Bex2 regulates cell proliferation and apoptosis in malignant glioma cells via the c-Jun NH2-terminal kinase pathway

JNK/MAPK pathway regulation by BEX2 gene silencing in alcoholic hepatitis mice: Effects on oxidative stress

BACKGROUND

Alcoholic hepatitis (AH) is a severe alcoholic-related liver disease that is a leading cause of morbidity and mortality, for which effective treatments are lacking. Brain-expressed X-linked gene 2 (BEX2) has been implicated in various diseases, but its association with AH has received limited attention. Thus, this study investigated BEX2's impact on the progression of AH by affecting the c-Jun NH2-terminal kinase/mitogen-activated protein kinase (JNK/MAPK) pathway.

METHODS

Microarray dataset GSE28619 from the Gene Expression Omnibus database was used to identify differentially expressed genes in AH. Immunohistochemistry, terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL), Western blot analysis, and flow cytometry were used to measure various factors in the liver tissue of AH mice.

RESULTS

BEX2 expression was significantly upregulated in the model. BEX2 gene silencing increased the levels of glutathione peroxidase and superoxide dismutase while decreasing malondialdehyde content; phosphorylation of JNK, c-JUN, and p38MAPK; apoptosis rate; and the extent of JNK/MAPK pathway activation.

CONCLUSIONS

These findings provide valuable insights into the mechanisms underlying AH development and highlight the potential role of BEX2 gene expression as a promising therapeutic target for AH.

Apoptosis Related Human Wharton's Jelly-Derived Stem Cells Differentiation into Osteoblasts, Chondrocytes, Adipocytes and Neural-like Cells-Complete Transcriptomic Assays

Wharton's jelly-derived mesenchymal stem cells (WJ-MSCs) exhibit multilineage differentiation potential, adhere to plastic, and express a specific set of surface markers-CD105, CD73, CD90. Although there are relatively well-established differentiation protocols for WJ-MSCs, the exact molecular mechanisms involved in their in vitro long-term culture and differentiation remain to be elucidated. In this study, the cells were isolated from Wharton's jelly of umbilical cords obtained from healthy full-term deliveries, cultivated in vitro, and differentiated towards osteogenic, chondrogenic, adipogenic and neurogenic lineages. RNA samples were isolated after the differentiation regimen and analyzed using an RNA sequencing (RNAseq) assay, which led to the identification of differentially expressed genes belonging to apoptosis-related ontological groups. ZBTB16 and FOXO1 were upregulated in all differentiated groups as compared to controls, while TGFA was downregulated in all groups. In addition, several possible novel marker genes associated with the differentiation of WJ-MSCs were identified (e.g., SEPTIN4, ITPR1, CNR1, BEX2, CD14, EDNRB). The results of this study provide an insight into the molecular mechanisms involved in the long-term culture in vitro and four-lineage differentiation of WJ-MSCs, which is crucial to utilize WJ-MSCs in regenerative medicine.

Comprehensive Analysis of the Brain-Expressed X-Link Protein Family in Glioblastoma Multiforme

Glioblastoma multiforme (GBM) is the most common, malignant, and deadly primary brain tumor in adults. Brain-expressed X-link (BEX) protein family is involved in tumorigenesis. Here, we have explored the biological function and the prognostic value of the BEX family in GBM. Differentially expressed BEX genes between GBM and normal tissue were screened by using The Cancer Genome Atlas (TCGA) database. Univariate and multivariate Cox regression analyses identified the prognosis‐related genes BEX1, BEX2, and BEX4, which were involved in the regulation of immune response. The results of correlation analysis and protein–protein interaction network (PPI network) showed that there was a significant correlation between the BEX family and TCEAL family in GBM. Furthermore, the expression of transcription elongation factor A (SII)-like (TCEAL) family is generally decreased in GBM and related to poor prognosis. With the use of the least absolute shrinkage and selection operator (LASSO) Cox regression, a prognostic model including the BEX family and TCEAL family was built to accurately predict the likelihood of overall survival (OS) in GBM patients. Therefore, we demonstrated that the BEX family and TCEAL family possessed great potential as therapeutic targets and prognostic biomarkers in GBM. Further investigations in large‐scale, multicenter, and prospective clinical cohorts are needed to confirm the prognostic model developed in our study.

