UNIPROT:P10415 - FACTA Search

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Query: UNIPROT:P10415 (Bcl-2)
33,771 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

CCAAT/enhancer-binding protein epsilon (C/EBPepsilon) plays a critical role in terminal myeloid differentiation. Differentiation is an integrated process of cell cycle arrest, morphological change, functional maturation, and apoptosis. However, the molecular networks underlying these events in C/EBPepsilon-induced differentiation remain poorly understood. To reveal these mechanisms, we performed a detailed molecular analysis of C/EBPepsilon-induced differentiation using an inducible form of C/EBPepsilon. The activation of C/EBPepsilon induced growth arrest, morphological differentiation, the expression of CD11b and secondary granule proteins, and apoptosis in myeloid cell lines. Unlike C/EBPalpha, C/EBPepsilon dramatically up-regulated p27 with a concomitant down-regulation of cdk4/6 and cyclin D2/A/E. Moreover, the anti-apoptotic proteins Bcl-2 and Bcl-x were down-regulated, whereas pro-apoptotic protein Bax remained unchanged. Using a variety of mutants, we revealed that these events were all regulated by the N-terminal activation domain of C/EBPepsilon. Interestingly, some of the differentiation processes such as the induction of secondary granule protein genes were clearly inhibited by c-Myc; however, inhibition of apoptosis by Bcl-x did not affect the entire differentiation processes. These data indicate the N terminus of C/EBPepsilon to be solely responsible for most aspects of myeloid differentiation, and these events were differentially affected by c-Myc.
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PMID:N-terminal region of CCAAT/enhancer-binding protein epsilon is critical for cell cycle arrest, apoptosis, and functional maturation during myeloid differentiation. 1653 5

In this study, we first report the chemopreventive effect of rugosin E in human breast cancer cell line, MDA-MB-231. Treatment with rugosin E decreased the cell proliferation of MDA-MB-231 cells in a dose-dependent manner. Rugosin E treatment arrested MDA-MB-231 cells at G0/G1 phase. This effect was strongly associated with concomitant decrease in the level of cyclin D1, cyclin D2, cyclin E, cdk2, cdk4, and cdk6, and increase of p21/WAF1. In addition, rugosin E also induced apoptotic cell death. Rugosin E increased in the expression of Bax, Bak, and Bcl-Xs, but decreased the levels of Bcl-2 and Bcl-X(L), and subsequently triggered mitochondria apoptotic pathway (release of cytochrome c, activation of caspase-9, and caspase-3). In addition, pre-treatment of cells with caspase-9 inhibitor blocked rugosin E-induced cell proliferation and apoptosis, indicating caspase-9 activation was involved in rugosin E-mediated MDA-MB-231 cells apoptosis. Rugosin E inhibited the constitutively activated and inducible NF-kappaB in both its DNA-binding activity and transcriptional activity. Furthermore, rugosin E also inhibited the TNF-alpha-activated NF-kappaB-dependent reporter gene expression of cyclin D1, c-Myc, XIAP, Bcl-2, and Bcl-X(L) were all downregulated by rugosin E. Our results indicated that rugosin E inhibits the activation of NF-kappaB, and this may provide a molecular basis for drug development in the prevention and treatment of cancer by rugosin E.
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PMID:Rugosin E, an ellagitannin, inhibits MDA-MB-231 human breast cancer cell proliferation and induces apoptosis by inhibiting nuclear factor-kappaB signaling pathway. 1696 81

The zinc-finger protein A20/TNFAIP3, an inhibitor of nuclear factor-kappaB (NF-kappaB) activation, has been shown to protect MCF-7 breast carcinoma cells from TNFalpha-induced apoptosis. As estrogen receptor (ER) status is an important parameter in the development and progression of breast cancer, we analysed the effect of 17beta-estradiol (E2) treatment on the expression of A20. We found that A20 is a new E2-regulated gene, whose expression correlates with ER expression in both cell lines and tumor samples. With the aim of investigating the impact of A20 expression on MCF-7 cells in response to ER ligands, we established stably transfected-MCF-7 cells overexpressing A20 (MCF-7-A20). These cells exhibited a phenotype of resistance to the 4-hydroxy-tamoxifen cytostatic and pro-apoptotic actions and of hyper-response to E2. Dysregulations in bax, bcl2, bak, phospho-bad, cyclin D1, cyclin E2, cyclin D2 and cyclin A2 proteins expression were shown to be related to the resistant phenotype developed by the MCF-7-A20 cells. Interestingly, we found that A20 was also overexpressed in MVLN and VP tamoxifen-resistant cell lines. Furthermore, high A20 expression levels were observed in more aggressive breast tumors (ER-negative, progesterone receptor-negative and high histological grade). These overall findings strongly suggest that A20 is a key protein involved in tamoxifen resistance, and thus represents both a new breast cancer marker and a promising target for developing new strategies to prevent the emergence of acquired mechanisms of drug resistance in breast cancer.
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PMID:A20/TNFAIP3, a new estrogen-regulated gene that confers tamoxifen resistance in breast cancer cells. 1729 53

