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)

Hematopoietic malignancies have been shown to depend on cytokine growth factor autocrine/paracrine loops for growth and differentiation. This results in the constitutive activation of cytokine-mediated transcription factors like signal transducer and activators of transcription (STAT) 3 in non-Hodgkin's lymphoma (NHL) and multiple myeloma (MM). Recent evidence demonstrates that cytokines also contribute to a drug-resistant phenotype in many tumor cell types. We hypothesized that inhibitors of the STAT3 pathway would sensitize drug-resistant and endogenous cytokine-dependent NHL and MM tumor cells to the cytotoxic effects of chemotherapeutic drugs. We examined an AIDS-related NHL cell line, 2F7, known to be dependent on interleukin (IL)-10 for survival and an MM cell line, U266, known to be dependent on IL-6 for survival. IL-10 and IL-6 signal the cells through the activation of Janus kinase (JAK)1 and JAK2, respectively. Thus, we investigated the effect of two chemical STAT3 pathway inhibitors, namely, piceatannol (JAK1/STAT3 inhibitor) and tyrphostin AG490 (JAK2/STAT3 inhibitor), on the tumor cells for sensitization to therapeutic drugs. We demonstrate by phosphoprotein immunoblotting analysis and electrophoretic mobility shift analysis that piceatannol and AG490 inhibit the constitutive activity of STAT3 in 2F7 and U266, respectively. Furthermore, piceatannol and AG490 sensitize 2F7 and U266 cells, respectively, to apoptosis by a range of therapeutic drugs including cisplatin, fludarabine, Adriamycin, and vinblastine. The specificity of the inhibitors was corroborated in experiments showing that piceatannol had no effect on U266 and, likewise, AG490 has no effect on 2F7. The sensitization observed by these inhibitors correlated with the inhibition of Bcl-2 expression in 2F7 and Bcl-xL expression in U266. Altogether, these results demonstrate that STAT3 pathway inhibitors are a novel class of chemotherapeutic sensitizing agents capable of reversing the drug-resistant phenotype of cytokine-dependent tumor cells.
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PMID:Inhibition of constitutive STAT3 activity sensitizes resistant non-Hodgkin's lymphoma and multiple myeloma to chemotherapeutic drug-mediated apoptosis. 1253 84

Elimination of tumor cells from hematopoietic stem cell products is a major goal of bone marow-suported high-dose cancer chemotherapy. In patients (pts) with low-grade lymphoma Gianni et al (2000) assessed the ability of Rituximab, given in combination with high-dose chemotherapy, to eradicate PCR-detectable disease and enable the harvesting of large amounts of uncontaminated circulating progenitor cells. Our study was conducted in 27 consecutive pts with untreated bcl2 positive NHL (follicular lymphoma--7, chronic lymphocytic leukemia--13 and NHL in leukemic phase--7), 14 pts received Rituximab. Patients received 4 courses of standard-dose chemotherapy (CHOP or FLU-CY), followed by one course of high-dose cyclophosphamid plus G-CSF. Patients allocated to Rituximab received i.v. infusions of 375 mg/m2 48 hours before stem cell collection and in 3 weekly doses after transplantation (R-CHT). Clinical response after transplantation was evaluated in 26 pts who completed the treatment. The complete response rate was in 100% in the Rituximab group (PCR negative in 79%) versus 50% of controls (p<0.01). Yield of purged CD34+ cells was with median 5.23x10(6)/kg in CHT and 8.76x10(6)/kg in R-CHT pts. Toxicity in the both arms was acceptated (no difference). No significant difference was observed between CHT and R-CHT group in the mean number of days spent with neutropenia and trombocytopenia. After a follow-up of 31 months, no patient relapsed. Aside from providing PCR-negative harvests, the chemoimmunotherapy treatment produced complete clinical (100%) and molecular remission in 79% of evaluable pts. We showed that Rituximab in combination with effective high-dose anti- lymphoma chemotherapy, allowed the harvesting of large amounts of tumor free progenitor cells in evaluable pts.
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PMID:Efficiency of in vivo purging with autologous stem cell transplantation and monoclonal antibody in B-cell lymphomas. 1268 74

