BEX2 promotes tumor proliferation in colorectal cancer

Construction of novel 7 integrin-related gene signatures in thyroid cancer construction of model based on integrin genes

Advanced and metastatic THCA patients usually have a poor prognosis. Thus, this study aimed to establish a risk model to discriminate the high risk population. The expression and clinical data were obtained from TCGA database. The cluster analysis, lasso, univariate and multivariate cox analyses were used to construct risk model. K-M, ROC and DCA were applied to validate the efficiency and stability of the model. GO, KEGG, and ssGSEA analysis were performed to identify the potential mechanism of signatures. The 7-gene prognosis model was constructed, including FAM27E3, FIGN, GSTM4, BEX5, RBPMS2, PHF13, and DCSTAMP. ROC and DCA results showed our model had a better prognosis prediction performance than other risk models. The high risk score was associated with the poor prognosis of THCA patients with different clinical characteristics. The risk score was closely related to cell cycle. Further, we found that the expressions of signatures were significantly dysregulated in THCA and associated with prognosis. These gene expressions were affected by some clinical characteristics, methylation and CNV. Some signatures played a role in drug sensitivity and pathway activation. We constructed a 7-gene signature model based on the integrin-related genes, which showed a great prognostic value in THCA.

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.

BEX2 is poor prognostic factor and required for cancer stemness in gastric cancer

Gastric cancer is the fifth most common malignancy worldwide. However, targeted therapy for advanced gastric cancer is still limited. Here, we report BEX2 (Brain expressed X-linked 2) as a poor prognostic factor in two gastric cancer cohorts. BEX2 expression was increased in spheroid cells, and its knockdown decreased aldefluor activity and cisplatin resistance. BEX2 was found to upregulate CHRNB2 (Cholinergic Receptor Nicotinic Beta 2 Subunit) expression, a cancer stemness-related gene, in a transcriptional manner, and the knockdown of which also decreases aldefluor activity. Collectively, these data are suggestive of the role of BEX2 in the malignant process of gastric cancer, and as a promising therapeutic target.

Chronic Inhalation Exposure to Antimony Trioxide Exacerbates the MAPK Signaling in Alveolar Bronchiolar Carcinomas in B6C3F1/N Mice

Antimony trioxide (AT) is used as a flame retardant in fabrics and plastics. Occupational exposure in miners and smelters is mainly through inhalation and dermal contact. Chronic inhalation exposure to AT particulates in B6C3F1/N mice and Wistar Han rats resulted in increased incidences and tumor multiplicities of alveolar/bronchiolar carcinomas (ABCs). In this study, we demonstrated Kras (43%) and Egfr (46%) hotspot mutations in mouse lung tumors (n = 80) and only Egfr (50%) mutations in rat lung tumors (n = 26). Interestingly, there were no differences in the incidences of these mutations in ABCs from rats and mice at exposure concentrations that did and did not exceed the pulmonary overload threshold. There was increased expression of p44/42 mitogen-activated protein kinase (MAPK) (Erk1/2) protein in ABCs harboring mutations in Kras and/or Egfr, confirming the activation of MAPK signaling. Transcriptomic analysis indicated significant alterations in MAPK signaling such as ephrin receptor signaling and signaling by Rho-family GTPases in AT-exposed ABCs. In addition, there was significant overlap between transcriptomic data from mouse ABCs due to AT exposure and human pulmonary adenocarcinoma data. Collectively, these data suggest chronic AT exposure exacerbates MAPK signaling in ABCs and, thus, may be translationally relevant to human lung cancers.

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.

BEX1 and BEX4 Induce GBM Progression through Regulation of Actin Polymerization and Activation of YAP/TAZ Signaling

GBM is a high-grade cancer that originates from glial cells and has a poor prognosis. Although a combination of surgery, radiotherapy, and chemotherapy is prescribed to patients, GBM is highly resistant to therapies, and surviving cells show increased aggressiveness. In this study, we investigated the molecular mechanism underlying GBM progression after radiotherapy by establishing a GBM orthotopic xenograft mouse model. Based on transcriptomic analysis, we found that the expression of BEX1 and BEX4 was upregulated in GBM cells surviving radiotherapy. We also found that upregulated expression of BEX1 and BEX4 was involved in the formation of the filamentous cytoskeleton and altered mechanotransduction, which resulted in the activation of the YAP/TAZ signaling pathway. BEX1- and BEX4-mediated YAP/TAZ activation enhanced the tumor formation, growth, and radioresistance of GBM cells. Additionally, latrunculin B inhibited GBM progression after radiotherapy by suppressing actin polymerization in an orthotopic xenograft mouse model. Taken together, we suggest the involvement of cytoskeleton formation in radiation-induced GBM progression and latrunculin B as a GBM radiosensitizer.

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.

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.

Interrupting Neuron-Tumor Interactions to Overcome Treatment Resistance

Neurons in the tumor microenvironment release neurotransmitters, neuroligins, chemokines, soluble growth factors, and membrane-bound growth factors that solid tumors leverage to drive their own survival and spread. Tumors express nerve-specific growth factors and microRNAs that support local neurons and guide neuronal growth into tumors. The development of feed-forward relationships between tumors and neurons allows tumors to use the perineural space as a sanctuary from therapy. Tumor denervation slows tumor growth in animal models, demonstrating the innervation dependence of growing tumors. Further in vitro and in vivo experiments have identified many of the secreted signaling molecules (e.g., acetylcholine, nerve growth factor) that are passed between neurons and cancer cells, as well as the major signaling pathways (e.g., MAPK/EGFR) involved in these trophic interactions. The molecules involved in these signaling pathways serve as potential biomarkers of disease. Additionally, new treatment strategies focus on using small molecules, receptor agonists, nerve-specific toxins, and surgical interventions to target tumors, neurons, and immune cells of the tumor microenvironment, thereby severing the interactions between tumors and surrounding neurons. This article discusses the mechanisms underlying the trophic relationships formed between neurons and tumors and explores the emerging therapies stemming from this work.

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.

Silencing of brain-expressed X-linked 2 (BEX2) promotes colorectal cancer metastasis through the Hedgehog signaling pathway

The incidence of colorectal cancer is increasing, and cancer metastasis is one of the major causes of poor outcomes. BEX2 has been reported to be involved in tumor development in several types of cancer, but its role in metastatic colorectal cancer remains largely undefined. Herein, we demonstrated that BEX2 knockout resulted in enhanced migratory and metastatic potential in colorectal cancer cells both in vitro and in vivo, and re-expression of BEX2 in knockout cells could reverse the enhanced migratory capacity. RNA-Seq results indicated that the hedgehog signaling pathway was activated after BEX2 knockout; moreover, the hedgehog signaling inhibitors, GANT61 and GDC-0449 could reverse the migratory enhancement of BEX2-/- colorectal cancer cells. We also demonstrated that the nuclear translocation of Zic2 after BEX2 silencing could activate the hedgehog signaling pathway, while Zic2 knockdown abrogated the migratory enhancement of BEX2-/- cells and inhibited the hedgehog signaling pathway. In summary, our findings suggest that BEX2 negatively modulates the hedgehog signaling pathway by retaining Zic2 in the cytoplasm in colorectal cancer cells, thereby inhibiting migration and metastasis of colorectal cancer cells.

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.