Role of antiproliferative B cell translocation gene-1 as an apoptotic sensitizer in activation-induced cell death of brain microglia

Single-cell characterization of human GBM reveals regional differences in tumor-infiltrating leukocyte activation

Glioblastoma (GBM) harbors a highly immunosuppressive tumor microenvironment (TME) which influences glioma growth. Major efforts have been undertaken to describe the TME on a single-cell level. However, human data on regional differences within the TME remain scarce. Here, we performed high-depth single-cell RNA sequencing (scRNAseq) on paired biopsies from the tumor center, peripheral infiltration zone and blood of five primary GBM patients. Through analysis of >45,000 cells, we revealed a regionally distinct transcription profile of microglia (MG) and monocyte-derived macrophages (MdMs) and an impaired activation signature in the tumor-peripheral cytotoxic-cell compartment. Comparing tumor-infiltrating CD8+ T cells with circulating cells identified CX3CR1high and CX3CR1int CD8+ T cells with effector and memory phenotype, respectively, enriched in blood but absent in the TME. Tumor CD8+ T cells displayed a tissue-resident memory phenotype with dysfunctional features. Our analysis provides a regionally resolved mapping of transcriptional states in GBM-associated leukocytes, serving as an additional asset in the effort towards novel therapeutic strategies to combat this fatal disease.

Reduced TREM2 activation in microglia of patients with Alzheimer's disease

Loss-of-function variants of triggering receptor expressed on myeloid cells 2 (TREM2) increase the risk of developing Alzheimer's disease (AD). The mechanism through which TREM2 contributes to the disease (TREM2 activation vs inactivation) is largely unknown. Here, we analyzed changes in a gene set downstream of TREM2 to determine whether TREM2 signaling is modified by AD progression. We generated an anti-human TREM2 agonistic antibody and defined TREM2 activation in terms of the downstream expression changes induced by this antibody in microglia developed from human induced pluripotent stem cells (iPSC). Differentially expressed genes (DEGs) following TREM2 activation were compared with the gene set extracted from microglial single nuclear RNA sequencing data of patients with AD, using gene set enrichment analysis. We isolated an anti-TREM2-specific agonistic antibody, Hyb87, from anti-human TREM2 antibodies generated using binding and agonism assays, which helped us identify 300 upregulated and 251 downregulated DEGs. Pathway enrichment analysis suggested that TREM2 activation may be associated with Th2-related pathways. TREM2 activation was lower in AD microglia than in microglia from healthy subjects or patients with mild cognitive impairment. TREM2 activation also showed a significant negative correlation with disease progression. Pathway enrichment analysis of DEGs controlled by TREM2 activity indicated that TREM2 activation in AD may lead to anti-apoptotic signaling, immune response, and cytoskeletal changes in the microglia. We showed that TREM2 activation decreases with AD progression, in support of a protective role of TREM2 activation in AD. In addition, the agonistic anti-TREM2 antibody can be used to identify TREM2 activation state in AD microglia.

Deletion of B-cell translocation gene 2 (BTG2) alters the responses of glial cells in white matter to chronic cerebral hypoperfusion

BACKGROUND

Subcortical ischemic vascular dementia, one of the major subtypes of vascular dementia, is characterized by lacunar infarcts and white matter lesions caused by chronic cerebral hypoperfusion. In this study, we used a mouse model of bilateral common carotid artery stenosis (BCAS) to investigate the role of B-cell translocation gene 2 (BTG2), an antiproliferation gene, in the white matter glial response to chronic cerebral hypoperfusion.

METHODS

Btg2-/- mice and littermate wild-type control mice underwent BCAS or sham operation. Behavior phenotypes were assessed by open-field test and Morris water maze test. Brain tissues were analyzed for the degree of white matter lesions and glial changes. To further confirm the effects of Btg2 deletion on proliferation of glial cells in vitro, BrdU incorporation was investigated in mixed glial cells derived from wild-type and Btg2-/- mice.

RESULTS

Relative to wild-type mice with or without BCAS, BCAS-treated Btg2-/- mice exhibited elevated spontaneous locomotor activity and poorer spatial learning ability. Although the severities of white matter lesions did not significantly differ between wild-type and Btg2-/- mice after BCAS, the immunoreactivities of GFAP, a marker of astrocytes, and Mac2, a marker of activated microglia and macrophages, in the white matter of the optic tract were higher in BCAS-treated Btg2-/- mice than in BCAS-treated wild-type mice. The expression level of Gfap was also significantly elevated in BCAS-treated Btg2-/- mice. In vitro analysis showed that BrdU incorporation in mixed glial cells in response to inflammatory stimulation associated with cerebral hypoperfusion was higher in Btg2-/- mice than in wild-type mice.

CONCLUSION

BTG2 negatively regulates glial cell proliferation in response to cerebral hypoperfusion, resulting in behavioral changes.

Identification of BTG1 Status in Solid Cancer for Future Researches Using a System Review and Meta-analysis

Abundant studies have been conducted to identify how B-cell translocation gene 1 protein (BTG1) gene affects the differentiation, proliferation, metastasis of cancer cells, and how it further regulates the generation or development of diseases to influence the prognosis of patients. However, the data from single research were not powerful enough. The correlations between BTG1 expression and mechanisms of tumorigenesis or prognosis of patients are still in controversial. Our system review and meta-analysis provided a complete explanation about the association between BTG1 expression and clinicopathological features or prognosis of patients, which further laid a foundation for future research on BTG1. Fifteen eligible studies consisting of 1992 participants were included. We uncovered that BTG1 expression in solid tumors was associated with lymph node status (RR=0.66, 95% CI: 0.58-0.75, P=0.142), TMN stage status (RR=2.13, 95% CI: 1.71-2.65, P=0.001), T category (RR=1.90, 95% CI: 1.20-3.00, P=0.000), histological differentiation (RR=1.91, 95% CI: 1.55-2.37, P=0.012), vascular invasion (RR=0.90, 95% CI: 0.57-1.41, P=0.001). BTG1 low expression was significantly associated with overall survival (OS) (HR=0.47, 95% CI: 0.38-0.67, P=0.000). It concluded that BTG1 possessed the potential value for future research and could be recommended as a significant biomarker in solid tumor.

Deletion of Btg1 Induces Prmt1-Dependent Apoptosis and Increased Stemness in Shh-Type Medulloblastoma Cells Without Affecting Tumor Frequency

About 30% of medulloblastomas (MBs), a tumor of the cerebellum, arise from cerebellar granule cell precursors (GCPs) undergoing transformation following activation of the Sonic hedgehog (Shh) pathway. To study this process, we generated a new MB model by crossing Patched1 heterozygous (Ptch1^+/−) mice, which develop spontaneous Shh-type MBs, with mice lacking B-cell translocation gene 1 (Btg1), a regulator of cerebellar development. In MBs developing in Ptch1^+/− mice, deletion of Btg1 does not alter tumor and lesion frequencies, nor affect the proliferation of neoplastic precursor cells. However, in both tumors and lesions arising in Ptch1^+/− mice, ablation of Btg1 increases by about 25% the apoptotic neoplastic precursor cells, as judged by positivity to activated caspase-3. Moreover, although Btg1 ablation in early postnatal GCPs, developing in the external granule cell layer, leads to a significant increase of proliferation, and decrease of differentiation, relative to wild-type, no synergy occurs with the Ptch1^+/− mutation. However, Btg1 deletion greatly increases apoptosis in postnatal GCPs, with strong synergy between Btg1-null and Ptch1^+/− mutations. That pronounced increase of apoptosis observed in Ptch1^+/−/Btg1 knockout young or neoplastic GCPs may be responsible for the lack of effect of Btg1 ablation on tumorigenesis. This increased apoptosis may be a consequence of increased expression of protein arginine methyltransferase 1 (Prmt1) protein that we observe in Btg1 knockout/Ptch1^+/− MBs. In fact, apoptotic genes, such as BAD, are targets of Prmt1. Moreover, in Btg1-null MBs, we observed a two-fold increase of cells positive to CD15, which labels tumor stem cells, raising the possibility of activation of quiescent tumor cells, known for their role in long-term resistance to treatment and relapses. Thus, Btg1 appears to play a role in cerebellar tumorigenesis by regulating the balance between apoptosis and proliferation during MB development, also influencing the number of tumor stem cells.