Chronic lymphocytic leukaemia (CLL) is the most common leukaemia of adults in Western countries. It is a systemic haematological malignancy that originates from B cells (B-CLL) in 95% of patients, while only a minority are derived through malignant transformation of T cells (T-CLL). Although B-CLL is classified as a non-Hodgkin's lymphoma, several issues make this leukaemia a unique entity among malignant lymphoma. Inhibition of the programmed cell death (apoptosis) and upregulation of the anti-apoptotic protein Bcl-2 are key elements of the pathophysiology of B-CLL cells and define clinical prognosis. Furthermore, B-CLL cells are arrested in G0/G1 phase of the cell cycle. Dysfunctional apoptosis and cell cycle are the main reasons for the clinical enigma, that CLL can not yet be cured with conventional chemotherapy. However, the molecular pathways that are responsible for this characteristic feature of the B-CLL cells still need further definition.Recently, considerable progress has been made in defining the molecular basis for the pathogenesis of CLL and in finding new therapeutic options. Recent studies indicate that B-CLL cells may be delineated from two main groups of normal B cells, i.e. pre- and postgerminal B cells, and can be distinguished through lack of or existence of mutations of the V heavy chain gene. This differential mutational status of the Ig V gene has significant impact on patient survival. Modern cytogenetic methods such as fluorescence in situ hybridisation (FISH) have opened a new era in the molecular analysis of CLL cells. Determining the chromosomal aberration of the leukaemic cells has become a standard scientific programme for each clinical trial. The cytogenetic profile may soon help to define a clinical risk profile and guide the various treatment strategies. Further progress has been made in the therapy of CLL. Purine analogues such as fludarabine were able to induce significant improvement in remission rates; however, they did not lead to improved survival. Chimera of murine or rat monoclonal antibodies and human antibodies were designed to treat CLL. Antibodies such as rituximab and alemtuzumab (Campath-1H), directed against CD20 and CD52, respectively, appear as attractive alternatives to conventional chemotherapy because of their lack of significant myelotoxicity. Studies using myeloablative chemotherapy followed by autologous or allogeneic stem cell transplantation were initiated with the hope of finding a cure for CLL. In contrast to autologous stem cell transplantation, allogeneic transplants appear to display a plateau of relapse rates. In conclusion, for many years CLL was considered as a chronic haematological malignancy that required only few diagnostic tools and for whom no hope of cure could be offered. The current review focuses on recent improvements in diagnosis and treatment of CLL that have opened a new era in the management of patients with this systemic malignancy.
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PMID:New directions in the diagnosis and treatment of chronic lymphocytic leukaemia. 1269 99

The components of the apoptotic pathway are targets for anticancer therapy. Bcl-2 protein inhibits apoptosis and confers resistance to treatment with traditional cytotoxic chemotherapy, radiotherapy, and monoclonal antibodies. Oblimersen sodium (G3139, Genasense, Genta Inc, Berkeley Heights, NJ) is an antisense oligonucleotide compound designed to specifically bind to the first six codons of the human bcl-2 mRNA sequence, resulting in degradation of bcl-2 mRNA and subsequent decrease in Bcl-2 protein translation. Oblimersen is the first oligonucleotide to demonstrate proof of principle of an antisense effect in human tumors by the documented downregulation of the target Bcl-2 protein. A growing body of preclinical and clinical evidence suggests that oblimersen synergizes with many cytotoxic and biologic/immunotherapeutic agents against a variety of hematologic malignancies and solid tumors. Randomized clinical trials are currently underway to evaluate the efficacy and tolerability of oblimersen in combination with cytotoxic chemotherapy in chronic lymphocytic leukemia (CLL), multiple myeloma (MM), malignant melanoma, and non-small cell lung cancer. In addition, nonrandomized trials are underway to evaluate oblimersen in non-Hodgkin's lymphoma (NHL), acute myeloid leukemia (AML), and hormone-refractory prostate cancer. Preclinical data support the clinical evaluation of oblimersen in additional tumor types, including chronic myelogenous leukemia, and breast, small cell lung, gastric, colon, bladder (CML), and Merkel cell cancers. Enhancement of the efficacy of anticancer treatments with oblimersen Bcl-2 antisense therapy represents a promising new apoptosis-modulating strategy, and ongoing clinical trials will test this therapeutic approach.
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PMID:Oblimersen sodium (G3139 Bcl-2 antisense oligonucleotide) therapy in Waldenstrom's macroglobulinemia: a targeted approach to enhance apoptosis. 1272 Jan 57

