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)

The reversibility of a differentiation program termed dedifferentiation, redifferentiation, or retrodifferentiation opens a spectrum of new possibilities for cellular development. During differentiation and retrodifferentiation, the expression of gene products associated with a differentiated phenotype and cell cycle regulation demonstrate inverse patterns. This effect requires a coordinated network that simultaneously controls cell growth and differentiation. In particular, crosstalk between induction of differentiation and G0/G1 cell cycle exit can be initiated and sustained by activated serine/threonine kinases and tyrosine kinases. Phosphorylation signals are relayed to certain genes or transcription factors such as Fos/Jun, EGR-1, NF-kappa B, MyoD, or the Myc/Max gene family. However, the precise regulation of these transcription factors to confer signals to differentiation-associated and cell cycle-regulatory genes remains unclear. Cell cycle exit into a transient G0'-arrest cycle or a terminal G0 phase is determined by a network of phosphorylation signals involving the retinoblastoma protein and a variety of factors such as the E2F family, cyclins, and cyclin-dependent kinases. In this context, a variety of differentiation-induced cell lines, including monocytic, neuronal, or muscle cells, can progress through the G0'-arrest cycle, whereby a certain population retains the capacity to retrodifferentiate and reenter the cell cycle. In contrast, the rest of the differentiated population enters the irreversible G0 phase (terminal commitment) that finally results in programmed cell death. The expression of growth arrest-specific (gas and gadd) genes is associated with the G0'-arrest cycle, and other factors, including c-myc, p53, mdm2, and bcl2/bclx, contribute to the regulation of the cell death program. Although the precise signaling cascade determining retrodifferentiation or cell death remains unclear, a coordinated inter- and intracellular regulation could establish a certain biological balance between these exclusive pathways. Consequently, a retrodifferentiation process may provide a potential for cell type conversion or transdifferentiation, whereby retrodifferentiated cells can be induced to develop via a different pathway according to tissue-specific requirements.
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PMID:Retrodifferentiation and cell death. 771 Nov 13

The current paradigm states that cancer progression is caused by random independent mutations, each selected for its survival advantages. The accelerated rates of phenotypic changes, the pleiotropic effect of several genes involved in progression--which need not be necessarily mutated for inducing the observed changes in cancer cell behaviour--lead us to propose an alternative hypothesis. Malignant progression might be a result of the unveiling of a cell-survival program, induced by various aggressions in the same way as the SOS system is induced and regulated in bacteria. This hypothesis depends on the homology between several genes involved in cancer progression (such as bcl2, mdm2, the mismatch repair genes, the heat shock protein genes, the pleiotropic resistance genes, the telomerase gene ...) and several genes involved in the survival of prokaryotes and eukaryotes under stress. The development of multicellular organisms could not take place without the building of a control program, exemplified by the so-called anti-oncogenes. However, this control program had to integrate some weaknesses, in order to allow for embryogenesis, growth, and wound healing. These weaknesses, neutral from an evolutionary point of view--since most cancers are sporadic and kill their hosts long after the birth of the offspring--are exploited by the survival program of individual cells, inherited from the genome of prokaryotes and unicellular eukaryotes, and repressed but not suppressed in animals. If this theory is true, it is probable that (i) no anti-oncogenes will be found in unicellular organisms, (ii) the sensitivity to mutations will be higher in genes involved in proliferation and in anti-oncogenes such as p53 and Rb, than in genes not involved in the cancer process, (iii) a process of transfer of genetic information exists in cancer cells as it exists in bacteria. The identification of the genes governing the survival program could lead to new therapeutic approaches.
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PMID:Tumour progression: random mutations or an integrated survival response to cellular stress conserved from unicellular organisms? 873 76

The present study was undertaken to examine the distribution of p53, p21, mdm-2 and bcl-2 protein expression in human colorectal adenocarcinomas in order to obtain combined information about the immunophenotypes characterising these tumours. Formalin-fixed, paraffin-embedded tissue sections from 52 cases of colorectal adenocarcinomas were stained using immunohistochemical methods for the detection of p53, p21/waf1, mdm2 and bcl-2 proteins. P53, p21/waf1, mdm2 and bcl-2 proteins were expressed in 35/52, 45/52, 9/52 and 27/52 cases, respectively. All nine mdm2+ cases expressed p53 and p21 proteins as well. The three patterns observed in p53/p21 expression were: p53+/p21+, p53+/p21- and p53-/p21+ in 28, 7, and 17 cases, respectively. Consequently, p53+/mdm2-/p21+, p53+/mdm-/p21- and p53-/mdm2-/p21+ immunophenotypes were expressed in 19, 7, and 17 cases respectively. Four patterns of p53/bcl2 expression were identified: p53+/bcl2+, 20 cases; p53+/bcl2-, 15 cases; p53-/bcl2+, 7 cases; p53-/bcl2-, 10 cases. It was noteworthy that 9 of the 10 p53-/bcl2-tumours had negative lymph node status. The present results suggest that both p53 dependent and p53-independent induction of p21 expression may be involved in the molecular mechanisms controlling these tumours. High expression of the p53 protein in colorectal carcinomas could be due not only to p53 gene mutations but also to binding to mdm2 protein which leads to p53 protein stabilisation. In addition, tumours with p53-/bcl2- immunophenotype are frequently associated to negative lymph node status and seem to be less aggressive.
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PMID:Immunohistochemical expression of p53, bcl-2, mdm2 and waf1/p21 proteins in colorectal adenocarcinomas. 925 82

