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)

Curcumin, a potent antioxidant and chemopreventive agent, has recently been found to be capable of inducing apoptosis in human hepatoma and leukemia cells by way of an elusive mechanism. Here, we demonstrate that curcumin also induces apoptosis in human basal cell carcinoma cells in a dose- and time-dependent manner, as evidenced by internucleosomal DNA fragmentation and morphologic change. In our study, consistent with the occurrence of DNA fragmentation, nuclear p53 protein initially increased at 12 h and peaked at 48 h after curcumin treatment. Prior treatment of cells with cycloheximide or actinomycin D abolished the p53 increase and apoptosis induced by curcumin, suggesting that either de novo p53 protein synthesis or some proteins synthesis for stabilization of p53 is required for apoptosis. In electrophoretic mobility gel-shift assays, nuclear extracts of cells treated with curcumin displayed distinct patterns of binding between p53 and its consensus binding site. Supportive of these findings, p53 downstream targets, including p21(CIP1/WAF1) and Gadd45, could be induced to localize on the nucleus by curcumin with similar p53 kinetics. Moreover, we immunoprecipitated extracts from basal cell carcinoma cells with different anti-p53 antibodies, which are known to be specific for wild-type or mutant p53 protein. The results reveal that basal cell carcinoma cells contain exclusively wild-type p53; however, curcumin treatment did not interfere with cell cycling. Similarly, the apoptosis suppressor Bcl-2 and promoter Bax were not changed with the curcumin treatment. Finally, treatment of cells with p53 antisense oligonucleotide could effectively prevent curcumin-induced intracellular p53 protein increase and apoptosis, but sense p53 oligonucleotide could not. Thus, our data suggest that the p53-associated signaling pathway is critically involved in curcumin-mediated apoptotic cell death. This evidence also suggests that curcumin may be a potent agent for skin cancer prevention or therapy.
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PMID:Curcumin induces a p53-dependent apoptosis in human basal cell carcinoma cells. 976 49

In the cellular response to genotoxic stress, cell cycle checkpoint and apoptosis are considered to be two of the major biological events in maintaining genomic stability. The tumor suppressor p53 has been shown to play critical roles in these stress-induced cellular responses at least in part through the activation of its down-stream genes, such as p21CIP1/WAF1, GADD45 and BAX. In addition, p53 has been found to down-regulate the expression of BCL-2, which is able to block apoptosis induced by both p53-dependent and independent signaling events. In this report, we have found that increased expression of Bcl-2 protein in the human Burkitt's lymphoma WMN cell line suppressed apoptosis induced by different DNA-damaging agents. The induction of p53-regulated genes including GADD45, p21CIP1/WAF1 and BAX by genotoxic stress was substantially reduced in cells expressing high levels of Bcl-2 protein. Furthermore, Bcl-2 protein was shown to specifically suppress the p53-mediated transactivation of p21CIP1/WAF1 and PG13-CAT, which is a typical p53-binding-site reporter construct. Similarly, the inhibitory effect of Bcl-2 protein was seen in a GADD45 promoter reporter construct after treatment with methylmethane sulfonate or UV-radiation. These results indicate that in addition to its apoptosis-suppressing activity, Bcl-2 protein is able to inhibit transactivation of p53-regulated genes, which function in multiple important cellular responses to genotoxic stress, including the control of cell cycle checkpoints, cell growth suppression and DNA repair.
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PMID:Inhibitory effect of Bcl-2 on p53-mediated transactivation following genotoxic stress. 992 86

We show here that the anti-apoptosis protein Bcl-2 potently inhibits p53-dependent transcriptional activation of various p53-responsive promoters in reporter gene co-transfection assays in human embryonic kidney 293 and MCF7 cells, without affecting nuclear accumulation of p53 protein. In contrast, Bcl-2(Deltatransmembrane (TM)), which lacks a hydrophobic membrane-anchoring domain, had no effect on p53 activity. Similarly, in MCF7 cells stably expressing either Bcl-2 or Bcl-2(DeltaTM), nuclear levels of p53 protein were up-regulated upon treatment with the DNA-damaging agents doxorubicin and UV radiation, whereas p53-responsive promoter activity and expression of p21(CIP1/WAF1) were strongly reduced in MCF7-Bcl-2 cells but not in MCF7-Bcl-2(DeltaTM) or control MCF7 cells. The issue of membrane anchoring was further explored by testing the effects of Bcl-2 chimeric proteins that contained heterologous transmembrane domains from the mitochondrial protein ActA or the endoplasmic reticulum protein cytochrome b5. Both Bcl-2(ActA) and Bcl-2(Cytob5) suppressed p53-mediated transactivation of reporter gene plasmids with efficiencies comparable to wild-type Bcl-2. These results suggest that (a) Bcl-2 not only suppresses p53-mediated apoptosis but also interferes with the transcriptional activation of p53 target genes at least in some cell lines, and (b) membrane anchoring is required for this function of Bcl-2. We speculate that membrane-anchored Bcl-2 may sequester an unknown factor necessary for p53 transcriptional activity.
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PMID:Inhibition of p53 transcriptional activity by Bcl-2 requires its membrane-anchoring domain. 1003 39

