Browsing by Subject "Proto-Oncogene Proteins c-bcl-2"
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Item Open AccessAn immunoglobulin C kappa-reactive single chain antibody fusion protein induces tolerance through receptor editing in a normal polyclonal immune system.(J Exp Med, 2005-03-07) Ait-Azzouzene, Djemel; Verkoczy, Laurent; Peters, Jorieke; Gavin, Amanda; Skog, Patrick; Vela, José Luis; Nemazee, DavidUnderstanding immune tolerance mechanisms is a major goal of immunology research, but mechanistic studies have generally required the use of mouse models carrying untargeted or targeted antigen receptor transgenes, which distort lymphocyte development and therefore preclude analysis of a truly normal immune system. Here we demonstrate an advance in in vivo analysis of immune tolerance that overcomes these shortcomings. We show that custom superantigens generated by single chain antibody technology permit the study of tolerance in a normal, polyclonal immune system. In the present study we generated a membrane-tethered anti-Igkappa-reactive single chain antibody chimeric gene and expressed it as a transgene in mice. B cell tolerance was directly characterized in the transgenic mice and in radiation bone marrow chimeras in which ligand-bearing mice served as recipients of nontransgenic cells. We find that the ubiquitously expressed, Igkappa-reactive ligand induces efficient B cell tolerance primarily or exclusively by receptor editing. We also demonstrate the unique advantages of our model in the genetic and cellular analysis of immune tolerance. Item Open AccessApoptosis in Drosophila: neither fish nor fowl (nor man, nor worm).(J Cell Sci, 2005-05-01) Kornbluth, Sally; White, KristinStudies in a wide variety of organisms have produced a general model for the induction of apoptosis in which multiple signaling pathways lead ultimately to activation of the caspase family of proteases. Once activated, these enzymes cleave key cellular substrates to promote the orderly dismantling of dying cells. A broad similarity exists in the cell death pathways operating in different organisms and there is a clear evolutionary conservation of apoptotic regulators such as caspases, Bcl-2 family members, inhibitor of apoptosis (IAP) proteins, IAP antagonists and caspase activators. Despite this, studies in Caenorhabditis elegans, Drosophila and vertebrates have revealed some apparent differences both in the way apoptosis is regulated and in the way individual molecules contribute to the propagation of the death signal. For example, whereas cytochrome c released from mitochondria clearly promotes caspase activation in vertebrates, there is no documented role for cytochrome c in C. elegans apoptosis and its role in Drosophila is highly controversial. In addition, the apoptotic potency of IAP antagonists appears to be greater in Drosophila than in vertebrates, indicating that IAPs may be of different relative importance in different organisms. Thus, although Drosophila, worms and humans share a host of apoptotic regulators, the way in which they function may not be identical. Item Open AccessBCL2 inhibits cell adhesion, spreading, and motility by enhancing actin polymerization.(Cell Res, 2010-04) Ke, Hengning; Parron, Vandy I; Reece, Jeff; Zhang, Jennifer Y; Akiyama, Steven K; French, John EBCL2 is best known as a multifunctional anti-apoptotic protein. However, little is known about its role in cell-adhesive and motility events. Here, we show that BCL2 may play a role in the regulation of cell adhesion, spreading, and motility. When BCL2 was overexpressed in cultured murine and human cell lines, cell spreading, adhesion, and motility were impaired. Consistent with these results, the loss of Bcl2 resulted in higher motility observed in Bcl2-null mouse embryonic fibroblast (MEF) cells compared to wild type. The mechanism of BCL2 regulation of cell adhesion and motility may involve formation of a complex containing BCL2, actin, and gelsolin, which appears to functionally decrease the severing activity of gelsolin. We have observed that the lysate from MCF-7 and NIH3T3 cells that