A new category of oncogenes regulating apoptosis, p53 and bcl-2, and the Epstein Barr virus (EBV) latent membrane protein-1 (LMP-1) have been related to Hodgkin's disease (HD) pathogenesis. We attempt to determine p53, mdm2, p21waf-1, bcl-2 and LMP-1 immunohistochemical expression in tissue sections from formalin-fixed, paraffin-embedded lymph node biopsies of pediatric HD. P53 was detected in the nucleus of Reed Sternberg cells and their variants (H-RS) in 68% of the HD cases. However, there was no statistically significant association with either clinical stages or with histological subtypes. P21waf-1, an indirect marker of p53 functional status, showed nuclear labelling of H-RS in all the studied cases. MDM2 co-expressed with p53 in 62% of the cases, suggesting that both proteins regulate one another, in HD by a self regulatory loop. Bcl-2 cytoplasmatic expression in H-RS was demonstrated in 65% of the cases. There was co-expression of bcl-2 and p53 in 51%, but it failed to correlate with a poor prognosis. LMP-1 labelling was shown in 51% of the cases, disclosing a statistically significant association with the under 6-year group (p = 0.005, Fisher's exact test). Since LMP-1 induces the expression of bcl-2 in vitro, the relation of both proteins was analysed and found to co-express in 15/37 cases, with a statistically significant association only in the under 6-year group (p = 0.001, Fisher's exact test). Abnormal accumulation of these oncoproteins in tumour cells could play a role in the pathogenesis of a subset of pediatric HD.
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PMID:Oncogene expression in tumour cells of pediatric Hodgkin's disease in Argentina--correlation with Epstein Barr virus presence. 954 44

Thirty-one cases of small cell lung carcinomas (SCLC) were investigated by immunohistochemistry for the expression of bcl-2, p53 and the wild-type (wt) p53- induced proteins mdm2 and p21/waf1. Bcl-2 protein was detected in 24/31 cases of SCLC(77%) and p53 protein in 13/31 cases (42%). No correlation was found between histological subtype of SCLC and bcl-2 or p53 expression. Comparison between bcl-2 and p53 expression showed that 14/31 cases (45%) were only bcl-2 positive, 3/31 (11%) were only p53 positive, 10/31 (32%) were positive for both proteins and 4/31 (13%) were negative for both proteins. Mdm2 protein was detected in 2/32 SCLC which were also p53 positive. P21 protein was detected in 6/32 SCLC. Four of the p21 positive SCLC were negative for both p53 and mdm2, and two were positive for both p53 and mdm2 proteins. The significant expression of bcl-2 protein in SCLC suggests that bcl-2 may be involved in the pathogenesis of most SCLC by inhibiting apoptosis during neoplastic transformation. The expression of p53 protein in SCLC is likely to be related to underlying p53 gene mutations since these genetic alterations are very frequent in SCLC. This can be supported by our findings that 11/13 p53 positive SCLC were mdm2 and p21 negative. The two cases with p53+/mdm2+/p21+ phenotype may represent tumours with wt p53 gene and p53 protein immunoexpression due to binding to mdm2 protein. The four cases with p53-/mdm2-/p21+ phenotype may represent tumours with p53-independent p21 protein expression. Coexpression of p53 and bcl-2 proteins in a proportion of SCLC suggests that in these tumours p53 doses not maintain its suppressive effect on bcl-2 expression as it has been reported in vitro. Further studies at DNA and RNA level are required to clarify the involvement of bcl-2, p53, mdm2 and waf1 genes in SCLC pathogenesis.
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PMID:Immunohistochemical detection of bcl2, p53, mdm2 and p21/waf1 proteins in small-cell lung carcinomas. 961 83

