Expression of far upstream element (FUSE) binding protein 1 in human glioma is correlated with c-Myc and cell proliferation

FUBP1 in human cancer: Characteristics, functions, and potential applications

Far upstream element-binding protein 1 (FUBP1) is a single-stranded nucleic acid-binding protein that binds to the Far Upstream Element (FUSE) sequence and is involved in important biological processes, including DNA transcription, RNA biogenesis, and translation. Recent studies have highlighted the significance of aberrant expression or mutations in FUBP1 in the development of various tumors, with FUBP1 overexpression often indicating oncogenic roles in different tumor types. However, it is worth noting that recent research has discovered its tumor-suppressive role in cancer, which is not yet fully understood and appears to be tissue- or context-dependent. This review summarizes the association between FUBP1 and diverse cancers and discusses the functions of FUBP1 in cancer. In addition, this review proposes potential clinical implications and outlines future research directions to pave the way for the development of targeted therapeutic strategies focusing on FUBP1.

RNA splicing alterations in lung cancer pathogenesis and therapy

RNA splicing alterations are widespread and play critical roles in cancer pathogenesis and therapy. Lung cancer is highly heterogeneous and causes the most cancer-related deaths worldwide. Large-scale multi-omics studies have not only characterized the mutational landscapes but also discovered a plethora of transcriptional and post-transcriptional changes in lung cancer. Such resources have greatly facilitated the development of new diagnostic markers and therapeutic options over the past two decades. Intriguingly, altered RNA splicing has emerged as an important molecular feature and therapeutic target of lung cancer. In this review, we provide a brief overview of splicing dysregulation in lung cancer and summarize the recent progress on key splicing events and splicing factors that contribute to lung cancer pathogenesis. Moreover, we describe the general strategies targeting splicing alterations in lung cancer and highlight the potential of combining splicing modulation with currently approved therapies to combat this deadly disease. This review provides new mechanistic and therapeutic insights into splicing dysregulation in cancer.

Glioblastoma glycolytic signature predicts unfavorable prognosis, immunological heterogeneity, and ENO1 promotes microglia M2 polarization and cancer cell malignancy

Glioblastomas are the most malignant brain tumors, whose progress was promoted by aberrate aerobic glycolysis. The immune environment was highly engaged in glioblastoma formation, while its interaction with aerobic glycolysis remained unclear. Herein, we build a 7-gene Glycolytic Score (GS) by Elastic Net in the training set and two independent validating sets. The GS predicted malignant features and poor survival with good performances. Immune functional analyses and Cibersort calculation identified depressed T cells, B cells, natural killer cells immunity, and high immunosuppressive cell infiltration in the high-GS group. Also, high expressions of the immune-escape genes were discovered. Subsequently, the single-cell analyses validated the glycolysis-related immunosuppression. The functional results manifested the high-GS neoplastic cells' association with T cells, NK cells, and macrophage function regulation. The intercellular cross-talk showed strong associations between high-GS neoplastic cells and M2 macrophages/microglia in several immunological pathways. We finally confirmed that ENO1, the key gene of the GS, promoted M2 microglia polarization and glioblastoma cell malignant behaviors via immunofluorescence, clone formation, CCK8, and transwell rescue experiments. These results indicated the interactions between cancerous glycolysis and immunosuppression and glycolysis' role in promoting glioblastoma progression. Conclusively, we built a robust model and discovered strong interaction between GS and immune, shedding light on prognosis management improvement and therapeutic strategies development for glioblastoma patients.

The "Superoncogene" Myc at the Crossroad between Metabolism and Gene Expression in Glioblastoma Multiforme

The concept of the Myc (c-myc, n-myc, l-myc) oncogene as a canonical, DNA-bound transcription factor has consistently changed over the past few years. Indeed, Myc controls gene expression programs at multiple levels: directly binding chromatin and recruiting transcriptional coregulators; modulating the activity of RNA polymerases (RNAPs); and drawing chromatin topology. Therefore, it is evident that Myc deregulation in cancer is a dramatic event. Glioblastoma multiforme (GBM) is the most lethal, still incurable, brain cancer in adults, and it is characterized in most cases by Myc deregulation. Metabolic rewiring typically occurs in cancer cells, and GBM undergoes profound metabolic changes to supply increased energy demand. In nontransformed cells, Myc tightly controls metabolic pathways to maintain cellular homeostasis. Consistently, in Myc-overexpressing cancer cells, including GBM cells, these highly controlled metabolic routes are affected by enhanced Myc activity and show substantial alterations. On the other hand, deregulated cancer metabolism impacts Myc expression and function, placing Myc at the intersection between metabolic pathway activation and gene expression. In this review paper, we summarize the available information on GBM metabolism with a specific focus on the control of the Myc oncogene that, in turn, rules the activation of metabolic signals, ensuring GBM growth.

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.

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

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.

Identification of a key glioblastoma candidate gene, FUBP3, based on weighted gene co-expression network analysis

BACKGROUND

Glioblastoma multiforme (GBM) is the most common aggressive malignant brain tumor. However, the molecular mechanism of glioblastoma formation is still poorly understood. To identify candidate genes that may be connected to glioma growth and development, weighted gene co-expression network analysis (WGCNA) was performed to construct a gene co-expression network between gene sets and clinical characteristics. We also explored the function of the key candidate gene.

METHODS

Two GBM datasets were selected from GEO Datasets. The R language was used to identify differentially expressed genes. WGCNA was performed to construct a gene co-expression network in the GEO glioblastoma samples. A custom Venn diagram website was used to find the intersecting genes. The GEPIA website was applied for survival analysis to determine the significant gene, FUBP3. OS, DSS, and PFI analyses, based on the UCSC Cancer Genomics Browser, were performed to verify the significance of FUBP3. Immunohistochemistry was performed to evaluate the expression of FUBP3 in glioblastoma and adjacent normal tissue. KEGG and GO enrichment analyses were used to reveal possible functions of FUBP3. Microenvironment analysis was used to explore the relationship between FUBP3 and immune infiltration. Immunohistochemistry was performed to verify the results of the microenvironment analysis.

