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)

Previous studies have indicated that isolated preneoplastic rat hepatocytes in vitro fail to induce nuclear p53 protein and fail to block replication in response to genotoxic compounds. This suggests that defects in the protection of genomic integrity are part of their premalignant character. In the present study, we have investigated if similar defects occur in vivo. Preneoplastic glutathione-S-transferase (GST) 7-7-positive foci were induced in male Wistar rats by diethylnitrosamine (DEN) initiation and promotion with 2-acetylaminofluorene (2-AAF)/partial hepatectomy (PH). The response to genotoxic damage was studied by X-irradiation. p53 protein was moderately expressed in nuclei in surrounding hepatocytes. This nuclear p53 staining had decreased 2 weeks after 2-AAF treatment. In foci, the protein was detected in the cytoplasm whereas the nuclei were negative. Levels of p21(waf1/cip1) protein were high in nuclei and cytoplasm of surrounding hepatocytes, whereas the expression in foci was low. A low level of Mdm2 in nuclei was observed in surrounding liver, while both Mdm2 and Bcl-2 protein were strongly expressed in the cytoplasm in foci. X-ray exposure further induced nuclear expression of p53, p21(waf1/cip1), and Mdm2 in surrounding hepatocytes, but focal nuclei were still negative. DNA replication was strongly reduced by X-irradiation in surrounding hepatocytes, but only partially reduced in the foci. These results indicate that the p53 pathway of response to genomic stress is impaired in preneoplastic cells in vivo. This may support their clonal expansion and their further malignant transformation because protection against genetic damage is diminished.
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PMID:Loss of nuclear p53 protein in preneoplastic rat hepatocytes is accompanied by Mdm2 and Bcl-2 overexpression and by defective response to DNA damage in vivo. 1117 56

Ovarian cancer is among the most lethal cancers in women because of its high metastatic potential and lack of response to therapy. An experimental model to study this disease was developed using a transformed granulosa cell line expressing a mutant p53 and Ha-ras. When injected into the ovary of nude mice in the presence of laminin-1, tumors develop in the ovary and peritoneum and metastasize to various organs, leading to death within 21 days. In contrast, when cells were injected in the presence of gelatin, development of tumors was slower and no metastases were observed by day 21. Here we investigated the possible mechanism by which laminin-1 exerts its promotion of tumorigenesis and metastasis. Cells were co-injected with laminin-1 and active laminin peptides from the alpha1; (A13: RQVFQVAYIIIKA, A12: WVTVTLDL RQVFQ, AG73: LQVQLSIR, IKVAV) and beta1 (YIGSR) chains. Ovarian tumor growth and metastasis were increased in the presence of laminin-1 plus either AG73 peptide, IKVAV, or A13, and were significantly reduced in the presence of A12 or YIGSR. Expression of Bcl-2 and Mdm2 was higher by 3.5- and about 100-fold, respectively, in ovarian tumors grown in the presence of laminin compared to tumors grown in the presence of gelatin. Moreover, peptides A13 and AG73 further elevated Bcl-2 expression by 6- and 7-fold respectively, while IKVAV yielded expression similar to laminin-1. YIGSR and A12 reduced the expression of Bcl-2 by 7- and 3-fold, respectively, compared to treatment with laminin-1. A13 and AG73 increased Mdm2 expression by 1.8- and 1.3-fold, respectively, while IKVAV, A12, and YIGSR were without effect. Thus, laminin-1 exerts its proliferative effect on the development of ovarian tumors via upregulation of survival genes such as Bcl-2 and Mdm2. Peptides A13 and AG73 (which increased tumor growth and spread) enhance the expression of these genes and A12 and YIGSR (which decrease tumor growth and spread) attenuate their expression. IKVAV probably enhances tumor growth and metastasis by another mechanism.
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PMID:Role of laminin in ovarian cancer tumor growth and metastasis via regulation of Mdm2 and Bcl-2 expression. 1129 35