Immune checkpoint modulation enhances HIV-1 antibody induction

Eliciting protective titers of HIV-1 broadly neutralizing antibodies (bnAbs) is a goal of HIV-1 vaccine development, but current vaccine strategies have yet to induce bnAbs in humans. Many bnAbs isolated from HIV-1-infected individuals are encoded by immunoglobulin gene rearrangments with infrequent naive B cell precursors and with unusual genetic features that may be subject to host regulatory control. Here, we administer antibodies targeting immune cell regulatory receptors CTLA-4, PD-1 or OX40 along with HIV envelope (Env) vaccines to rhesus macaques and bnAb immunoglobulin knock-in (KI) mice expressing diverse precursors of CD4 binding site HIV-1 bnAbs. CTLA-4 blockade augments HIV-1 Env antibody responses in macaques, and in a bnAb-precursor mouse model, CTLA-4 blocking or OX40 agonist antibodies increase germinal center B and T follicular helper cells and plasma neutralizing antibodies. Thus, modulation of CTLA-4 or OX40 immune checkpoints during vaccination can promote germinal center activity and enhance HIV-1 Env antibody responses.

Elucidation of broadly neutralizing antibodies (bnAb) is a goal in HIV vaccine development. Here, Bradley et al. show that administration of CTLA-4 blocking antibody with vaccine antigens increases HIV-1 envelope antibody responses in macaques and a bnAb precursor mouse model.

Role of B-Cell Translocation Gene 1 in the Pathogenesis of Endometriosis

Estrogen affects endometrial cellular proliferation by regulating the expression of the c-myc gene. B-cell translocation gene 1 (BTG1), a translocation partner of the c-myc, is a tumor suppressor gene that promotes apoptosis and negatively regulates cellular proliferation and cell-to-cell adhesion. The aim of this study was to determine the role of BTG1 in the pathogenesis of endometriosis. BTG1 mRNA and protein expression was evaluated in eutopic and ectopic endometrium of 30 patients with endometriosis (endometriosis group), and in eutopic endometrium of 22 patients without endometriosis (control group). The effect of BTG1 downregulation on cellular migration, proliferation, and apoptosis was evaluated using transfection of primarily cultured human endometrial stromal cells (HESCs) with BTG1 siRNA. BTG1 mRNA expression level of eutopic and ectopic endometrium of endometriosis group were significantly lower than that of the eutopic endometrium of the control group. Migration and wound healing assays revealed that BTG1 downregulation resulted in a significant increase in migration potential of HESCs, characterized by increased expression of matrix metalloproteinase 2 (MMP2) and MMP9. Downregulation of BTG1 in HESCs significantly reduced Caspase 3 expression, indicating a decrease in apoptotic potential. In conclusion, our data suggest that downregulation of BTG1 plays an important role in the pathogenesis of endometriosis.

Tumor suppressors BTG1 and BTG2: Beyond growth control

Since the identification of B‐cell translocation gene 1 (BTG1) and BTG2 as antiproliferation genes more than two decades ago, their protein products have been implicated in a variety of cellular processes including cell division, DNA repair, transcriptional regulation and messenger RNA stability. In addition to affecting differentiation during development and in the adult, BTG proteins play an important role in maintaining homeostasis under conditions of cellular stress. Genomic profiling of B‐cell leukemia and lymphoma has put BTG1 and BTG2 in the spotlight, since both genes are frequently deleted or mutated in these malignancies, pointing towards a role as tumor suppressors. Moreover, in solid tumors, reduced expression of BTG1 or BTG2 is often correlated with malignant cell behavior and poor treatment outcome. Recent studies have uncovered novel roles for BTG1 and BTG2 in genotoxic and integrated stress responses, as well as during hematopoiesis. This review summarizes what is currently known about the roles of BTG1 and BTG2 in these and other cellular processes. In addition, we will highlight the molecular mechanisms and biological consequences of BTG1 and BTG2 deregulation during cancer progression and elaborate on the potential clinical implications of these findings.

EZH2 Represses the B Cell Transcriptional Program and Regulates Antibody-Secreting Cell Metabolism and Antibody Production

Epigenetic remodeling is required during B cell differentiation. However, little is known about the direct functions of epigenetic enzymes in Ab-secreting cells (ASC) in vivo. In this study, we examined ASC differentiation independent of T cell help and germinal center reactions using mice with inducible or B cell-specific deletions of Ezh2 Following stimulation with influenza virus or LPS, Ezh2-deficient ASC poorly proliferated and inappropriately maintained expression of inflammatory pathways, B cell-lineage transcription factors, and Blimp-1-repressed genes, leading to fewer and less functional ASC. In the absence of EZH2, genes that normally gained histone H3 lysine 27 trimethylation were dysregulated and exhibited increased chromatin accessibility. Furthermore, EZH2 was also required for maximal Ab secretion by ASC, in part due to reduced mitochondrial respiration, impaired glucose metabolism, and poor expression of the unfolded-protein response pathway. Together, these data demonstrate that EZH2 is essential in facilitating epigenetic changes that regulate ASC fate, function, and metabolism.

B-cell translocation gene 1 is downregulated by promoter methylation in ovarian carcinoma

A better understanding of tumor biology is important in the identification of molecules that are downregulated in malignancy and in determining their role in tumor suppression. B-cell translocation gene 1 (BTG1) has been shown to act as a tumor suppressor in several types of human malignancy. In this study, we analyzed BTG1 expression in ovarian carcinoma cell lines, and we investigated the mechanism underlying the observed alterations. The methylation status of the BTG1 promoter region was determined by methylation-specific polymerase chain reaction, and the effect of demethylation on BTG1 expression was analyzed. BTG1 protein expression in ovarian high-grade serous carcinoma tissue samples was evaluated using immunohistochemistry. BTG1 mRNA and protein expression were reduced in ovarian carcinoma cells. In BTG1-silenced ovarian cancer cells, the BTG1 promoter was highly methylated. Treatment with 5-aza-deoxycytidine significantly elevated BTG1 mRNA and protein expression. Immunostaining demonstrated that BTG1 expression was significantly lower in ovarian carcinoma tissue samples than nonpathological ovaries and fallopian tubes. We demonstrated that BTG1 silencing in ovarian carcinoma occurs through epigenetic repression and is involved in the ovarian carcinogenesis. Our data suggest that BTG1 is a potential therapeutic target for patients with ovarian carcinoma.

Identification of Candidate Genes Related to Inflammatory Bowel Disease Using Minimum Redundancy Maximum Relevance, Incremental Feature Selection, and the Shortest-Path Approach

Identification of disease genes is a hot topic in biomedicine and genomics. However, it is a challenging problem because of the complexity of diseases. Inflammatory bowel disease (IBD) is an idiopathic disease caused by a dysregulated immune response to host intestinal microflora. It has been proven to be associated with the development of intestinal malignancies. Although the specific pathological characteristics and genetic background of IBD have been partially revealed, it is still an overdetermined disease and the blueprint of all genetic variants still needs to be improved. In this study, a novel computational method was built to identify genes related to IBD. Samples from two subtypes of IBD (ulcerative colitis and Crohn's disease) and normal samples were employed. By analyzing the gene expression profiles of these samples using minimum redundancy maximum relevance and incremental feature selection, 21 genes were obtained that could effectively distinguish samples from the two subtypes of IBD and the normal samples. Then, the shortest-path approach was used to search for an additional 20 genes in a large network constructed using protein-protein interactions based on the above-mentioned 21 genes. Analyses of the 41 genes obtained indicate that they are closely associated with this disease.

Prostaglandin E2 potentiates interferon-γ-induced nitric oxide production in cultured rat microglia

Prostaglandin E₂ (PGE₂ ) plays crucial roles in managing microglial activation through the prostanoid EP₂ receptor, a PGE₂ receptor subtype. In this study, we report that PGE₂ enhances interferon-γ (IFN-γ)-induced nitric oxide production in microglia. IFN-γ increased the release of nitrite, a metabolite of nitric oxide, which was augmented by PGE₂ , although PGE₂ by itself slightly affects nitrite release. The potentiating effect of PGE₂ was positively associated with increased expression of inducible nitric oxide synthase. In contrast to nitrite release induced by IFN-γ, lipopolysaccharide-induced nitrite release was not affected by PGE₂ . An EP₂ agonist, ONO-AE1-259-01 also augmented IFN-γ-induced nitrite release, while an EP₁ agonist, ONO-DI-004, an EP₃ agonist, ONO-AE-248, or an EP₄ agonist, ONO-AE1-329, did not. In addition, the potentiating effect of PGE₂ was inhibited by an EP₂ antagonist, PF-04418948, but not by an EP₁ antagonist, ONO-8713, an EP₃ antagonist, ONO-AE3-240, or an EP₄ antagonist, ONO-AE3-208, at 10^-6  M. Among the EP agonists, ONO-AE1-259-01 alone was able to accumulate cyclic adenosine monophosphate (AMP), and among the EP antagonists, PF-04418948 was the only one able to inhibit PGE₂ -increased intracellular cyclic AMP accumulation. On the other hand, IFN-γ promoted phosphorylation of signal transducer and activator of transcription 1, which was not affected by PGE₂ . Furthermore, other prostanoid receptor agonists, PGD₂ , PGF_2α , iloprost, and U-46119, slightly affected IFN-γ-induced nitrite release. These results indicate that PGE₂ potentiates IFN-γ-induced nitric oxide production in microglia through the EP₂ receptor, which may shed light on one of the pro-inflammatory aspects of PGE₂ .