Aqueous humor proteomic analysis of acute angle-closure glaucoma with visual field loss

Background

Acute angle-closure glaucoma (AACG) is an ophthalmic emergency that occurs over the course of hours or days and may cause irreversible blindness if not treated immediately. In most cases, optic nerve damage is the cause of visual field (VF) loss in AACG. There has been no reliable biomarker found to evaluate optic nerve damage to date. Aqueous humor (AH) proteome analysis might reveal the proteomic alterations in AACG and provide helpful clues in the search for an AH biomarker of optic nerve damage and VF loss.

Methods

In this study, we used the AH proteome to explore the functions of differentially expressed proteins (DEPs) during disease progression. The AH proteins from the early-stage group and late-stage group were extracted and analyzed by the data-independent acquisition (DIA) method. The DEPs functions were annotated, and parallel reaction monitoring (PRM) was used to validate the key DEPs.

Results

A total of 87 DEPs were found. Gene Ontology analysis showed that most DEPs were enriched in immunology, hemodynamics, and apoptosis. Ingenuity pathway analysis found that vascular endothelial growth factor (VEGF) signaling, the production of reactive oxygen species (ROS) in macrophages, and the nuclear factor erythroid 2-related factor 2 (NRF2)-mediated oxidative stress response were active pathways in the late stage of AACG. The mechanism of retinal ganglion cell (RGC) death was hypothesized on the basis of DEP functional analysis. A total of 20 DEPs were validated by using PRM, and prostaglandin-H2 D-isomerase was found to have the potential to evaluate optic nerve damage.

Conclusions

This study showed that AH proteomic analysis could reveal the proteomic alterations in the pathogenesis of VF loss in AACG and help to provide objective protein biomarkers to evaluate VF loss. These findings will benefit the application of the AH proteome to clinical research.

Synergistic alterations in the multilevel chromatin structure anchor dysregulated genes in small cell lung cancer

Small cell lung cancer (SCLC) is an aggressive form of lung cancer that uniquely changes the chromosomal structure, although the basis of aberrant gene expression in SCLC remains largely unclear. Topologically associated domains (TADs) are structural and functional units of the human genome. Genetic and epigenetic alterations in the cancer genome can lead to the disruption of TAD boundaries and may cause gene dysregulation. To understand the potential regulatory role of this process in SCLC, we developed the TAD boundary alteration-related gene identification in tumors (TARGET) computational framework, which enables the systematic identification of candidate dysregulated genes associated with altered TAD boundaries. Using TARGET to compare gene expression profiles between SCLC and normal human lung fibroblast cell lines, we identified >100 genes in this category, of which 24 were further verified in samples from patients with SCLC using NanoString. The analysis revealed synergistic chromatin structure alteration at the A/B compartment and TAD boundary levels that underlies aberrant gene expression in SCLC. TARGET is a novel and powerful tool that can be used to explore the relationship of chromatin structure alteration to gene dysregulation related to SCLC tumorigenesis, progression, and prognosis.

BEX2 is required for maintaining dormant cancer stem cell in hepatocellular carcinoma

Cancer stem cells (CSCs) are responsible for therapy resistance and share several properties with normal stem cells. Here, we show that brain‐expressed X‐linked gene 2 (BEX2), which is essential for dormant CSCs in cholangiocarcinoma, is highly expressed in human hepatocellular carcinoma (HCC) lesions compared with the adjacent normal lesions and that in 41 HCC cases the BEX2^high expression group is correlated with a poor prognosis. BEX2 localizes to Ki67‐negative (nonproliferative) cancer cells in HCC tissues and is highly expressed in the dormant fraction of HCC cell lines. Knockdown of BEX2 attenuates CSC phenotypes, including sphere formation ability and aldefluor activity, and BEX2 overexpression enhances these phenotypes. Moreover, BEX2 knockdown increases cisplatin sensitivity, and BEX2 expression is induced by cisplatin treatment. Taken together, these data suggest that BEX2 induces dormant CSC properties and affects the prognosis of patients with HCC.