Human and rat granulosa cells express receptors to leptin which synergies with glucocorticoid hormones in stimulation of ovarian steroidogenesis. To examine whether leptin affects follicular development and maturation, we injected recombinant ovine leptin (300 ng-10 microg/animal) daily to immature 21 day-old female rats. Non-treated rats reached puberty at 44.5+/-1.6 (n=9) days. In contrast, in leptin treated animals, puberty was reached at 34.5+/-1.6 (n=9) days. Ovarian sections revealed hypertrophy of granulosa cells in leptin treated animals. Moreover, the number of ovulations was 2-fold higher in the treated animals compared to controls (3-4 ovulations versus 7-8 on the first three estrous cycles, P<0.001). Leptin dramatically reduced incidence of follicular apoptosis measured by TUNEL, and was already evident after 7 days of leptin injection (12% of apoptosis in leptin treated group compared to 52% in controls, P<0.001). Maximal protection against apoptosis was achieved at 1-3 microg leptin/animal. The levels of FSH, LH, progesterone and the steroidogenic factors ADX and STAR were elevated earlier in development in the leptin treated animals compared to control animals which is in line with the achievement of early puberty in the leptin treated animals compared to non treated ones. To reveal whether modulation of death and survival genes is involved in leptin attenuation of follicular apoptosis, we examined the expression of the survival gene Bcl-2 and the death gene Bax in Western blots of ovarian homogenates. There was a pronounced elevation in Bcl-2 expression during 7-14 days of leptin injections up to 16.3-fold (P<0.001) compared to Bcl-2 expression in controls. Bax expression was elevated only 3.4 fold (P<0.001), leading to an increase in the Bcl-2/Bax ratio of 4.7 fold (P<0.001). Expression of the tumor suppressor gene p 53 and the oncogene Mdm2 did not change significantly. Our data suggests that leptin may be involved in accelerating follicular maturation by attenuating follicular atresia and increasing the ratio of Bcl-2/Bax.
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PMID:Leptin attenuates follicular apoptosis and accelerates the onset of puberty in immature rats. 1160 38

The ARF and p53 tumor suppressors mediate Myc-induced apoptosis and suppress lymphoma development in E mu-myc transgenic mice. Here we report that the proapoptotic Bcl-2 family member Bax also mediates apoptosis triggered by Myc and inhibits Myc-induced lymphomagenesis. Bax-deficient primary pre-B cells are resistant to the apoptotic effects of Myc, and Bax loss accelerates lymphoma development in E mu-myc transgenics in a dose-dependent fashion. Eighty percent of lymphomas arising in wild-type E mu-myc transgenics have alterations in the ARF-Mdm2-p53 tumor suppressor pathway characterized by deletions in ARF, mutations or deletions of p53, and overexpression of Mdm2. The absence of Bax did not alter the frequency of biallelic deletion of ARF in lymphomas arising in E mu-myc transgenic mice or the rate of tumorigenesis in ARF-null mice. Furthermore, Mdm2 was overexpressed at the same frequency in lymphomas irrespective of Bax status, suggesting that Bax resides in a pathway separate from ARF and Mdm2. Strikingly, lymphomas from Bax-null E mu-myc transgenics lacked p53 alterations, whereas 27% of the tumors in Bax(+/-) E mu-myc transgenic mice contained p53 mutations or deletions. Thus, the loss of Bax eliminates the selection of p53 mutations and deletions, but not ARF deletions or Mdm2 overexpression, during Myc-induced tumorigenesis, formally demonstrating that Myc-induced apoptotic signals through ARF/Mdm2 and p53 must bifurcate: p53 signals through Bax, whereas this is not necessarily the case for ARF and Mdm2.
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PMID:Bax loss impairs Myc-induced apoptosis and circumvents the selection of p53 mutations during Myc-mediated lymphomagenesis. 1160 1

Peripheral T-cell lymphomas (PTCL) are usually characterized by aggressive clinical behaviour and poor clinical outcome, but their biological background has not been extensively investigated to date, due to their low incidence, about 10% of all non-Hodgkin's lymphoma cases in Western countries, and also to the paucity of specific molecular-genetic abnormalities. Neverthless, there is increasing biological and clinical evidence that primary nodal PTCL should be considered separately from extra-nodal cases, but little is known about biological factors of possible clinical and prognostic impact. This immunohistochemical study has analysed the expression of p53, Mdm2, p21(WAF1), BCL-2 and p-glycoprotein (MDR-1 gene product) in a series of 45 cases of nodal peripheral T-cell lymphomas (PTCL) with 'high-grade' histology. The immunohistochemical findings were then correlated with proliferative activity and clinical outcome. p53 was over-expressed in 13 cases (28.9%). p53 positive cases showed significantly higher proliferative activity (p<0.01), more frequent expression of Bcl-2 (p<0.01) and less frequent expression of p21(WAF1) than p53 negative cases. Mdm2 and p-glycoprotein were expressed in 4/13 (30.8%) and 8/13 (61.5%) p53 positive cases respectively, and in none (0%) of the p53 negative cases (p<0.01). Analysis of the survival curves showed that p53 positive cases were associated with a significantly poorer clinical outcome than p53 negative cases, in terms of both overall survival (p=0.0032) and event-free survival (p=0.0004). Furthermore, multivariate analysis showed that p53 expression was the most important independent prognostic variable. These findings indicate that p53 over-expression identifies a subset of nodal PTCL cases with a distinctive biological profile (higher proliferative activity, less frequent expression of p21(WAF1) and more frequent expression of Bcl-2, Mdm2 and p-glycoprotein than p53 negative cases) and poor clinical outcome. The immunohistochemical analysis of p53 expression is a simple, rapid and low-cost method which may provide information of potential clinical and prognostic value in nodal peripheral T-cell lymphomas.
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PMID:p53 over-expression identifies a subset of nodal peripheral T-cell lymphomas with a distinctive biological profile and poor clinical outcome. 1167 35