Diffuse large B-cell lymphomas (DLBCL) display defects in cell cycle and apoptosis regulation. Therefore, the immunohistochemical expression patterns of the proteins p14, p21, Hdm2 and cyclin D2 were analyzed in relation to the previously reported expression of other major cell cycle proteins (p53, Rb, p16, p27, Ki-67 and cyclins A, B1, D2, D3 and E), apoptosis-associated proteins (bcl2, bcl-xl, bax, bak, bad and bid) and the B-cell differentiation immunophenotypes. Expression of the proteins p14, p21, Hdm2 and cyclin D2 was observed in 62/71 (87%), 22/76 (29%), 35/74 (47%) and 11/77 (14%) cases, respectively. Immunohistochemical alterations of the p53 (p53-Hdm2-p21-p14), Rb (Rb-p16-cyclin D [D2 or D3]) and p27 (p27-cyclin E) pathways were found in 56/77 (73%), 53/79 (67%) and 54/79 (68%) cases, respectively. Concomitant alterations of the p53-Rb, p53-p27 and Rb-p27 pathways were found in 40/77 (52%), 38/77 (50%) and 36/79 (46%) cases, respectively. Three concomitant alterations of the p53-Rb-p27 pathways were found in 28/79 (35%) cases. The main findings of the present study were the following: alterations of the p27 pathway were associated with higher expression of Ki-67 (p = 0.023); concomitant alterations of the p53Rb pathways and the p53-p27 pathways were associated with higher expression of cyclin A (p = 0.015 and p = 0.021, respectively) and concomitant alterations of the p53, Rb and p27 pathways were associated with higher expression of cyclin A (p = 0.013). Since cyclin A supports DNA replication, centrosome duplication and mitosis, these findings indicate that concomitant alterations of the p53, Rb and p27 pathways in DLBCL may have cooperative effects resulting in increased neoplastic cell proliferation. This might explain, at least partially, the association between concurrent aberrations of the p53, Rb and p27 pathways and aggressive clinical behavior in DLBCL.
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PMID:Alterations of the p53, Rb and p27 tumor suppressor pathways in diffuse large B-cell lymphomas. 1769 24

Excessive cell proliferation and decreased apoptosis have been implicated in the pathogenesis of ovarian granulosa cell tumors (GCTs). We hypothesized that transcription factor GATA-4 controls expression of the antiapoptotic factor Bcl-2 and the cell cycle regulator cyclin D2 in normal and neoplastic granulosa cells. To test this hypothesis, a tissue microarray based on 80 GCTs was subjected to immunohistochemistry for GATA-4, Bcl-2, and cyclin D2, and the data were correlated to clinical and histopathological parameters. In addition, quantitative RT-PCR for GATA-4, Bcl-2, and cyclin D2 was performed on 21 human GCTs. A mouse GCT model was used to complement these studies. The role of GATA-4 in the regulation of Bcl2 and ccdn2 (coding for cyclin D2) was studied by transactivation assays, and by disrupting GATA-4 function with dominant negative approaches in mouse and human GCT cell lines. We found that GATA-4 expression correlated with Bcl-2 and cyclin D2 expression in human and murine GCTs. Moreover, GATA-4 enhanced Bcl-2 and cyclin D2 promoter activity in murine GCT cells. Whereas GATA-4 overexpression up-regulated and dominant negative GATA-4 suppressed Bcl-2 expression in human GCT cells, the effects on cyclin D2 were negligible. Our results reveal a previously unknown relationship between GATA-4 and Bcl-2 in mammalian granulosa cells and GCTs, and suggest that GATA-4 influences granulosa cell fate by transactivating Bcl-2.
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PMID:GATA-4 regulates Bcl-2 expression in ovarian granulosa cell tumors. 1865 21