The B-cell translocation gene 1 (CgBTG1) identified in oyster Crassostrea gigas exhibit multiple functions in immune response

B-cell translocation gene 1 (BTG1) is a member of the anti-proliferative gene family, which plays important roles in regulation of cell cycle. In the present study, a B-cell translocation gene 1 molecule homologue (designed CgBTG1) are identified and characterized in oyster Crassostrea gigas. CgBTG1 contains a conserved BTG domain with Box A and Box B motifs, and it shares high similarities with both BTG1 and BTG2 proteins in vertebrates. CgBTG1 mRNA is predominantly expressed in hemocytes, and its expression level in hemocytes is significantly up-regulated at 6 h (5.40-fold, p < 0.01) post Vibrio splendidus stimulation. The apoptosis rate of oyster hemocytes is significantly decreased (p < 0.05) after CgBTG1 interfered by dsRNA (dsCgBTG1). This is indicated that CgBTG1 participated in the regulation of oyster hemocytes apoptosis. Furthermore, CgBTG1 could also induce the apoptosis of cancer cells (HeLa, A549 and BEL7402) in vitro. Compared with normal oysters, both vessel-like structures and muscle fibers in CgBTG1 interfered oysters are severely damaged after V. splendidus challenge in paraffin section, considering that CgBTG1 possessed an analogous feature of angiogenesis for maintenance of vessel-like structures in adductor muscle of oyster. The results suggests that CgBTG1 is a multi-functional molecule involved in the immune response of C. gigas against pathogen infection, which provides more clues for intensive studies of BTG family proteins in invertebrates.

Endothelial cell signaling and ventilator-induced lung injury: molecular mechanisms, genomic analyses, and therapeutic targets

Mechanical ventilation is a life-saving intervention in critically ill patients with respiratory failure due to acute respiratory distress syndrome (ARDS). Paradoxically, mechanical ventilation also creates excessive mechanical stress that directly augments lung injury, a syndrome known as ventilator-induced lung injury (VILI). The pathobiology of VILI and ARDS shares many inflammatory features including increases in lung vascular permeability due to loss of endothelial cell barrier integrity resulting in alveolar flooding. While there have been advances in the understanding of certain elements of VILI and ARDS pathobiology, such as defining the importance of lung inflammatory leukocyte infiltration and highly induced cytokine expression, a deep understanding of the initiating and regulatory pathways involved in these inflammatory responses remains poorly understood. Prevailing evidence indicates that loss of endothelial barrier function plays a primary role in the development of VILI and ARDS. Thus this review will focus on the latest knowledge related to 1) the key role of the endothelium in the pathogenesis of VILI; 2) the transcription factors that relay the effects of excessive mechanical stress in the endothelium; 3) the mechanical stress-induced posttranslational modifications that influence key signaling pathways involved in VILI responses in the endothelium; 4) the genetic and epigenetic regulation of key target genes in the endothelium that are involved in VILI responses; and 5) the need for novel therapeutic strategies for VILI that can preserve endothelial barrier function.

Could Intrathymic Injection of Myelin Basic Protein Suppress Inflammatory Response After Co-culture of T Lymphocytes and BV-2 Microglia Cells?

BACKGROUND

The interaction between activated microglia and T lymphocytes can yield abundant pro-inflammatory cytokines. Our previous study proved that thymus immune tolerance could alleviate the inflammatory response. This study aimed to investigate whether intrathymic injection of myelin basic protein (MBP) in mice could suppress the inflammatory response after co-culture of T lymphocytes and BV-2 microglia cells.

METHODS

Totally, 72 male C57BL/6 mice were randomly assigned to three groups (n = 24 in each): Group A: intrathymic injection of 100 μl MBP (1 mg/ml); Group B: intrathymic injection of 100 μl phosphate-buffered saline (PBS); and Group C: sham operation group. Every eight mice in each group were sacrificed to obtain the spleen at postoperative days 3, 7, and 14, respectively. T lymphocytes those were extracted and purified from the spleens were then co-cultured with activated BV-2 microglia cells at a proportion of 1:2 in the medium containing MBP for 3 days. After identified the T lymphocytes by CD3, surface antigens of T lymphocytes (CD4, CD8, CD152, and CD154) and BV-2 microglia cells (CD45 and CD54) were detected by flow cytometry. The expressions of pro-inflammatory factors of BV-2 microglia cells (interleukin [IL]-1β, tumor necrosis factor-α [TNF-α], and inducible nitric oxide synthase [iNOS]) were detected by quantitative real-time polymerase chain reaction (PCR). One-way analysis of variance (ANOVA) and the least significant difference test were used for data analysis.

RESULTS

The levels of CD152 in Group A showed an upward trend from the 3rd to 7th day, with a downward trend from the 7th to 14th day (20.12 ± 0.71%, 30.71 ± 1.14%, 13.50 ± 0.71% at postoperative days 3, 7, and 14, respectively, P < 0.05). The levels of CD154 in Group A showed a downward trend from the 3rd to 7th day, with an upward trend from the 7th to 14th day (10.00 ± 0.23%, 5.28 ± 0.69%, 14.67 ± 2.71% at postoperative days 3, 7, and 14, respectively, P < 0.05). The ratio of CD4+/CD8 + T in Group A showed a downward trend from the 3rd to 7th day, with the minimum at postoperative day 7, then an upward trend from the 7th to 14th day (P < 0.05). Meanwhile, the levels of CD45 and CD54 in Group A were found as the same trend as the ratio of CD4+/CD8 + T (CD45: 83.39 ± 2.56%, 82.74 ± 2.09%, 87.56 ± 2.11%; CD54: 3.80 ± 0.24%, 0.94 ± 0.40%, 3.41 ± 0.33% at postoperative days 3, 7, and 14, respectively, P < 0.05). The expressions of TNF-α, IL-1β, and iNOS in Group A were significantly lower than those in Groups B and C, and the values at postoperative day 7 were the lowest compared with those at postoperative days 3 and 14 (P < 0.05). No significant difference was found between Groups B and C.

CONCLUSIONS

Intrathymic injection of MBP could suppress the immune reaction that might reduce the secondary immune injury of brain tissue induced by an inflammatory response.

Diversity of clinical implication of B-cell translocation gene 1 expression by histopathologic and anatomic subtypes of gastric cancer

BACKGROUND

Genetic signatures may differ by histopathologic and anatomic subtypes of gastric cancer (GC). B-cell translocation gene 1 (BTG1) was identified as one of genes downregulated in GC tissues from our microarray data.

AIMS

To evaluate the clinical implications of BTG1 expression in GC and the genetic diversity among GC subtypes.

METHODS

BTG1 mRNA expression was analyzed in GC cell lines and 233 pairs of surgical specimens. The mutational and methylation status of BTG1 in GC cell lines was analyzed, and immunohistochemistry was conducted to determine the distribution of BTG1. The pattern and prognostic significance of BTG1 expression were correlated with the three proposed GC subtypes.

RESULTS

BTG1 mRNA was downregulated in 82 % of GC cell lines and in 88 % of clinical GC tissues. Promoter hypermethylation events or sequence mutations were not detected in GC cell lines. The pattern of BTG1 expression as observed by immunohistochemistry was consistent with that of its mRNA. Downregulation of BTG1 mRNA in GCs was significantly associated with shorter disease-specific and recurrence-free survival. Multivariate analysis of disease-specific survival identified downregulation of BTG1 transcription as an independent prognostic factor. BTG1 mRNA expression was more strongly suppressed in proximal nondiffuse and diffuse GC compared with distal nondiffuse GC, and subgroup analysis revealed that BTG1 downregulation led to adverse prognosis, specifically in patients with proximal nondiffuse and diffuse GC.

CONCLUSIONS

Altered expression of BTG1 is a potential biomarker for carcinogenesis and progression of GC, particularly for proximal nondiffuse and diffuse GC.