RESULTS

GSE70231 and GSE108474 were selected from GEO Datasets, then 715 and 694 differentially expressed genes (DEGs) from GSE70231 and GSE108474, respectively, were identified. We then performed weighted gene co-expression network analysis (WGCNA) and identified the most downregulated gene modules of GSE70231 and GSE108474, and 659 and 3915 module genes from GSE70231 and GSE108474, respectively, were selected. Five intersection genes (FUBP3, DAD1, CLIC1, ABR, and DNM1) were calculated by Venn diagram. FUBP3 was then identified as the only significant gene by survival analysis using the GEPIA website. OS, DSS, and PFI analyses verified the significance of FUBP3. Immunohistochemical analysis revealed FUBP3 expression in GBM and adjacent normal tissue. KEGG and GO analyses uncovered the possible function of FUBP3 in GBM. Tumor microenvironment analysis showed that FUBP3 may be connected to immune infiltration, and immunohistochemistry identified a positive correlation between immune cells (CD4 + T cells, CD8 + T cells, and macrophages) and FUBP3.

CONCLUSION

FUBP3 is associated with immune surveillance in GBM, indicating that it has a great impact on GBM development and progression. Therefore, interventions involving FUBP3 and its regulatory pathway may be a new approach for GBM treatment.

Comprehensive Analyses of Glucose Metabolism in Glioma Reveal the Glioma-Promoting Effect of GALM

Glioma is the most common tumor with the worst prognosis in the central nervous system. Current studies showed that glucose metabolism could affect the malignant progression of tumors. However, the study on the dysregulation of glucose metabolism in glioma is still limited. Herein, we firstly screened 48 differentially expressed glucose metabolism-related genes (DE-GMGs) by comparing glioblastomas to low-grade gliomas. Then a glucose metabolism-related gene (GMG)-based model (PC, lactate dehydrogenase A (LDHA), glucuronidase beta (GUSB), galactosidase beta 1 (GLB1), galactose mutarotase (GALM), or fructose-bisphosphatase 1 (FBP1)) was constructed by a protein-protein interaction (PPI) network and Lasso regression. Thereinto, the high-risk group encountered a worse prognosis than the low-risk group, and the M2 macrophage was positively relevant to the risk score. Various classical tumor-related functions were enriched by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses. Since protein GALM was rarely studied in glioma, we detected high expression of GALM by western blot and immunohistochemistry in glioma tissues. And experiments in vitro showed that GALM could promote the epithelial-to-mesenchymal transition (EMT) process of glioma cells and could be regulated by TNFAIP3 in glioma cells. Overall, our study revealed the critical role of glucose metabolism in the prognosis of patients with glioma. Furthermore, we demonstrated that GALM was significantly related to the malignancy of glioma and could promote glioma cells' EMT process.

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

Background

Recent 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.

Method

Here, 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.

Results

CircACTN4 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.

Conclusion

Our 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.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12943-021-01383-x.

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.

C-Myc Signaling Pathway in Treatment and Prevention of Brain Tumors

Brain tumors are responsible for high morbidity and mortality worldwide. Several factors such as the presence of blood-brain barrier (BBB), sensitive location in the brain, and unique biological features challenge the treatment of brain tumors. The conventional drugs are no longer effective in the treatment of brain tumors, and scientists are trying to find novel therapeutics for brain tumors. In this way, identification of molecular pathways can facilitate finding an effective treatment. c-Myc is an oncogene signaling pathway capable of regulation of biological processes such as apoptotic cell death, proliferation, survival, differentiation, and so on. These pleiotropic effects of c-Myc have resulted in much fascination with its role in different cancers, particularly brain tumors. In the present review, we aim to demonstrate the upstream and down-stream mediators of c-Myc in brain tumors such as glioma, glioblastoma, astrocytoma, and medulloblastoma. The capacity of c-Myc as a prognostic factor in brain tumors will be investigated. Our goal is to define an axis in which the c-Myc signaling pathway plays a crucial role and to provide direction for therapeutic targeting in these signaling networks in brain tumors.

Using protein microarray to identify and evaluate autoantibodies to tumor-associated antigens in ovarian cancer

The aim of this study was to develop a noninvasive serological diagnostic approach in identifying and evaluating a panel of candidate autoantibodies to tumor‐associated antigens (TAAs) based on protein microarray technology for early detection of ovarian cancer (OC). Protein microarray based on 154 proteins encoded by 138 cancer driver genes was used to screen candidate anti‐TAA autoantibodies in a discovery cohort containing 17 OC and 27 normal controls (NC). Indirect enzyme‐linked immunosorbent assay (ELISA) was used to detect the content of candidate anti‐TAA autoantibodies in sera from 140 subjects in the training cohort. Differential anti‐TAA autoantibodies were further validated in the validation cohort with 328 subjects. Subsequently, 112 sera from the patients with ovarian benign diseases with 104 OC sera and 104 NC sera together were recruited to identify the specificity of representative autoantibodies to OC among ovarian diseases. Five TAAs (GNAS, NPM1, FUBP1, p53, and KRAS) were screened out in the discovery phase, in which four of them presented higher levels in OC than controls (P < .05) in the training cohort, which was consistent with the result in the subsequent validation cohort. An optimized panel of three anti‐TAA (GNAS, p53, and NPM1) autoantibodies was identified to have relatively high sensitivity (51.2%), specificity (86.0%), and accuracy (68.6%), respectively. This panel can identify 51% of OC patients with CA125 negative. This study supports our assumption that anti‐TAA autoantibodies can be considered as potential diagnostic biomarkers for detection of OC; especially a panel of three anti‐TAA autoantibodies could be a good tool in immunodiagnosis of OC.

Interaction network of immune-associated genes affecting the prognosis of patients with glioblastoma

Glioblastoma multiforme (GBM) is a common malignant tumor type of the nervous system. The purpose of the present study was to establish a regulatory network of immune-associated genes affecting the prognosis of patients with GBM. The GSE4290, GSE50161 and GSE2223 datasets from the Gene Expression Omnibus database were screened to identify common differentially expressed genes (co-DEGs). A functional enrichment analysis indicated that the co-DEGs were mainly enriched in cell communication, regulation of enzyme activity, immune response, nervous system, cytokine signaling in immune system and the AKT signaling pathway. The co-DEGs accumulated in immune response were then further investigated. For this, the intersection of those co-DEGs and currently known immune-regulatory genes was obtained and a differential expression analysis of these overlapping immune-associated genes was performed. A risk model was established using immune-regulatory genes that affect the prognosis of patients with GBM. The risk score was significantly associated with the prognosis of patients with GBM and had a significant independent predictive value. The risk model had high accuracy in predicting the prognosis of patients with GBM [area under the receiver operating characteristic curve (AUC)=0.764], which was higher than that of a previously reported model of prognosis-associated biomarkers (AUC=0.667). Furthermore, an interaction network was constructed by using immune-regulatory genes and transcription factors affecting the prognosis of patients with GBM and the University of California Santa Cruz database was used to perform a preliminary analysis of the transcription factors and immune genes of interest. The interaction network of immune-regulatory genes constructed in the present study enhances the current understanding of mechanisms associated with poor prognosis of patients with GBM. The risk score model established in the present study may be used to evaluate the prognosis of patients with GBM.