Adult T-cell leukemia (ATL) is a fatal malignancy of T lymphocytes caused by human T-cell leukemia virus type 1 (HTLV-1) infection and remains incurable. Carotenoids are a family of natural pigments and have several biological functions. Among carotenoids, fucoxanthin is known to have antitumorigenic activity, but the precise mechanism of action is not elucidated. We evaluated the anti-ATL effects of fucoxanthin and its metabolite, fucoxanthinol. Both carotenoids inhibited cell viability of HTLV-1-infected T-cell lines and ATL cells, and fucoxanthinol was approximately twice more potent than fucoxanthin. In contrast, other carotenoids, beta-carotene and astaxanthin, had mild inhibitory effects on HTLV-1-infected T-cell lines. Importantly, uninfected cell lines and normal peripheral blood mononuclear cells were resistant to fucoxanthin and fucoxanthinol. Both carotenoids induced cell cycle arrest during G(1) phase by reducing the expression of cyclin D1, cyclin D2, CDK4 and CDK6, and inducing the expression of GADD45alpha, and induced apoptosis by reducing the expression of Bcl-2, XIAP, cIAP2 and survivin. The induced apoptosis was associated with activation of caspase-3, -8 and -9. Fucoxanthin and fucoxanthinol also suppressed IkappaBalpha phosphorylation and JunD expression, resulting in inactivation of nuclear factor-kappaB and activator protein-1. Mice with severe combined immunodeficiency harboring tumors induced by inoculation of HTLV-1-infected T cells responded to treatment with fucoxanthinol with suppression of tumor growth, showed extensive tissue distribution of fucoxanthinol, and the presence of therapeutically effective serum concentrations of fucoxanthinol. Our preclinical data suggest that fucoxanthin and fucoxanthinol could be potentially useful therapeutic agents for patients with ATL.
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PMID:Anti-adult T-cell leukemia effects of brown algae fucoxanthin and its deacetylated product, fucoxanthinol. 1879 63

In chronic myeloid leukemia K562 cells, differentiation is also blocked because of low levels of ganglioside GM3, derived by the high expression of sialidase Neu3 active on GM3. In this article, we studied the effects of Neu3 silencing (40-70% and 63-93% decrease in protein content and activity, respectively) in these cells. The effects were as follows: (a) gangliosides GM3, GM1, and sialosylnorhexaosylceramide increased markedly; (b) cell growth and [(3)H]thymidine incorporation diminished relevantly; (c) as mRNA, cyclin D2, and Myc were much less expressed, whereas cyclin D1 was expressed more like its inhibitor p21; (d) as mRNA, pro-apoptotic proteins Bax and Bad increased with concurrent decrease and increase in the anti-apoptotic proteins Bcl-2 and Bcl-XL, respectively; (e) the apoptosis inducers etoposide and staurosporine were active on Neu3 silencing cells but not on mock cells; (f) as mRNA, the megakaryocytic markers CD10, CD44, CD41, and CD61 increased similar to the case of mock cells stimulated with PMA; (g) the signaling cascades mediated by PLC-beta2, PKC, RAF, ERK1/2, RSK90, and JNK were largely activated. The induction of a GM3-rich ganglioside pattern in K562 cells by treatment with brefeldin A elicited a phenotype similar to that of Neu3 silencing cells. In conclusion, upon Neu3 silencing, K562 cells show a decrease in proliferation, propensity to undergo apoptosis, and megakaryocytic differentiation.
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PMID:Silencing of membrane-associated sialidase Neu3 diminishes apoptosis resistance and triggers megakaryocytic differentiation of chronic myeloid leukemic cells K562 through the increase of ganglioside GM3. 1882 Jun 43

We established a myeloma cell line (RPMI8226) with cyclin D1 overexpression in which the transfected cyclin D1 gene was stably expressed. D1 transfectants showed down-regulation of cyclin D2. Cell proliferation analysis did not show any differences among RPMI8226, mock control, and D1 transfectants. The number of S-phase cells increased while the number of G0/G1- and G2/M-phase cells decreased in D1 transfectants, which indicates a prolonged S-phase caused by cyclin D1 transfection. A decreased number of G2/M-phase cells was also detected in myeloma cells of patients with translocation t(11;14)(q13;q32). Western blot analysis revealed an increase in the hyperphosphorylated form of retinoblastoma (Rb) protein in D1 transfectants; however, the expression of p53, p16, Bax, Bad, Bcl-2, and Mcl-1 did not significantly change. Treatment with anti-myeloma drugs (melphalan, dexamethasone, bortezomib and immunomodulatory compounds) induced apoptosis earlier in D1 transfectants compared with RPMI8226 and mock control via the activation of both caspase-8 and -9. However, we could not detect a relationship between cyclin D1 expression and the response to treatment with VAD and bortezomib. Therefore, we assume that high sensitivity to anti-myeloma drugs depends on the duration of the S-phase, but a clinical response might depend on the number of myeloma cells with cyclin D1 overexpression.
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PMID:Ectopic cyclin D1 overexpression increases chemosensitivity but not cell proliferation in multiple myeloma. 1902 Jul 53