Determinants of differentiation and apoptosis in myelomonocytic leukemia cells (U937) exposed to the novel hybrid polar compound SAHA (suberoylanilide hydroxamic acid) have been examined. In contrast to hexamethylenbisacetamide (HMBA), SAHA-related maturation was limited and accompanied by marked cytoxicity. SAHA-mediated apoptosis occurred within the G0G1 and S phase populations, and was associated with decreased mitochondrial membrane potential, caspase-3 activation, PARP degradation, hypophosphorylation/cleavage of pRB, and down-regulation of c-Myc, c-Myb, and B-Myb. Enforced expression of Bcl-2 or Bcl-XL inhibited SAHA-induced apoptosis, but only modestly potentiated differentiation. While SAHA induced the cyclin-dependent kinase inhibitor p21CIP1, antisense ablation of this CDKI increased, rather than decreased, SAHA-related lethality. In contrast, conditional expression of wild-type p53 failed to modify SAHA actions, but markedly potentiated HMBA-induced apoptosis. Finally, SAHA modestly increased expression/activation of the stress-activated protein kinase (SAPK/JNK); moreover, SAHA-related lethality was partially attenuated by a dominant-negative c-Jun mutant protein (TAM67). SAHA did not stimulate mitogen-activated protein kinase (MAPK), nor was lethality diminished by the specific MEK/MAPK inhibitor PD98059. These findings indicate that SAHA potently induces apoptosis in human leukemia cells via a pathway that is p53-independent but at least partially regulated by Bcl-2/Bcl-XL, p21CIP1, and the c-Jun/AP-1 signaling cascade.
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PMID:Induction of apoptosis in U937 human leukemia cells by suberoylanilide hydroxamic acid (SAHA) proceeds through pathways that are regulated by Bcl-2/Bcl-XL, c-Jun, and p21CIP1, but independent of p53. 1059 2

Bone morphogenetic proteins (BMPs), members of the transforming growth factor (TGF)-beta superfamily, are a group of related proteins that are capable of inducing the formation of cartilage and bone but are now regarded as multifunctional cytokines. We show in this report a novel function of BMPs in hematopoietic cells: BMP-2 induces apoptosis not only in human myeloma cell lines (U266, RPMI 8226, HS-Sultan, IM-9, OPM-2, and KMS-12 cells), but also in primary samples from patients with multiple myeloma. The mechanism of BMP-2-induced apoptosis was investigated with the use of U266 cells, which are dependent on the interleukin-6 autocrine loop. We showed that BMP-2 caused cell-cycle arrest in the G1 phase and the subsequent apoptosis of myeloma cells. BMP-2 up-regulated the expression of cyclin-dependent kinase inhibitors (p21(CIP1/WAF1) and p27(KIP1)) and caused hypophosphorylation of retinoblastoma (Rb) protein. In studies of apoptosis-associated proteins, BMP-2 was seen to down-regulate the expression of Bcl-x(L); however, BMP-2 had no effects on the expression of Bcl-2, Bax, or Bad. Therefore, BMP-2 induces apoptosis in various human myeloma cells by means of the down-regulation of Bcl-x(L) and by cell-cycle arrest through the up-regulation of p21(CIP1/WAF1) and p27(KIP1) and by the hypophosphorylation of Rb. Further analysis showed that the signal transducer and activator of transcription 3 (STAT3) was inactivated immediately after BMP-2 treatment. We conclude that BMP-2 would be useful as a novel therapeutic agent in the treatment of multiple myeloma both by means of its antitumor effect of inducing apoptotis and through its original bone-inducing activity, because bone lesions are frequently seen in myeloma patients.
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PMID:Bone morphogenetic protein-2 induces apoptosis in human myeloma cells with modulation of STAT3. 1097 40