Proteomics reveals protein phosphatase 1γ as a biomarker associated with Hippo signal pathway in glioma

Hub proteins related with Hippo signal pathway in glioma were investigated using proteomics methods (Tandem Mass Tag, TMT) to determine the differentially expressed proteins in glioblastoma (GBM). Ingenuity Pathway Analysis (IPA) was performed to complement proteomic findings by identifying the top canonical pathways as well as to suggest novel proteins for the targeted therapy of glioma. A total of 222 formalin-fixed paraffin-embedded (FFPE) glioma tissue samples were used to verify the expression of protein phosphatase 1γ (PP1γ), Yes-associated protein 1 (YAP1), and SOX2 via immunohistochemistry. Bioinformatics analysis revealed these proteins as crucial in the Hippo signaling pathway in GBM. Spearman correlation was performed to analyze the relationship of these three proteins, and survival analysis was conducted to investigate their effects on prognosis. Among the 5808 proteins identified by TMT with the standard of P-value < 0.05 and fold change (FC) of>1.2 or <0.83, 1398 upregulated and 1060 downregulated differentially expressed proteins were found. IPA revealed that the Hippo signaling was activated in the top 10 canonical pathways, and PP1γ was activated in the Hippo signaling. Immunohistochemistry analysis indicated that PP1γ, YAP1, and SOX2 were highly and positively expressed in glioma. PP1γ expression was related to WHO grade (p = 0.003) and ki-67 expression (p = 0.012). Low PP1γ expression was associated with IDH1-mut in low-grade glioma (LGG; WHO grades II and III) (p = 0.037). PP1γ was positively correlated with YAP1 (p < 0.001; r = 0.259) and SOX2 (p = 0.009; r = 0.175). In survival analysis, age, WHO grade, ki-67 expression, and PP1γ expression independently predicted a short OS in total cohort (p < 0.05). Therefore, PP1γ is a hub protein associated with Hippo signal pathway in glioma, and its expression indicates poor prognosis in patients with glioma. Therefore, PP1γ may be a promising prognostic biomarker and a therapeutic target in glioma.

High expression of FUSE binding protein 1 in breast cancer stimulates cell proliferation and diminishes drug sensitivity

Breast cancer is the most common malignant tumor affecting women worldwide and is divided into the following subtypes: Luminal A, Luminal B, HER-2 overexpression and triple-negative breast cancer (TNBC). TNBC accounts for approximately 15-20% of all breast cancer cases. Due to the characteristics of low differentiation, the likelyhood of recurrence and metastasis, strong invasiveness and the lack of hormone receptors and human epidermal growth factor receptor 2 (HER2), patients with TNBC cannot benefit from endocrine therapy or other available targeted agents. Chemotherapy is one of the main treatments for patients with TNBC, and cisplatin is one of the most commonly used and effective drugs. The human far upstream element binding protein 1 (FBP1) is a potent pro-proliferative and anti-apoptotic oncoprotein, which is overexpressed in numerous tumor types. The present study demonstrated that FBP1 and its target, c-Myc, were more highly expressed in breast cancer tissues compared with para-carcinoma tissues, and the FBP1 and c-Myc levels are decreased by cisplatin treatment. The knockdown of FBP1 in TNBC cells decreased cell proliferation by arresting the cell cycle at the G2 phase. The knockdown of FBP1 decreased the expression of G2 phase-associateed protein cyclin A2, whereas it increased that of cyclin B1 and p-CDC2. Furthermore, the knockdown of FBP1 decreased cell migration and metastasis by downregulating matrix metalloproteinase 2 expression, and enhanced the sensitivity of TNBC cells to cisplatin by inducing apoptosis. These results thus suggest that FBP1 is a potential novel biological marker for the diagnosis and treatment of TNBC.

Multiple Functions of Fubp1 in Cell Cycle Progression and Cell Survival

The discovery of novel and critical genes implicated in malignant development is a topic of high interest in cancer research. Intriguingly, a group of genes named “double-agent” genes were reported to have both oncogenic and tumor-suppressive functions. To date, less than 100 “double-agent” genes have been documented. Fubp1 is a master transcriptional regulator of a subset of genes by interacting with a far upstream element (FUSE). Mounting evidence has collectively demonstrated both the oncogenic and tumor suppressive roles of Fubp1 and the debate regarding its roles in tumorigenesis has been around for several years. Therefore, the detailed molecular mechanisms of Fubp1 need to be determined in each context. In the present study, we showed that the Fubp1 protein level was enriched in the S phase and we identified that Fubp1 deficiency altered cell cycle progression, especially in the S phase, by downregulating the mRNA expression levels of Ccna genes encoding cyclin A. Although this Fubp1-cyclin A axis appears to exist in several types of tumors, Fubp1 showed heterogeneous expression patterns among various cancer tissues, suggesting it exhibits multiple and complicated functions in cancer development. In addition, we showed that Fubp1 deficiency confers survival advantages to cells against metabolic stress and anti-cancer drugs, suggesting that Fubp1 may play both positive and negative roles in malignant development.

Upregulation of far upstream element-binding protein 1 (FUBP1) promotes tumor proliferation and unfavorable prognosis in tongue squamous cell carcinoma

Background:

A well-known transcriptional regulator of the proto-oncogene c-Myc, far-upstream element (FUSE) binding protein 1 (FUBP1) has been demonstrated by previous work to be aberrantly expressed in lots of cancers and plays a critical role in tumor progression; however, its expression and function in tongue squamous cell carcinoma (TSCC) remains unclear.

Methods:

Evaluations with immunohistochemistry, quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot were performed to assess FUBP1 expression. The correlations of FUBP1 expression levels with various clinicopathological factors were evaluated with univariate and multivariate analyses. In addition, the role of FUBP1 in TSCC proliferation was studied in TSCC cells by silencing FUBP1. The role of FUBP1 on proliferation and apoptosis was confirmed by cell counting Kit-8, colony formation, cell cycle, and cell apoptosis assays.