The p53 tumor suppressor gene product interacts with the p300 transcriptional coactivator that regulates the transactivation of p53-inducible genes. The adenovirus E1A protein has been shown to bind to p300 and inhibit its function. E1A inhibits p53 transactivation and also promotes p53 accumulation by a p300-dependent mechanism. Murine double minute 2 (Mdm2) is a transcriptional target of p53 that binds to p53 and inhibits its transcriptional activity. E1A inhibited mdm2 transactivation without affecting the expression of p21(WAF1) or Bax, which resulted in high levels of p53 accumulation and apoptosis. Ectopic expression of p300 restored Mdm2 levels and inhibited p53-dependent apoptosis, as did ectopic expression of Mdm2. Thus, p300 is required for mdm2 induction by p53 and the subsequent inhibition of p53 stabilization. Inhibition of p300 by E1A results in stabilization of p53 and causes apoptosis. Moreover, E1B 19K or Bcl-2 expression in E1A-transformed cells abrogated p53-dependent apoptosis by restoring mdm2 transactivation by p53. Hence, p300 regulation of mdm2 expression controls apoptotic activity of p53, and 19K or Bcl-2 bypass E1A inhibition of p300 transactivation of Mdm2.
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PMID:Suppression of the p300-dependent mdm2 negative-feedback loop induces the p53 apoptotic function. 964 2

Thirty-one cases of small cell lung carcinomas (SCLC) were investigated by immunohistochemistry for the expression of bcl-2. P53 and the wild-type (wt) p53-induced proteins mdm2 and p21/waf1. Bcl-2 protein was detected in 24/31 cases of SCLC(77%) and p53 protein in 13/31 cases (42%). No correlation was found between histological subtype of SCLC and bcl-2 or p53 expression. Comparison between bcl-2 and p53 expression showed that 14/31 cases (45%) were only bcl-2 positive, 3/31 (11%) were only p53 positive, 10/31 (32%) were positive for both proteins and 4/31 (13%) were negative for both proteins. Mdm2 protein was detected in 2/32 SCLC which were also p53 positive. P21 protein was detected in 6/32 SCLC. Four of the p21 positive SCLC were negative for both p53 and mdm2, and two were positive for both p53 and mdm2 proteins. The significant expression of bcl-2 protein in SCLC suggests that bcl-2 may be involved in the pathogenesis of most SCLC by inhibiting apoptosis during neoplastic transformation. The expression of p53 protein in SCLC is likely to be related to underlying p53 gene mutations since these genetic alterations are very frequent in SCLC. This can be supported by our findings that 11/13 p53 positive SCLC were mdm2 and p21 negative. The two cases with p53+/mdm2+/p21+ phenotype may represent tumours with wt p53 gene and p53 protein immunoexpression due to binding to mdm2 protein. The four cases with p53-/mdm2-/p21+ phenotype may represent tumours with p53-independent p21 protein expression. Coexpression of p53 and bcl-2 proteins in a proportion of SCLC suggests that in these tumours p53 does not maintain its suppressive effect on bcl-2 expression as has been reported in vitro. Further studies at the DNA and RNA level are required to clarify the involvement of bcl-2, p53, mdm2 and wafl genes in SCLC pathogenesis.
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PMID:Immunohistochemical detection of bcl2, p53, mdm2 and p21/waf1 proteins in small-cell lung carcinomas. 967 91

We have investigated by immunohistochemistry 38 cases of B-cell MALT-NHL comprising 23 high grade (HG) and 15 low grade-(LG) tumours for the expression of p53, mdm2, p21, Rb, Ki67, bcl2 and Bax proteins. P53, mdm2 and p21 proteins were found in at least 5% of the tumour cells in 13/23, 2/23 and 11/23 HG tumours, respectively. These proteins were detected in very rare tumour cells in LG tumours. The following patterns were recorded in HG tumours: p53+/p21+/mdm2+ (2 cases), p53+/p21+/mdm2- (7 cases), p53+/p21-/mdm2- (4 cases), p53-/p21-/mdm2- (18 cases) and p53-/p21+/mdm2-(2 cases). Proliferative Ki67 index and Rb protein expression were higher in HG than in LG MALT-NHL. Bcl2 protein was expressed in all LG MALT-NHL, whereas only 2/23 HG MALT-NHL were bcl2 positive in most tumour cells. Bax protein was expressed in all MALT-NHL with HG tumours being positive in higher proportion of tumour cells than LG tumours. These findings show that significant expression of p53, mdm2, p21,Ki67 and Rb proteins occurs more frequently in aggressive histotypes of MALT-NHL. The parallel Rb/Ki67 expression suggests that Rb protein expression in MALT-NHL is normally regulated in relation to the proliferative growth fraction of the tumours. The pattern p53+/p21+/mdm2 +/- may represent MALT-NHL with wild type (wt) p53 gene since mdm2 and p21 proteins are inducible by wt p53 gene. The pattern p53+/mdm2-/p21-may represent MALT-NHL with p53 gene mutations unable to activate expression of mdm2 and p21 proteins. MALT-NHL with the p53-/mdm2-/p21 + pattern may be consistent with p53-independent p21 expression. Bax protein expression in all MALT-NHL suggests a role for this protein in the pathogenesis of these tumours.
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PMID:Expression of p53, p21, mdm2, Rb, bax and Ki67 proteins in lymphomas of the mucosa-associated lymphoid (MALT) tissue. 970 86

