Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P10415 (Bcl-2)
 33,771 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Isolated murine splenic B cells undergo spontaneous apoptosis. Motifs containing unmethylated CpG dinucleotides in bacterial DNA or in synthetic oligodeoxynucleotides (ODN) are known to activate murine B cells. Now we show that ODN that induce spleen B cell cycle entry also inhibit spontaneous apoptosis in a sequence-specific fashion. Reversal of the CG to GC abolished activity. Methylation of the central cytosine decreased activity. When CpG is preceded by a cytosine or followed by a guanine, activity was abolished. Other substitutions at the same positions had no effect. Dose-response curves for apoptosis protection and G1 entry suggested that a uniform population of ODN recognition sites controlled downstream ODN effects. A CpG ODN with a nuclease-resistant phosphorothioate backbone (S-ODN) was also active, and increased the levels of c-myc, egr-1, c-jun, bclXL, and bax mRNA and c-Myc, c-Jun, Bax, and BclXL protein in spleen B cells. Levels of c-myb, myn, c-Ki-ras, and bcl2 mRNA remained unchanged. When protein synthesis was inhibited, at 16 h ODN-induced cell cycle entry was abolished and apoptosis protection was partially preserved. Under these conditions, c-Myc was still present, but c-Jun and BclXL were not detected. Our results suggest that CpG containing ODN motifs provide signals for both survival and cell cycle entry. Single base changes determine whether this signal proceeds through a rate-limiting step governing at least two steps in apoptosis (plasma membrane transition, DNA cleavage) and two phases of the cell cycle (G1 and S phase entry). This biologic action is associated with increased c-Myc, c-Jun, and BclXL expression.
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PMID:CpG oligodeoxyribonucleotides rescue mature spleen B cells from spontaneous apoptosis and promote cell cycle entry. 963 2

c-myb is expressed in human and murine colonic mucosa and elevated expression occurs in premalignant adenomatous polyps and carcinomas. c-Myb is required for colon cell proliferation, and there is evidence of c-myb down-regulation during differentiation. Recently, c-myb has been implicated in hematopoietic cell survival via regulation of bcl-2 gene expression. However, c-myb expression during terminal differentiation and apoptosis in the colonic crypt has not been examined. The experiments in this study examine the spatial and temporal expression of c-Myb protein in vivo using human colonic crypt sections and in vitro in human colon tumor cell lines undergoing butyrate-induced differentiation and apoptosis. Electron microscopy, together with molecular and biochemical analysis, was used to define the differentiation status of the cells. Results demonstrate a decrease in c-Myb expression during the commitment of cells to differentiation and apoptosis. Decreased levels of c-Myb are accompanied by a decrease in Bcl-2. These data suggest that the transcription factor c-Myb has a role in regulating the balance between proliferation, differentiation, and apoptosis in the colonic crypt. Furthermore, elevated c-Myb levels in colon tumor cells may lead to persistent bcl-2 expression, thus protecting tumor cells from programmed cell death.
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PMID:c-Myb down-regulation is associated with human colon cell differentiation, apoptosis, and decreased Bcl-2 expression. 982 28

The mammalian colon develops from a simple tube of undifferentiated cells into a complex, highly ordered organ, with a continuously self-renewing epithelial layer. We have previously described c-Myb expression in the epithelia of murine and human colon crypts and documented increased expression in colorectal adenocarcinoma cells. To investigate the role of c-Myb in colonic epithelium development, we have used embryos with a disrupted c-myb gene. Prior to the in utero death of these embryos at E15, we excised colon tissue and transplanted it under the kidney capsule of recipient mice to allow further development and cyto-differentiation. Compared to the colons of wildtype and heterozygous littermates, the c-myb homozygous knockout colon is highly irregular with a disordered epithelium and abnormal crypts. In addition, the expression of Bcl-2, a known target of c-Myb, is reduced and apoptosis is increased, indicating a critical requirement for c-Myb in normal colon development.
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PMID:c-Myb is critical for murine colon development. 1052 63

The proto-oncogene c-myb is constitutively expressed in murine leukemia virus-induced myeloid leukemia (MML) due to the integration of virus at this locus. Our recent focus has been the determination of genes regulated by this transcription factor that may be involved in transformation. Data presented here, using conditional expression of Myb in myeloid cells, show that c-Myb directly transactivates the endogenous c-myc and Bcl-2 genes, which explains at least in part how c-Myb regulates proliferation and survival. In addition, c-Myb prevents expression at the RNA level of the tumor suppressor INK4b gene. This gene encodes a cyclin-dependent kinase inhibitor, p15INK4b, that is normally upregulated at the mRNA level during myeloid differentiation and promotes growth arrest. The MMLs are generally characterized as differentiated monocytic tumors and possess the phenotype that is normally associated with p15INK4b expression. c-Myb inhibits expression of this gene, however, and therefore acts to promote a pathway which is abnormal in mature cells. This activity of c-Myb collaborates with its maintenance of c-myc expression to promote growth.
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PMID:Three genes with different functions in transformation are regulated by c-Myb in myeloid cells. 1125 71