Discovery of a chemical compound that suppresses expression of BEX2, a dormant cancer stem cell-related protein

Cancer stem cells (CSCs) are believed to cause cancer metastasis and recurrence. BEX2 (brain expressed X-linked gene 2) is a CSC-related gene that is expressed in dormant CSCs in cholangiocarcinoma and induces resistance against chemotherapy. The aim of the present study was to identify small compounds that have activity to inhibit BEX2 expression and result in the attenuation of CSC-related phenotypes. We screened 9600 small chemical compounds in high-throughput screening using cholangiocarcinoma cell line HuCCT1 expressing BEX2 protein fused with NanoLuc, and identified a compound, BMPP (1, 3-Benzenediol, [4-(4-methoxyphenyl)-1H-pyrazol-3-yl]). BMPP was found to exert decreasing effects on BEX2 protein expression and G₀ phase population of the tumor cells, and increasing effects on ATP levels and chemotherapeutic sensitivity of the cells. These findings indicate that BMPP is a valuable chemical compound for reducing dormant CSC-related phenotypes. Thus, the identification of BMPP as a potential CSC suppressor provides scope for the development of novel therapeutic modalities for the treatment of cancers with BEX2 overexpressing CSCs.

Differential gene expression in cisplatin-resistant and -sensitive testicular germ cell tumor cell lines

Testicular germ cell tumors (TGCTs) represent a well curable malignity due to their exceptional response to cisplatin (CDDP). Despite remarkable treatment results, approximately 5% of TGCT patients develop CDDP resistance and die. Exceptional curability makes TGCTs a highly valuable model system for studying the molecular mechanisms of CDDP sensitivity. Our study was aimed at revealing difference in gene expression between the CDDP-resistant and -sensitive TGCT cell lines, and hence at identifying candidate genes that could serve as potential biomarkers of CDDP response. Using gene expression array, we identified 281 genes that are differentially expressed in CDDP-resistant compared to -sensitive TGCT cell lines. The expression of 25 genes with the highest fold change was validated by RT-qPCR. Of them, DNMT3L, GAL, IGFBP2, IGFBP7, L1TD1, NANOG, NTF3, POU5F1, SOX2, WNT6, ZFP42, ID2, PCP4, SLC40A1 and TRIB3, displayed comparable expression change in gene expression array and RT-qPCR, when all CDDP-resistant TGCT cell lines were pairwise combined with all -sensitive ones. Products of the identified genes are pluripotency factors, or are involved in processes, such as cell metabolism, proliferation or migration. We propose that, after clinical validation, these genes could serve as prognostic biomarkers for early detection of CDDP response in TGCT patients.

BEX2 suppresses mitochondrial activity and is required for dormant cancer stem cell maintenance in intrahepatic cholangiocarcinoma

Cancer stem cells (CSCs) define a subpopulation of cancer cells that are resistant to therapy. However, little is known of how CSC characteristics are regulated. We previously showed that dormant cancer stem cells are enriched with a CD274^low fraction of cholangiocarcinoma cells. Here we found that BEX2 was highly expressed in CD274^low cells, and that BEX2 knockdown decreased the tumorigenicity and G₀ phase of cholangiocarcinoma cells. BEX2 was found to be expressed predominantly in G₀ phase and starvation induced the USF2 transcriptional factor, which induced BEX2 transcription. Comprehensive screening of BEX2 binding proteins identified E3 ubiquitin ligase complex proteins, FEM1B and CUL2, and a mitochondrial protein TUFM, and further demonstrated that knockdown of BEX2 or TUFM increased mitochondria-related oxygen consumption and decreased tumorigenicity in cholangiocarcinoma cells. These results suggest that BEX2 is essential for maintaining dormant cancer stem cells through the suppression of mitochondrial activity in cholangiocarcinoma.

