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)

We have established three lymphoma cell lines, HF-1 from one follicular lymphoma (FL) patient, and HF-4 and HF-9 from another. All cell lines carry the characteristic t(14;18) chromosomal translocation and express constitutively the bcl-2 gene product (Bcl-2 protein). Cross-linking of their surface membrane Igs (sIgs) with relevant antibodies triggers a vigorous calcium signal in all three lines but only HF-1 is induced to apoptosis. Treatment with anti-Ig arrests the proliferation of HF-1 within 6-12 h, nucleosomal DNA fragmentation is evident in 18 h and a morphologically complete apoptosis is seen in 24-48 h. While bcl-2 was expressed at equal levels in all lines, the apoptosis-sensitive HF-1 line displayed a much lower expression of c-myc than seen in the apoptosis-resistant line. This finding challenges the concept that expression of bcl-2 per se renders resistance to apoptosis but that the balance between the expression of bcl-2 and c-myc may dictate the outcome of sIg cross-linking. HF-1 is a unique, phenotypically mature human B cell line expressing surface IgG. This cell line offers a new tool for investigations on apoptosis and induction of tolerance in mature B lymphocytes. Our results suggest that some FLs may be amenable to anti-cancer treatment based on anti-sIg antibody induced apoptosis.
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PMID:Cross-linking of surface IgG induces apoptosis in a bcl-2 expressing human follicular lymphoma line of mature B cell phenotype. 769 2

The proto-oncogene bcl-2, isolated from the t(14;18) chromosomal breakpoint in follicular B-lymphoma, and a bcl-2-related gene bcl-x (ref. 4) prevent apoptotic cell death induced by various treatments. Although a mechanism has been proposed that involves Bcl-2 activity on reactive oxygen species (ROS), expression of Bcl-2 or Bcl-xL prevents cell death induced by withdrawal of oxygen (hypoxia), which drastically decreases the net formation of oxygen free radicals and does not increase oxidized lipid, protein or DNA. Furthermore, neither ROS scavenger nor inhibitor of ROS scavenger affects cell death, regardless of the expression of Bcl-2 or Bcl-xL. Thus our data suggest that Bcl-2 and Bcl-xL exert an anti-cell death function by a mechanism other than regulation of ROS activity.
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PMID:Prevention of hypoxia-induced cell death by Bcl-2 and Bcl-xL. 772 26

The bcl-2 gene was originally cloned because of its involvement in B-cell lymphomas and encodes a 25-kD integral membrane protein that has been shown to inhibit programmed cell death (also termed apoptosis) in a wide variety of circumstances. The Epstein-Barr Virus (EBV) also has been implicated in B-cell malignancies and interestingly contains an open reading frame (BHRF-1) predicting a 19-kD protein with 22% homology to Bcl-2. To compare the functions of p26-Bcl-2 and p19-BHRF-1, we stably introduced expression plasmids encoding these proteins into a murine interleukin-3 (IL-3)-dependent hemopoietic cell line, 32D. Removal of IL-3 from cultures of control-transfected 32D cells resulted in internucleosomal DNA cleavage (a hallmark of programmed cell death) and loss of cell survival. In contrast, 32D cells containing high levels of p26-Bcl-2 or p19-BHRF-2 proteins exhibited prolonged survival and markedly delayed DNA degradation under the same conditions of IL-3 deprivation. As a first attempt to determine the functional importance of amino acid sequences that are conserved between the Bcl-2 and BHRF-1 proteins, we used site-specific mutagenesis to replace two conserved cysteine residues with alanines (positions 158 and 219) in the human Bcl-2 protein. Comparisons of the wild-type and cysteine-minus human Bcl-2 proteins in S49 lymphoma cells revealed equivalent ability to block glucocorticoid-induced cell death and DNA fragmentation, indicating that these two conserved cysteines are not critical for Bcl-2 oncoprotein function. Investigations in 32D cells of an avian homolog of Bcl-2 cloned from the chicken also revealed conservation of function with the human Bcl-2 protein, despite the presence of a 48-amino-acid region of divergent sequence. Taken together, these data demonstrate that despite marked differences in their predicted amino-acid sequences, the human, chicken, and EBV versions of Bcl-2 have retained the structural characteristics necessary to interface with pathways involved in the regulation of programmed cell death in murine cells. The findings thus contribute to the mapping of functional domains in Bcl-2 proteins, and raise the possibility that the EBV-encoded p19-BHRF-1 protein may be able to substitute for p26-Bcl-2 in the development of some types of cancer.
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PMID:Evolutionary conservation of function among mammalian, avian, and viral homologs of the Bcl-2 oncoprotein. 777 49

