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)

Senescent phenotype can be attained by diverse agents, thus suggesting that there might be molecular differences between the senescence achieved in vivo and the senescence-like state attained in vitro under culture conditions. In this study we compare the senescent phenotype reached by cells derived from young animals when cultured in vitro with the one associated with the in vivo aging process. Several in vitro senescence parameters, including MTT reduction, proliferation rate, DNA synthesis, SA-beta-gal staining, and both in vivo and in vitro Bcl-2 content, were determined. Alterations in DNA electrophoretic mobility were evaluated to test differences in bulk chromatin structure. Our results indicate that although it is possible to achieve a senescent phenotype with cells derived from young animals aged in culture, this phenotype differs from the one observed in older animals, due to lack of in vivo damage inducers to which cells are being exposed during natural aging.
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PMID:Senescent phenotype achieved in vitro is indistinguishable, with the exception of Bcl-2 content, from that attained during the in vivo aging process. 1535 May 99

Excessive stimulation of the NMDA receptor by glutamate induces cell death and has been implicated in the development of several neurodegenerative diseases. While apoptosis plays a role in glutamate-mediated toxicity, the mechanisms underlying this process have yet to be completely determined. Recent evidence has shown that exposure to excitatory amino acids regulates the expression of the antiapoptotic protein, Bcl-2, and the proapoptotic protein, Bax, in neurons. Since it has been suggested that the ratio of Bax to Bcl-2 is an important determinant of neuronal survival, the reciprocal regulation of these Bcl-2 family proteins may play a role in the neurotoxicity mediated by glutamate. Here, we have used a differentiable neuronal cell line, N1E-115, to investigate the molecular properties of glutamate-induced cell death. Annexin V staining was used to determine apoptotic cell death between 0 and 5 days differentiation with DMSO/low serum. Immunoblot analysis was used to determine whether the expression of Bcl-2 or Bax was modulated during the differentiation process. Bcl-2 protein levels were increased during maturation while Bax expression remained unchanged. Maximum Bcl-2 expression was observed following 5 days of differentiation. Examination of Bcl-2 and Bax following glutamate treatment revealed that the expression of these proteins was inversely regulated. Exposure to glutamate (0.001-10 mM) for 20+/-2 h resulted in a dose-dependent decrease in cell survival (as measured by MTT analysis) that was maximal at 10 mM. These results further support the role of apoptosis in glutamate-mediated cell death. Furthermore, a significant decrease in Bcl-2 levels was observed at 1 mM and 10 mM glutamate (32.1%+/-4.8 and 33.7+/-12.8%, respectively) while a significant upregulation of Bax expression (88.2+/-17.9%) was observed at 10 mM glutamate. Interestingly, Bcl-2 and Bax levels in cells treated with glutamate from 12-24 h were not significantly different from those of control. Taken together, these findings provide additional evidence for the reciprocal regulation of Bcl-2 and Bax expression by glutamate and suggest that neuronal excitotoxicity may, in part, result from the inverse regulation of these proteins.
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PMID:Glutamate mediates cell death and increases the Bax to Bcl-2 ratio in a differentiated neuronal cell line. 1536 91