Results:

Immunohistochemistry, qRT-PCR and Western blot results showed FUBP1 expression was higher in TSCC tissues in comparison with adjacent non-cancerous tissues ( P <0.05), as well as in patients with advanced-stage disease or cervical lymph node metastasis ( P<0.001). The 5-year survival rate was significantly lower in the group with high FUBP1 expression than in that with low FUBP1 expression ( P=0.035). FUBP1 expression was also an independent predictor for overall survival in TSCC patients, and was closely related to poor prognosis. FUBP1 knockdown inhibited cancer cell proliferation, and induced cell cycle arrest and apoptosis.

Conclusion:

FUBP1 was overexpressed in TSCC, and correlated with TSCC cell proliferation and poor prognosis. FUBP1 appears to act as a potential oncogene in TSCC, and may be considered a novel biomarker for TSCC.

The transcriptional regulator FUBP1 influences disease outcome in murine and human myeloid leukemia

The transcriptional regulator far upstream element binding protein 1 (FUBP1) acts as an oncoprotein in solid tumor entities and plays a role in the maintenance of hematopoietic stem cells. However, its potential function in leukemia is unknown. In murine models of chronic (CML) and acute myeloid leukemia (AML) induced by BCR-ABL1 and MLL-AF9, respectively, knockdown of Fubp1 resulted in prolonged survival, decreased numbers of CML progenitor cells, decreased cell cycle activity and increased apoptosis. Knockdown of FUBP1 in CML and AML cell lines recapitulated these findings and revealed enhanced DNA damage compared to leukemia cells expressing wild type FUBP1 levels. FUBP1 was more highly expressed in human CML compared to normal bone marrow cells and its expression correlated with disease progression. In AML, higher FUBP1 expression in patient leukemia cells was observed with a trend toward correlation with shorter overall survival. Treatment of mice with AML with irinotecan, known to inhibit topoisomerase I and FUBP1, significantly prolonged survival alone or in combination with cytarabine. In summary, our data suggest that FUBP1 acts as cell cycle regulator and apoptosis inhibitor in leukemia. We demonstrated that FUBP1 might play a role in DNA repair, and its inhibition may improve outcome in leukemia patients.

The master regulator FUBP1: its emerging role in normal cell function and malignant development

The human Far Upstream Element (FUSE) Binding Protein 1 (FUBP1) is a multifunctional DNA- and RNA-binding protein involved in diverse cellular processes. FUBP1 is a master regulator of transcription, translation, and RNA splicing. FUBP1 has been identified as a potent pro-proliferative and anti-apoptotic factor by modulation of complex networks. FUBP1 is also described either as an oncoprotein or a tumor suppressor. Especially, FUBP1 overexpression is observed in a growing number of cancer and leads to a deregulation of targets that includes the fine-tuned MYC oncogene. Moreover, recent loss-of-function analyses of FUBP1 establish its essential functions in hematopoietic stem cell maintenance and survival. Therefore, FUBP1 appears as an emerging suspect in hematologic disorders in addition to solid tumors. The scope of the present review is to describe the advances in our understanding of the molecular basis of FUBP1 functions in normal cells and carcinogenesis. We also delineate the recent progresses in the understanding of the master role of FUBP1 in normal and pathological hematopoiesis. We conclude that FUBP1 is not only worth studying biologically but is also of clinical relevance through its pivotal role in regulating multiple cellular processes and its involvement in oncogenesis.

Histone deacetylase SIRT6 inhibits glioma cell growth through down-regulating NOTCH3 expression

Gliomas are the most common brain tumors of the central nervous system. In this study, we investigated the molecular mechanisms and biological function of SIRT6 in human gliomas. The expression levels of SIRT6 in glioma tissues and cells were analyzed by qRT-PCR and western blot analysis. CCK8 and clonogenicity assays were performed to detect the cell proliferation. Furthermore, the migration and invasion of glioma cells were examined by transwell assays. It was found that the expression of SIRT6 was significantly lower in human glioma tissues or cell lines compared with the normal brain tissue or NHA. Up-regulated SIRT6 significantly decreased cell proliferation, migration and invasion of U87 and U251 cells. By contrast, knockdown of SIRT6 dramatically increased cell proliferation, migration and invasion of U87 and U251 cells. Moreover, over expression of NOTCH3 significantly increased the cell proliferation, migration, and invasion of U87 and U251 cells. However, these effects were abolished after overexpression of SIRT6. These results suggest that SIRT6 may suppress cell proliferation, migration, and invasion via inhibition of the NOTCH3 signaling pathway in glioma.

BICD1 expression, as a potential biomarker for prognosis and predicting response to therapy in patients with glioblastomas

There is variation in the survival and therapeutic outcome of patients with glioblastomas (GBMs). Therapy resistance is an important challenge in the treatment of GBM patients. The aim of this study was to identify Temozolomide (TMZ) related genes and confirm their clinical relevance. The TMZ-related genes were discovered by analysis of the gene-expression profiling in our cell-based microarray. Their clinical relevance was verified by in silico meta-analysis of the Cancer Genome Atlas (TCGA) and the Chinese Glioma Genome Atlas (CGGA) datasets. Our results demonstrated that BICD1 expression could predict both prognosis and response to therapy in GBM patients. First, high BICD1 expression was correlated with poor prognosis in the TCGA GBM cohort (n=523) and in the CGGA glioma cohort (n=220). Second, high BICD1 expression predicted poor outcome in patients with TMZ treatment (n=301) and radiation therapy (n=405). Third, multivariable Cox regression analysis confirmed BICD1 expression as an independent factor affecting the prognosis and therapeutic response of TMZ and radiation in GBM patients. Additionally, age, MGMT and BICD1 expression were combinedly utilized to stratify GBM patients into more distinct risk groups, which may provide better outcome assessment. Finally, we observed a strong correlation between BICD1 expression and epithelial-mesenchymal transition (EMT) in GBMs, and proposed a possible mechanism of BICD1-associated survival or therapeutic resistance in GBMs accordingly. In conclusion, our study suggests that high BICD1 expression may result in worse prognosis and could be a predictor of poor response to TMZ and radiation therapies in GBM patients.

