhibition of caspase 3‐dependent cleavage and decreased Smurf2. Our results demonstrate, for the first time, that FUBP1 is an oncogene, initiating the development of CSCs, as well as a new powerful endogenous Wnt‐signaling agonist that could provide an important prognostic factor and therapeutic target for metastasis in both KRAS‐mutant and wild‐type CRC.

LCAT3, a novel m6A-regulated long non-coding RNA, plays an oncogenic role in lung cancer via binding with FUBP1 to activate c-MYC

BackgroundLong non-coding RNAs (lncRNAs) are important epigenetic regulators, which play critical roles in diverse physiological and pathological processes. However, the regulatory mechanism of lncRNAs in lung carcinogenesis remains elusive. Here, we characterized a novel oncogenic lncRNA, designated as Lung Cancer Associated Transcript 3 (LCAT3).MethodsWe predicted and validated LCAT3 by analyzing RNA-sequencing (RNA-seq) data of lung cancer tissues from TCGA. Methylated RNA immunoprecipitation was performed to assess m6A modification on LCAT3. The LCAT3-FUBP1-MYC axis was assessed by dual-luciferase reporter, RNA immunoprecipitation and Chromatin immunoprecipitation assays. Signaling pathways altered by LCAT3 knockdown were identified using RNA-seq. Furthermore, the mechanism of LCAT3 was investigated using loss-of-function and gain-of-function assays in vivo and in vitro.ResultsLCAT3 was found to be up-regulated in lung adenocarcinomas (LUAD), and its over-expression was associated with the poor prognosis of LUAD patients. LCAT3 upregulation is attributable to N6-methyladenosine (m6A) modification mediated by methyltransferase like 3 (METTL3), leading to LCAT3 stabilization. Biologically, loss-of-function assays revealed that LCAT3 knockdown significantly suppressed lung cancer cell proliferation, migration and invasion in vitro, and inhibited tumor growth and metastasis in vivo. LCAT3 knockdown induced cell cycle arrest at the G1 phase. Mechanistically, LCAT3 recruited Far Upstream Element Binding Protein 1 (FUBP1) to the MYC far-upstream element (FUSE) sequence, thereby activating MYC transcription to promote proliferation, survival, invasion and metastasis of lung cancer cells.ConclusionsTaken together, we identified and characterized LCAT3 as a novel oncogenic lncRNA in the lung, and validated the LCAT3-FUBP1-MYC axis as a potential therapeutic target for LUAD.

Two Hematopoietic Transcription Factors, RUNX1 and FUBP1, Control the Expression of KIT Oncogene in Pre-B Lymphoblasts

Hematopoiesis involves an elaborate network of transcription factors articulated with transcriptional cooperators. RUNX1 geneencodes a transcription factor playing a key role in hematopoiesis. Abnormal functions of RUNX1 protein are implicated in blood cancer, notably in pediatric B-cell precursor acute lymphoblastic leukemia (BCP-ALL). To unravel the mechanisms behind the modulation of the transcriptional activity of RUNX1, we performed experiments of RUNX1-specific chromatin immunoprecipitation (ChIP) followed by mass spectrometry, and identified Far Upstream Element Binding Protein 1 (FUBP1) as a potential functional cooperator of RUNX1. The helicase and transcriptional regulator FUBP1 has recently been described to be essential for expansion and self-renewal of hematopoietic stem cells and to function as a potential cancer driver gene in lymphoblastic leukemia. Our goals were to validate the protein interaction between RUNX1 and its putative cooperator FUBP1, to identify gene(s) transcriptionally controlled by both RUNX1 and FUBP1, and finally to demonstrate the biological consequence of the cooperation between RUNX1 and its cooperator FUBP1.Co-immunoprecipitation and colocalization experiments demonstrate that RUNX1 colocalizes with FUBP1 in pre-B cell lines, in pre-B lymphoblasts isolated from BCP-ALL patients, and more generally in other hematopoietic progenitors. To characterize some target genes directly regulated by FUBP1 and RUNX1, we performed ChIP combined with sequencing (ChIP-seq) for FUBP1 and RUNX1. Those binding signals were compared to different histone marks and reveal that a subset of FUBP1 and RUNX1 binding signals are enriched within primed enhancer regions characterized by histone H3K4me1 marks. Our data show that RUNX1 signal is also enriched within FUBP1 regions, demonstrating that they are often retrieved on same chromatin regions, bound by FUBP1. Interestingly, FUBP1 is widely distributed in the genome, therefore only a subset of RUNX1 binding signals overlaps with FUBP1 binding signals. To go further, using qPCR, we investigated the expression level of several potential target candidate genes in pre-B cells overexpressed for FUBP1 or RUNX1. We found that both FUBP1 and RUNX1 positively regulate KIT transcript. KIT is a tyrosine kinase receptor expressed on hematopoietic progenitors cell surface and is an oncogene overexpressed notably in different types of leukemia. With the comparison of data from FUBP1 and RUNX1 ChiP-seq, we found that FUBP1 and RUNX1 share two common DNA binding regions on KIT gene, including one overlapping with histone H3K4me1 mark. ChIP-qPCR analyses confirm the binding of FUBP1 and RUNX1 on the KIT enhancer. Moreover, using reporter gene assay, we demonstrated that they can both activate this enhancer. With supervised and unsupervised approaches, we were able to determine FUBP1 and RUNX1 binding motifs that are functionally important for the enhancer activation. Finally, we demonstrated that FUBP1 overexpression in a pre-B cell line increases the expression of KIT protein and exacerbates one of the KIT downstream pathways. FUBP1 overexpression increases also cell proliferation by promoting cell cycle progression in vitro . Concordantly, in vivo, xenografted immunodeficient mice injected with overexpressed FUBP1 cells present a shorter survival time than control mice.To conclude, we demonstrate a regulatory network involving RUNX1 and FUBP1 for the control of a KIT enhancer. Indeed, FUBP1 and RUNX1 can colocalize on chromatin, regulate KIT transcription by binding to a common region in a KIT enhancer, and promote cell cycle progression. These findings suggest a new mechanism for the control of the proliferation of pre-B lymphoblasts. Because FUBP1 and KIT are overexpressed in some types of leukemia, abnormalities in this regulatory network could participate in the onset or the maintenance of RUNX1-related leukemia.This work is supported by Ligue Régionale Contre le Cancer, Région Bretagne, Rennes Métropole, French Research Ministry, Société Française de lutte contre les Cancers et les leucémies de l'Enfant et de l'adolescent, Fédération Enfants et Santé, Société Française de Biochimie et Biologie Moléculaire, Société Française d'Hématologie, Mrs. M-Dominique Blanc-Bert and the Marie Curie Actions of the European Union FP7 under REA grant agreement n°291851. DisclosuresNo relevant conflicts of interest to declare.