It is clear that COX-2 plays an important role in tumor and endothelial cell biology. Increased expression of COX-2 occurs in multiple cells within the tumor microenvironment that can impact on angiogenesis. COX-2 appears to: (a) play a key role in the release and activity of proangiogenic proteins; (b) result in the production of eicosanoid products TXA2, PGI2, PGE2 that directly stimulate endothelial cell migration and angiogenesis in vivo, and (c) result in enhanced tumor cell, and possibly, vascular endothelial cell survival by upregulation of the antiapoptotic proteins Bcl-2 and/or activation of PI3K-Akt. Selective pharmacologic inhibition of COX-2 represents a viable therapeutic option for the treatment of malignancies. Agents that selectively inhibit COX-2 appear to be safe, and well tolerated suggesting that chronic treatment for angiogenesis inhibition is feasible [107-110]. Because these agents inhibit angiogenesis, they should have at least additive benefit in combination with standard chemotherapy [111] and radiation therapy [24, 112]. In preclinical models, a selective inhibitor of COX-2 was shown to potentiate the beneficial antitumor effects of ionizing radiation with no increase in normal tissue cytotoxicity [113-115]. More recently, metronomic dosing regimens of standard chemotherapeutic agents without extended rest periods were shown to target the microvasculature in experimental animal models and result in significant antitumor activity [116-118]. This antiangiogenic chemotherapy regimen could be enhanced by the concurrent administration of an angiogenesis inhibitor [116-119]. Trials that will evaluate continuous low dose cyclophosphamide in combination with celecoxib are underway in patients with metastatic renal cancer, and non-Hodgkin's lymphoma [120]. Given the safety and tolerability of the selective COX-2 inhibitors, and the potent antiangiogenic properties of these agents, the combination of antiangiogenic chemotherapy with a COX-2 inhibitor warrants clinical evaluation [118, 121, 122]. The effects of selective COX-2 inhibitors on angiogenesis may also be due, in part, to COX-independent mechanisms [123-125]. Several reports have confirmed COX-independent effects of celecoxib, at relatively high concentrations (50 microM), where apoptosis is stimulated in cells that lack both COX-1 and COX-2 [126]. More recently, Song et al. [127] described structural modifications to celecoxib that revealed no association between the COX-2 inhibitory and proapoptotic activities of celecoxib [125]. Some of the COX-independent mechanisms for NSAIDs and selective COX-2 inhibitors include activation of protein kinase G, inhibition of NF-kappa B activation, downregulation of the antiapoptotic protein Bcl-XL, inhibition of PPAR delta, and activation of PPAR gamma. One or more of these COX-independent effects could contribute to the antiangiogenic properties of NSAIDs and selective COX-2 inhibitors. In order to take advantage of both the COX-dependent and COX-independent benefits of NSAIDs and selective COX-2 inhibitors, will require evaluation of these agents in neoplastic disease settings, using cancer-specific biomarkers. In conclusion, the contribution of COX-2 at multiple points in the angiogenic cascade makes it an ideal target for pharmacologic inhibition. The reported success of selective COX-2 inhibitors in cancer prevention could be related to angiogenesis inhibition [109]. As premalignant lesions progress towards malignancy, there is a switch to the angiogenic phenotype that is subsequently followed by rapid tumor growth [128, 129]. Intervention with angiogenesis inhibitors at this early stage of carcinogenesis has been shown to attenuate tumor growth in transgenic mouse models [130, 131]. The continued dependence on angiogenesis for later stages of tumorigenesis suggests that COX-2 inhibitors also will have clinical utility in the management of advanced cancers.
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PMID:Therapeutic potential of selective cyclooxygenase-2 inhibitors in the management of tumor angiogenesis. 1279 55