Molecular cloning, sequence analysis, and cadmium stress-rated expression changes of BTG1 in freshwater pearl mussel (Hyriopsis schlegelii)

The B cells translocation gene 1 (BTG1) is a member of the BTG/TOB family of anti-proliferative genes, which have recently emerged as important regulators of cell growth and differentiation among verteates. Here, for the first time we cloned the full-length cDNA sequence of Hyriopsis schlegelii (Hs-BTG1), an economically important freshwater shellfish and potential indicator of environmental heavy metal pollution, for the first time. Using rapid amplification of cDNA ends (RACE) together with splicing the EST sequence from a haemocyte cDNA liary, we found that Hs-BTG1 contains a 525 bp open reading frame (ORF) encoding a 174 amino-acid polypeptide, a 306 bp 5' untranslated region (5' UTR), and a 571 bp 3' UTR with a Poly(A) tail as well as a transcription termination signal (AATAAA). Homologue searching against GenBank revealed that Hs-BTG1 was closest to Crassostrea gigas BTG1, sharing 50.57% of protein identities. Hs-BTG1 also shares some typical features of the BTG/TOB family, possessing two well-conserved A and B boxes. Clustering analysis of Hs-BTG1 and other known BTGs showed that Hs-BTG1 was also closely related to BTG1 of C. gigas from the inverteate BTG1 clade. Function prediction via homology modeling showed that both Hs-BTG1 and C. gigas BTG1 share a similar three-dimensional structure with Homo sapiens BTG1. Tissue-specific expression analysis of the Hs-BTG1 via real-time PCR showed that the transcripts were constitutively expressed, with the highest levels in the hepatopancreas and gills, and the lowest in both haemocyte and muscle tissue. Expression levels of Hs-BTG1 in hepatopancreas (2.03-fold), mantle (2.07-fold), kidney (2.2-fold) and haemocyte (2.5-fold) were enhanced by cadmium (Cd²⁺) stress, suggesting that Hs-BTG1 may have played a significant role in H. schlegelii adaptation to adverse environmental conditions.

TRAIL pathway is associated with inhibition of colon cancer by protopanaxadiol

Among important components of American ginseng, protopanaxadiol (PPD) showed more active anticancer potential than other triterpenoid saponins. In this study, we determined the in vivo effects of PPD in a mouse cancer model first. Then, using human colorectal cancer cell lines, we observed significant cancer cell growth inhibition by promoting G1 cell cycle redistribution and apoptosis. Subsequently, we characterized the downstream genes targeted by PPD in HCT-116 cancer cells. Using Affymetrix high density GeneChips, we obtained the gene expression profile of the cells. Microarray data indicated that the expression levels of 76 genes were changed over two-fold after PPD, of which 52 were upregulated while the remaining 24 were downregulated. Ingenuity pathway analysis of top functions affected was carried out. Data suggested that by regulating the interactions between p53 and DR4/DR5, the tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) pathway played a key role in the action of PPD, a promising colon cancer inhibitory compound.

B‑cell translocation gene 1 serves as a novel prognostic indicator of hepatocellular carcinoma

Although the B‑cell translocation gene 1 (BTG1) plays an important role in apoptosis and negatively regulates cell proliferation, BTG1 expression in hepatocellular carcinoma (HCC) has not been evaluated. In this study expression analysis of BTG1 was conducted to clarify the role of BTG1 in the initiation of HCC carcinogenesis and progression. BTG1 mRNA expression levels were determined for HCC cell lines and 151 surgical specimen pairs using quantitative real‑time reverse transcription polymerase chain reaction (RT‑qPCR) assay. The mutational and methylation status of HCC cell lines were analyzed via high resolution melting (HRM) analysis and direct sequencing analysis to elucidate the regulatory mechanisms of BTG1 expression. The expression and distribution of the BTG1 protein in liver tissues were evaluated using immunohistochemistry (IHC). Decreased expression of BTG1 mRNA was confirmed in the majority of HCC cell lines (89%) and clinical HCC tissues (85%) compared with non‑cancerous liver tissues. Mutations or promoter hypermethylation were not identified in HCC cell lines. BTG1 mRNA expression levels were not influenced by background liver status. The pattern of BTG1 protein expression was consistent with that of BTG1 mRNA. Downregulation of BTG1 mRNA in HCC was significantly associated with shorter disease‑specific and recurrence‑free survival rates. Multivariate analysis of disease‑specific survival rates identified BTG1 mRNA downregulation as an independent prognostic factor for HCC (hazard ratio 2.12, 95% confidence interval 1.12‑4.04, P=0.022). Our results indicate that altered BTG1 expression might affect hepatocarcinogenesis and may represent a novel biomarker for HCC carcinogenesis and progression.

Expression of BTG1 in hepatocellular carcinoma and its correlation with cell cycles, cell apoptosis, and cell metastasis

This study aimed to analyze the expression, clinical significance of B cell translocation gene 1 (BTG1) in hepatocellular carcinoma, and the biological effect in its cell line by BTG1 overexpression. Immunohistochemistry and Western blot were used to analyze BTG1 protein expression in 70 cases of hepatocellular cancer and 32 cases of normal tissues to study the relationship between BTG1 expression and clinical factors. Recombinant lentiviral vector was constructed to overexpress BTG1 and then infect hepatocellular cancer HepG2 cell line. The level of BTG1 protein expression was found to be significantly lower in hepatocellular cancer tissue than normal tissues (P < 0.05). Decreased expression of BTG1 was significantly correlated with tumor invasion, lymph node metastasis, clinic stage, and histological grade of patients with hepatocellular cancer (P < 0.05). Meanwhile, loss of BTG1 expression correlated significantly with poor overall survival time by Kaplan-Meier analysis (P < 0.05). The result of biological function has shown that HepG2 cell-transfected BTG1 had a lower survival fraction; higher percentage of the G0/G1 phases; higher cell apoptosis; significant decrease in migration and invasion; and lower Cyclin D1 (CND1), B cell lymphoma 2 (Bcl-2), and matrix metalloproteinases (MMP)-9 protein expression compared with HepG2 cell-untransfected BTG1 (P < 0.05). BTG1 expression decreased in hepatocellular cancer and correlated significantly with lymph node metastasis, clinic stage, histological grade, poor overall survival, proliferation, and metastasis in hepatocellular cancer cell by regulating CND1, Bcl-2, and MMP-9 protein expression, suggesting that BTG1 may play important roles as a negative regulator to hepatocellular cancer cell.

BTG1 expression in thyroid carcinoma: diagnostic indicator and prognostic marker

We determined the expression and function of B cell translocation gene 1 (BTG1) in thyroid carcinoma. Thyroid samples were obtained from cancer lesions (n=83) and adjacent normal tissue (n=35) in thyroid cancer patients immediately after endoscopic biopsy. BTG1 expression was determined by immunohistochemistry and western blotting. The effect of BTG1 overexpression was examined in vitro utilizing the human thyroid cancer cell line FTC-133, stably transfected with a recombinant lentivirus (LeBTG1 cells) and compared to empty vector transfected controls (LeEmpty). BTG1 overexpression was verified by reverse transcription quantitative polymerase chain reaction (RT-qPCR) and western blotting. The expression of proteins involved in cell cycle regulation (cyclin D1), apoptosis (Bcl-2) and cell migration (MMP-9) in LeBTG1 cells was analyzed by western blotting. The effect of BTG1 overexpression on cell viability and proliferation was assessed by MTT assay in LeBTG1 and LeEmpty cells. Flow cytometric analyses were used to evaluate the effect of BTG1 expression on cell cycle distribution and apoptosis. The migration and invasion potential of LeBTG1 cells was examined by plating cells in Matrigel-coated chambers. BTG1 protein expression was significantly lower in thyroid cancer tissue biopsies compared to normal tissue as measured by immunohistochemistry (36.1 vs. 80.0% of tissues; P<0.05) and western blotting (0.251±0.021 vs. 0.651±0.065; P<0.05). Decreased expression of BTG1 was significantly correlated with thyroid cancer lymph node metastasis, clinical stage and pathological differentiation (P<0.05), as well as with reduced overall 10‑year survival rates compared to patients with higher expression levels (30.2 vs. 66.7%; P<0.05). In vitro analyses revealed that LeBTG1 cells had a reduced survival fraction compared to control LeEmpty cells, with higher rates of apoptosis (11.6±2.1 vs. 2.1±0.4%; P<0.05). The proportion of LeBTG1 cells in G0/G1 stage and S phase was also significantly different from LeEmpty cells (81.8±6.3 and 10.2±1.0%, vs. 62.4±4.9 and 25.5±2.6%, respectively; P<0.05), and the migration and invasion of LeBTG1 cells was significantly impaired with respect to LeEmpty cells (72.0±8.0 and 55.0±7.0 vs. 113.0±16.0 and 89.0±9.0, respectively; P<0.05). These effects were accompanied by decreased protein expression of cyclin D1, Bcl-2 and MMP-9 in LeBTG1 cells (0.234±0.018, 0.209±0.021, 0.155±0.017, respectively) compared to control LeEmpty cells (0.551±0.065, 0.452±0.043, 0.609±0.072, respectively; P<0.05). Reduced BTG1 expression is associated with increased disease severity, suggesting it is a negative regulator of thyroid cancer and can serve as a prognostic indicator.