The circACTN4 interacts with FUBP1 to promote tumorigenesis and progression of breast cancer by regulating the expression of proto-oncogene MYC

BackgroundRecent studies have revealed that circular RNAs (circRNAs) play significant roles in the occurrence and development of many kinds of cancers including breast cancer (BC). However, the potential functions of most circRNAs and the molecular mechanisms underlying progression of BC remain elusive.MethodHere, Circular RNA microarray was executed in 4 pairs of breast cancer tissues and para-cancer tissues. The expression and prognostic significance of circACTN4 in BC cells and tissues were determined by qRT-PCR and in situ hybridization. Gain-and loss-of-function experiments were implemented to observe the impacts of circACTN4 on the growth, invasion, and metastasis of BC cells in vitro and in vivo. Mechanistically, chromatin immunoprecipitation, luciferase reporter, RNA pulldown, mass spectrum, RNA immunoprecipitation, fluorescence in situ hybridization and co-immunoprecipitation assays were executed.ResultsCircACTN4 was significantly upregulated in breast cancer tissues and cells, its expression was correlated with clinical stage and poor prognosis of patients with BC. Ectopic expression of circACTN4 strikingly facilitated the growth, invasion, and metastasis of breast cancer cells in vitro and in vivo. Whereas knockdown of circACTN4 revealed opposite roles. CircACTN4 was mainly distributed in the nucleus. Further mechanistic research proved that circACTN4 could competitively bind to far upstream element binding protein 1 (FUBP1) to prevent the combination between FUBP1 and FIR, thereby activating MYC transcription and facilitating tumor progression of breast cancer. Furthermore, we found that upstream transcription factor 2 (USF2) might promote the biogenesis of circACTN4.ConclusionOur findings uncover a pivotal mechanism that circACTN4 mediated by USF2 might interact with FUBP1 to promote the occurrence and development of breast cancer via enhancing the expression of MYC. CircACTN4 could be a novel potential target for diagnosis and treatment of breast cancer.

TNPO1-Mediated Nuclear Import of FUBP1 Contributes to Tumor Immune Evasion by Increasing NRP1 Expression in Cervical Cancer.

Far upstream element binding protein 1 (FUBP1), a DNA-binding protein, participates in diverse tumor-promoting behaviors by regulating the expression of oncogenes in the nucleus, but the underlying mechanisms remain to be elucidated. In the present study, we found that FUBP1 mRNA and protein expressions were markedly upregulated and closely linked with poor prognosis in cervical cancer. In vitro, functional experiments showed that knockdown of FUBP1 inhibited CC cell proliferation and migration. Therefore, FUBP1 plays a prooncogenic function in CC progression. Further investigations for the first time demonstrated that nuclear localization of FUBP1 regulated the gene expression of immune checkpoint NRP1. Moreover, our work demonstrated that FUBP1 translocated into the nucleus which was mediated by interacting with Transportin-1 (TNPO1). Collectively, this study revealed that FUBP1 might be a potential therapeutic target for the restriction of tumor progression.