Diagnostic and prognostic value of the BEX family in lung adenocarcinoma

Previous studies have demonstrated that members of the brain-expressed X-linked (BEX) family participate in a wide range of biological functions in normal and tumor tissues. However, their role and clinical significance in lung adenocarcinoma (LUAD) remains unclear. The present study investigated The Cancer Genome Atlas data and revealed that the BEX family was downregulated in LUAD tissues compared with adjacent non-cancerous tissues. Additionally, analysis of LUAD cohorts from the Oncomine database revealed similar results. Furthermore, the expression of BEX members was significantly decreased in several LUAD cell lines compared with normal lung epithelial cells in vitro. The aforementioned data mining and in vitro results suggested that the BEX family may be involved in the development of LUAD. Furthermore, receiver operating characteristic curve analysis revealed that BEX members exhibited high sensitivity and specificity for the diagnosis of patients with LUAD. The low expression levels of BEX1, BEX4 and BEX5 were associated with certain pathologic features, particularly in advanced LUAD. Survival analysis demonstrated that BEX members, particularly BEX4, were involved in the prognosis of patients with LUAD at early and late clinical stages. The results obtained in the current study suggested that BEX members may serve as potential tumor biomarkers for the diagnosis and prognosis of patients with LUAD.

MicroRNA-370 functions as a tumor suppressor in hepatocellular carcinoma via inhibition of the MAPK/JNK signaling pathway by targeting BEX2

Hepatocellular carcinoma (HCC) is a primary malignancy of the liver and occurs predominantly in patients with underlying chronic liver disease and cirrhosis. Accumulating studies have revealed that microRNAs (miRNAs) play a critical role in the development and progression of HCC. Through microarray-based gene expression profiling of HCC, miR-370, and BEX2 were identified in HCC. Hence, this study aimed to evaluate their abilities on the cellular processes in HCC. It was determined that BEX2 was highly expressed and miR-370 was poorly expressed in HCC cell lines and tissues. Then, the cell line presenting with the highest BEX2 expression and the lowest miR-370 expression was selected for subsequent gain- and loss-of-function experimentation. The antitumor effect of miR-370 on HCC cell proliferation, invasion, migration, and apoptosis, as well as the MAPK/JNK signaling pathway was examined. Meanwhile, the interaction among miR-370, BEX2, and MAPK/JNK signaling pathway was identified. BEX2 is verified to be a target of miR-370. Moreover, miR-370 exerted antitumor effect on HCC development through suppression of the MAPK/JNK signaling pathway by targeting BEX2. Later, it was further verified by in vivo experiment that overexpression of miR-370 inhibited tumor growth. Above results provide evidence that miR-370 could downregulate BEX2 gene and inhibit activation of MAPK/JNK signaling pathway, thus inhibiting the development of HCC. It provides a worth-trying novel therapeutic target for HCC treatment.

Molecular functions of brain expressed X-linked 2 (BEX2) in malignancies

Over the last decade there has been growing evidence that Brain Expressed X-Linked 2 (BEX2) has a significant role in the process of carcinogenesis. Collectively, available studies suggest a pro-oncogenic function for this gene in multiple malignancies, including breast, colorectal and hepatocellular cancers in addition to brain tumors. The identification of BEX2 in breast cancer resulted from gene expression microarray studies. Subsequent studies showed that BEX2 promotes breast cancer cell growth and survival by modulating the mitochondrial apoptotic pathway and G1 cell cycle. In this process, BEX2 has cross-talk with the NF-κB, c-Jun/JNK and ErbB2 pathways. Of note, several studies have found a pro-oncogenic function for BEX2 in other malignancies associated with a similar signaling function to that observed in breast cancer. In brain tumors, BEX2 promotes cell migration and invasion in oligodendroglioma and glioblastoma cells. In addition, BEX2 expression protects glioma cells against apoptosis mediated through the JNK pathway and is required for glioma cell proliferation through the NF-κB p65. Furthermore, it has been shown that BEX2 promotes cell proliferation through the JNK/c-Jun pathway and regulates JNK/c-Jun phosphorylation in colorectal cancer. Most recently, it has been demonstrated that BEX2 expression is required for cell proliferation and Hepatitis B Virus-mediated development of hepatocellular carcinoma. Therefore, a pro-oncogenic function for BEX2 is supported by reproducible data in multiple malignancies and the NF-κB and JNK/c-Jun pathways are commonly regulated by BEX2 in this process. In view of these findings, targeting BEX2 may provide an attractive therapeutic strategy in multiple malignancies.