overexpressed BCL2 enhanced actin polymerization in cell-free in vitro assays. Confocal immunofluorescent localization of BCL2 and F-actin during spreading consistently showed that increased expression of BCL2 resulted in increased F-actin polymerization. Thus, the formation of BCL2 and gelsolin complexes (which possibly contain other proteins) appears to play a critical role in the regulation of cell adhesion and migration. Given the established correlation of cell motility with cancer metastasis, this result may explain why the expression of BCL2 in some tumor cell types reduces the potential for metastasis and is associated with improved patient prognosis. Item Open AccessGenetic variants of NOXA and MCL1 modify the risk of HPV16-associated squamous cell carcinoma of the head and neck.(BMC cancer, 2012-05) Zhou, Ziyuan; Sturgis, Erich M; Liu, Zhensheng; Wang, Li-E; Wei, Qingyi; Li, GuojunThe cooperation between phorbol 12-myristate 13-acetate induced protein 1 (NOXA) and myeloid cell leukemia 1 (MCL1) is critical in the intrinsic apoptotic pathway. Human papillomavirus 16 (HPV16), by inducing p53 and pRb-E2F degradation, may play an essential role in development of squamous cell carcinoma of the head and neck (SCCHN) through NOXA-MCL1 axis-mediated apoptosis. Therefore, genetic variants of NOXA and MCL1 may modify the SCCHN risk associated with HPV16 seropositivity.HPV16 serology was obtained by immunoadsorption assay. Four functional SNPs in the promoter of NOXA (rs9957673, rs4558496) and MCL1 (rs9803935, rs3738485) were genotyped for 380 cases and 335 frequency-matched cancer-free controls of non-Hispanic whites.Associations between the four polymorphisms and SCCHN risk were not significant, while we observed a significantly joint effect on SCCHN risk between the polymorphisms and HPV16 seropositivity. Notably, this effect modification was particularly pronounced for oropharyngeal cancer in subgroups including never smokers, never drinkers and younger subjects.Our results suggested that polymorphisms of NOXA and MCL1 may modify the risk of HPV16-associated oropharyngeal cancer. The further identification of population subgroups at higher risk provides evidence that HPV-targeting treatment may help benefit SCCHN. However, larger studies are needed to validate our findings. Item Open AccessBcl2l1 Deficiency in Osteoblasts Reduces the Trabecular Bone Due to Enhanced Osteoclastogenesis Likely through Osteoblast Apoptosis.(International journal of molecular sciences, 2023-12) Moriishi, Takeshi; Kawai, Yosuke; Fukuyama, Ryo; Matsuo, Yuki; He, You-Wen; Akiyama, Haruhiko; Asahina, Izumi; Komori, ToshihisaBcl2l1 (Bcl-XL) belongs to the Bcl-2 family, Bcl2 and Bcl2-XL are major anti-apoptotic proteins, and the apoptosis of osteoblasts is a key event for bone homeostasis. As the functions of Bcl2l1 in osteoblasts and bone homeostasis remain unclear, we generated osteoblast-specific Bcl2l1-deficient (Bcl2l1fl/flCre) mice using 2.3-kb Col1a1 Cre. Trabecular bone volume and the trabecular number were lower in Bcl2l1fl/flCre mice of both sexes than in Bcl2l1fl/fl mice. In bone histomorphometric analysis, osteoclast parameters were increased in Bcl2l1fl/flCre mice, whereas osteoblast parameters and the bone formation rate were similar to those in Bcl2l1fl/fl mice. TUNEL-positive osteoblastic cells and serum TRAP5b levels were increased in Bcl2l1fl/flCre mice. The deletion of Bcl2l1 in osteoblasts induced Tnfsf11 expression, whereas the overexpression of Bcl-XL had no effect. In a co-culture of Bcl2l1-deficient primary osteoblasts and wild-type bone-marrow-derived monocyte/macrophage lineage cells, the numbers of multinucleated TRAP-positive cells and resorption pits increased. Furthermore, serum deprivation or the deletion of Bcl2l1 in primary osteoblasts increased apoptosis and ATP levels in the medium. Therefore, the reduction in trabecular bone in Bcl2l1fl/flCre mice may be due to enhanced bone resorption through osteoblast apoptosis and the release of ATP from apoptotic osteoblasts, and Bcl2l1 may inhibit bone resorption by preventing osteoblast apoptosis. Item Open AccessImmunohistochemical double-hit score is a strong predictor of outcome in patients with diffuse large B-cell lymphoma treated with rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone.