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)

Irradiation of mammalian cells can cause cell cycle perturbations and apoptotic cell death. We have investigated the modulation of these physiologic end points by growth factor stimulation: irradiation of a murine hematopoietic cell line in the presence of interlekin-3 (IL-3) induces G1 arrest, and irradiation in the absence of IL-3 results in rapid apoptotic cell death. Both of these end points are dependent on p53. Transient removal of IL-3 at the time of irradiation results in decreased clonogenic survival of irradiated cells. The removal of IL-3 results in a failure of the irradiated cells to arrest at the G1 checkpoint, despite induction of p53 and p21WAF1/CIP1, and then the cells enter S-phase where they undergo apoptosis. There are no cytokine-related changes in Bcl-2, Bax, or Bcl-x protein levels that could account for the modulation of G1 arrest versus apoptosis by growth factors. In contrast, rapid p53-independent alterations of basal levels of gadd45 and p21WAF1/CIP1 expression are linked to IL-3 withdrawal, suggesting a potential mechanism for this modulation. Constitutive activation of cytokine-like pathways with induced expression of v-Src or activated c-Raf inhibits the radiation-induced apoptosis and the alterations in p21WAF1/CIP1 and gadd45 expression. These observations suggest additional molecular mechanisms that can contribute to the development of radioresistance and resistance to apoptosis during tumorigenesis and provide an explanation for the observed lack of p53 mutations in some tumor types. In addition, these data suggest that oncogenic changes occurring during multistep tumorigenesis could be classified as those that either enhance or decrease apoptosis tendencies.
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PMID:Growth factor modulation of p53-mediated growth arrest versus apoptosis. 769 49

The accumulation of wild-type p53 protein results in two pathways, cell cycle G1 arrest by p21WAF1/CIP1/SDI1 and apoptosis inhibited by bcl2, which together carry out the tumor suppressor function. Since genetic alterations of p53 are frequently observed in gastric cancers, the expression of p21 and bcl2 may be altered in gastric carcinogenesis. We therefore analyzed normal mucosa, nondysplastic lesions, hyperplastic polyps, adenomas and carcinomas of the human stomach using immuno-histochemistry, polymerase chain reaction-single-strand conformation polymorphism and DNA sequencing. In normal gastric mucosa, the expression of p21, bcl2 and p53 was topographically restricted: a) p21 expression was limited to foveolar epithelial cells; b) bcl2 and p53 expression was confined to only a few regenerative epithelial cells of the mucous neck region. In chronic gastritis or intestinal metaplasia, topographic expression became more obvious. This topographic expression was altered in hyperplastic polyps and adenomas. Hyper-plastic polyp showed an increased p21 and p53 expression with no bcl2 expression. Where as bcl2 expression increased and extended up parabasal and superficial dysplastic epithelium, p21 expression increased and was limited to surface dysplastic epithelium. Weak p53 expression was in full thickness of dysplastic epithelium. p21 and bcl2 expression in adenoma was higher than in intestinal type of carcinoma. In carcinomas, this topography was abrogated, but p53 mutation (36%) was present. There was no relationship between p53, p21 and bcl2 expression. As a result, in normal gastric epithelial cells, there was a precisely ordered topographic pattern of p21, bcl2 and wild-type p53 expression that becomes disordered during neoplasia. These results suggest that altered cell cycle and apoptosis control by wild-type p53 and its mediators appears to be an early event in gastric carcinogenesis that may facilitate tumor progression.
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PMID:Altered topographic expression of p21WAF1/CIP1/SDI1, bcl2 and p53 during gastric carcinogenesis. 965 43