Up-regulation of brain-expressed X-linked 2 is critical for hepatitis B virus X protein-induced hepatocellular carcinoma development

Hepatocellular carcinoma (HCC) is the third leading cause of cancer-related death worldwide. Chronic hepatitis B virus (HBV) infection is a major cause for HCC. Hepatitis B virus X (HBx), one of four proteins encoded by HBV genome, plays a vital role in the pathogenesis of HBV-induced HCC. However, the molecular mechanisms of HBx-triggered HCC remain largely undetermined. Here we revealed that the expression of Brain-expressed X-linked 2 (BEX2) and Osteopontin (OPN) were elevated in liver tissues of HBV transgenic mice and human HCC specimens. Moreover, a positive correlation between BEX2 and OPN was exhibited in samples from HCC patients with HBV infection. The protein levels of BEX2 and OPN were both higher in HBV-positive HCC specimens compared to that of HBV-negative HCC specimens. HBx potentiated OPN expression through up-regulation of BEX2. Importantly, the depletion of BEX2 suppressed tumorigenic potential of HCC cells with highly expressed HBx. We demonstrated the important role of BEX2 in HCC pathogenesis, and BEX2 may be a novel therapeutic target for HCC patients with HBV infection. The newly identified HBx/BEX2/OPN signaling cassette is implicated in the pathogenesis of HBV-induced HCC.

BEX2 promotes tumor proliferation in colorectal cancer

BEX2 has been suggested to promote the tumor growth in breast cancer and glioblastoma, while inhibit the proliferation of glioma cells. Thus, the role of BEX2 in tumor was still in debate. Additionally, the biological functions of BEX2 in colorectal cancer (CRC) have not yet been clarified. Here, we reported that BEX2 was overexpressed in advanced CRC from both the GSE14333 database and fresh CRC tissue specimens, and positively correlated with clinical staging. Knockdown of BEX2 significantly decreased the in vitro proliferation of SW620 colorectal cancer cells, suppressed subcutaneous xenograft growth and enhanced the survival of mice with cecal tumors. These effects were mainly mediated by the JNK/c-Jun pathway. Knockdown of BEX2 inhibited JNK/c-Jun phosphorylation, while BEX2 overexpression activated JNK/c-Jun phosphorylation. Moreover, the administration of the JNK-specific inhibitor SP600125 to SW620 with BEX2 overexpression abolished the effect of BEX2 on SW620 cell proliferation. This study reveals that BEX2 promotes colorectal cancer cell proliferation via the JNK/c-Jun pathway, suggesting BEX2 as a potential candidate target for the treatment of CRC.

Oncogenic microtubule hyperacetylation through BEX4-mediated sirtuin 2 inhibition

Five brain-expressed X-linked (BEX) gene members (BEX1–5) are arranged in tandem on chromosome X, and are highly conserved across diverse species. However, little is known about the function and role of BEX. This study represents a first attempt to demonstrate the molecular details of a novel oncogene BEX4. Among BEX proteins, BEX4 localizes to microtubules and spindle poles, and interacts with α-tubulin (α-TUB) and sirtuin 2 (SIRT2). The overexpression of BEX4 leads to the hyperacetylation of α-TUB by inhibiting SIRT2-mediated deacetylation. Furthermore, we found BEX4 expression conferred resistance to apoptotic cell death but led to acquisition of aneuploidy, and also increased the proliferating potential and growth of tumors. These results suggest that BEX4 overexpression causes an imbalance between TUB acetylation and deacetylation by SIRT2 inhibition and induces oncogenic aneuploidy transformation.

Decreased brain-expressed X-linked 4 (BEX4) expression promotes growth of oral squamous cell carcinoma

Background

Brain-expressed X-linked (BEX) 4 is a member of BEX family. The functional role of BEX4 in oral squamous cell carcinoma (OSCC) remains unknown.

Methods

Expression level of BEX family members (BEX1-5) in OSCC tissues and the paired normal epithelial were examined. Functions of epigenetic changes (DNA methylation and histone modifications) on BEX4 suppression in OSCC were examined by zebularine and trichostatin A (TSA) treatment on OSCC cell lines. Lentivector containing full-length BEX4 was used to generate OSCC cell lines with stable BEX4 expression. Effects of BEX4 expression on OSCC proliferation were monitored with xCELLigence RTCA real-time cell analyzer. BEX4-overexpressing CAL27 was implanted into nude mice to evaluate the effects on tumor growth in vivo. The signaling pathways regulated by BEX4 in OSCC was explored using human whole-transcript expression microarray.