LncRNA-TP53TG1 Participated in the Stress Response Under Glucose Deprivation in Glioma

Gliomas are the most common brain tumors of the center nervous system. And long non-coding RNAs (lncRNAs) are non-protein coding transcripts, which have been considered as one type of gene expression regulator for cancer development. In this study, we investigated the role of lncRNA-TP53TG1 in response to glucose deprivation in human gliomas. The expression levels of TP53TG1 in glioma tissues and cells were analyzed by qRT-PCR. In addition, the influence of TP53TG1 on glucose metabolism related genes at the mRNA level during both high and low glucose treatment was detected by qRT-PCR. MTT, clonogenicity assays, and flow cytometry were performed to detect the cell proliferation and cell apoptosis. Furthermore, the migration of glioma cells was examined by Transwell assays. The expression of TP53TG1 was significantly higher in human glioma tissues or cell lines compared with normal brain tissue or NHA. Moreover, TP53TG1 and some tumor glucose metabolism related genes, such as GRP78, LDHA, and IDH1 were up-regulated significantly in U87 and LN18 cells under glucose deprivation. In addition, knockdown of TP53TG1 decreased cell proliferation and migration and down-regulated GRP78 and IDH1 expression levels and up-regulated PKM2 levels in U87 cells under glucose deprivation. However, over-expression of TP53TG1 showed the opposite tendency. Moreover, the effects of TP53TG1 were more remarkable in low glucose than that in high glucose. Our data showed that TP53TG1 under glucose deprivation may promote cell proliferation and migration by influencing the expression of glucose metabolism related genes in glioma. J. Cell. Biochem. 118: 4897-4904, 2017. © 2017 Wiley Periodicals, Inc.

Expression of far upstream element-binding protein 1 correlates with c-Myc expression in sacral chordomas and is associated with tumor progression and poor prognosis

The far upstream element (FUSE)-binding protein 1 (FUBP1), a well-known transcriptional regulator of the proto-oncogene c-Myc, has been demonstrated by previous work to be aberrantly expressed in a variety of tumors and plays a critical role in tumor progression; however, its expression and function in relatively rare and aggressive chordomas remains unclear. In this retrospective study, we reviewed clinicopathologic characteristics of 40 patients diagnosed with sacral chordoma, and analyzed 40 tumor and 20 distant normal tissues obtained from patients during the primary surgical tumor excision. Using immunohistochemistry, we observed an up-regulation in the expression of FUBP1 and c-Myc in sacral chordomas compared with the normal tissues (P = 0.001 for both). Additionally, positive correlations of FUBP1 expression with c-Myc (γ = 0.651, P < 0.001) and the cell proliferation index Ki-67 expression (γ = 0.447, P = 0.004) were indicated using Spearman's rank correlation coefficient. Increased expression of FUBP1 was significantly associated with tumor invasion into the surrounding muscles (P = 0.002). Kaplan-Meier curves demonstrated the association between FUBP1 levels and the patients' local recurrence-free survival (LRFS) (P < 0.001) but not with the overall survival (OS) (P = 0.070). The independent prognostic significance of FUBP1 levels for the LRFS was indicated by multivariate analysis (HR = 4.272; 95% CI, 1.133-16.112; P = 0.032). Our findings demonstrate an association between FUBP1 levels and chordoma progression and prognosis, suggesting that FUBP1 can be used as a biomarker and a potential therapeutic target.

MiR-16-1 Targeted Silences Far Upstream Element Binding Protein 1 to Advance the Chemosensitivity to Adriamycin in Gastric Cancer

Chemotherapy can prevent metastasis and recurrence of gastric cancer (GC), and is a well supplement for operation. But, chemotherapy resistance has severely restricted the application of chemotherapy. This study aimed to investigate the regulatory roles and molecular mechanism of miR-16-1 to the chemosensitivity to adriamycin in GC. In this study, the expression of miR-16-1 and FUBP1 was down-regulated and up-regulated respectively in adriamycin-resistant GC tissues and cell lines, and represented a negative relationship between them. MiR-16-1 could silence FUBP1 directly and specifically, FUBP1 was a target gene of miR-16-1. Silence of FUBP1 inhibited the half maximal inhibitory concentration (IC50) of SGC7901/AR cell line to adriamycin, chemosensitivity enhanced significantly. Moreover, FUBP1 silence in SGC7901/AR cell line also inhibited proliferation and invasion, and advanced cell apoptosis. To sum up, the expression of miR-16-1 was positively related with the chemosensitivity of GC to adriamycin, and miR-16-1 could targeted silence FUBP1 to advance the chemosensitivity to adriamycin in GC, which might be a novel potential therapeutic target for GC.

DTX3L is upregulated in glioma and is associated with glioma progression

Gliomas are the most common primary brain tumors of the central nervous system (CNS). Due to the poor prognosis of glioma patients, it is urgent to develop more effective therapies. Deltex-3-like (DTX3L), also known as B-lymphoma and BAL-associated protein (BBAP), has been reported to play an important role in the progression of many tumors. This study aimed to investigate the clinical significance and biological function of DTX3L in human glioma. Clinically, the protein expression level of DTX3L is increased in glioma tissues compared with that observed in normal brain tissues. Immunohistochemical analysis demonstrated that DTX3L was highly expressed in the glioma tissues and its level was correlated with the grade of malignancy. Multivariate analysis revealed the association between high expression of DTX3L and the poor prognosis of glioma patients. In addition, knockdown of DTX3L by siRNA transfection increased glioma cell apoptosis. Moreover, suppression of DTX3L expression was shown to significantly inhibit the migration and invasion of glioma cells. These data indicate that DTX3L plays an important role in the pathogenic process of glioma, suggesting that DTX3L could be a potential prognostic biomarker for glioma.

Upregulation of Far Upstream Element-Binding Protein 1 (FUBP1) Promotes Tumor Proliferation and Tumorigenesis of Clear Cell Renal Cell Carcinoma

OBJECTIVE

The far upstream element (FUSE)-binding protein 1 (FUBP1) is a transactivator of human c-myc proto-oncogene transcription, with important roles in carcinogenesis. However, the expression pattern and potential biological function of FUBP1 in clear cell renal cell carcinoma (ccRCC) is yet to be established.