In addition to breast and ovarian cancer in women, recent evidence suggests that germ-line mutations of the breast cancer susceptibility gene-1 (BRCA1) also confer an increased life-time risk for prostate cancer in male probands. However, it is not known if and how BRCA1 functions in prostate cancer. We stably expressed wild-type (wt) and tumor-associated mutant BRCA1 transgenes in DU-145, a human prostate cancer cell line with low endogenous expression of BRCA1. As compared with parental cells and vector transfected clones, wtBRCA1 clones exhibited: (1) a slightly decreased proliferation rate (doubling time = 25 h as compared with 22 h for control cells); (2) a (3-6)-fold increase in sensitivity to chemotherapy drugs (adriamycin, camptothecin, and taxol); (3) increased susceptibility to drug-induced apoptosis; (4) reduced repair of single-strand DNA strand breaks; and (5) alterations in expression of key cellular regulatory proteins (including BRCA2, p300, Mdm-2, p21(WAF1/CIP1), Bcl-2 and Bax). Clones transfected with the 5677insA breast cancer-associated mutant BRCA1 (insBRCA1) displayed a similar phenotype to wtBRCA1 clones, except that insBRCA1 clones had a significantly decreased proliferation rate (doubling time = 42 h). On the other hand, cells transfected with with 185delAG mutant BRCA1 showed no obvious phenotype as compared with parental or vector transfected cells. These findings suggest that BRCA1 may function as a human prostate tumor suppressor by virtue of its ability to modulate proliferation and various components of the cellular damage response. They also suggest several potential target gene products for a BRCA1 prostate tumor suppressor function.
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PMID:BRCA1 as a potential human prostate tumor suppressor: modulation of proliferation, damage responses and expression of cell regulatory proteins. 966 40

6-[3-(1-Adamantyl)-4-hydroxyphenyl]-2-naphthalene carboxylic acid (AHPN or CD437), originally identified as a retinoic acid receptor gamma-selective retinoid, was previously shown to induce growth inhibition and apoptosis in human breast cancer cells. In this study, we investigated the role of AHPN/CD437 and its mechanism of action in human lung cancer cell lines. Our results demonstrated that AHPN/CD437 effectively inhibited lung cancer cell growth by inducing G0/G1 arrest and apoptosis, a process that is accompanied by rapid induction of c-Jun, nur77, and p21(WAF1/CIP1). In addition, we found that expression of p53 and Bcl-2 was differentially regulated by AHPN/CD437 in different lung cancer cell lines and may play a role in regulating AHPN/CD437-induced apoptotic process. On constitutive expression of the c-JunAla(63,73) protein, a dominant-negative inhibitor of c-Jun, in A549 cells, nur77 expression and apoptosis induction by AHPN/CD437 were impaired, whereas p21(WAF1/CIP1) induction and G0/G1 arrest were not affected. Furthermore, overexpression of antisense nur77 RNA in A549 and H460 lung cancer cell lines largely inhibited AHPN/CD437-induced apoptosis. Thus, expression of c-Jun and nur77 plays a critical role in AHPN/CD437-induced apoptosis. Together, our results reveal a novel pathway for retinoid-induced apoptosis and suggest that AHPN/CD437 or analogs may have a better therapeutic efficacy against lung cancer.
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PMID:Molecular determinants of AHPN (CD437)-induced growth arrest and apoptosis in human lung cancer cell lines. 967 82

Scatter factor (SF) (hepatocyte growth factor) is a cytokine that may play a role in human breast cancer invasiveness and angiogenesis. We now report that SF can block the induction of apoptosis by various DNA damaging-agents, including cytotoxic agents used in breast cancer therapy. SF protected MDA-MB-453 human breast cancer cells, EMT6 mouse mammary tumor cells and MDCK renal epithelial cells against apoptosis induced by adriamycin (ADR), X-rays, ultraviolet radiation, and other agents. Protection was observed in assays of DNA fragmentation, cell viability (MTT), and clonogenic survival. Protection of MDA-MB-453 cells against ADR was dose- and time-dependent; maximal protection required pre-incubation with 75-100 ng/ml of SF for 48 h or more. Protection required functional SF receptor (c-Met), but was not dependent on p53. Western blotting analysis revealed that pre-treatment of MDA-MB-453 cells with SF inhibited the ADR-induced decreases in the levels of Bcl-XL, an anti-apoptotic protein related to Bcl-2; and the dose-response and time course characteristics for SF-mediated increases in the Bcl-XL protein levels of ADR-treated cells were consistent with the degrees of protection against apoptosis observed under the same conditions. Furthermore, Bcl-XL levels were not down-regulated by ADR in MDA-MB-231 breast cancer cells, consistent with the finding that SF failed to protect these cells against ADR, despite the fact that they contain functional c-Met receptor. In contrast to Bcl-XL, SF blocked ADR-induced increases in c-Myc and inhibited the expression of p21WAF1/CIP1 and of the BRCA1 protein in MDA-MB-453 cells. However, SF did not cause significant changes in the cell cycle distribution of ADR-treated cells. These findings suggest that SF-mediated protection of human breast cancer cells may involve inhibition of one or more pathways required for the activation of apoptosis and may particularly target the anti-apoptotic mitochondrial membrane pore-forming protein Bcl-XL as a component of the protective mechanism. By implication, the accumulation of SF within human breast cancers may contribute to the development of a radio- or chemoresistant phenotype.
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PMID:Scatter factor protects epithelial and carcinoma cells against apoptosis induced by DNA-damaging agents. 967 97