Results

Among the 5 BEX family members, BEX1 and BEX4 showed significant down-regulation in OSCC (P < 0.001). BEX3, in comparison, was overexpressed in the primary tumor. BEX4 expression in OSCC cell lines was re-activated after zebularine and TSA treatment. High BEX4 expression could suppress proliferation of OSCC in vitro. Subcutaneous tumor volume of BEX4-overexpressing CAL27 was remarkably reduced in nude mice. Microarray experiment showed that S100A family members (S100A7, S100A7A, S100A8, S100A9 & S100A12) might be the downstream targets of BEX4 in OSCC.

Conclusions

BEX4 functions as tumor suppressor by inhibiting proliferation and growth of oral cancer. Decreased BEX4 contributes to the increased proliferative propensity of OSCC.

Transcriptome Analysis of Bovine Ovarian Follicles at Predeviation and Onset of Deviation Stages of a Follicular Wave

For two libraries (PDF1 and ODF1) using Illumina sequencing 44,082,301 and 43,708,132 clean reads were obtained, respectively. After being mapped to the bovine RefSeq database, 15,533 genes were identified to be expressed in both types of follicles (cut-off RPKM > 0.5), of which 719 were highly expressed in bovine follicles (cut-off RPKM > 100). Furthermore, 83 genes were identified as being differentially expressed in ODF1 versus PDF1, where 42 genes were upregulated and 41 genes were downregulated. KEGG pathway analysis revealed two upregulated genes in ODF1 versus PDF1, CYP11A1, and CYP19A1, which are important genes in the steroid hormone biosynthesis pathway. This study represents the first investigation of transcriptome of bovine follicles at predeviation and onset of deviation stages and provides a foundation for future investigation of the regulatory mechanisms involved in follicular development in cattle.

Brain-Expressed X-linked (BEX) proteins in human cancers

The Brain-Expressed X-linked (BEX) family proteins are comprised of five human proteins including BEX1, BEX2, BEX3, BEX4 and BEX5. BEX family proteins are expressed in a wide range of tissues and are known to play a role in neuronal development. Recent studies suggest a role of BEX family proteins in cancers. BEX1 expression is lost in a subgroup of patients with acute myeloid leukemia (AML) and chronic myeloid leukemia (CML). Expression of BEX1 controls cell surface receptor signaling and restores imatinib response in resistant cells. BEX2 is overexpressed in a group of breast cancer patients and also in gliomas. Increased BEX2 expression led to enhanced NF-κB signaling as well as cell proliferation. Although BEX2 acts as tumor promoter in a subset of breast cancer, BEX3 expression displayed an opposite role. Overexpression of BEX3 resulted in inhibition of tumor formation in breast cancer mouse xenograft models. The role of BEX4 and BEX5 in cancer has not yet been defined. Collectively this suggests that BEX family members have distinct roles in cancers. While BEX1 and BEX3 act as tumor suppressors, BEX2 seems to act as an oncogene.

Hugl-1 inhibits glioma cell growth in intracranial model

Drosophila lethal (2) giant larvae (lgl) has been reported as a tumor suppressor and could regulate the Drosophila hippo signaling. Human giant larvae-1(Hugl-1), one human homologue of Drosophila lgl, also has been reported to be involved in the development of some human cancers. However, whether Hugl-1 is associated with the pathogenesis of malignant gliomas remains poorly understood. In the present work, we examined the effect of Hugl-1 on glioma cell growth both in vitro and in vivo. Firstly, we found that Hugl-1 protein levels decreased in the human glioma tissues, suggesting that Hugl-1 is involved in glioma progression. Unfortunately, either stably or transiently over-expressing Hugl-1 did not affect glioma cell proliferation in vitro. In addition, Hugl-1 over-expression did not regulate hippo signaling pathway. Interestingly, over-expression of Hugl-1 not only inhibited gliomagenesis but also markedly inhibited cell proliferation and promoted the apoptosis of U251 cells in an orthotopic model of nude mice. Taken together, this study provides the evidence that Hugl-1 inhibits glioma cell growth in intracranial model of nude mice, suggesting that Hugl-1 might be a potential tumor target for glioma therapy.