The expression of BTG1 is downregulated in nasopharyngeal carcinoma and possibly associated with tumour metastasis

To determine the expression and function of B cell translocation gene 1 (BTG1) in nasopharyngeal carcinoma. Nasopharyngeal samples were taken from cancer lesions (n = 75) and adjacent normal tissue (n = 33) in nasopharyngeal cancer patients immediately after endoscopic biopsy. BTG1 expression was determined by immunohistochemistry and Western blotting. The effect of BTG1 overexpression was examined in vitro utilizing a human nasopharyngeal cancer cell line CNE2 stably transfected with a recombinant lentivirus (LeBTG1 cells) and compared to empty vector-transfected controls (LeEmpty). BTG1 overexpression was verified by real-time reverse transcriptase polymerase chain reaction and Western blot. The expression of proteins involved in cell cycle regulation (cyclin D1), apoptosis (Bcl-2) and cell migration (MMP-9) in LeBTG1 cells were analyzed by Western blot. The effect of BTG1 overexpression on cell viability and proliferation was assessed by an MTT assay in LeBTG1 and LeEmpty cells. Flow cytometric analyses were used to evaluate the effect of BTG1 expression on cell cycle distribution and apoptosis. The migration and invasion potential of LeBTG1 cells was examined by plating cells in Matrigel-coated chambers. BTG1 protein expression was significantly lower in nasopharyngeal cancer tissue biopsies than normal tissue as measured by immunohistochemistry (36.0 vs. 81.8 % of tissues; P < 0.05) and Western blotting (0.221 ± 0.019 vs. 0.652 ± 0.055; P < 0.05). Decreased expression of BTG1 was significantly correlated with nasopharyngeal cancer tumor stage, lymph node metastasis, clinical stage and pathologic differentiation (P < 0.05), as well as with reduced overall five-year survival rates compared to patients with higher expression levels (31.2 vs. 70.2 %; P < 0.05). In vitro analyses revealed that LeBTG1 cells had a reduced survival fraction compared to control LeEmpty cells, with higher rates of apoptosis (9.3 ± 0.7 vs. 2.3 ± 0.3 %; P < 0.05). The proportion of LeBTG1 cells in G0/G1 stage and S phase was also significantly different from LeEmpty cells (82.6 ± 3.8 and 10.1 ± 1.0 %, vs. 62.2 ± 2.4 and 28.9 ± 2.0 %, respectively; Ps < 0.05), and the migration and invasion of LeBTG1 cells was significantly impaired with respect to LeEmpty cells (96.0 ± 13.0 and 91.0 ± 11.0 vs. 158.0 ± 17.0 and 142.0 ± 15.0, respectively; Ps < 0.05). These effects were accompanied by decreased protein expression of cyclin D1, Bcl-2 and MMP-9 in LeBTG1 cells (0.231 ± 0.021, 0.413 ± 0.046, 0.131 ± 0.011, respectively) compared to control LeEmpty cells (0.636 ± 0.067, 0.821 ± 0.083, 0.451 ± 0.041, respectively; Ps < 0.05). Reduced BTG1 expression is associated with increased disease severity, suggesting it is a negative regulator of nasopharyngeal cancer and can serve as a prognostic indicator.

BTG1 underexpression is an independent prognostic marker in esophageal squamous cell carcinoma

To determine the expression and function of B cell translocation gene 1 (BTG1) in esophageal carcinoma, esophageal samples were taken from cancer lesions (n = 74) and adjacent normal tissue (n = 34) in esophageal cancer patients immediately after endoscopic biopsy. BTG1 expression was determined by immunohistochemistry and Western blotting. The effect of BTG1 overexpression was examined in vitro utilizing a human esophageal cancer cell line ECA-109 stably transfected with a recombinant lentivirus (LeBTG1 cells) and compared to empty vector-transfected controls (LeEmpty). BTG1 overexpression was verified by real-time reverse transcriptase polymerase chain reaction (RT-PCR) and Western blot. The expression of proteins involved in cell cycle regulation (cyclin D1) and apoptosis (Bcl-2) and cell migration (MMP-9) in LeBTG1 cells was analyzed by Western blot. The effect of BTG1 overexpression on cell viability and proliferation was assessed by an MTT assay in LeBTG1 and LeEmpty cells. Flow cytometric analyses were used to evaluate the effect of BTG1 expression on cell cycle distribution and apoptosis. The migration and invasion potential of LeBTG1 cells was examined by plating cells in Matrigel-coated chambers. The level of BTG1 protein expression was found to be significantly lower in esophageal cancer tissue than normal tissues (P < 0.05). Decreased expression of BTG1 was significantly correlated with lymph node metastasis, clinical stage, and histological grade of patients with esophageal cancer (P < 0.05). Meanwhile, loss of BTG1 expression correlated significantly with poor overall survival time by Kaplan-Meier analysis (P < 0.05). The result of biological function shown that Eca-109 cell-transfected BTG1 had a lower survival fraction, higher percentage of the G0/G1 phases, higher cell apoptosis, significant decrease in migration and invasion, and lower cylin D1, Bcl-2, and MMP-9 protein expression compared with Eca-109 cell-untransfected BTG1 (P < 0.05). Reduced BTG1 expression is associated with increased disease severity, suggesting it is a negative regulator of esophageal cancer and can serve as a prognostic indicator.

BTG1 expression correlates with the pathogenesis and progression of breast carcinomas

This study aimed to analyze the expression, clinical significance of B cell translocation gene 1 (BTG1) in breast carcinoma and the biological effect in its cell line by BTG1 overexpression. Immunohistochemistry and western blot were used to analyze BTG1 protein expression in 72 cases of breast cancer and 36 cases of normal tissues to study the relationship between BTG1 expression and clinical factors. Recombinant lentiviral vector was constructed to over-express EMP-1 and then infect breast cancer MCF-7 cell line. Quantitative real-time RT-PCR (qRT-PCR) and western blot were used to detect the mRNA level and protein of BTG1. MTT assay, cell apoptosis, cell cycles, migration and invasion assays were also conducted as to the influence of the upregulated expression of BTG1 that might be found on MCF-7 cells biological effect. The level of BTG1 protein expression was found to be significantly lower in breast cancer tissue than normal tissues (P < 0.05). Decreased expression of BTG1 was significantly correlated with tumor invasion, lymph node metastasis, clinic stage and histological grade of patients with breast cancer (P < 0.05). Meanwhile, loss of BTG1 expression correlated significantly with poor overall survival time by Kaplan-Meier analysis (P < 0.05). The result of biological function shown that MCF-7 cell transfected BTG1 had a lower survival fraction, higher percentage of the G0/G1 phases, higher cell apoptosis, significant decrease in migration and invasion, and lower CyclinD1, Bcl-2, and MMP-9 protein expression compared with MCF-7 cell untransfected BTG1 (P < 0.05). BTG1 expression decreased in breast cancer and correlated significantly lymph node metastasis, clinic stage, histological grade, poor overall survival, proliferation, and metastasis in breast cancer cell by regulating CyclinD1, Bcl-2, and MMP-9 protein expression, suggesting that BTG1 may play important roles as a negative regulator to breast cancer cell.

The expression of BTG1 is downregulated in NSCLC and possibly associated with tumor metastasis

This study aimed to analyze the expression, clinical significance of B cell translocation gene 1 (BTG1) in nonsmall cell lung cancer (NSCLC) and the biological effect in its cell line by BTG1 overexpression. Immunohistochemistry and western blot were used to analyze BTG1 protein expression in 82 cases of NSCLC and 38 cases of normal tissues to study the relationship between BTG1 expression and clinical factors. Recombinant lentiviral vector was constructed to overexpress EMP-1 and then infect NSCLC H1299 cell line. Quantitative real-time RT-PCR and western blot were used to detect the mRNA level and protein of BTG1. 3-[4,5-dimethylthiazol -2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay, cell apoptosis, cell cycles, and migration and invasion assays were also conducted as to the influence of the upregulated expression of BTG1 that might be found on H1299 cells biological effect. The level of BTG1 protein expression was found to be significantly lower in NSCLC tissue than normal tissues (P < 0.05). Decreased expression of BTG1 was significantly correlated with lymph node metastasis, clinic stage, and histological grade of patients with NSCLC (P < 0.05). Meanwhile, loss of BTG1 expression correlated significantly with poor overall survival time by Kaplan-Meier analysis (P < 0.05). The result of biological function show that H1299 cell transfected BTG1 had a lower survival fraction; higher percentage of the G0/G1 phases; higher cell apoptosis; significant decrease in migration and invasion; and lower CyclinD1, Bcl-2, and MMP-9 protein expression compared with H1299 cell untransfected BTG1 (P < 0.05). BTG1 expression decreased in NSCLC and correlated significantly with lymph node metastasis; clinical stage; histological grade; poor overall survival; cell proliferation; cell cycles; cell apoptosis; and migration and invasion in NSCLC cell by regulating CyclinD1, Bcl-2, and MMP-9 protein expression, suggesting that BTG1 may play important roles as a negative regulator to NSCLC cell.