The extracellular signal-regulated kinase (ERK) pathway is among several signal transduction pathways that are activated in response to exposure to the DNA damage-inducing chemotherapeutic agent cisplatin. We have previously reported that inhibition of cisplatin-induced ERK activity enhances sensitivity to cisplatin. Furthermore, we have demonstrated that cisplatin-induced ERK activation is required for optimal p53 protein accumulation following cisplatin-induced DNA damage. In the present study, we expanded our investigations to examine the effect of cisplatin-induced ERK activation on the expression of p53-targeted genes that have been shown to be important in the cellular response to DNA damage including Bax, Bcl-2, Bcl-x1, Cyclin G, Gadd45, p21WAF1, and Mdm2. In the ovarian carcinoma cell line A2780, cisplatin was shown to induce expression of p21WAF1, Gadd45 and Mdm2, but cisplatin had no effect on expression of Bax, Bcl-2, Bcl-x1, or Cyclin G. Inhibition of cisplatin-induced ERK activity by PD98059 resulted in decreased levels of p21WAF1, Gadd45 and Mdm2. These results provide evidence that ERK activity during the cisplatin DNA damage response, regulates in part, these cell cycle control (p21WAF1, Gadd45), DNA repair (Gadd45) and p53-regulatory (Mdm2) proteins.
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PMID:Regulation of p53 target gene expression by cisplatin-induced extracellular signal-regulated kinase. 1176 56

To determine the influence of Bcl-2 on the developmental biology of myocytes, we analyzed the population dynamics of this cell type in the heart of transgenic (TG) mice overexpressing Bcl-2 under the control of the alpha-myosin heavy chain promoter. TG mice and non-TG (wild type, WT) mice were studied at 24 days, 2 months, and 4 months after birth. Bcl-2 overexpression produced a significant increase in the percentage of cycling myocytes and their mitotic index. These effects were strictly connected to the expression of the transgene, as demonstrated in isolated myocytes. The formation of mitotic spindle and contractile ring was identified in replicating cells. These typical aspects of mitosis were complemented with the demonstration of karyokinesis and cytokinesis to provide structural evidence of cell division. Apoptosis was low at all ages and was not affected by Bcl-2. The higher cell replication rate in TG was conditioned by a decrease in the expression of the cell-cycle inhibitors, p21(WAF1) and p16(INK4a), and by an increase in Mdm2-p53 complexes. In comparison with WT, TG had 0.4 x 10(6), 0.74 x 10(6), and 1.2 x 10(6) more myocytes in the left ventricle at 24 days, 2 months, and 4 months, respectively. Binucleated myocytes were 12% and 25% larger in WT than in TG mice at 2 and 4 months of age. Taken together, these observations reveal a previously uncharacterized replication-enhancing function of Bcl-2 in myocytes in vivo in the absence of stressful conditions.
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PMID:bcl-2 overexpression promotes myocyte proliferation. 1198 15