Oxidative stress affecting DNA integrity may be an important mediator of cell death induced by cerebral ischemia followed by reperfusion. Genes involved in the DNA repair processes may play an important role in cell viability. We studied the spatial expression of the DNA damage inducible gene p53 and its transcriptional targets p21WAF1/CIP1, cyclin G1, and Bax and compared their expression with markers of early DNA damage following 10 min of transient forebrain ischemia in rats. Cyclin G1 and p21WAF1/CIP1 mRNA levels increased significantly between 2.5 and 4-fold in neurons of the hippocampus, cortex, and striatum during the first 24 hr after reperfusion and decreased at 48 hr of reperfusion. Significant increases in the protein levels of Cyclin G1 and p21 WAF1/CIP1 were only seen in the striatum at 48 hr of reperfusion. The mRNA levels of the p21 family members p27KIP1 or p57KIP2 demonstrated no significant changes. p53, baxalpha, and bcl-xl mRNA levels increased in all areas of the hippocampus by 12 to 24 hr and decreased over the next 2 days of reperfusion. baxalpha mRNA was specifically induced in neurons of the outer cortical layers at 12 and 24 hr after reperfusion, and protein levels increased in the striatum at 48 hr. No changes in protein levels of p53, Bcl-xl, or Bcl-2 were detected in the cerebral cortex, hippocampus, or striatum at any time point following reperfusion. Single-stranded DNA breaks detected with DNA polymerase I-mediated in situ nick translation partly overlapped with nuclear cyclin G1 protein in the striatum, cortex, and hippocampus at 24 hr, however at 48 hr cyclin G1 remained elevated only in neurons bordering areas exhibiting DNA damage. Nuclear p53 protein, p21 mRNA, and baxalpha mRNA were absent in cells stained with the in situ nick translation method but p21 mRNA and baxalpha mRNA were increased in neurons adjacent to those with detectable DNA nick ends at 24 and 48 hr following reperfusion. The enhanced expression of cyclin G1, p21WAF1/CIP1, and baxalpha in neurons surviving transient forebrain ischemia may indicate their participation in an adaptive response to cerebral ischemia and reperfusion.
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PMID:Increased expression of cyclin G1 and p21WAF1/CIP1 in neurons following transient forebrain ischemia: comparison with early DNA damage. 969 56

Human granulocytic ehrlichiosis (HGE) is an occasionally severe and even fatal disease caused by an agent closely related to Ehrlichia equi and Ehrlichia phagocytophila, which is transmitted by ticks. Little is known about the pathogen itself, which only very recently has been isolated. The agent can be cultivated in vitro because it replicates in human promyelocytic leukemic HL-60 cells. Using multiparameter flow cytometry and laser scanning cytometry (LSC) we have investigated changes in HL-60 cells following their infection with the pathogen. Its presence within the infected HL-60 cells was detected and its intracellular level measured inmmunocytochemically using antibodies obtained from HGE-infected patients. The percentage of the infected cells measured by flow cytometry or LSC correlated well with the estimates by microscopy on the Giemsa-stained specimens. In the infected cultures, the cells had diminished levels of cyclins D3 and E as well as the cyclin dependent kinase inhibitor p21WAF1/CIP1 and were arrested predominantly in G0/1. The apoptosis-associated regulatory proteins were also affected by cell infection: expression of Bcl-2 was decreased in the infected cells whereas expression of Bax become more variable, with some cells showing higher levels of this protein. The infected cells developed numerous DNA strand breaks characteristic of apoptosis. The presence of the pathogen was also detected by LSC in cells from peripheral blood of the infected patients; after relocation and visual inspection ("CompuSort") the pathogen-positive cells were identified as leukocytes. This unique ability of LSC to detect, quantify, and visualize HGE in infected cells made this instrument particularly useful to measure the degree of infection in peripheral blood of the patients and study effects of the infectious agent on the cell cycle and apoptosis of the host cells.
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PMID:Cell cycle effects and induction of apoptosis caused by infection of HL-60 cells with human granulocytic ehrlichiosis pathogen measured by flow and laser scanning cytometry. 972 58