Β-catenin is involved in Bex2 down-regulation induced glioma cell invasion/migration inhibition

Previously, we found that brain expressed X-linked gene 2 (Bex2) regulates the invasion/migration ability of glioma cells. However, the mechanism of this effect remains unknown. In current study, we reported that Bex2 down-regulation inhibited glioma cell migration and invasion by decreasing the nucleus and cytoplasm protein level of β-catenin. We found that the protein levels of Bex2 and β-catenin were up-regulated and showed direct correlation in glioma tissues. Bex2 down-regulation significantly decreased β-catenin protein levels but not its mRNA levels. Furthermore, the decreased protein level of β-catenin was located in the nucleus and cytoplasm but not in the cell membrane. Further study found that the effects of Bex2 down-regulation on the invasion and migration of glioma cell could be reversed by β-catenin over-expression. Taken together, Bex2 affects the invasion and migration ability of glioma cells by regulating β-catenin.

Gene targeting study reveals unexpected expression of brain-expressed X-linked 2 in endocrine and tissue stem/progenitor cells in mice

Identification of genes specifically expressed in stem/progenitor cells is an important issue in developmental and stem cell biology. Genome-wide gene expression analyses in liver cells performed in this study have revealed a strong expression of X-linked genes that include members of the brain-expressed X-linked (Bex) gene family in stem/progenitor cells. Bex family genes are expressed abundantly in the neural cells and have been suggested to play important roles in the development of nervous tissues. However, the physiological role of its individual members and the precise expression pattern outside the nervous system remain largely unknown. Here, we focused on Bex2 and examined its role and expression pattern by generating knock-in mice; the enhanced green fluorescence protein (EGFP) was inserted into the Bex2 locus. Bex2-deficient mice were viable and fertile under laboratory growth conditions showing no obvious phenotypic abnormalities. Through an immunohistochemical analysis and flow cytometry-based approach, we observed unique EGFP reporter expression patterns in endocrine and stem/progenitor cells of the liver, pyloric stomach, and hematopoietic system. Although Bex2 seems to play redundant roles in vivo, these results suggest the significance and potential applications of Bex2 in studies of endocrine and stem/progenitor cells.

Bex2 controls proliferation of human glioblastoma cells through NF-κB signaling pathway

Glioblastoma is the most common and fatal human brain malignancy in adults with highly proliferative capacity. Despite advances in surgery and adjuvant therapy, the median survival of patients has changed little over recent decades. Identifying molecules critical for glioma development is significant for devising effective targeted therapy. We previously reported that Bex2, a member of the brain expressed X-linked gene family, promoted the progression of glioma by promoting cell proliferation. In the present study, we investigated the main mechanism of Bex2 promoting the proliferation of glioblastoma cells. We found that Bex2 downregulation inhibited glioma cell proliferation and the expression of NF-κB p65, but Bex2 overexpression promoted them. Similarly, the proliferation of glioma cells was inhibited by p65 downregulation but increased by p65 overexpression. In addition, Bex2 overexpression-induced cell proliferation was abolished by p65 downregulation. Furthermore, Bex2 with nuclear localization signal deleted no longer promoted p65 expression. In conclusion, this study demonstrates that Bex2 promotes proliferation of human glioblastoma cells via NF-κB signaling pathway and Bex2 nuclear location is critical for p65 expression.

Significance of C-Jun expression in esophageal squamous cell carcinoma

AIM: To investigate the relationship between C-Jun protein expression and clinical biological behavior of esophageal squamous cell carcinoma (ESCC).

METHODS: Immunohistochemistry and RT-PCR were used to detect the expression of C-Jun protein and mRNA in 96 cases of ESCC tissue and matched tumor-adjacent esophageal tissue. The correlation between C-Jun protein expression and clinical biological behavior of ESCC was analyzed.

RESULTS: C-Jun expression in ESCC was significantly higher in ESCC tissue than in matched tumor-adjacent esophageal tissue (0.7703 ± 0.3330 vs 0.2546 ± 0.1328, t = -11.23, P < 0.05). C-Jun protein expression was correlated with lymph node metastasis and TNM stage in ESCC (both P < 0.05).

CONCLUSION: C-Jun protein is highly expressed in ESCC, which correlates with lymph node metastasis and TNM stage. This finding suggests that high expression C-Jun protein may be related to the occurrence and development of ESCC.