The primary abnormality in chronic lymphocytic leukemia (CLL) is a defect in apoptosis, probably related to alterations in the expressions of Bcl-2 family members. In transgenic mice over expressing the anti-apoptotic Bcl-2 family member, myeloid cell factor-1 (Mcl-1), B cell lymphomas occur. Moreover, mice conditional for the loss of Mcl-1 display a profound reduction in B and T lymphocytes. This suggests that Mcl-1 is an essential survival factor in lymphocytes. In the present study, we have evaluated the role of Mcl-1 in CLL. Mcl-1 protein expression was measured by Western blot analysis in the CLL cells of 45 patients and correlated with clinical variables and survival. Mcl-1 levels were similar in 29 patients to normal B and T lymphocytes, were decreased in 8 patients and increased in 12 patients. An inverse correlation was found between Mcl-1 expression and Rai stage (P = 0.001). When assessed by flow cytometry, Mcl-1 expressions were normally distributed among CLL cells in individual patients and the mean levels correlated with those obtained by Western blotting. To evaluate the role of Mcl-1 in drug resistance, Mcl-1 levels were sequentially measured in the leukemic cells of 4 CLL patients during therapy with fludarabine (Flu). The Mcl-1 levels were found to increase in 2 patients while the peripheral blood lymphocyte counts dropped, suggesting that the residual drug-resistant cells had the highest Mcl-1 levels. Primary CLL cells were also treated with chlorambucil (CLB) or Flu in vitro and the Mcl-1 levels decreased correlating with the sensitivity of these cells to undergo apoptosis. Drug sensitivities of the CLL cells to CLB and Flu were also measured by MTT assay and the concentrations of drug required to decrease cell viability by 50% (IC50) varied from 1.9 to 9.27 microM for Flu (median, 9.4 microM) and 10 to 32.5 microM (median, 5.5 microM) for CLB. The sensitivities of the leukemic cells to CLB correlated inversely with Mcl-1 levels (P < 0.05). These results suggest that Mcl-1 may contribute to cell survival in CLL.
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PMID:Role of myeloid cell factor-1 (Mcl-1) in chronic lymphocytic leukemia. 1537 Feb 46

DNA-dependent protein kinase (DNA-PK), a nuclear serine/threonine kinase, is responsible for the DNA double-strand break repair. Cells lacking or with dysfunctional DNA-PK are often associated with mis-repair, chromosome aberrations, and complex exchanges, all of which are known to contribute to the development of human cancers including glioblastoma. Two human glioblastoma cell lines were used in the experiment, M059J cells lacking the catalytic subunit of DNA-PK, and their isogenic but DNA-PK proficient counterpart, M059K. We found that M059K cells were much more sensitive to staurosporine (STS) treatment than M059J cells, as demonstrated by MTT assay, TUNEL detection, and annexin-V and propidium iodide (PI) staining. A possible mechanism responsible for the different sensitivity in these two cell lines was explored by the examination of Bcl-2, Bax, Bak, and Fas. The cell death stimulus increased anti-apoptotic Bcl-2 and decreased pro-apoptotic Bcl-2 members (Bak and Bax) and Fas in glioblastoma cells deficient in DNA-PK. Activation of DNA-PK is known to promote cell death of human tumor cells via modulation of p53, which can down-regulate the anti-apoptotic Bcl-2 member proteins, induce pro-apoptotic Bcl-2 family members and promote a Bax-Bak interaction. Our experiment also demonstrated that the mode of glioblastoma cell death induced by STS consisted of both apoptosis and necrosis and the percentage of cell death in both modes was similar in glioblastoma cell lines either lacking DNA-PK or containing intact DNA-PK. Taken together, our findings suggest that DNA-PK has a positive role in the regulation of apoptosis in human glioblastomas. The aberrant expression of Bcl-2 family members and Fas was, at least in part, responsible for decreased sensitivity of DNA-PK deficient glioblastoma cells to cell death stimuli.
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PMID:Glioblastoma cells deficient in DNA-dependent protein kinase are resistant to cell death. 1549 13

Recently, a mitochondrial ceramidase has been identified and cloned, whose mitochondrial localization strongly suggests the existence of an unexpected mitochondrial pathway of ceramide metabolism that may play a key role in mitochondrial functions, especially in the regulation of apoptosis. To explore the biological effect of mitochondrial ceramidase on cells, pcDNA 3.1/His-CDase plasmid, containing mitochondrial ceramidase cDNA sequence, was transducted into K562 cells mediated by liposome, and G418 was used to screen for positive colonies. A stable transfected K562 cell line was established and named as 'K562TC'. The difference between K562 and K562TC cells in chemotheraputic cytotoxicity response and serum-withdrawal resistance and Bcl-2 protein expression were evaluated by MTT assay, annexin V/PI test, flow cytometry or Western blotting, respectively. The results showed that although survival was comparable between K562 and K562TC cells after exposed to adriamycin, etoposide or arsenious acid, K562TC cells with elevated Bcl-2 protein expression level as identified by FCM or Western blotting revealed stronger resistance to apoptosis induced by serum withdrawal than their parental cells. Inhibition of mitochondrial ceramidase expression in K562TC cells by its specific antisense oligodeoxynucleotide was correlated with a decrease in Bcl-2 protein level. N, N-dimethylsphingosine, a sphingosine kinase inhibitor, depleted intracellular sphingosine-1-phosphate production, also abrogated Bcl-2 protein expression in K562TC cells, while Bcl-2 protein level in K562 cells was up-regulated by exogenous sphingosine-1-phosphate. It is concluded that mitochondrial ceramidase overexpression in K562 cells leads to markedly elevated level of Bcl-2 protein and results in more resistance to serum withdrawal. This effect is initiated not by sphingosine, the direct metabolite of mitochondrial ceramidase, but via sphingosine-1-phosphate, its phosphorylated form. This is the first evidence that mitochondrial ceramidase, through its sphingoid metabolite sphingosine-1-phosphate, up-regulates Bcl-2 protein expression in K562 cells.
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PMID:mitochondrial ceramidase overexpression up-regulates Bcl-2 protein level in K562 cells, probably through its metabolite sphingosine-1-phosphate. 1549 14