BTG1 inhibits breast cancer cell growth through induction of cell cycle arrest and apoptosis

BTG1, which belongs to the BTG/Tob family, regulates cell cycle progression in a variety of cell types and appears to play roles in inhibiting proliferation, promoting apoptosis and stimulating cellular differentiation in multiple cell types. However, it remains unclear whether BTG1 is a breast cancer suppressor gene, and the role of BTG1 in breast cancer cell growth has not yet been determined. In the present study, we observed that BTG1 was weakly expressed in human breast tumors and in breast cancer cells (MCF-7 and MDA-MB-231). In addition, we investigated the potential effects of BTG1 on breast cancer cell proliferation, cell cycle distribution and apoptosis after stable transfection with the BTG1 expression vector. We found that overexpression of BTG1 inhibited cell proliferation, induced G0/G1 cell cycle arrest and promoted apoptosis. Further investigation indicated that overexpression of BTG1 was involved in the inhibition of the expression of cell cycle-related proteins, cyclin B1 and cyclin D1, and pro-apoptotic factors, Bax and caspase-3, and was also involved in the promotion of anti-apoptotic factor Bcl-2. In vivo, animal experiments showed that tumors overexpressing BTG1 displayed a slower growth rate than the control xenografts. TUNEL end staining assay revealed that BTG1 induced tumor necrosis and apoptosis. Taken together, our data revealed that, in breast cancer cells, BTG1 inhibits cell growth through induction of cell cycle arrest and apoptosis. These results indicate that BTG1 may be used as a novel therapeutic target for human breast cancer treatment.

The RNA-binding protein human antigen R controls global changes in gene expression during Schwann cell development

An important prerequisite to myelination in peripheral nerves is the establishment of one-to-one relationships between axons and Schwann cells. This patterning event depends on immature Schwann cell proliferation, apoptosis, and morphogenesis, which are governed by coordinated changes in gene expression. Here, we found that the RNA-binding protein human antigen R (HuR) was highly expressed in immature Schwann cells, where genome-wide identification of its target mRNAs in vivo in mouse sciatic nerves using ribonomics showed an enrichment of functionally related genes regulating these processes. HuR coordinately regulated expression of several genes to promote proliferation, apoptosis, and morphogenesis in rat Schwann cells, in response to NRG1, TGFβ, and laminins, three major signals implicated in this patterning event. Strikingly, HuR also binds to several mRNAs encoding myelination-related proteins but, contrary to its typical function, negatively regulated their expression, likely to prevent ectopic myelination during development. These functions of HuR correlated with its abundance and subcellular localization, which were regulated by different signals in Schwann cells.

Multiple sclerosis is not a disease of the immune system

Multiple sclerosis is a complex neurodegenerative disease, thought to arise through autoimmunity against antigens of the central nervous system. The autoimmunity hypothesis fails to explain why genetic and environmental risk factors linked to the disease in one population tend to be unimportant in other populations. Despite great advances in documenting the cell and molecular mechanisms underlying MS pathophysiology, the autoimmunity framework has also been unable to develop a comprehensive explanation of the etiology of the disease. I propose a new framework for understanding MS as a dysfunction of the metabolism of lipids. Specifically, the homeostasis of lipid metabolism collapses during acute-phase inflammatory response triggered by a pathogen, trauma, or stress, starting a feedback loop of increased oxidative stress, inflammatory response, and proliferation of cytoxic foam cells that cross the blood brain barrier and both catabolize myelin and prevent remyelination. Understanding MS as a chronic metabolic disorder illuminates four aspects of disease onset and progression: 1) its pathophysiology; 2) genetic susceptibility; 3) environmental and pathogen triggers; and 4) the skewed sex ratio of patients. It also suggests new avenues for treatment.

Circulating microRNAs involved in multiple sclerosis

Multiple sclerosis (MS) is an immune-mediated, demyelinating and neurodegenerative disease of the central nervous system. After traumatic brain injury, it is the leading cause of neurology disability in young adults. Considerable advances have been made in identifying genes involved in MS but the genetic and phenotypic complexity associated with this disease significantly hinders any progress. A novel class of small RNA molecules, microRNAs (miRNAs) has acquired much attention because they regulate the expression of up to 30% of protein-coding genes and may play a pivotal role in the development of many, if not all, complex diseases. Seven published studies investigated miRNAs from peripheral blood mononuclear cells, CD4+, CD8+ T cell, B lymphocytes, peripheral blood leukocytes, whole blood and brain astrocytes with MS risk. The absence of MS studies investigating plasma miRNA prompted the current investigation of identifying a circulating miRNA signature in MS. We conducted a microarray analysis of over 900 known miRNA transcripts from plasma samples collected from four MS individuals and four sex-aged and ethnicity matched healthy controls. We identified six plasma miRNA (miR-614, miR-572, miR-648, miR-1826, miR-422a and miR-22) that were significantly up-regulated and one plasma miRNA (miR-1979) that was significantly down-regulated in MS individuals. Both miR-422a and miR-22 have previously been implicated in MS. The present study is the first to show a circulating miRNA signature involved in MS that could serve as a potential prognostic and diagnostic biomarker for MS.

High frequency of BTG1 deletions in acute lymphoblastic leukemia in children with down syndrome

Previous cytogenetic studies of myeloid and acute lymphoblastic leukemias in children with Down syndrome (ML-DS and DS-ALL) have revealed significant differences in abnormality patterns between such cases and acute leukemias in general. Also, certain molecular genetic aberrations characterize DS-related leukemias, such as GATA1 mutations in ML-DS and deregulation of the CRLF2 gene in DS-ALL. Whether microdeletions/microduplications also vary between DS and non-DS cases is presently unclear. To address this issue, we performed single nucleotide polymorphism array analyses of eight pediatric ML-DS and 17 B-cell precursor DS-ALL. In the ML-DS cases, a total of 29 imbalances (20 gains and nine losses) and two partial uniparental isodisomies (pUPDs) were detected. None of the 11 small (defined as <10 Mb) imbalances were recurrent, nor were the pUPDs, whereas of the 18 large aberrations, three were recurrent-dup(1q), +8 and +21. In contrast, several frequent changes were identified in the DS-ALL cases, which harbored 82 imbalances (30 gains and 52 losses) and four pUPDs. Of the 40 large changes, 28 were gains and 12 losses, with +X, dup(Xq), dup(1q), del(7p), dup(8q), del(9p), dup(9p), del(12p), dup(17q), and +21 being recurrent. Of the 40 microdeletions identified, several targeted specific genes, with the following being repeatedly deleted: BTG1 and CDKN2A/B (29% of cases), ETV6, IKZF1, PAX5 and SERP2 (18%), and BTLA, INPP4B, P2RY8, and RB1 (12%). Loss of the SERP2 and INPP4B genes, encoding the stress-associated endoplasmic reticulum protein family member 2 and the inositol polyphosphate 4-phosphatase-II, respectively, has previously never been implicated in leukemia. Although deletions of the other genes have been associated with ALL, the high frequency of BTG1 loss is a novel finding. Such deletions may characterize a clinical subgroup of DS-ALL, comprising mainly boys with a high median age. In conclusion, ML-DS and DS-ALL are genetically distinct, with mainly gains in ML-DS and deletions in DS-ALL. Furthermore, DS-ALL is characterized by several recurrent gene deletions, with BTG1 loss being particularly frequent.

Combination of host susceptibility and Mycobacterium tuberculosis virulence define gene expression profile in the host

Progression and outcome of tuberculosis is governed by extensive crosstalk between pathogen and host. Analyses of global changes in gene expression during immune response to infection with Mycobacterium tuberculosis (M.tb) can help identify molecular markers of disease state and progression. Global distribution of M.tb strains with different degrees of virulence and drug resistance, especially for the immunocompromised host, make closer analyses of host responses more pressing than ever. Here, we describe global transcriptional responses of inducible nitric oxide synthase-deficient (iNOS(-/-)) and WT mice infected with two related M.tb strains of markedly different virulence, namely the M.tb laboratory strains H37Rv and H37Ra. Both hosts exhibited highly similar resistance to infection with H37Ra. In contrast, iNOS(-/-) mice rapidly succumbed to H37Rv, whereas WT mice developed chronic course of disease. By differential analyses, virulence-specific changes in global host gene expression were analyzed to identify molecular markers characteristic for chronic versus acute infection. We identified several markers unique for different stages of disease progression and not previously associated with virulence-specific host responses in tuberculosis.