Histologic criteria defining malignancy in smooth muscle tumors are currently site specific. This study was undertaken to determine whether, in leiomyosarcomas (LMS) occurring in different anatomic locations, there were differences in patterns of expression of molecules that have been demonstrated to be associated with biologically aggressive behavior in malignant neoplasms, and also to determine their diagnostic utility. Formalin-fixed paraffin-embedded tissue blocks were selected from 16 extrauterine leiomyosarcomas (EULMS), 14 cases of uterine leiomyosarcomas (ULMS) and from five cases each of uterine and extrauterine leiomyomas (LM). Utilizing immunohistochemical (ABC) techniques with antigen retrieval, we assessed serial sections of each tumor for immunoreactivity with Glut1, CD44s, bcl2, cyclin D1, and estrogen receptor. Molecular genotyping for detecting k-ras-2 point mutation, p53 gene loss, and mdm2 gene amplification was performed on microdissected tumor samples from the same histologic sections. All of the uterine and extrauterine LM were diffusely positive for CD44s, bcl2, and cyclin D1, and uniformly negative for Glut1. In contrast, 50% of the ULMS and 25% of EULMS were Glutl positive. Moreover, Glut1 positivity closely correlated with aggressive biologic behavior reflected by distant metastatic spread. Eighty-percent of LM and 70% of the ULMS were estrogen receptor positive, whereas only one retroperitoneal tumor had focal weak positivity. Over 80% of the extrauterine and 50% of the uterine sarcomas showed absence of CD44s immunoreactivity. Percentage of cyclin D1 immunoreactivity was independent of tumor grade and inversely proportional to the percent of bcl2 positivity. An LMS of the male breast contained k-ras-2 exon 1 point mutation (codon 12 aspartate substitution of glycine). P53 allelic imbalance was present in 29% of ULMS and 57% EULMS. Mdm2 amplification was present in three of six EULMS but not in ULMS. In addition to clinical staging, Glut1 positivity together with patterns of immunoreactivity of CD44 and bcl2 may be helpful in identifying aggressive smooth muscle tumors of the uterus and some EULMS. The presence of estrogen receptor staining may be helpful in identifying uterine versus nonuterine LMS. Although sample numbers are too small for definite conclusions, this study suggests that there are differences in glucose transport, expression of adhesion molecules, and estrogen receptors in ULMS and EULMS, which in part may be due to the estrogen dependency of the ULMS. P53 mutations and mdm2 amplifications appear to be more frequent in EULMS.
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PMID:Comparative immunohistochemical and molecular analysis of uterine and extrauterine leiomyosarcomas. 1057 96

The MDM2 oncoprotein has been shown to inhibit p53-mediated growth arrest and apoptosis. It also confers growth advantage to different cell lines in the absence of p53. Recently, the ability of MDM2 to arrest the cell cycle of normal human fibroblasts has also been described. We report a novel function for this protein, showing that overexpression of MDM2 promotes apoptosis in p53-deficient, human medullary thyroid carcinoma cells. These cells, devoid of endogenous MDM2 protein, exhibited a significant growth retardation after stable transfection with mdm2. Cell cycle distribution of MDM2 transfectants [medullary thyroid tumor (MTT)-mdm2] revealed a fraction of the cell population in a hypodiploid status, suggesting that MDM2 is sufficient to promote apoptosis. This circumstance is further demonstrated by annexin V labeling. MDM2-induced apoptosis is partially reverted by transient transfection with p53 and p19ARF. Both MTT and MTT-mdm2 cells were tumorigenic when injected into nude mice. However, the percentage ofapoptotic nuclei in tumor sections derived from MDM2-expressing cells was significantly higher relative to that in the parental cell line. MDM2-mediated programmed cell death is at least mediated by a down-regulation of the antiapoptotic protein Bcl-2. Protein levels of caspase-2, which are undetectable in the parental cell line, appear clearly elevated in MTT-mdm2 cells. Caspase-3 activation does not participate in MDM2-induced apoptosis, as determined by protein levels or poly(ADP-ribose) polymerase fragmentation. The results observed in this medullary carcinoma cell line show for the first time that the product of the mdm2 oncogene mediates cell death by apoptosis in p53-deficient tumor cells.
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PMID:The MDM2 oncoprotein promotes apoptosis in p53-deficient human medullary thyroid carcinoma cells. 1061 65


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