METHODS

FUBP1 expression was detected in ccRCC tissues and cell lines by real-time RT-PCR, Western blot analysis, and immunohistochemistry. The correlations of FUBP1 mRNA expression levels with clinicopathological factors were evaluated. The biological function of FUBP1 during tumor cell proliferation was studied by MTS, colony formation, and soft-agar colony formation. The effects of FUBP1 on cell cycle distribution and apoptosis were analyzed by flow cytometry. Western blot analysis was used to identify the potential mechanism of FUBP1 regulating cell cycle and apoptosis.

RESULTS

The levels of FUBP1 mRNA and protein expression were upregulated in human ccRCC tissues compared with adjacent noncancerous tissues. High levels of FUBP1 mRNA expression were associated with higher tumor stage and tumor size. FUBP1 knockdown inhibited cell proliferation and induced cell cycle arrest and apoptosis. Meanwhile, the expression levels of c-myc and p21 mRNA were correlated with that of FUBP1 mRNA.

CONCLUSIONS

FUBP1 acts as a potential oncogene in ccRCC and may be considered as a novel biomarker or an attractive treatment target of ccRCC.

Specific autoantigens identified by sera obtained from mice that are immunized with testicular germ cells alone

There are various autoimmunogenic antigens (AIs) in testicular germ cells (TGCs) recognized as foreign by the body's immune system. However, there is little information of TGC-specific AIs being available. The aim of this study is to identify TGC-specific AIs. We have previously established that immunization using viable syngeneic TGC can also induce murine experimental autoimmune orchitis (EAO) without using any adjuvant. This study is to identify TGC-specific AIs by TGC liquid chromatography-tandem mass spectrometry analysis, followed by two-dimensional gel electrophoresis that reacted with serum IgG from EAO mice. In this study, we identified 11 TGC-specific AIs that reacted with serum from EAO mice. Real-time RT-PCR analysis showed that the mRNA expressions of seven TGC-specific AIs were significantly higher in only mature testis compared to other organs. Moreover, the recombinant proteins of identified 10 (except unnamed protein) TGC-specific AIs were created by using human embryonic kidney 293 (HEK293) cells and these antigencities were reconfirmed by Western blot using EAO serum reaction. These results indicated Atp6v1a, Hsc70t, Fbp1 and Dazap1 were candidates for TGC-specific AIs. Identification of these AIs will facilitate new approaches for understanding infertility and cancer pathogenesis and may provide a basis for the development of novel therapies.

Expression of far upstream element binding protein 1 in B‑cell non‑Hodgkin lymphoma is correlated with tumor growth and cell‑adhesion mediated drug resistance

Cell adhesion‑mediated drug resistance (CAM‑DR) remains a major obstacle to the effectiveness of chemotherapeutic treatment of lymphoma. Far upstream element binding protein 1 (FBP1) is a multifunctional protein that is highly expressed in proliferating cells of several solid neoplasms; however, its expression and biological function in B‑cell lymphoma is largely unknown. FBP1 expression in both reactive lymphoid tissues and several B‑cell lymphomas, including follicular lymphoma and diffuse large B‑cell lymphoma were detected by immunohistochemistry analysis. FBP1 expression in B‑cell lymphoma was also associated with poor survival outcomes. Functionally, small interfering RNA‑mediated silencing of FBP1 was able to inhibit the proliferation of B‑cell lymphoma cells, resulting in G0/G1 phase cell cycle arrest. Furthermore, results of a cell adhesion assay demonstrated that adhesion to fibronectin or bone marrow stromal cells induced FBP1 expression, which in turn facilitated cell adhesion. Finally, FBP1 knockdown reversed CAM‑DR. These findings support a role for FBP1 in non‑Hodgkin lymphoma cell proliferation, adhesion and drug resistance, and may lead to the generation of a novel therapeutic approach targeting this molecule.

Karyopherinβ1 regulates proliferation of human glioma cells via Wnt/β-catenin pathway

Karyopherinβ1 (KPNB1), one of the cytosolic factors involved in the selective protein transport across nucleus, docked at nuclear pore complex and transported through nuclear envelope in an ATP-dependent style, assisting proteins to be recognized as import substrates. It has been reported to be bound up with the origination and progress of lung cancer, cervical cancer, head and neck cancer and hepatocellular carcinoma. In current study, we demonstrated for the first time that the role of KPNB1 in human glioma. KPNB1 was over-expressed as the well-known trend of Ki-67(p < 0.01) and tightly closed to poor prognosis, as an independent prognostic factor. In vitro, up-regulation of KPNB1 was accompanied by certain rising levels of proliferation markers, employing U251 and U87MG cells as serum-starve models. Silencing KPNB1 in U251 and U87MG led to G1 phase arrested directly via flow cytometry analysis. In the nucleus of KPNB1-depletion cell models, the decreasing expression of KPNB1 and β-catenin was detected respectively, which indicated that KPNB1 functioned via β-catenin signal. Besides, the interaction between KPNB1 and β-catenin was proved clearly by immunoprecipitation. Taken together, it showed that KPNB1 might enhance human glioma proliferation via Wnt/β-Catenin Pathway.

The Diagnostic Use of Immunohistochemical Surrogates for Signature Molecular Genetic Alterations in Gliomas

A number of key mutations that affect treatment and prognosis have been identified in human gliomas. Two major ways to identify these mutations in a tumor sample are direct interrogation of the mutated DNA itself and immunohistochemistry to assess the effects of the mutated genes on proteins. Immunohistochemistry is an affordable, robust, and widely available technology that has been in place for decades. For this reason, the use of immunohistochemical approaches to assess molecular genetic changes has become an essential component of state-of-the-art practice. In contrast, even though DNA sequencing technologies are undergoing rapid development, many medical centers do not have access to such methodologies and may be thwarted by the relatively high costs of sending out such tests to reference laboratories. This review summarizes the current experience using immunohistochemistry of glioma samples to identify mutations in IDH1, TP53, ATRX, histone H3 genes, BRAF, EGFR, MGMT, CIC, and FUBP1 as well as guidelines for prudent use of DNA sequencing as a supplemental method.