Deregulated expression of the proto-oncogene c-myb, which results from provirus integration, is thought to be responsible for transformation in a set of murine leukemia virus (MuLV)-induced myeloid leukemias (MML). We reported recently that this transcription factor promotes proliferation by directly transactivating c-myc and inhibits cell death through its up-regulation of Bcl-2 (Schmidt et al., 2000). To understand more about how these cells become transformed we looked at how they deal with cellular pathways inducing growth arrest. Specifically, we were interested in the expression of the tumor suppressor gene Cdkn2b (p15(INK4b)) in MML because this gene is expressed during myeloid differentiation and its inactivation by methylation has been shown to be important for the development of human acute myeloid leukemia. mRNA levels for p15(INK4b) and another INK4 gene p16(INK4a) were examined in monocytic Myb tumors and were compared with expression of the same genes in c-myc transformed monocytic tumors that do not express c-Myb. The Cdkn2a (p16(INK4a)) gene was generally not expressed in either tumor type, an observation explained by methylation or deletion in the promoter region. Although Cdkn2b (p15(INK4b)) mRNA was expressed in the Myc tumors, many transcripts were aberrant in size and contained only exon 1. Surprisingly, in the majority of the Myb tumors there was no p15(INK4b) transcription and neither deletion nor methylation could explain this result. Additional experiments demonstrated that, in the presence of constitutive c-Myb expression, the induction of p15(INK4b) mRNA that accompanies differentiation of M1 cells to monocytes does not occur. Therefore, the transcriptional regulator c-Myb appears to prevent activation of a growth arrest pathway that normally accompanies monocyte maturation.
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PMID:Deregulated c-Myb expression in murine myeloid leukemias prevents the up-regulation of p15(INK4b) normally associated with differentiation. 1159 29

Oligonucleotides (ON) have been used in vitro, in vivo and clinically for the treatment viral infections, malignancies and inflammatory diseases. This review will focus on the application of ON-based therapeutics for hematological disease. The primary application of ONs has been as sequence specific inhibitors of gene expression, ie, antisense oligonucleotides (AS ON) and ribozymes. Based upon the unique expression of the Bcl-Abl neogene in CML cells, numerous studies have targeted this product with AS ONs and ribozymes. These studies demonstrate that ON targeting the breakpoint region selectively inhibit the proliferation of CML cells. Subsequent studies suggest that this effect may not be due to a true antisense effect of the ON. Other targets, which are being exploited for the treatment of hematological malignancies, include ON targeting c-myb gene, p53 and Bcl-2. All three have entered clinical trials and have been shown to be tolerated by patients. In addition to inhibition of gene expression, ON can be selected for sequence specific binding to proteins (aptamer). In particular an ON that binds to thrombin with high affinity is being explored as a potential anticoagulant. These early studies have identified limitations for first generation ON which may be solvable with newer ON chemistries and/or formulations. Although the technology is still nascent it continues to show promise.
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PMID:Oligonucleotide therapeutics: clothing the emperor. 1171 94

This study was aimed at the level and implication of expression of c-myb and bcl-2 proteins in C6 glioma. The therapeutic effect of oncogene c-myb antisense oligodeoxynucleotide on C6 glioma in nude mice was studied. C6 glioma cells were implanted into the cutis of 36 nude mice. Ten days later, the nude mice were randomly divided into three groups and were treated with SON, AON and normal saline respectively. Three mice of every group were killed at 4 days, 8 days, 12 days and 16 days after treatment, respectively. The levels of c-myb and Bcl-2 proteins expression in the three groups were observed by the S-P immunohistochemical method. The results showed the expression of c-myb and bcl-2 proteins was significantly decreased in the AON group, compared with that in the SON and control groups (P < 0.05). These data suggest that c-myb and bcl-2 proteins may play an important role in malignant glioma, and c-myb gene and bcl-2 gene may be involved in the tumorigenesis and development of glioma.
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PMID:[Expression and implication of c-myb and bcl-2 proteins in C6 gliomas]. 1254 15