Dideoxypetrosynol A, a polyacetylene from the sponge Petrosia sp., is known to exhibit significant selective cytotoxicity against several human tumor cell lines. In the present study, we investigated the possible mechanisms by which dideoxypetrosynol A exerts its anti-proliferative action in cultured human SK-MEL-2 skin melanoma cells. Exposure of SK-MEL-2 cells to dideoxypetrosynol A resulted in growth inhibition and induction of apoptosis in a dose-dependent manner as measured by MTT assay, fluorescent microscopy and flow cytometry analysis. The increase in apoptosis was associated with a dose-dependent up-regulation in proapoptotic Bax expression and down-regulation of anti-apoptotic Bcl-2. Apoptosis-inducing concentrations of dideoxypetrosynol A induced caspase-3 and caspase-9 activation accompanied by proteolytic degradation of poly(ADP-ribose)-polymerase and selective down-regulation of cIAP-1. Taken together, these findings provide important new insights into the possible molecular mechanisms of the anti-cancer activity of dideoxypetrosynol A.
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PMID:Induction of apoptosis by dideoxypetrosynol A, a polyacetylene from the sponge Petrosia sp., in human skin melanoma cells. 1554 80

Sodium butyrate (NaBu), a potent histone deacetylase inhibitor, modulates the expression of a large number of genes. The purpose of this study was to determine whether this dietary agent could induce apoptosis in MCF-7 cells, a breast cancer cell line that lacks caspase-3 activity, and to identify the mechanisms that underlie NaBu toxicity in these cells. Cell viability assessed by the activity of mitochondrial succinate dehydrogenase (MTT assay) revealed a dose-dependent reduction of MCF-7 cellular growth in response to NaBu treatment. Restoring caspase-3 function by transfection did not modify NaBu toxicity in these cells. Following a 24-h exposure, NaBu-induced cell growth arrest in G2/M phase in a dose-dependent fashion in association with stable expression of CDC25A, a G1-specific regulator of the cell cycle. The anti-proliferative effects of NaBu were accompanied by diminished expression of p53. Similarly, mRNA encoding c-Myc, a well-known regulator of p53, was decreased in NaBu-treated cells, while p21(Waf1/Cip1) mRNA was increased. Furthermore, bax mRNA level was up-regulated whereas a decline in Bcl-2 both protein and mRNA levels were detected in NaBu-treated cells. Apoptosis was observed following a treatment with 2 mM NaBu, reflected by Annexin-V staining and by the cleavage of poly(ADP-ribose) polymerase, whereas DNA laddering was absent. Apoptosis was associated with a pronounced depletion of intracellular glutathione levels. Finally, NaBu treatment significantly increased the activities of several antioxidant enzymes, including glutathione reductase, glutathione peroxidase, and catalase. Together, these data suggest that the pro-apoptotic effects of NaBu observed in MCF-7 cells are associated with oxidative stress.
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PMID:The histone deacetylase inhibitor sodium butyrate induces breast cancer cell apoptosis through diverse cytotoxic actions including glutathione depletion and oxidative stress. 1554 8