Multiple myeloma is still uncurable. Myeloma cells become resistant to common drugs and patients eventually die of tumour progression. Therefore, new targets and drugs are urgently needed. NVP-BGT226 is a novel, orally bioavailable small-molecule inhibitor of phosphoinositol-3-kinase and mammalian target of rapamycin. Here, we show that NVP-BGT226 inhibits growth in common myeloma cell lines and primary myeloma cells at nanomolar concentrations in a time-dependent and dose-dependent manner. Western blots for the detection of caspase 3 cleavage and annexin-V-fluorescein isothiocyanate/propidium iodide assays revealed induction of apoptosis in common myeloma cells lines. Induction of apoptosis was accompanied by upregulation of proapoptotic Bim and a moderate upregulation of Mcl-1 and Bad and a downregulation of Bcl-2, Bax and Bcl-Xl. Inhibition of cell growth was mainly due to inhibition of myeloma cell proliferation, as shown by the 5-bromo-2'-deoxyuridine assay. Cell cycle analysis revealed induction of cell cycle arrest in the G1 phase, which was due to downregulation of cyclin D1, cyclin D2, pRb and cdc25a. NVP-BGT226 inhibited phosphorylation of protein kinase B (Akt), P70S6k and 4E-BP-1 in a time-dependent and dose-dependent manner. Furthermore, we show that the stimulatory effect of insulin-like growth factor 1, interleukin-6 and conditioned medium of HS-5 stromal cells on myeloma cell growth is completely abrogated by NVP-BGT226. Overall, inhibition of phosphoinositol-3-kinase/mammalian target of rapamycin by NVP-BGT226 is highly effective, and NVP-BGT226 represents a potential new candidate for targeted therapy in multiple myeloma.
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PMID:Simultaneous targeting of PI3K and mTOR with NVP-BGT226 is highly effective in multiple myeloma. 2195 32

Osteosarcoma is the second leading cause of cancer-related death for children and young adults. In this study, we have subcutaneously injected-with and without matrigel-athymic mice (Fox1nu/nu) with human osteosarcoma 3AB-OS pluripotent cancer stem cells (CSCs), which we previously isolated from human osteosarcoma MG63 cells. Engrafted 3AB-OS cells were highly tumorigenic and matrigel greatly accelerated both tumor engraftment and growth rate. 3AB-OS CSC xenografts lacked crucial regulators of beta-catenin levels (E-cadherin, APC, and GSK-3beta), and crucial factors to restrain proliferation, resulting therefore in a strong proliferation potential. During the first weeks of engraftment 3AB-OS-derived tumors expressed high levels of pAKT, beta1-integrin and pFAK, nuclear beta-catenin, c-Myc, cyclin D2, along with high levels of hyperphosphorylated-inactive pRb and anti-apoptotic proteins such as Bcl-2 and XIAP, and matrigel increased the expression of proliferative markers. Thereafter 3AB-OS tumor xenografts obtained with matrigel co-injection showed decreased proliferative potential and AKT levels, and undetectable hyperphosphorylated pRb, whereas beta1-integrin and pFAK levels still increased. Engrafted tumor cells also showed multilineage commitment with matrigel particularly favoring the mesenchymal lineage. Concomitantly, many blood vessels and muscle fibers appeared in the tumor mass. Our findings suggest that matrigel might regulate 3AB-OS cell behavior providing adequate cues for transducing proliferation and differentiation signals triggered by pAKT, beta1-integrin, and pFAK and addressed by pRb protein. Our results provide for the first time a mouse model that recapitulates in vivo crucial features of human osteosarcoma CSCs that could be used to test and predict the efficacy in vivo of novel therapeutic treatments.
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PMID:Modeling human osteosarcoma in mice through 3AB-OS cancer stem cell xenografts. 2268 21

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