Differentially Expressed Long Noncoding RNAs Involved in FUBP1 Promoting Hepatocellular Carcinoma Cells Proliferation.

Background Far upstream element-binding protein 1 (FUBP1) is reported to be involved in cancer development by regulating the transcription of c-myc gene through binding to far upstream element. Highly expressed FUBP1 was negatively correlated with survival rate of patients with hepatocellular carcinoma (HCC) and could promote the proliferation of HCC cells. However, the downstream mechanism of FUBP1 has not yet been clearly explained. This study is aimed at identifying the expression profiles of long noncoding RNA (lncRNA) in HCC cells in response to FUBP1 overexpression and at investigating the possible lncRNAs that participated in cell proliferation process regulated by FUBP1. Methods The overexpression of FUBP1 was mediated by lentiviral infection on 3 different types of HCC cell lines (MHCC97-H, MHCC97-L, and Huh-7). The expression of target genes was detected by quantitative reverse transcription-PCR (RT-PCR) and western blotting assays. Microarray and quantitative RT-PCR were applied to screen the differentially expressed lncRNAs in HCC cells after FUBP1 overexpression. The Cell Counting Kit-8 assay was used to confirm the growth vitality of HCC cells. Results The growth vitality of HCC cells was significantly increased after lentivirus infection. A total of 12 lncRNAs had the same expression trend in the 3 HCC cell lines in response to FUBP1 overexpression, including 3 upregulated lncRNAs and 9 downregulated lncRNAs. Coexpression analysis of dysregulated lncRNAs-mRNAs network showed that lnc-LYZ-2 was the lncRNA most relevant to FUBP1. Inhibition of lnc-LYZ-2 could significantly relieve the proproliferation effect of FUBP1 on HCC cells, suggesting that lnc-LYZ-2 was partially involved in proproliferation regulation of FUBP1. Conclusions Our results indicated that FUBP1 induced the abnormal expression of lncRNAs and the FUBP1-lncRNAs coexpression network in HCC cells, which could provide theoretical and experimental basis for FUBP1-lncRNAs network involved in HCC development.

Protein and Signaling Pathway Responses to rhIL-6 Intervention Before Lobaplatin Treatment in Osteosarcoma Cells.

Lobaplatin is a third-generation platinum-based antineoplastic agent and is widely used for osteosarcoma treatment before and after tumor removal. However, treatment failure often results from lobaplatin drug resistance. In our study, we found that SaOS-2 and SOSP-9607 osteosarcoma cells became less sensitive to lobaplatin after treatment with exogenous interleukin (IL)-6. Quantitative proteomic analysis was performed to elucidate the underlying mechanism in SaOS-2 osteosarcoma cells. Cells were divided into a control group (CG), a lobaplatin treatment group (LG), a recombinant human IL-6 (rhIL-6), and a lobaplatin treatment group (rhILG). We performed three biological replicates in each group to compare the differential protein expression between groups using a tandem mass tag (TMT) labeling technology based on liquid chromatography-tandem mass spectrometry (LC-MS/MS). A total of 1,313 proteins with significant differential expression was identified and quantified. The general characteristics of the significantly enriched proteins were identified by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses, and protein–protein interaction (PPI) analysis was conducted using IntAct and STRING. In total, 31 proteins were further verified by parallel reaction monitoring (PRM), among which ras GTPase-activating protein-binding protein 1 (G3BP1), fragile X mental retardation syndrome-related protein 1 (hFXR1p), and far upstream element-binding protein 1 (FUBP1) were significantly differentially expressed. Immunohistochemistry results showed that these three proteins are highly expressed in specimens from platinum-resistant osteosarcoma patients, while the proteins are negatively or weakly expressed in specimens from platinum-sensitive osteosarcoma patients. The immunofluorescence staining results were in accord with the immunohistochemistry staining results. siRNA knockdown of FUBP1 showed a strikingly decreased IC50 value for lobaplatin in FUBP1-silenced cells, which verified the role of FUBP1 in the drug susceptibility of osteosarcoma and the potential therapeutic value for increasing the sensitivity to lobaplatin. This is the first proteomic study on a rhIL-6 intervention before lobaplatin treatment in osteosarcoma cells.

FUBP1 mediates the growth and metastasis through TGFβ/Smad signaling in pancreatic adenocarcinoma.