The incidence of non-Hodgkin's lymphoma (NHL) has been increasing and is now the leading cause of death in males aged 15-54. Diffuse large cell lymphoma (DLCL) is the most common subtype of NHL. These cells are notable for the high expression of the transcription factor nuclear factor kappa beta (NF-kappaB), raising the possibility that constitutive activation of the NF-kappaB pathway may contribute to the poor prognosis of DLCL patients. Soy isoflavone genistein promotes apoptosis by decreasing NF-kappaB activity. The combination of cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) remains the standard therapy for DLCL with a cure rate of approximately 40%. The WSU-DLCL(2) cell line and its severe combined immunodeficient (SCID) xenograft have constitutively active NF-kappaB which provides us with an excellent model in which to study NF-kappaB modulation and CHOP sensitization by genistein. The antitumor activity of CHOP with or without a genistein was evaluated in our WSU-DLCL(2) model. In vivo, WSU-DLCL(2)-bearing SCID mice received genistein alone (800 micro g kg(-1) day(-1), p.o. as gavages for 5 days), CHOP alone ("C", 40 mg/kg, i.v.; "H", 3.3 mg/kg, i.v.; "O", 0.5 mg/kg, i.v.; and "P", 0.2 mg/kg, every day for 5 days, p.o.), or genistein for 5 days followed by CHOP. Tumor growth inhibition (T/C), tumor growth delay (T - C), and log(10) kill for genistein, CHOP, and genistein followed by CHOP were 33.6%, 19.2%, and 5.2%; 7, 8, and 17 days; and 1.0, 1.2, and 2.6, respectively. To begin elucidating the mechanism of genistein-induced sensitization of WSU-DLCL(2) cells to CHOP chemotherapy in this xenograft mouse model, we studied the in vitro effect of genistein on WSU-DLCL(2) growth inhibition, cell cycle, Bax:Bcl-2 ratio, NF-kappaB DNA binding, and apoptosis in vitro. At 30 micro M, genistein inhibited the growth significantly, induced G(2)-M arrest, increased Bax:Bcl-2 ratio, decreased NF-kappaB DNA binding, and induced apoptosis. Genistein also inhibited NF-kappaB DNA binding in vivo, whereas CHOP enhanced it. Our results show that genistein has growth modulatory effects on WSU-DLCL(2) cells and enhances the antitumor activity of CHOP. Because soy isoflavone genistein is a widely available nutritional supplement, its use in combination with CHOP chemotherapy should be further explored in a clinical trial in patients with NHL.
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PMID:Genistein sensitizes diffuse large cell lymphoma to CHOP (cyclophosphamide, doxorubicin, vincristine, prednisone) chemotherapy. 1470 77

The regulation of apoptosis is an important potential target for anticancer therapy. The mitochondrial Bcl-2 protein inhibits apoptosis and is therefore an important mediator of resistance to treatment with traditional cytotoxic chemotherapy, radiotherapy and monoclonal antibody therapy. Oblimersen (Genasense, Aventis Pharmaceuticals / Genta Inc) is a 18mer antisense-oligonucleotide (ASO), which specifically binds to the first 6 codons of the human bcl-2 mRNA, resulting in degradation and destruction of the mRNA by RNAse H. Subsequently there is a significant decrease of bcl-2 translation. A growing number of preclinical and clinical studies suggests that the combination of cytotoxic therapy with Oblimersen results in synergistic anticancer efficacy in many hematologic and solid tumors. Due to its low toxicity profile, oblimersen is an ideal combination partner with conventional chemotherapy. Three randomized phase-III trials (malignant melanoma, chronic lymphocytic leukemia, multiple myeloma) have recently finished recruitment. The results of these studies will be available by the end of 2003. Based on preclinical data, a lot of nonrandomized phase-II studies on several different tumor types like AML, CML, NHL, prostate cancer and breast cancer are underway. The manipulation of proapoptotic and antiapoptotic factors in favor of proapoptotic factors by inhibition of the bcl-2 protein translation in order to enhance the efficacy of anticancer treatments represents a promising new treatment concept in oncology.
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PMID:[Proapoptotic therapy with oblimersen (bcl-2 antisense oligonucleotide)--review of preclinical and clinical results]. 1471 45