Studies from our laboratory have demonstrated that the major green tea polyphenol, (-)-epigallocatechin 3-gallate (EGCG), exerts potent neuroprotective actions in the mice model of Parkinson's disease. These studies were extended to neuronal cell culture employing the parkinsonism-inducing neurotoxin, 6-hydroxydopamine (6-OHDA). Pretreatment with EGCG (0.1-10 microm) attenuated human neuroblastoma (NB) SH-SY5Y cell death, induced by a 24-h exposure to 6-OHDA (50 microm). Potential cell signaling candidates involved in this neuroprotective effect were further examined. EGCG restored the reduced protein kinase C (PKC) and extracellular signal-regulated kinases (ERK1/2) activities caused by 6-OHDA toxicity. However, the neuroprotective effect of EGCG on cell survival was abolished by pretreatment with PKC inhibitor GF 109203X (1 microm). Because EGCG increased phosphorylated PKC, we suggest that PKC isoenzymes are involved in the neuroprotective action of EGCG against 6-OHDA. In addition, gene expression analysis revealed that EGCG prevented both the 6-OHDA-induced expression of several mRNAs, such as Bax, Bad, and Mdm2, and the decrease in Bcl-2, Bcl-w, and Bcl-x(L). These results suggest that the neuroprotective mechanism of EGCG against oxidative stress-induced cell death includes stimulation of PKC and modulation of cell survival/cell cycle genes.
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PMID:Involvement of protein kinase C activation and cell survival/ cell cycle genes in green tea polyphenol (-)-epigallocatechin 3-gallate neuroprotective action. 1205 35

p21(WAF1) appears to be a major determinant of the cell fate in response to anticancer therapy. It was shown previously that HCT116 human colon cancer cells growing in vitro enter a stable arrest upon DNA damage, whereas cells with a defective p21(WAF1) response undergo apoptosis. Here we report that the enhanced sensitivity of HCT116/p21(-/-) cells to chemotherapeutic drug-induced apoptosis correlates with an increased expression of p53 and a modification of their Bax/Bcl-2 ratio in favor of the pro-apoptotic protein Bax. Treatment of HCT116/p21(-/-) cells with daunomycin resulted in a reduction of the mitochondrial membrane potential and in activation of caspase-9, whereas no such changes were observed in HCT116/p21(+/+) cells, providing evidence that p21(WAF1) exerts an antagonistic effect on the mitochondrial pathway of apoptosis. Moreover, the role of p53 in activation of this pathway was demonstrated by the fact that inhibition of p53 activity by pifithrin-alpha reduced the sensitivity of HCT116/p21(-/-) cells to daunomycin-induced apoptosis and restored a Bax/Bcl-2 ratio similar to that observed in HCT116p21(+/+) cells. Enhancement of p53 expression after disruption of p21(WAF1) resulted from a stabilization of p53, which correlated with an increased expression of the tumor suppressor p14(ARF), an inhibitor of the ubiquitin ligase activity of Mdm2. In accordance with the role of p14(ARF) in p53 stabilization, overexpression of p14(ARF) in HCT116/p21(+/+) cells resulted in a strong increase in p53 activity. Our results identify a novel mechanism for the anti-apoptotic effect of p21(WAF1) consisting in maintenance of mitochondrial homeostasis that occurs in consequence of a negative control of p14(ARF) expression.
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PMID:Inactivation of p21WAF1 sensitizes cells to apoptosis via an increase of both p14ARF and p53 levels and an alteration of the Bax/Bcl-2 ratio. 1215 95

Tumor necrosis factor (TNF)-alpha and TNF-related apoptosis inducing ligand (TRAIL) share a common signaling pathway. Here we show a novel potentiating effect of cadmium on TNF-alpha- or TRAIL-mediated cell death via distinct signaling. TNF-alpha or TRAIL sensitized otherwise resistant NIH3T3 embryo fibroblast cells to death, when exposed to cadmium. The potentiating effects elicited by TNF-alpha or TRAIL on cell death were NF-kappaB- and SAPK/JNK-independent and were not diminished by the expression of Bcl-2. TNF-alpha potentiated the cadmium-induced accumulation of p53 but did not affect expression levels of Bax, Mdm2 and p21(WAF/CIP). A similar pattern of p53 accumulation was also observed in Balbc/3T3 fibroblasts but not in human tumor cell lines, MCF7 and HeLa cells. The synergistic cell death evoked by TNF-alpha and cadmium was attenuated by transient expression of a dominant negative p53(Val135) mutant in NIH3T3 cells and was not observed in p53(-/-) mouse embryo fibroblasts, indicating that p53 accumulation appears to contribute to cell death. In contrast, TRAIL did not further increase the cadmium-induced accumulation of p53 despite its potentiation effects on the cadmium-induced cell death. Expression of p53(Val135) mutant did not reduce TRAIL- and cadmium-mediated cell death. Taken together, these results suggest that TNF-alpha and TRAIL potentiate the cadmium-mediated cell death via distinct p53 expression patterns.
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PMID:Sensitizing effects of cadmium on TNF-alpha- and TRAIL-mediated apoptosis of NIH3T3 cells with distinct expression patterns of p53. 1218 81


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