The functional role of the cyclin-dependent kinase inhibitor (CDKI) p21CIP1 in differentiation of human myelomonocytic leukemia cells (U937) exposed to low concentrations of the antimetabolite 1-beta-D-arabino-furanosylcytosine (ara-C) was examined utilizing a cell line stably expressing a p21CIP1 antisense construct. Continuous exposure to 50 nM ara-C led to marked induction of p21CIP1 at 48-72 h in empty-vector control cells but not in their antisense-expressing counterparts (p21AS/F4 and B8). Such treatment induced expression of the myelomonocytic differentiation marker CD11b in approximately 35% of control cells, but no evidence of maturation was noted in antisense-expressing lines. However, antisense-expressing cells exposed to low concentrations of ara-C exhibited a reciprocal increase in apoptosis, manifested by the appearance of cells with classic morphologic features and hypodiploid quantities of DNA, reduced mitochondrial membrane potential (deltapsim), an increase in cytochrome c release into the cytosol, cleavage/activation of procaspases-9 and -3, and degradation of PARP and p27Kip1. Whereas empty-vector control cells exposed to 50 nM ara-C exhibited a decline in Bcl-2 expression, dephosphorylation of pRb, and an initial accumulation in S-phase, antisense-expressing cells did not. However, c-Myc down-regulation induced by low concentrations of ara-C was, if anything, more complete in antisense-expressing cells. Exposure of control but not antisense-expressing cells to ara-C led to phosphorylation/activation of MAP kinase at 24 h; moreover, the specific MEK/MAP kinase inhibitor PD98059 enhanced low-dose ara-C-mediated apoptosis only in wild-type cells. Lastly, exposure to 50 nM ara-C for 72 h resulted in detectable levels of cytoplasmic p21CIP1, a phenomenon associated with resistance to apoptosis, only in empty vector controls. Collectively, these findings demonstrate a functional role for p21CIP1 in leukemic cell maturation induced by low concentrations of ara-C. They also indicate that, as in the case of more conventional differentiation-inducers such as phorbol esters, disruption of the p21CIP1 response after exposure to low concentrations of the cytotoxic drug ara-C prevents leukemic cells from engaging a maturation program, but instead directs them along an apoptotic pathway.
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PMID:Evidence of a functional role for the cyclin-dependent kinase inhibitor p21CIP1 in leukemic cell (U937) differentiation induced by low concentrations of 1-beta-D-arabinofuranosylcytosine. 1099 87

The impact of dysregulation of the cyclin-dependent kinase inhibitor p21WAF1/CIP1/MDA6 has been examined in U937 human monocytic leukemia cells in relation to cell cycle arrest and differentiation following treatment with the histone deacetylase inhibitor sodium butyrate (SB). Cells stably transfected with a p21WAF1/CIP1/MDA6 antisense construct, in marked contrast to their wild-type counterparts, failed to up-regulate p21WAF1/CIP1/MDA6, undergo G1 arrest, or express the maturation marker CD11b when exposed to 1 or 3 mM SB. However, antisense-expressing cells were significantly more susceptible to SB-mediated mitochondrial injury and apoptosis, manifested by increased cytosolic translocation of cytochrome c, activation of pro-caspase 3, and degradation of PARP. Dysregulation of p21WAF1/CIP1/MDA6 did not modify the extent of SB-induced histone acetylation, but did result in cleavage of p27KIP1, Bcl-2 and pRb, as well as diminished levels of full-length underphosphorylated pRb. Finally, dysregulation of p21WAF1/CIP1/MDA6 did not modify SB-mediated down-regulation of E2F-1 or c-Myc, but was associated with enhanced down-regulation of cyclins D1 and E. Together, these findings indicate that in U937 leukemia cells, p21WAF1/CIP1/MDA6 plays a critical functional role in SB-mediated G1 arrest and maturation, and suggest that cells displaying dysregulation of this CDKI respond to SB by engaging a default apoptotic program.
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PMID:Evidence of a functional role for the cyclin-dependent kinase-inhibitor p21WAF1/CIP1/MDA6 in promoting differentiation and preventing mitochondrial dysfunction and apoptosis induced by sodium butyrate in human myelomonocytic leukemia cells (U937). 1140 41

Follicular lymphomas (FLs) are neoplastic counterparts of normal germinal center (GC) B cells. FLs are characterized by t(14;18) with deregulation of the Bcl-2 (BCL2) gene. The presence of t(14;18) and overexpression of Bcl-2 is necessary, but not sufficient, to cause this disease. An array containing 588 complementary DNAs (cDNAs) was used to compare the gene expression between GC B cells and FL cells. To specifically monitor genes expressed in normal GC B and FL cells and not the entire tissue compartment, normal and malignant B cells were purified from tissues. Using the array, 37 genes were up-regulated and 28 were down-regulated in FL cells as compared to normal GC B cells. The expression level of each differentially expressed gene was verified by quantitative polymerase chain reaction. Following these studies 24 genes were up-regulated and 8 genes down-regulated with a P value less than.1. Included among the genes that were up-regulated in FLs were cell cycle regulator proteins CDK10, p120, p21CIP1, and p16INK4A; transcription factors/regulators Pax-5 and Id-2, which are involved in normal B-cell development; and genes involved in cell-cell interactions, tumor necrosis factor, interleukin-2R gamma (IL-2R gamma), and IL-4R alpha. Among the genes that were down-regulated in FLs were MRP8 and MRP14, which are involved in adhesion. Interestingly, several of these genes are localized within chromosomal regions already described to be altered in FLs. These findings provide a basis for future studies into the pathogenesis and pathophysiology of FL and may lead to the identification of potential therapeutic targets as well as antigens for immunotherapeutic strategies.
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PMID:Gene expression profiling of follicular lymphoma and normal germinal center B cells using cDNA arrays. 1175 83