Recent studies have reported that the expression levels of far upstream element-binding protein 1 (FUBP1) were upregulated and served a crucial role in several types of cancer. However, the underlying molecular mechanisms and clinical significance of FUBP1 in pancreatic adenocarcinoma (PAAD) remain unclear. The present study aimed to determine the expression levels of FUBP1 in patients with PAAD and subsequently investigated the biological functions and mechanisms of FUBP1 using in vitro assays. FUBP1 expression levels and survival outcomes in patients with PAAD were analyzed using The Cancer Genome Atlas and starBase databases. Reverse transcription-quantitative PCR was used to analyze the mRNA expression levels of FUBP1 in PAAD and adjacent normal tissues. In addition, the expression of FUBP1 was knocked down with small interfering RNA and overexpressed using FUBP1-overexpressed plasmids, and the effects on biological functions, including cell proliferation, migration and invasion, were investigated. Western blotting and immunofluorescence assays were used to determine the role of FUBP1 in epithelial-mesenchymal transition (EMT). The results of the present study revealed that the expression levels of FUBP1 were upregulated in PAAD tissues compared with adjacent normal tissues and the upregulated expression was significantly associated with poor survival. The knockdown of FUBP1 expression significantly inhibited the proliferative, migratory and invasive abilities of the PAAD PaTu8988 cell line, while the overexpression of FUBP1 promoted cell proliferation, migration and invasion in the PAAD SW1990 cell line. Furthermore, the knockdown of FUBP1 downregulated the expression levels of EMT-related markers, including N-cadherin, β-catenin and vimentin, while the expression levels of E-cadherin were upregulated. The knockdown of FUBP1 was also revealed to regulate the TGFβ/Smad signaling cascade by downregulating phosphorylated-Smad2/3 and TGFβ1 expression levels. Conversely, the overexpression of FUBP1 reversed these effects. In conclusion, the findings of the present study indicated that FUBP1 may be a potential oncogene that mediates the EMT of PAAD via TGFβ/Smad signaling. These data suggested that FUBP1 may represent a potential biomarker for the diagnosis of PAAD or a target for the treatment of patients with PAAD.

Long non-coding RNA small nucleolar RNA host gene 6 aggravates pancreatic cancer through upregulation of far upstream element binding protein 1 by sponging microRNA-26a-5p.

BackgroundPancreatic cancer (PC) is a highly deadly malignancy with few effective therapies. We aimed to unmask the role that long non-coding RNA small nucleolar RNA host gene 6 (SNHG6) plays in PC cells by targeting far upstream element binding protein 1 (FUBP1) via microRNA-26a-5p (miR-26a-5p).MethodsSNHG6 expression was predicted by bioinformatics, followed by verification via reverse transcription quantitative polymerase chain reaction. Then, the interactions among SNHG6, miR-26a-5p, and FUBP1 were detected through online software analysis, dual luciferase reporter assay and RNA pull-down. After that, cells were treated with different small interfering RNAs and/or mimic to determine the interactions among SNHG6, miR-26a-5p, and FUBP1 and their roles in PC cells. Finally, the role of SNHG6 in tumor growth in vivo was evaluated by measuring the growth and weight of transplanted tumors in nude mice. A t-test, one-way and two-way analysis of variance were used for data analysis.ResultsCompared with that in normal tissues, SNHG6 was highly expressed in PC tissues (1.00 ± 0.05 vs. 1.56 ± 0.06, t = 16.03, P < 0.001). Compared with that in human pancreatic duct epithelial cells (HPDE6-C7), SNHG6 showed the highest expression in PANC-1 cells (1.00 ± 0.06 vs. 3.87 ± 0.13, t = 34.72, P < 0.001) and the lowest expression in human pancreatic cancer cells (MIAPaCa-2) (1.00 ± 0.06 vs. 1.41 ± 0.07, t = 7.70, P = 0.0015). Compared with the levels in the si-negative control group, SNHG6 (0.97 ± 0.05 vs. 0.21 ± 0.06, t = 16.85, P < 0.001), N-cadherin (0.74 ± 0.05 vs. 0.41 ± 0.04, t = 8.93, P < 0.001), Vimentin (0.55 ± 0.04 vs. 0.25 ± 0.03, t = 10.39, P < 0.001), and β-catenin (0.62 ± 0.05 vs. 0.32 ± 0.03, t = 8.91, P < 0.001) were decreased, while E-cadherin (0.65 ± 0.06 vs. 1.36 ± 0.07, t = 13.34, P < 0.001) was increased after SNHG6 knockdown or miR-26a-5p overexpression, accompanied by inhibited cell proliferation, migration, and invasion. SNHG6 overexpression exerted the opposite effects. SNHG6 upregulated FUBP1 expression by sponging miR-26a-5p. Silencing SNHG6 blocked the growth of PC in vivo.ConclusionSilencing SNHG6 might ameliorate PC through inhibition of FUBP1 by sponging miR-26a-5p, thus providing further supporting evidence for its use in PC treatment.