Basal cell carcinoma (BCC) is typically a slow-growing malignant tumour, composed of cells similar to those in the basal area of the epidermis. We investigated the expression of bcl-2 (B-cell leukaemia/lymphoma-2) in BCC, and also in squamous cell carcinoma (SCC) of the skin. The proto-oncogene bcl-2 encodes a protein which inhibits programmed cell death (apoptosis). The protein is expressed in basal cells in normal human epithelium, but not in the suprabasal cell layers. Immunohistochemical localization using a monoclonal anti-Bcl-2 antibody revealed bcl-2 expression in all the BCCs (15 patients). SCCs did not express bcl-2 (five patients). The positive Bcl-2 staining of BCC tumour cells supports the hypothesis that BCCs originate from the basal layer of the epidermis. The bcl-2 expression of BCC tumour cells also suggests a neoplastic transformation caused by extended cell survival rather than increased cell proliferation. This type of neoplastic growth is possibly associated with less aggressive tumour behaviour.
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PMID:Expression of the apoptosis-suppressing protein Bcl-2 in non-melanoma skin cancer. 777 78

The p53 gene located in the short arm of chromosome 17 at position 17p13, is involved in the negative regulation of cellular growth. p53 mutation seems to be the most frequent genetic alteration found in human cancer. Mutant conformation of the p53 gene is associated with cell proliferation and tumour progression, and in most cases implies p53 stabilization, which renders the p53 protein detectable through the use of immunohistochemical techniques. p53 expression is a frequent finding in high grade lymphomas of either B or T cell lineage, having been detected in 30% of cases in our series. The focal presence of p53+ cells was seen in a wide range of low and high grade lymphomas, including lymphadenitis and reactive tonsils. In 37.5% of cases this increased expression of p53 was secondary to mutation in highly conserved regions (exons 5-8). Unlike findings reported in other tumours, in lymphomas, p53 expression seems to be secondary to genetic alterations other than p53 mutation. Initial data suggest that the MDM2 protein could be involved in inactivating p53 protein in most of these cases. Finally, p53 expression has been found to be a poor prognostic marker in high grade B-cell lymphomas in a large series of cases. High p53 expression was associated with a short survival, this relation being stronger in cases with simultaneous bcl2 expression.
Leuk Lymphoma 1995 Mar
PMID:p53 expression in non-Hodgkin's lymphomas: a marker of p53 inactivation? 777 62

Overexpression of the B cell leukemia/lymphoma-2 (bcl-2) gene has been shown to confer a survival advantage on cells by inhibiting apoptosis. In epithelia, the bcl-2 gene is also related to development and differentiation, and the protein is strongly expressed in the embryo in the epithelial cells of the developing mammary gland. To investigate directly the effect of bcl-2 on human epithelial cells, we used an amphotropic recombinant retrovirus to introduce the gene into nontumorigenic cell lines developed from luminal epithelial cells cultured from milk. Here we demonstrate that while bcl-2 overexpression does not directly induce the tumorigenic phenotype, it provides a survival advantage to the mammary epithelial cells by inhibiting cell death at confluence or under conditions of serum starvation, bcl-2 can also affect the phenotype of the original epithelial cells, and promote epithelial-mesenchymal conversion, accompanied by loss of the cell adhesion molecules E-cadherin and alpha 2 beta 1 integrin. The extent of the epithelial-mesenchymal conversion varies with small differences in the phenotype of the parental line and with the level of expression of Bcl-2 and in some cases cell lines emerge with a mixed phenotype. The increased survival of Bcl-2-expressing cells at confluence results in multilayering, and the development of three- dimensional structures. Where a mixed phenotype is observed these structures consist of an outer layer of polarized epithelial cells separated by a basement membrane-like layer from an inner mass of fibroblastoid cells. Branching morphogenesis of bcl-2 transfectants is also observed in collagen gels (in the absence of fibroblast growth factors). The results strongly indicate that by increasing their survival under restrictive growth conditions, and by modifying the epithelial phenotype, bcl-2 can influence the specific morphogenetic behavior of mammary epithelial cells.
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PMID:bcl-2 overexpression inhibits cell death and promotes the morphogenesis, but not tumorigenesis of human mammary epithelial cells. 777 80