(Journal of clinical oncology : official journal of the American Society of Clinical Oncology, 2012-10) Green, Tina Marie; Young, Ken H; Visco, Carlo; Xu-Monette, Zijun Y; Orazi, Attilio; Go, Ronald S; Nielsen, Ole; Gadeberg, Ole V; Mourits-Andersen, Torben; Frederiksen, Mikael; Pedersen, Lars Møller; Møller, Michael BoePURPOSE: Approximately 5% of diffuse large B-cell lymphomas (DLBCLs) are double-hit lymphomas (DHLs) with translocations of both MYC and BCL2. DHLs are characterized by poor outcome. We tested whether DLBCLs with high expression of MYC protein and BCL2 protein share the clinical features and poor prognosis of DHLs. PATIENTS AND METHODS: Paraffin-embedded lymphoma samples from 193 patients with de novo DLBCL who were uniformly treated with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) were studied using immunohistochemistry for MYC, BCL2, CD10, BCL6, and MUM1/interferon regulatory factor 4, and fluorescent in situ hybridization (FISH) for MYC and BCL2. RESULTS: FISH analysis identified DHL in 6% of patients, who showed the expected poor overall survival (OS; P = .002). On the basis of immunohistochemical MYC and BCL2 expression, a double-hit score (DHS) was assigned to all patients with DLBCL. The DHS-2 group, defined by high expression of both MYC and BCL2 protein, comprised 29% of the patients. DHS 2 was significantly associated with lower complete response rate (P = .004), shorter OS (P < .001), and shorter progression-free survival (PFS; P < .001). The highly significant correlation with OS and PFS was maintained in multivariate models that controlled for the International Prognostic Index and the cell-of-origin subtype (OS, P < .001; PFS, P < .001). DHS was validated in an independent cohort of 116 patients who were treated with R-CHOP. CONCLUSION: The immunohistochemical DHS defined a large subset of DLBCLs with double-hit biology and was strongly associated with poor outcome in patients treated with R-CHOP. Item Open AccessMYC/BCL2 protein coexpression contributes to the inferior survival of activated B-cell subtype of diffuse large B-cell lymphoma and demonstrates high-risk gene expression signatures: a report from The International DLBCL Rituximab-CHOP Consortium Program.(Blood, 2013-05) Hu, Shimin; Xu-Monette, Zijun Y; Tzankov, Alexander; Green, Tina; Wu, Lin; Balasubramanyam, Aarthi; Liu, Wei-min; Visco, Carlo; Li, Yong; Miranda, Roberto N; Montes-Moreno, Santiago; Dybkaer, Karen; Chiu, April; Orazi, Attilio; Zu, Youli; Bhagat, Govind; Richards, Kristy L; Hsi, Eric D; Choi, William WL; Zhao, Xiaoying; van Krieken, J Han; Huang, Qin; Huh, Jooryung; Ai, Weiyun; Ponzoni, Maurilio; Ferreri, Andrés JM; Zhou, Fan; Slack, Graham W; Gascoyne, Randy D; Tu, Meifeng; Variakojis, Daina; Chen, Weina; Go, Ronald S; Piris, Miguel A; Møller, Michael B; Medeiros, L Jeffrey; Young, Ken HDiffuse large B-cell lymphoma (DLBCL) is stratified into prognostically favorable germinal center B-cell (GCB)-like and unfavorable activated B-cell (ABC)-like subtypes based on gene expression signatures. In this study, we analyzed 893 de novo DLBCL patients treated with R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone). We show that MYC/BCL2 protein coexpression occurred significantly more commonly in the ABC subtype. Patients with the ABC or GCB subtype of DLBCL had similar prognoses with MYC/BCL2 coexpression and without MYC/BCL2 coexpression. Consistent with the notion that the prognostic difference between the 2 subtypes is attributable to MYC/BCL2 coexpression, there is no difference in gene expression signatures between the 2 subtypes in the absence of MYC/BCL2 coexpression. DLBCL with MYC/BCL2 coexpression demonstrated a signature of marked downregulation of genes encoding extracellular matrix proteins, those involving matrix deposition/remodeling and cell adhesion, and upregulation of proliferation-associated genes. We conclude that MYC/BCL2 coexpression in DLBCL is associated with an aggressive clinical course, is more common in the ABC subtype, and contributes to the overall inferior prognosis of patients with ABC-DLBCL. In conclusion, the data suggest that MYC/BCL2 coexpression, rather than cell-of-origin classification, is a better predictor of prognosis in patients with DLBCL treated with R-CHOP. Item Open AccessRelaxed negative selection in germinal centers and impaired affinity maturation in bcl-xL transgenic mice.