Global genomic characterization of acute lymphoblastic leukemia

A key goal in cancer research is to identify the total complement of genetic and epigenetic alterations that contribute to tumorigenesis. We are currently witnessing the rapid evolution and convergence of multiple genome-wide platforms that are making this goal a reality. Leading this effort are studies of the molecular lesions that underlie pediatric acute lymphoblastic leukemia (ALL). The recent application of microarray-based analyses of DNA copy number abnormalities (CNAs) in pediatric ALL, complemented by transcriptional profiling, resequencing and epigenetic approaches, has identified a high frequency of common genetic alterations in both B-progenitor and T-lineage ALL. These approaches have identified abnormalities in key pathways, including lymphoid differentiation, cell cycle regulation, tumor suppression, and drug responsiveness. Moreover, the nature and frequency of CNAs differ markedly among ALL genetic subtypes. In this article, we review the key findings from the published data on genome-wide analyses of ALL and highlight some of the technical aspects of data generation and analysis that must be carefully controlled to obtain optimal results.

Inhibition of microglial neurotoxicity by ethanol extract of Artemisia asiatica Nakai

Artemisia asiatica Nakai has been used for the treatment of infections and inflammatory disorders in traditional Oriental medicine. Previously, an ethanol extract of A. asiatica has been shown to exert antioxidative and antiinflammatory activities and to exhibit protective effects against experimentally induced damage in the gastrointestinal system, liver and pancreas. This study examined whether the ethanol extract of A. asiatica affects inflammatory activation of microglia in the central nervous system, and whether the antiinflammatory activity of A. asiatica is related to neuroprotective effects. The extract of A. asiatica inhibited inflammatory activation of mouse microglial cells as determined by the production of nitric oxide and the expression of inducible nitric oxide synthase and inflammatory cytokine. The extract also protected nerve growth factor-differentiated PC12 cells against microglial cytotoxicity, indicating that the ethanol extract of A. asiatica may be neuroprotective by inhibiting microglial neurotoxicity.

Regulation of Toll-like receptor 4 expression and its signaling by hypoxia in cultured microglia

Hypoxia is an important biological signal that regulates a wide variety of physiological responses. At the same time, hypoxia is involved in multiple pathological situations. In particular, hypoxia is closely associated with neural injury in the brain. Hypoxia has been recently proposed as a neuroinflammatogen, as it can induce the inflammatory activation of microglia, a major cellular source of inflammatory mediators in the brain. In this article, we present evidence that hypoxia enhances Toll-like receptor 4 (TLR4) expression in cultured microglia and differentially regulates the downstream signaling pathways of TLR4. Hypoxia up-regulated TLR4 expression at the mRNA and protein levels in a microglia cell line, as well as in primary microglia cultures. Hypoxia, however, differentially regulated MyD88-dependent and -independent pathways of TLR4 signaling: Hypoxia enhanced lipopolysaccharide (LPS)-induced interferon regulatory factor-3 (IRF-3) activation and the subsequent expression of IFNbeta (MyD88-independent pathway), whereas it suppressed LPS-induced NF-kappaB activation (MyD88-dependent pathway). Hypoxia did not affect IFNgamma signaling, which was represented by signal transducer and activator of transcription-1 (STAT1) activation and interferon-regulatory factor-1 (IRF-1) induction. Taken together, although hypoxia up-regulates TLR4 expression, its downstream signaling pathways appear to be differentially modulated by hypoxia.

Janus faces of microglia in multiple sclerosis

Multiple sclerosis (MS) is the most common cause of neurological disability in young adults. The disease is characterized by inflammatory reactions, demyelination and axonal loss in the brain, spinal cord and optic nerves. Microglia seem to play an important role in the inflammatory processes in MS, since they are found in actively demyelinating lesions. Their role in the differentiation of T cells could led to the expansion of inflammation and tissue destruction. However, microglia are also involved in the termination of an inflammatory response and produce protective factors. To be able to therapeutically manipulate microglia, their exact function in the onset and development of MS needs to be clarified. This review provides an overview of the functions of the most important microglia-associated molecules in MS, being CD40, B7-1 and B7-2, interferon-gamma, tumor necrosis factor-alpha, chemokines, prostanoids, and nitric oxide.

STAT1 as a key modulator of cell death

Signal transducers and activators of transcription (STATs) are latent cytoplasmic transcription factors that mediate various biological responses, including cell proliferation, survival, apoptosis, and differentiation. Among the members of the STAT family, accumulating evidence now indicates an important role for STAT1 in various forms of cell death. Depending upon stimuli or cell types, STAT1 can modulate a broad spectrum of cell death, comprising both apoptotic and non-apoptotic pathways. STAT1-dependent regulation of cell death is largely dependent on a transcriptional mechanism such as the activation of death-promoting genes. However, non-transcriptional mechanisms such as STAT1 interaction with TRADD, p53, or HDAC have been implicated in the regulation of cell death by STAT1. Furthermore, STAT1 itself is also subject to complex forms of regulation such as post-translational protein modification, which can critically affect STAT1 signaling and STAT1-dependent cell death. Given the reports showing that dysregulation of STAT1 signaling is associated with various pathological conditions, including the development of cancer, a better understanding of the mechanism underlying STAT1 regulation of cell death may lead to successful strategies for targeting STAT1 in such pathological settings.

Different neurotropic pathogens elicit neurotoxic CCR9- or neurosupportive CXCR3-expressing microglia

What mechanism that determines microglia accomplishing destructive or constructive role in CNS remains nebulous. We report here that intracranial priming and rechallenging with Toxoplasma gondii in mice elicit neurotoxic CCR9+ Irg1+ (immunoresponsive gene 1) microglia, which render resistance to apoptosis and produce a high level of TNF-alpha; priming and rechallenging with lymphocytic choriomeningitis virus elicit neurosupportive CXCR3+ Irg1- microglia, which are sensitive to apoptosis and produce a high level of IL-10 and TGF-beta. Administration of CCR9 and/or Irg1 small interfering RNA alters the frequency and functional profiles of neurotoxic CCR9+ Irg1+ and neurosupportive CXCR3+ Irg1- microglia in vivo. Moreover, by using a series of different neurotropic pathogens, including intracellular parasites, chronic virus, bacteria, toxic substances, and CNS injury to intracranially prime and subsequent rechallenge mice, the bi-directional elicitation of microglia has been confirmed as neurotoxic CCR9+ Irg1+ and neurosupportive CXCR3+ Irg1- cells in these mouse models. These data suggest that there exist two different types of microglia, providing with a novel insight into microglial involvement in neurodegenerative and neuroinflammatory pathogenesis such as Alzheimer's disease and AIDS dementia.

B cell translocation gene 1 contributes to antisense Bcl-2-mediated apoptosis in breast cancer cells

The antiapoptotic protein Bcl-2 is overexpressed in a majority of breast cancers, and is associated with a diminished apoptotic response and resistance to various antitumor agents. Bcl-2 inhibition is currently being explored as a possible strategy for sensitizing breast cancer cells to standard chemotherapeutic agents. Antisense Bcl-2 oligonucleotides represent one method for blocking the antiapoptotic effects of Bcl-2. In this study, we show that antisense Bcl-2 efficiently blocks Bcl-2 expression, resulting in the apoptosis of breast cancer cells. Antisense Bcl-2-mediated cytotoxicity was associated with the induction of the B cell translocation gene 1 (BTG1). Importantly, knockdown of BTG1 reduced antisense Bcl-2-mediated cytotoxicity in breast cancer cells. Furthermore, BTG1 expression seems to be negatively regulated by Bcl-2, and exogenous expression of BTG1 induced apoptosis. These results suggest that BTG1 is a Bcl-2-regulated mediator of apoptosis in breast cancer cells, and that its induction contributes to antisense Bcl-2-mediated cytotoxic effects.