Protein phosphatase 1γ regulates the proliferation of human glioma via the NF-κB pathway

Protein phosphatase 1γ (PP1γ), a member of mammalian protein phosphatases, serine/threonine phosphatases, catalyzes the majority of protein dephosphorylation events and regulates diverse cellular processes, such as neuronal signaling, muscle contraction, glycogen synthesis, and cell proliferation. However, its expression and potential functions in human glioma is unclear. In this study, we detected the high expression of PP1γ and phosphorylated p65 (p-p65) in human glioma tissues. Besides, we demonstrated that upregulation of PP1γ was tightly related to poor 5-year survival via systemic statistical analysis. Employing serum-starved and re-feeding models of U251 and U87MG, we observed the increasing expression of PP1γ and p-p65 were accompanied by the cell proliferation markers cyclin D1 and proliferating cell nuclear antigen (PCNA). Employing depletion-PP1γ models, we found downregulated PP1γ and p-p65 compared with upregulated IκBα, which indicates the inhibition of NF-κB pathway, and flow cytometry analysis confirmed the weakened cell proliferation. Moreover, we found that the translocation of p65 into the nucleus was impaired. Collectively, we identified the positive correlation between upregulation of PP1γ and human glioma cell proliferation and that knock-down of PP1γ alleviated the glioma proliferation by reducing p65 transportation into the nucleus. The results showed that PP1γ could accelerate human glioma proliferation via the NF-κB pathway.

Far Upstream Element Binding Protein Plays a Crucial Role in Embryonic Development, Hematopoiesis, and Stabilizing Myc Expression Levels

The transcription factor far upstream element binding protein (FBP) binds and activates the MYC promoter when far upstream element is via TFIIH helicase activity early in the transcription cycle. The fundamental biology and pathology of FBP are complex. In some tumors FBP seems pro-oncogenic, whereas in others it is a tumor suppressor. We generated an FBP knockout (Fubp1(-/-)) mouse to study FBP deficiency. FBP is embryo lethal from embryonic day 10.5 to birth. A spectrum of pathology is associated with FBP loss; besides cerebral hyperplasia and pulmonary hypoplasia, pale livers, hypoplastic spleen, thymus, and bone marrow, cardiac hypertrophy, placental distress, and small size were all indicative of anemia. Immunophenotyping of hematopoietic cells in wild-type versus knockout livers revealed irregular trilineage anemia, with deficits in colony formation. Despite normal numbers of hematopoietic stem cells, transplantation of Fubp1(-/-) hematopoietic stem cells into irradiated mice entirely failed to reconstitute hematopoiesis. In competitive transplantation assays against wild-type donor bone marrow, Fubp1(-/-) hematopoietic stem cells functioned only sporadically at a low level. Although cultures of wild-type mouse embryo fibroblasts set Myc levels precisely, Myc levels of mouse varied wildly between fibroblasts harvested from different Fubp1(-/-) embryos, suggesting that FBP contributes to Myc set point fixation. FBP helps to hold multiple physiologic processes to close tolerances, at least in part by constraining Myc expression.

High expression of adenylate cyclase-associated protein 1 accelerates the proliferation, migration and invasion of neural glioma cells

Adenylate cyclase-associated protein 1 (CAP1), a conserved member of cyclase-associated proteins was reported to be associated with the proliferation, migration or invasion of the tumors of pancreas, breast and liver, and was involved in astrocyte proliferation after acute Traumatic Brain Injury (TBI). In this study, we sought to investigate the character of CAP1 in the pathological process of human glioma by detecting human glioma specimens and cell lines. 43 of 100 specimens showed high expression of CAP1 via immunohistochemistry. With statistics analysis, we found out the expression level of CAP1 was correlated with the WHO grades of human glioma and was great positively related to Ki-67 (p<0.01). In vitro, silencing CAP1 in U251 and U87MG, the glioma cell lines with the relatively higher expression of CAP1, induced the proliferation of the cells significantly retarded, migration and invasion as well. Obviously, our results indicated that CAP1 participated in the molecular pathological process of glioma indeed, and in a certain sense, CAP1 might be a potential and promising molecular target for glioma diagnosis and therapies in the future.

Nucleostemin promotes the proliferation of human glioma via Wnt/β-Catenin pathway

Nucleostemin, nucleolar guanosine triphosphate (GTP)-binding protein 3, is a member of the MMR1/HSR1 GTP-binding protein family. The important roles of nucleostemin in self-renewal, cell cycle regulation, apoptosis, and cell proliferation of various cancer types as been shown. Nevertheless, its expression and potential functions in human glioma is still unclear. In the present study, we demonstrated that up-regulation of nucleostemin was tightly related to poor 5-year-survival ratios. In serum-starved and re-feeding models of U251 and U373MG, we observed the rising expression of nucleostemin and p-β-Catenin (p-Tyr645) were accompanied with cell proliferation markers (cyclin D1 and proliferating cell nuclear antigen (PCNA)). Employing nucleostemin-depletion models, we found down-regulated nucleostemin and p-β-Catenin. The flow cytometry analysis proved the weakened cell proliferation. Moreover, we detected the translocation of β-Catenin into the nucleus was impaired, meaning the inhibition of the Wnt/β-Catenin pathway. Taken together, we identified a positive correlation between up-regulation of nucleostemin and human glioma cell proliferation and that knocking-down nucleostemin alleviated glioma proliferation by reducing β-Catenin transportation into the nucleus. All results suggested that nucleostemin might accelerate human glioma proliferation via the Wnt/β-Catenin pathway.

Far upstream element-binding protein 1 (FUBP1) is a potential c-Myc regulator in esophageal squamous cell carcinoma (ESCC) and its expression promotes ESCC progression

The human far upstream element (FUSE) binding protein 1 (FUBP1) belongs to an ancient family which is required for proper regulation of the c-Myc proto-oncogene. Although c-Myc plays an important role in development of various carcinomas, the relevance of FUBP1 and their contribution to esophageal squamous cell carcinoma (ESCC) development remain unclear. In this study, we aimed to investigate the relationship between FUBP1 and c-Myc as well as their contribution to ESCC development. Western blot and immunohistochemical analyses were performed to evaluate FUBP1 expression. Coimmunoprecipitation analysis was performed to explore the correlation between FUBP1 and c-Myc in ESCC. In addition, the role of FUBP1 in ESCC proliferation was studied in ESCC cells through knocking FUBP1 down. The regulation of FUBP1 on proliferation was confirmed by Cell Counting Kit-8 (CCK-8) assay, flow cytometric assays, and clone formation assays. The expressions of FUBP1 and c-Myc were both upregulated in ESCC tissues. In addition to correlation between expression of FUBP1 and tumor grade, we also confirmed the correlation of FUBP1, c-Myc, and Ki-67 expression by twos. Moreover, upregulation of FUBP1 and c-Myc in ESCC was associated with poor survival. FUBP1 was confirmed to activate c-Myc in ESCC tissues and cells. FUBP1 was demonstrated to promote proliferation of ESCC cells. Moreover, downregulation of both FUBP1 and c-Myc was confirmed to inhibit proliferation of ESCC cells. Our results indicated that FUBP1 may potentially stimulate c-Myc expression in ESCC and its expression may promote ESCC progression.