p53 has been implicated as a determinant of chemosensitivity and radiosensitivity. We measured chemosensitivity of human tumor cell lines (n = 11), with or without wild-type p53, following exposure to clinically useful chemotherapeutic drugs (n = 4). Chemosensitivity and apoptosis induction were correlated independently of p53 status or Bcl-2 protein levels in vitro. Wild-type p53 correlated with chemosensitivity in ovarian carcinoma and some Burkitt's lymphoma cells, but not in leukemia or lung cancer. Bcl-2 levels correlated with chemoresistance only in Burkitt's lymphoma. p53-dependent p21(WAF1/CIP1) induction and cell cycle arrest occurred at sublethal doses of chemotherapy, whereas at lethal doses of chemotherapy apoptotic death was observed, consistent with models proposing a relationship between the level of DNA damage versus survival or death. Loss of apoptosis induction was observed in drug-resistant ML-1 and HL-60 leukemia cells, without changes in p53 or Bcl-2. Targeted loss of p53 protein in H460 lung cancer cells using HPV-16 E6 inhibited the etoposide-induced G1 checkpoint but did not decrease chemosensitivity. Our studies suggest that the simple measurement of apoptosis induction may be a useful predictor of chemosensitivity, at least in vitro, and confirm that p53 status and Bcl-2 expression may be useful predictors of chemosensitivity in certain cell types.
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PMID:Apoptotic death of tumor cells correlates with chemosensitivity, independent of p53 or bcl-2. 981 12

It is now generally accepted that massive neuronal death due to oxidative stress is a regular feature of brains in neurodegenerative diseases. However, much less attention has been given to the death of glial cells. In this study, we examined p53-sensitive apoptosis of cells by using human glioblastoma A172 cells and p53-deficient mouse astrocytes. In human A172 cells, hydrogen peroxide (H2O2) caused cell death in a time- and concentration-dependent manner, accompanied by nucleosomal DNA fragmentation and chromatin condensation. After treatment with H2O2, p53 protein was highly expressed and protein levels of Bak, p21WAF1/CIP1 and GADD45 were also enhanced. However, the protein levels of Bcl-2 and Bax did not change. On the other hand, primary cultured astrocytes from p53-deficient mouse brain grew faster than wild-type and heterozygous astrocytes. In addition, p53-deficient astrocytes were more resistant to H2O2-induced apoptosis than wild-type and heterozygous astrocytes. These results suggest that glial proliferation and the repair of damaged DNA may be regulated by p53-induced p21WAF1/CIP1 and GADD45, and that glial apoptosis caused by oxidative stress may be mediated by p53-induced Bak.
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PMID:Hydrogen peroxide-induced apoptosis mediated by p53 protein in glial cells. 989 Jun 30

Defects in the mechanisms controlling the cell cycle are crucial in cell transformation and/or tumour progression. p21WAF1/CIP1 is an inhibitor of cyclin-dependent kinases, induced by p53-dependent and p53-independent pathways, which can block progression through the cell cycle. p21WAF1/CIP1 expression has been investigated immunohistochemically in a series of 191 patients with colorectal cancer of known p53 status. The purpose of the study was two-fold: to assess the relationship between p21WAF1/CIP1 immunoreactivity and p53 alterations, and to evaluate the prognostic significance of p21WAF1/CIP1 expression. In 96 carcinomas (51 per cent), p21WAF1/CIP1 was expressed in over 10 per cent of tumour cells, whereas in 26, p21WAF1/CIP1 was detected in under 10 per cent of neoplastic cells; 69 tumours lacked p21WAF1/CIP1 expression. Immunoreactivity was more frequent in tumours of the right colon (p < 0.003) and was inversely correlated with tumour stage (p < 0.03), p53 gene mutations (p < 0.0007), p53 protein accumulation (p < 0.019), and Bcl-2 expression (p < 0.0005). In univariate analysis, down-regulation of p21WAF1/CIP1 expression was associated with poor overall (p = 0.0022) and disease-free survival (p = 0.0009). Multivariate analysis, however, did not confirm any independent prognostic significance of p21WAF1/CIP1 expression. The results indicate that p21WAF1/CIP1 is associated with abnormal accumulation of p53 protein and the occurrence of p53 gene mutations in colorectal cancer and that lack of p21WAF1/CIP1 expression is correlated with reduced patient survival in univariate analysis. These data underline the crucial pathogenetic role of the p53-p21WAF1/CIP1 pathway in carcinomas of the large bowel.
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PMID:p21WAF1/CIP1 expression in colorectal carcinoma correlates with advanced disease stage and p53 mutations. 1039 83


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