Differential effects of ethanol on glial signal transduction initiated by lipopolysaccharide and interferon-gamma

Although the pathogenic effects of alcohol abuse on brain are well established, its specific effects on the intracellular signal transduction pathways of glial cells in the central nervous system (CNS) are poorly understood. In this study, we evaluated how ethanol affects the glial signal transduction associated with inflammatory activation. Lipopolysaccharide (LPS), gangliosides, and interferon (IFN)-gamma induced the inflammatory activation of glia, which was differentially influenced by ethanol: 1) ethanol inhibited LPS- or gangliosides-induced, but not IFNgamma-induced, glial activation as demonstrated by the production of nitric oxide and the expression of inflammatory genes such as interleukin-1beta, tumor necrosis factor-alpha, IP-10, and CD86; 2) nuclear factor (NF)-kappaB or JAK/STAT1 pathway was necessary for LPS- or IFNgamma-induced glial activation, respectively; 3) ethanol inhibited LPS-induced NF-kappaB activation; and 4) ethanol did not significantly affect IFNgamma-induced STAT1/IRF-1 activation. Based on these results, ethanol seems to inhibit selectively some parts of the glial signal transduction pathways that are associated with inflammatory activation, which may lead to the deregulation of CNS inflammatory responses.

Interferon-gamma induces microglial-activation-induced cell death: a hypothetical mechanism of relapse and remission in multiple sclerosis

Relapse and remission are characteristics of multiple sclerosis (MS). The underlying mechanisms, however, remain uncertain. Interferon-gamma (IFN-gamma) disturbs the immunological privilege of the central nervous system (CNS) by inducing major histocompatibility complex antigen expression in CNS cells and activating microglia to become antigen-presenting and effector cells. Thus, IFN-gamma and microglia are thought to play important roles in the initiation and development of MS. Here, we show that IFN-gamma induces microglial apoptosis as the activation-induced cell death. This microglial apoptosis was associated with the up-regulation of pro-apoptosis proteins, especially Bax. Microglial apoptosis was also observed in peak EAE mice, but not in early EAE mice. Therefore, IFN-gamma may act on microglia as part of a self-limiting negative feedback system. The activation and subsequent death of microglia induced by IFN-gamma may play pivotal roles in the mechanism of MS relapse and remission.

TLR4, but not TLR2, signals autoregulatory apoptosis of cultured microglia: a critical role of IFN-beta as a decision maker

TLRs mediate diverse signaling after recognition of evolutionary conserved pathogen-associated molecular patterns such as LPS and lipopeptides. Both TLR2 and TLR4 are known to trigger a protective immune response as well as cellular apoptosis. In this study, we present evidence that TLR4, but not TLR2, mediates an autoregulatory apoptosis of activated microglia. Brain microglia underwent apoptosis upon stimulation with TLR4 ligand (LPS), but not TLR2 ligands (Pam(3)Cys-Ser-Lys(4), peptidoglycan, and lipoteichoic acid). Based on studies using TLR2-deficient or TLR4 mutant mice and TLR dominant-negative mutants, we also demonstrated that TLR4, but not TLR2, is necessary for microglial apoptosis. The critical difference between TLR2 and TLR4 signalings in microglia was IFN regulatory factor-3 (IRF-3) activation, followed by IFN-beta expression: while TLR4 agonist induced the activation of IRF-3/IFN-beta pathway, TLR2 did not. Nevertheless, both TLR2 and TLR4 agonists strongly induced NF-kappaB activation and NO production in microglia. Neutralizing Ab against IFN-beta attenuated TLR4-mediated microglial apoptosis. IFN-beta alone, however, did not induce a significant cell death. Meanwhile, TLR2 activation induced microglial apoptosis with help of IFN-beta, indicating that IFN-beta production following IRF-3 activation determines the apoptogenic action of TLR signaling. TLR4-mediated microglial apoptosis was mediated by MyD88 and Toll/IL-1R domain-containing adaptor-inducing IFN-beta, and was associated with caspase-11 and -3 activation rather than Fas-associated death domain protein/caspase-8 pathway. Taken together, TLR4 appears to signal a microglial apoptosis via autocrine/paracrine IFN-beta production, which may act as an apoptotic sensitizer.

Pro-apoptotic activity of N-myc in activation-induced cell death of microglia

Brain microglial cells are thought to undergo apoptosis following the exposure to inflammatory stimuli such as lipopolysaccharide (LPS) and IFNgamma, which is considered as an autoregulatory mechanism to control their own activation state. Here, we report that N-myc constitutes a novel apoptotic pathway of LPS/IFNgamma-activated microglia. The expression of N-myc was synergistically enhanced by LPS and IFNgamma in microglia. Tetracycline-based conditional expression of N-myc sensitized microglia to nitric oxide (NO)-induced apoptosis. Knockdown of N-myc expression using small interfering RNA (siRNA) attenuated LPS/IFNgamma-induced microglial apoptosis. An increase in N-myc expression, however, did not affect microglial production of NO or TNFalpha. The synergistic effect of LPS/IFNgamma on the microglial N-myc induction was mediated through Janus kinase (JAK)/STAT1 (signal transducer and activator of transcription 1) pathway. Taken together, LPS/IFNgamma-induced N-myc participated in the activation-induced cell death of microglia by sensitizing the cells to NO-induced apoptosis; however, N-myc did not influence the processes of inflammatory activation of microglia.

Regulation of Neuroinflammation by Herbal Medicine and Its Implications for Neurodegenerative Diseases

Herbal medicine has long been used to treat neural symptoms. Although the precise mechanisms of action of herbal drugs have yet to be determined, some of them have been shown to exert anti-inflammatory and/or anti-oxidant effects in a variety of peripheral systems. Now, as increasing evidence indicates that neuroglia-derived chronic inflammatory responses play a pathological role in the central nervous system, anti-inflammatory herbal medicine and its constituents are being proved to be a potent neuroprotector against various brain pathologies. Structural diversity of medicinal herbs makes them valuable source of novel lead compounds against therapeutic targets that are newly discovered by genomics, proteomics, and high-throughput screening.

Identification of B-cell translocation gene 1 as a biomarker for monitoring the remission of acute myeloid leukemia

Acute myeloid leukemia (AML) is a biologically heterogeneous disease of the hematopoietic system characterized by a clonal accumulation of immature blast cells in bone marrow. We used a proteomic approach based on two-dimensional electrophoresis and mass spectrometry to search for biomarkers related to the complete remission (CR) state of AML patients. We detected one AML-related protein, which was identified as the B-cell translocation gene 1 (BTG1) protein that belongs to anti-proliferative protein family. In the CR state of AML-M2 and M3 patients (by French-American-British subtype classification), the BTG1 protein was upregulated in bone marrow mononuclear cells. It was also expressed robustly in normal bone marrow mononuclear cells. In addition, the BTG1 levels in AML-M2 patients in a non-remission state after therapy did not increase as they did before therapy. Overexpression of BTG1 mRNA was also observed in the CR state of all-trans-retinoic acid (ATRA)-treated AML-M3 patients and ATRA-treated HL-60 cells. Taken together, these results suggest that BTG1 may play a role in the differentiation process of myeloid cells and can therefore be used as a potential treatment-related biomarker for monitoring the remission status of AML-M2 and M3 patients.

Protein interfaces in signaling regulated by arginine methylation

Posttranslational modifications are well-known effectors of signal transduction. Arginine methylation is a covalent modification that results in the addition of methyl groups to the nitrogen atoms of the arginine side chains. A probable role of arginine methylation in signal transduction is emerging with the identification of new arginine-methylated proteins. However, the functional consequences of arginine methylation and its mode of regulation remain unknown. The identification of the protein arginine methyltransferase family and the development of methylarginine-specific antibodies have raised renewed interest in this modification during the last decade. Arginine methylation was mainly observed on abundant proteins such as RNA-binding proteins and histones, but recent advances have revealed a plethora of arginine-methylated proteins implicated in a variety of cellular processes, including signaling by interferon and cytokines, and in T cell signaling. We discuss these recent advances and the role of arginine methylation in signal transduction.

Global gene expression in the immature brain after hypoxia-ischemia

Ischemia induces a complex response of differentially expressed genes in the brain. In order to understand the specific mechanisms of injury in the developing brain, it is important to obtain information on global changes in the transcriptome after neonatal hypoxia-ischemia. In this study, oligonucleotide arrays were used to investigate genomic changes at 2, 8, 24, and 72 hours after neonatal hypoxia-ischemia, which was induced in 9-day-old mice by left carotid artery ligation followed by hypoxia (10% O2). In total, 343 genes were differentially expressed in cortex, hippocampus, thalamus, and striatum 2 to 72 hours after hypoxia-ischemia, when comparing ipsilateral with contralateral hemispheres and with controls, using the significance analysis for microarrays. A total of 283 genes were upregulated and 60 were downregulated, and 94% of the genes had not previously been shown after neonatal hypoxia-ischemia. Genes related to transcription factors and metabolism had mostly upregulated transcripts, whereas most downregulated genes belonged to the categories of ion and vesicular transport and signal transduction. Genes involved in transcription, stress, and apoptosis were induced early after the insult, and many new genes that may play important roles in the pathophysiology of neonatal hypoxia-ischemia were identified.