Spy1 induces de-ubiquitinating of RIP1 arrest and confers glioblastoma's resistance to tumor necrosis factor (TNF-α)-induced apoptosis through suppressing the association of CLIPR-59 and CYLD

Glioblastoma multiforme (GBM), a grade-IV glioma, is resistant to TNF-α induced apoptosis. CLIPR-59 modulates ubiquitination of RIP1, thus promoting Caspase-8 activation to induce apoptosis by TNF-α. Here we reported that CLIPR-59 was down-regulated in GBM cells and high-grade glioma tumor samples, which was associated with decreased cancer-free survival. In GBM cells, CLIPR-59 interacts with Spy1, resulting in its decreased association with CYLD, a de-ubiquitinating enzyme. Moreover, experimental reduction of Spy1 levels decreased GBM cells viability, while increased the lysine-63-dependent de-ubiquitinating activity of RIP1 via enhancing the binding ability of CLIPR-59 and CYLD in GBM, thus promoting Caspase-8 and Caspase-3 activation to induce apoptosis by TNF-α. These findings have identified a novel Spy1-CLIPR-59 interplay in GBM cell's resistance to TNF-α-induced apoptosis revealing a potential target in the intervention of malignant brain tumors.

Overexpression of CCT8 and its significance for tumor cell proliferation, migration and invasion in glioma

Overexpression of chaperonin containing t-complex polypeptide 1 (TCP1), or CCT, has been reported in various classes of malignancies. However, little is known about the expression of t-complex protein subunits TCP1theta (CCT8) in gliomas. In this study, the expression of CCT8 protein was detected using blotting analysis and immunohistochemistry. CCT8 was found to be overexpressed in gliomas and to correlate with the WHO grade of gliomas. To further investigate the biological function of CCT8 in gliomas, CCT8-silenced U87 glioblastoma multiforme (GBM) and U251MG cells were constructed using a small interference RNA (siRNA) sequence. The knockdown effect of CCT8 on proliferation and invasion in these cells was analyzed using the CCK8, flow cytometry cycle, scratch, transwell invasion and fluorescence assays. Compared with the controls, the glioma cells expressing CCT8-siRNA exhibited a significantly decreased proliferation and invasion capacity, as well as a dysregulated cell cytoskeleton. This study showed that high CCT8 protein expression might be related to poor outcome of glioma, and that CCT8 regulates the proliferation and invasion of glioblastomas.

Fuse binding protein antagonizes the transcription activity of tumor suppressor protein p53

Background

FUSE binding protein1 (FBP1) is a transactivator of transcription of human c-myc proto-oncogene and expressed mainly in undifferentiated cells. It is also present in differentiated normal cells albeit with very low background. FBP1 is abundantly expressed in the majority of hepatocellular carcinoma tumors and has been implicated in tumor development. Although it down-regulates the expression of proapoptotic p21 protein, it is not known whether FBP1 also interacts and antagonizes the function of tumor suppressor protein p53.

Methods

Western blotting was carried out to detect the expression level of FBP1, p21 and p53, and also p53 regulatory factors, BCCIP and TCTP; real-time quantitative PCR was done to determine the fold change in mRNA levels of target proteins; immunoprecipitation was carried out to determine the interaction of FBP1 with p53, BCCIP and TCTP. Cells stably knockdown for either FBP1; p53 or BCCIP were examined for p53 reporter activity under normal and radiation-induced stress.

Results

FBP1 physically interacted with p53, impairing its transcription activity and reducing p53-mediated sensitivity to cellular stress. Knockdown of FBP1 expression activated p53-mediated response to cellular stress while transient expression of FBP1 in FBP-knockdown cells restored the inhibition of p53 activity. FBP1 not only interacted with both BCCIP and TCTP, which, respectively, function as positive and negative regulators of p53, but also regulated their expression under cellular stress. In FBP knockdown cells, TCTP expression was down-regulated under radiation-induced stress whereas expression of BCCIP and p21 were significantly up-regulated suggesting FBP1 as a potential regulator of these proteins. We hypothesize that the FBP1-mediated suppression of p53 activity may occur via preventing the interaction of p53 with BCCIP as well as by FBP1-mediated regulation of p53 regulatory proteins, TCTP and BCCIP. Since FBP1 suppresses p53 activity and is overexpressed in most HCC tumors, it may have a possible role in tumorigenesis.

Conclusion

FBP1 physically interacts with p53, functions as a regulator of p53-regulatory proteins (TCTP and BCCIP), and suppresses p53 transactivation activity under radiation-induced cellular stress. Since it is abundantly expressed in most HCC tumors, it may have implication in tumorigenesis and thus may be a possible target for drug development.

The splicing factor FUBP1 is required for the efficient splicing of oncogene MDM2 pre-mRNA

Alternative splicing of the oncogene MDM2 is a phenomenon that occurs in cells in response to genotoxic stress and is also a hallmark of several cancer types with important implications in carcinogenesis. However, the mechanisms regulating this splicing event remain unclear. Previously, we uncovered the importance of intron 11 in MDM2 that affects the splicing of a damage-responsive MDM2 minigene. Here, we have identified discrete cis regulatory elements within intron 11 and report the binding of FUBP1 (Far Upstream element-Binding Protein 1) to these elements and the role it plays in MDM2 splicing. Best known for its oncogenic role as a transcription factor in the context of c-MYC, FUBP1 was recently described as a splicing regulator with splicing repressive functions. In the case of MDM2, we describe FUBP1 as a positive splicing regulatory factor. We observed that blocking the function of FUBP1 in in vitro splicing reactions caused a decrease in splicing efficiency of the introns of the MDM2 minigene. Moreover, knockdown of FUBP1 in cells induced the formation of MDM2-ALT1, a stress-induced splice variant of MDM2, even under normal conditions. These results indicate that FUBP1 is also a strong positive splicing regulator that facilitates efficient splicing of the MDM2 pre-mRNA by binding its introns. These findings are the first report describing the regulation of alternative splicing of MDM2 mediated by the oncogenic factor FUBP1.