(J Exp Med, 1999-08-02) Takahashi, Y; Cerasoli, DM; Dal Porto, JM; Shimoda, M; Freund, R; Fang, W; Telander, DG; Malvey, EN; Mueller, DL; Behrens, TW; Kelsoe, GThe role of apoptosis in affinity maturation was investigated by determining the affinity of (4-hydroxy-3-nitrophenyl)acetyl (NP)-specific antibody-forming cells (AFCs) and serum antibody in transgenic mice that overexpress a suppressor of apoptosis, Bcl-xL, in the B cell compartment. Although transgenic animals briefly expressed higher numbers of splenic AFCs after immunization, the bcl-xL transgene did not increase the number or size of germinal centers (GCs), alter the levels of serum antibody, or change the frequency of NP-specific, long-lived AFCs. Nonetheless, the bcl-xL transgene product, in addition to endogenous Bcl-xL, reduced apoptosis in GC B cells and resulted in the expansion of B lymphocytes bearing VDJ rearrangements that are usually rare in primary anti-NP responses. Long-lived AFCs bearing these noncanonical rearrangements were frequent in the bone marrow and secreted immunoglobulin G(1) antibodies with low affinity for NP. The abundance of noncanonical cells lowered the average affinity of long-lived AFCs and serum antibody, demonstrating that Bcl-xL and apoptosis influence clonal selection/maintenance for affinity maturation. Item Open AccessSynergistic antitumor effects of 9.2.27-PE38KDEL and ABT-737 in primary and metastatic brain tumors.(PloS one, 2019-01-09) Yu, Xin; Dobrikov, Mikhail; Keir, Stephen T; Gromeier, Matthias; Pastan, Ira H; Reisfeld, Ralph; Bigner, Darell D; Chandramohan, VidyalakshmiStandard treatment, unfortunately, yields a poor prognosis for patients with primary or metastatic cancers in the central nervous system, indicating a necessity for novel therapeutic agents. Immunotoxins (ITs) are a class of promising therapeutic candidates produced by fusing antibody fragments with toxin moieties. In this study, we investigated if inherent resistance to IT cytotoxicity can be overcome by rational combination with pro-apoptotic enhancers. Therefore, we combined ITs (9.2.27-PE38KDEL or Mel-14-PE38KDEL) targeting chondroitin sulfate proteoglycan 4 (CSPG4) with a panel of Bcl-2 family inhibitors (ABT-737, ABT-263, ABT-199 [Venetoclax], A-1155463, and S63845) against patient-derived glioblastoma, melanoma, and breast cancer cells/cell lines. In vitro cytotoxicity assays demonstrated that the addition of the ABT compounds, specifically ABT-737, sensitized the different tumors to IT treatment, and improved the IC50 values of 9.2.27-PE38KDEL up to >1,000-fold. Mechanistic studies using 9.2.27-PE38KDEL and ABT-737 revealed that increased levels of intracellular IT, processed (active) exotoxin, and PARP cleavage correlated with the enhanced sensitivity to the combination treatment. Furthermore, we confirmed the synergistic effect of 9.2.27-PE38KDEL and ABT-737 combination therapy in orthotopic GBM xenograft and cerebral melanoma metastasis models in nude mice. Our study defines strategies for overcoming IT resistance and enhancing specific antitumor cytotoxicity in primary and metastatic brain tumors. Item Open AccessThe channel of death.(The Journal of cell biology, 2001-11-26) Degterev, A; Boyce, M; Yuan, JThe proapoptotic members of the Bcl-2 family have been proposed to participate in the formation of a channel that releases these apoptogenic factors when mitochondria receive apoptotic signals. A recent study provides the first direct, biophysical measurement of a potentially apoptosis-specific mitochondrial channel, which is regulated by Bcl-2 family members and may play a primary role in the release of the proapoptotic factors.