The mechanisms underlying the autonomous accumulation of malignant B cells remain elusive. We show in this study that non-Hodgkin's lymphoma (NHL) B cells express B cell-activating factor of the TNF family (BAFF) and a proliferation-inducing ligand (APRIL), two powerful B cell-activating molecules usually expressed by myeloid cells. In addition, NHL B cells express BAFF receptor, which binds BAFF, as well as transmembrane activator and calcium modulator and cyclophilin ligand interactor (TACI) and B cell maturation Ag (BCMA), which bind both BAFF and APRIL. Neutralization of endogenous BAFF and APRIL by soluble TACI and BCMA decoy receptors attenuates the survival of NHL B cells, decreases activation of the prosurvival transcription factor NF-kappaB, down-regulates the antiapoptotic proteins Bcl-2 and Bcl-x(L), and up-regulates the proapoptotic protein Bax. Conversely, exposure of NHL B cells to recombinant or myeloid cell-derived BAFF and APRIL attenuates apoptosis, increases NF-kappaB activation, up-regulates Bcl-2 and Bcl-x(L), and down-regulates Bax. In some NHLs, exogenous BAFF and APRIL up-regulate c-Myc, an inducer of cell proliferation; down-regulate p53, an inhibitor of cell proliferation; and increase Bcl-6, an inhibitor of B cell differentiation. By showing that nonmalignant B cells up-regulate BAFF and APRIL upon stimulation by T cell CD40 ligand, our findings indicate that NHL B cells deregulate an otherwise physiological autocrine survival pathway to evade apoptosis. Thus, neutralization of BAFF and APRIL by soluble TACI and BCMA decoy receptors could be useful to dampen the accumulation of malignant B cells in NHL patients.
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PMID:Lymphoma B cells evade apoptosis through the TNF family members BAFF/BLyS and APRIL. 1497 35

Multiple mechanisms exist by which tumour cells can escape CD95-mediated apoptosis. Previous studies by our laboratory have shown that primary B cells from non-Hodgkin's Lymphoma (B-NHL) were resistant to CD95-induced cell death. In the current study, we have analysed the mechanisms underlying CD95 resistance in primary human lymphoma B cells. We report that FADD (FAS-associated death domain protein) and caspase-8 were constitutively expressed in lymphoma B cells and that the CD95 pathway was blocked upstream to caspase-8 activation. However, caspase-8 was processed and functional after treatment with staurosporine (STS). We found that the expression levels of FLICE (FADD-like interleukin-1 beta-converting enzyme)-Inhibitory Protein (c-FLIP) and Bcl-2-related proteins were heterogeneous in B-NHL cells and were not related to CD95 resistance. Finally, we report the absence of a CD95-induced signalling complex [death-inducing signalling complex (DISC)] in lymphoma B cells, with no FADD and caspase-8 recruitment to CD95 receptor. In contrast, DISC formation was observed in CD95-resistant non-tumoural (NT) B cells. Therefore, we propose that the absence of DISC formation in primary lymphoma B cells may contribute to protect these cells from CD95-induced apoptosis.
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PMID:Impairment of death-inducing signalling complex formation in CD95-resistant human primary lymphoma B cells. 1500 62

We have recently reported that Rituximab (anti-CD20) sensitizes drug-resistant 2F7 and 10C9 B Non-Hodgkin's lymphoma (NHL) cell lines to the apoptotic effects of various chemotherapeutic drugs by downregulation of IL-10 and Bcl-2 expression. The mechanism by which Rituximab induces downregulation of IL-10 was examined. We hypothesized that Rituximab may inhibit p38 MAPK activity that regulates IL-10 expression via Sp1. Treatment of 2F7 cells with Rituximab or the p38 inhibitor SB203580 inhibited the constitutive p38 MAPK activity and resulted in the inhibition of Sp1, IL-10, STAT3, and Bcl-2. Inhibition of the Src-family PTKs, Lyn, and Src-family PTKs upstream signaling molecules of the p38MAPK pathway, by PP2, a specific Src-family kinase inhibitor, resulted in the inhibition of p38MAPK and IL-10 expression. In addition to p38 MAPK, Rituximab also inhibited NF-kappaB activity. Inhibition of the Src PTKs, MAPK, and NF-kappaB activities by Rituximab or by specific chemical inhibitors sensitized the cells to CDDP-mediated apoptosis. The above signaling-mediated effects by Rituximab were observed with similar kinetics beginning at 1 h following treatment. Thus, altogether, these results demonstrate that signaling by Rituximab results in the inhibition of the p38MAPK pathway, which in turn inhibits the transcription of IL-10 via Sp1. Inhibition of the IL-10 autocrine/paracrine loop results in the inhibition of STAT3 activity and, consequently, inhibition of Bcl-2 expression and sensitization to drugs-apoptosis. Further, Rituximab-mediated signaling identifies several new intracellular targets in NHL that may be of potential therapeutic interest for the development of new drugs in the treatment of drug-refractory NHL tumor cells.
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PMID:Rituximab inhibits p38 MAPK activity in 2F7 B NHL and decreases IL-10 transcription: pivotal role of p38 MAPK in drug resistance. 1507 78

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