Phenylacetate is a differentiation agent and has anticancer activity with relatively low toxicity. In the present study, we examined the anticancer effect of six synthetic phenylacetate derivatives in human lung cancer cells in our search for more effective phenylacetate analogous. Results showed that the antiproliferative effects of these synthetic compounds were stronger than those of phenylacetate, and that N-butyl-2-(2-fluorolphenyl)acetamide (SCK6) is the most potent compound. To address the mechanism of the antiproliferative effect of SCK6, cell cycle analysis was performed. Result showed that SCK6 (1 mM) induced G(1) arrest in CH27 cells. Western blot analysis of G(1) phase regulatory proteins demonstrated that the protein levels of cyclin-dependent kinase 2 (Cdk2), Cdk4, Cyclin E and Cyclin D3 were decreased after treatment with SCK6 but not those of Cdk6, Cyclin D1 and D2. In contrast, SCK6 increased the protein levels of p53 and p21(CIP1/WAF1). Data from in situ terminal transferase-mediated dUTP-fluorescensin nick end-labeling (TUNEL) assay and DNA fragmentation analysis demonstrated that SCK6 induced apoptotic cell death in CH27 cells. This SCK6-induced apoptosis was accompanied by a downregulation of Bcl-2 protein and activation of the caspase-9 cascade. Overexpression of Bcl-2 by adeno-Bcl-2 vector infection significantly inhibited SCK6-induced apoptosis. Moreover, treatment with caspase inhibitors also markedly reduced cell death induced by SCK6. Taken together, these results suggest that downregulation of G(1)-associated Cdks and cyclins and upregulation of p53 and p21(CIP1/WAF1) may contribute to SCK6-mediated G(1)-phase arrest. Furthermore, the decrease in Bcl-2 and the activation of caspase-9/caspase-3 may be the effector mechanism through which SCK6 induces apoptosis.
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PMID:A phenylacetate derivative, SCK6, inhibits cell proliferation via G1 cell cycle arrest and apoptosis. 1270 52

Effects of the histone deacetylase (HDAC) inhibitor MS-275 have been examined in human leukemia and lymphoma cells (U937, HL-60, K562, and Jurkat) as well as in primary acute myelogenous leukemia blasts in relation to differentiation and apoptosis. MS-275 displayed dose-dependent effects in each of the cell lines. When administered at a low concentration (e.g., 1 micro M), MS-275 exhibited potent antiproliferative activity, inducing p21(CIP1/WAF1)-mediated growth arrest and expression of differentiation markers (CD11b) in U937 cells. These events were accompanied by an increase in hypophosphorylated retinoblastoma protein and down-regulation of cell cycle-related proteins including cyclin D1. However, at higher concentrations (e.g., 5 micro M), MS-275 potently induced cell death, triggering apoptosis in approximately 70% of cells at 48 h. In contrast to other HDAC inhibitors such as apicidin, the extrinsic, receptor-mediated pathway played a minimal role in MS-275 lethality. However, MS-275 potently induced a very early (e.g., within 2 h) increase in reactive oxygen species (ROS), followed by the loss of mitochondrial membrane potential (Delta psi(m)) and cytosolic release of cytochrome c. These events culminated in activation of the caspase cascade, manifested by poly(ADP-ribose) polymerase, p21(CIP1/WAF1), p27(KIP), Bcl-2, and retinoblastoma protein degradation. MS-275 exposure also resulted in diminished expression of cyclin D1 and the antiapoptotic proteins Mcl-1 and XIAP. Administration of the free radical scavenger L-N-acetylcysteine blocked MS-275-mediated mitochondrial injury and apoptosis, suggesting a primary role for ROS generation in MS-275-associated lethality. Lastly, U937 cells stably expressing a p21(CIP1/WAF1) antisense construct were significantly more sensitive to MS-275-mediated apoptosis than controls, but they were impaired in their differentiation response. Together, these findings demonstrate that MS-275 exerts dose-dependent effects in human leukemia cells, i.e., p21(CIP1/WAF1)-dependent growth arrest and differentiation at low drug concentrations and a marked induction of ROS, mitochondrial damage, caspase activation, and apoptosis at higher concentrations.
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PMID:The histone deacetylase inhibitor MS-275 promotes differentiation or apoptosis in human leukemia cells through a process regulated by generation of reactive oxygen species and induction of p21CIP1/WAF1 1. 1283 53


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