Apoptosis has been hypothesized to be mediated through the induction of free radicals via oxidative pathways. Furthermore, it has been proposed that Bcl-2 acts to inhibit apoptosis induced by a wide variety of stimuli by preventing the production of oxygen-derived free radicals. Since the generation of oxygen free radicals is dependent upon oxygen concentration, this hypothesis would lead to the prediction that the concentration of oxygen should affect the induction of apoptosis. In order to test this prediction, we have examined the induction of apoptosis in T-lymphoma cell lines S49.1 and WEHI 7.1 by dexamethasone and by withdrawal of serum from myc-immortalized fibroblasts in 95% oxygen, atmospheric oxygen (20%), and hypoxic conditions of up to 125-fold less oxygen. Culture in 95% oxygen induced apoptosis in all cells tested, confirming that oxidative damage can lead to apoptosis. However, for one cell line, WEHI 7.1, hypoxia also induced apoptosis. Furthermore, for the other cell lines tested, induction of apoptosis by either dexamethasone or by serum withdrawal was not affected by hypoxia. These results are not consistent with the hypothesis that apoptosis is mediated via oxygen-generated free radical formation.
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PMID:Induction of apoptosis at different oxygen tensions: evidence that oxygen radicals do not mediate apoptotic signaling. 786 11

With the recent advances in molecular technology, diagnostic procedures of the diseases at a DNA level have been introduced in hematological fields. The diagnostic methods used are Southern blotting to detect gene rearrangements, Northern blotting to find gene expressions, RT-PCR (reverse transcriptase-polymerase chain reaction) to identify transcribed fusion messages, and PCR-SSCR (single strand conformation polymorphism) to detect mutated genes. Rearrangements within major Bcr (breakpoint cluster region) were observed in almost all cases in chronic myelogenous leukemia, and breakpoint were found within minor Bcr in Philadelphia-positive leukemia. The rearrangements within the second intron of the retinoic acid receptor-alpha and sixth intron (bcr 1), third intron (bcr 3) and sixth exon (bcr 2) of the PML gene were detected in all cases with acute promyelocytic leukemia. In malignant lymphoma, the rearrangements of immunoglobulin and T-cell receptor genes, and new genes such as Bcl-1, Bcl-2, Bcl-5, Tal-1, and Tal-2 were also reported and rearrangements of the Bcl-5 gene were found in this study using Bcl-5 specific probe which we have cloned. Point mutations and deletions of the genes involved in the coagulation and fibrinolysis system have been reported. One base insertion resulting in elongation of carboxy terminal region and one amino acid deletion in alpha 2-plasmin inhibitor gene were found in two cases of its deficiency. Further study revealed that mutated proteins were retained in the endoplasmic reticulum in the cells. With the development of the PCR method, identification of gene mutation is gradually carried out as a routine work.
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PMID:[Molecular study of hematological diseases]. 791 42

A technique for extracting DNA from archival and fresh tissue from fine needle biopsy (FNB) samples for the polymerase chain reaction (PCR) is described. The method was used to detect the bcl-2 oncogene in various cytologic lymphoid preparations. The DNA was amplified with primers specific for the major break point region of the t(14;18) translocation, and the presence of the bcl-2 oncogene was correlated with clinical, cytomorphologic, histologic and immunologic findings. Thirty patients who had FNB of lymphoid tissue were randomly selected, 18 retrospectively and 12 prospectively. Bcl-2 was present in 3 of 8 cases of reactive lymphadenopathy and 9 of 22 cases of non-Hodgkin's lymphoma. Of these, seven had follicular small cleaved cell lymphoma, and two had large cell lymphoma. Smears, both archival and fresh, and cell suspensions provided sufficient DNA for PCR amplification. The technique has potential applications in several areas of cytologic and hematologic practice.
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PMID:Use of archival and fresh cytologic material for the polymerase chain reaction. Detection of the bcl-2 oncogene in lymphoid tissue obtained by fine needle biopsy. 791 45

The bcl-2 gene is expressed in many types of human tumours and becomes transcriptionally deregulated in the majority of non-Hodgkin's lymphomas as the result of t(14;18) chromosomal translocations. The 26-kDa Bcl-2 protein has been shown to block programmed cell death (apoptosis) induced by many types of stimuli, including a wide variety of chemotherapeutic drugs and radiation. The presence of bcl-2 in tumor cells has been correlated with poor responses to therapy in patients with some types of cancer. To explore further the relevance of bcl-2 to drug resistance, we used antisense (As) approaches to achieve reductions in the levels of steady state Bcl-2 protein levels in t(14;18)-containing human lymphoma cell lines. Both synthetic bcl-2-As oligonucleotides and inducible expression plasmids that produce bcl-2-As transcripts induced reductions in bcl-2 expression, resulting in a marked enhancement in the sensitivity of neoplastic cells to conventional chemotherapeutic drugs such as cytosine arabinoside (ara-C) and methotrexate (MTX). These results suggest that novel therapeutics targeted against bcl-2 could provide the means for improved treatment of cancer by affecting physiological pathways distal to the targets of cytotoxic drugs.
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PMID:Reversal of chemoresistance of lymphoma cells by antisense-mediated reduction of bcl-2 gene expression. 795 Mar 2


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