c-Myb is a transcription factor employed in the haematopoietic system and gastrointestinal tract to regulate the exquisite balance between cell division, differentiation and survival. In its absence, these tissues either fail to form, or show aberrant biology. Mice lacking a functional c-myb gene die in utero by day 15 of development. When inappropriately expressed, as is common in leukaemia and epithelial cancers of the breast, colon and gastro-oesophagus, c-Myb appears to activate gene targets of key importance to cancer progression and metastasis. These genes include cyclooxygenase-2 (COX-2), Bcl-2, BclX(L) and c-Myc, which influence diverse processes such as angiogenesis, proliferation and apoptosis. The clinical potential for blocking c-Myb expression in malignancies is based upon strong preclinical data and some trial-based evidence. The modest clinical experience to date has been with haematopoietic malignancies, but other disease classes may be amenable to similar interventions. The frontline agents to achieve this are nuclease-resistant oligodeoxynucleotides (ODNs), which are proving to be acceptable therapeutic reagents in terms of tolerable toxicities and delivery. Nevertheless, further effort must be focused on improving their efficacy, eliminating non-specific toxicity and optimising delivery. Optimisation issues aside, it would appear that anti-c-Myb therapies will be used with most success when combined with other agents, some of which will be established cytotoxic and differentiation-inducing drugs. This review will explore the future strategic use of ODNs in vivo, focusing on a wide spectrum of diseases, including several beyond the haematopoietic malignancies, in which c-Myb appears to play a role.
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PMID:Targeting c-Myb expression in human disease. 1266

Neuroectodermal tumors are highly malignant and increasingly common tumors. Because the cure rate of these neoplasias by conventional treatment is very low, new therapeutic approaches are needed. Entrapping high concentrations of cytotoxic drugs and/or oligonucleotides within stabilized liposomal formulations represents an emerging modality of antitumor treatment. Here, we tested the in vitro and in vivo antitumor effects of a novel antisense oligodeoxynucleotide (asODN) liposomal formulation, the coated cationic liposomes (CCL), by targeting the c-myc and the c-myb oncogenes on melanoma and neuroblastoma, respectively, through the use of a monoclonal antibody against the disialoganglioside GD2, selectively expressed by neuroectoderma-derived tumors. Our methods produced GD2-targeted liposomes that stably entrapped 90 percent of added asODNs. These liposomes showed selective binding for GD2-positive tumor cells in vitro. Neuroblastoma cells treated with free myb-as or nontargeted CCL-myb-as showed the same level of c-myb protein expression as control cells. In contrast, c-myb protein expression of cells treated with aGD2-CCL-myb-as was inhibited by approximately 70 percent. Melanoma and neuroblastoma cell proliferation was inhibited to a greater extent by GD2-targeted liposomes containing c-myc or c-myb asODNs than by nontargeted liposomes or free asODNs. Mice bearing established subcutaneous human melanoma xenografts treated with aGD2-CCL-myc-as exhibited significantly reduced tumor growth and increased survival. The mechanism for the antitumor effects appears to be downregulation of the expression of the c-myc protein, induction of p53, and inhibition of Bcl-2 proteins, leading to extensive tumor cell apoptosis. In contrast, the increased life span obtained in a neuroblastoma pseudometastatic mouse model with the liposomal c-myb asODNs seems to be due to a synergistic mechanism: specific targeting to neuroblastoma cancer cells, downmodulation of c-myb protein expression, and stimulation of the innate immune system. These results suggest that inhibition of c-myc or c-myb proto-oncogenes by GD2-targeted antisense therapy could provide an effective approach for the treatment of neuroectodermal tumors in an adjuvant setting.
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PMID:Targeted delivery of oncogene-selective antisense oligonucleotides in neuroectodermal tumors: therapeutic implications. 1565 Feb 35

The c-myb gene is preferentially expressed in primitive hematopoietic cell and plays a central role in the control of cell proliferation, differentiation and survival by regulating the transcription of several genes implicated in these processes including the antiapoptotic Bcl-2. We show here that, compared to wild-type c-Myb, overexpression of a degradation resistant c-Myb mutant [Delta(358-452) c-Myb] enhances the clonogenic potential of hematopoietic progenitors as indicated by increased cytokine-dependent primary and secondary colony formation of Lin(-) Sca-1(+) Kit(+) mouse marrow cells. Moreover, proliferation assays of IL-3 dependent myeloid precursor 32Dcl3 cells co-expressing Bcl-2 and c-Myb indicate that these cells continue to proliferate in the absence of IL-3 and this effect is more apparent in cells expressing the degradation resistant Delta(358-452) c-Myb. Interestingly, overexpression of Delta(358-452) c-Myb is by itself sufficient to protect 32Dcl3 cells from apoptosis induced by IL-3 deprivation; moreover, these cells are also increased in number which most likely reflects the enhanced proliferative potential conferred by Delta(358-452) c-Myb to apoptosis-resistant cells.
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PMID:A degradation-resistant c-Myb mutant cooperates with Bcl-2 in enhancing proliferative potential and survival of hematopoietic cells. 1764 12


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