Flavopiridol is a synthetic flavone that has shown an antitumor effect against several cancers. Here, we investigated the in vitro effect of flavopiridol alone and the combined effect of low-dose flavopiridol plus radiation on esophageal squamous cell carcinoma cell lines. Esophageal squamous cell carcinoma cell lines (TE8, TE9 and KE4) were exposed to flavopiridol (0.05-400 nmol/L) for 48 h. Growth inhibition was evaluated by MTT assay, cell cycle distribution was determined by flow cytometry, and cyclin D1, Bcl-2 and Rb protein expression was detected by Western blotting. The effect of 0.05 nmol/L flavopiridol as a radio-sensitizer was determined by clonogenic assay. The IC50 was approximately 110-250 nmol/L. Exposure to 0.05 nmol/L flavopiridol for 48 h increased the G2/M population, while 300 nmol/L increased the G1 population. At a concentration of 300 nmol/L, nuclear fragmentation and chromatin condensation were observed in all three cell lines. Exposure to 300 nmol/L flavopiridol decreased the levels of cyclin D1 and Rb protein in all three cell lines and Bcl-2 protein was also decreased in TE8 and KE4 cells. Moreover, exposure to 0.05 nmol/L flavopiridol slightly decreased the levels of cyclin D1, Rb and Bcl-2 protein in KE4 cells. Flavopiridol treatment (0.05 nmol/L) enhanced the radio-sensitivity in all three cell lines. Low-dose flavopiridol augmented the response of esophageal squamous cell carcinoma cell lines to radiation. Administration of a low dose of flavopiridol could be a potent new therapeutic approach for improving the efficacy of radiotherapy against esophageal cancer.
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PMID:Flavopiridol as a radio-sensitizer for esophageal cancer cell lines. 1556 74

It is important to elucidate whether the leptin receptor, especially the long signal-transducing form of the leptin receptor (OB-Rb) is expressed in human osteoblasts. We detected the expression of human OB-Rb in cultured commercially available human osteoblasts (NHOst cells) using real-time quantitative reverse transcriptase polymerase chain reaction (RT-PCR). After confirming the expression of OB-Rb, we investigated the effect of leptin on NHOst cells. Leptin enhanced cell proliferation of the cells shown by the MTT assay. Furthermore, leptin changed the copy numbers of Bax and Bcl-2 mRNAs in the cultured cells as shown by real-time quantitative RT-PCR, although the effect was not consistent. Leptin did not change the production of osteocalcin and osteopontin by the cells. Leptin did not change the expression of OB-Rb mRNA in the cells. In conclusion, OB-Rb mRNA is expressed in cultured commercially available human osteoblasts. Leptin may have some effects on bone metabolism by directly modulating cell proliferation and apoptosis of osteoblasts in humans.
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PMID:The leptin receptor in human osteoblasts and the direct effect of leptin on bone metabolism. 1562 71

To investigate whether F951, a novel bcl-2 antisense oligodeoxynucleotide, increases the sensitivity of HL-60 cells to Ara-C, HL-60 cells were cultured with F951 in different doses alone or with F951 combined with low-dose Ara-C; the proliferation of HL-60 cells was assayed by MTT and trypan blue exclusion test; expression of Bcl-2 protein and its mRNA were measured by FACS and RT-PCR, respectively; the apoptotic cells were detected by DNA ladder and TUNEL assay. The results showed that F951 combined with low dose Ara-C revealed stronger effects in the aspects of inhibiting the HL-60 cells proliferation than in different doses of F951 alone or Ara-C alone. HL-60 cells treated with F951 + Ara-C had significantly lower trypan blue exclusion rate than that treated with Ara-C alone. The inhibition rates of HL-60 cells treated with FNS, Ara-C, F951 and F951 + Ara-C were -2.8%, 27.63%, 37.66%, 57.24%, respectively. F951 significantly down-regulated the expression of bcl-2 mRNA and protein in HL-60 cells. HL-60 cells treated with F951 + Ara-C showed more apparent DNA ladder and more apoptotic cells. It is concluded that F951 can inhibit bcl-2 gene expression and enhance the cytotoxicity of Ara-C through promoting apoptosis in HL-60 cells, hence increases the antitumor effect of Ara-C.
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PMID:[A novel bcl-2 antisense oligodeoxynucleotide F951 increases sensitivity of HL-60 cells to Ara-C]. 1563 54


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