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)

Many tumor cells are inherently resistant to curative treatment due to an altered pattern of gene expression. It is an attractive and logical proposition to use this difference within the lymphoma cell to eradicate the malignant process. One such new therapeutic approach based on the "silencing" of genes involved in the prevention of apoptosis is Bcl-2 antisense oligonucleotide (AO) therapy. In the field of lymphoma, obvious targets included follicular lymphoma with the t(15;18) translocation, which results in deregulated expression of the Bcl-2 gene, chemoresistance, and subsequent protection against lymphoma cell death. Targeting the initiating codon of the Bcl-2 gene decreases both cell viability and Bcl-2 protein expression in lymphoma and leukemia cell lines that overexpress Bcl-2. Preclinical toxicity studies using a Bcl-2 AO G3139 (Genta, San Diego, CA) show good tolerance at a dose of 10 mg/kg, which is considerably higher than the dose required for good antilymphoma efficacy. In a phase I clinical study, G3139 was well tolerated with minimal toxicity in a dose escalation up to 147.2 mg/m2/d. Evidence of efficacy includes a responder with stage IVB follicular lymphoma who achieved complete clinical and radiologic response that has lasted more than 2 years. The main dose-limiting toxicity has been reversible thrombocytopenia related to the thioate backbone. Other antisense reagents are also in development to combat non-Hodgkin's lymphoma (NHL). These include oligonucleotides that target the messages of the Bcl-X(L) and protein kinase-Calpha (PKCalpha) genes. AOs may also have an application in tumors expressing mutant p53. AOs against MDM2 genes have shown the ability to restore wild-type p53 expression, suggesting that as oncogenic pathways are unraveled, normal cell growth and death patterns may be restored by molecular manipulation. Downregulation of antiapoptosis by AOs in the human setting has low toxicity and antilymphoma activity in cases in which conventional chemotherapy has failed. In the future, antisense therapy followed by chemotherapy may overcome chemoresistance to provide effective therapy for a range of malignancies.
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PMID:Antisense therapy of hematologic malignancies. 1053 Jul 11

Pancreatic cancer is the fifth leading cause of cancer related deaths in the United States. Despite many recent advances in the treatment modalities, the mortality rate still remains very high. Paclitaxel (Taxol) and Caffeine have been used for the treatment of this disease, however the molecular mechanisms of these agents are not fully understood, which may be partly responsible for the failure of these agents in the treatment of pancreatic cancer. Human pancreatic adenocarcinoma cell lines, HPAC and PANC-1 containing wild-type and mutant p53 respectively, were used to investigate the effects of Taxol and Caffeine on cell growth, and their effects on the modulation of cell cycle and apoptosis related genes. Protein extracts from these cells treated with 100 nM of Taxol or 4 mM of Caffeine were subjected to Western blot analysis for this study. Drug treated cells were also analyzed to calculate the number of cells undergoing apoptosis. Dose and time dependent growth inhibition was observed in both PANC-1 and HPAC cells when treated with either Taxol or Caffeine. Western blot analysis showed an up-regulation of p21WAF1 in both cell lines treated with either Taxol or Caffeine. Furthermore, down-regulation of cyclin B and cdk1 was observed in Taxol and Caffeine treated HPAC cells. However, the results were drastically different in PANC-1 cells where cyclin B was down regulated only by Caffeine treatment and the level of cdk1 protein was undetectable in this cell line. Moreover, up-regulation of p53 and down-regulation of Bcl-2 was observed only in HPAC cells treated with Taxol. Apoptotic cell death analysis showed increasing number of cells undergoing apoptosis between 24 and 48 h of Caffeine treatment, however only Taxol showed greater than 50% cells under-going apoptosis only in HPAC cells. The up-regulation of p21WAF1 and down-regulation of cyclin B and cdk1 suggest their possible roles in G2/M cell cycle arrest caused by both Taxol and Caffeine as reported earlier. From these results we conclude that the differential molecular changes observed in this study may determine the cellular effects of these agents on pancreatic adenocarcinoma cells and that the effects of chemotherapeutic agents may be determined by the endogenous status of p53 mutation and, in turn, may determine the therapeutic effects of these agents in the treatment of pancreatic cancer.
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PMID:Molecular effects of taxol and caffeine on pancreatic cancer cells. 1053 72

The role of p53 as a determinant of sensitivity of ten childhood acute lymphoblastic leukemia (ALL) cell lines to Adriamycin (ADR) was investigated. ADR-sensitive cell lines were found to have wild-type (wt) p53, whereas resistant cell lines contained point mutations in the gene. The basal level of wt p53 protein in sensitive cells was lower than that of mutant p53 in resistant cells, however, after ADR treatment a 6- to 20-fold dose-dependent increase in wt p53 was observed, whereas mutant p53 increased only twofold. The percentage of apoptotic cells in ADR-sensitive lines with wt p53 ranged from 43 to 93% following ADR treatment, whereas that in resistant lines with mutant p53 was only 8-13%. The ratio of constitutive levels of Bax/Bcl-2 was significantly higher in cells containing wt p53 than in cells with mutant p53. These results suggest that p53 gene status and the ability of p53 to induce apoptosis may be determinants of sensitivity to ADR in childhood ALL cells.
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PMID:p53 gene status and chemosensitivity of childhood acute lymphoblastic leukemia cells to adriamycin. 1057 31

Apoptosis can be described as multiple pathways converging from numerous different initiating events and insults, such as anticancer agents. These pathways converge on a common irreversible execution phase in which proteases and nucleases digest the doomed cell. Counteracting the signals to die are a variety of pathways that enhance cell survival and that may become constitutively active as a result of oncogenic transformation. Studies of apoptosis have identified many cellular factors that play a role in the decision as to whether a cell lives or dies. These factors include the p53 tumor suppressor, the Bcl-2 family of proteins, and a variety of intracellular signal transduction pathways, all of which may provide novel therapeutic targets. It also is possible to take advantage of the defect in cell cycle regulation that occurs in cells with mutant p53; such cells are susceptible to agents that inhibit DNA damage-induced cell cycle checkpoints at S and G2 phase. Cell cycle perturbation occurs following treatment with all anticancer drugs and a knowledge of the kinetics of such events should facilitate design of synergistic rather than antagonistic schedules. These concepts have been developed in cell culture models and it is essential to determine whether the mechanisms defined also occur in patients receiving therapy. Accordingly, tumors need to undergo serial biopsies during therapy and be analyzed for perturbation in cell cycle or apoptosis-regulating proteins. The results of such studies should facilitate the rational design of chemotherapy combinations.
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PMID:Modulation of apoptosis signaling pathways and cell cycle regulation. 1058 3

Bcl-2 is known to have dual antiproliferative and antiapoptotic roles. Overexpression of Bcl-2 in the mammary gland using a whey acidic protein (WAP) promoter-driven Bcl-2 transgene inhibits apoptosis in the mammary gland during pregnancy, lactation, and involution, and also counteracts apoptosis induced by overexpression of a mutant p53 transgene (WAP-p53 172 R-L). WAP-Bcl-2 mice and nontransgenic controls were treated with the carcinogen dimethylbenz(a)anthracene (DMBA). Surprisingly, the nontransgenic mice developed mammary tumors with decreased latency. Tumors arising in WAP-Bcl-2 mice displayed substantially reduced levels of proliferation relative to those seen in nontransgenic mice (P < 0.015), perhaps resulting in the observed increase in tumor latency following carcinogen treatment. This WAP-Bcl-2 mouse tumor model reflects the situation seen in some human breast cancers overexpressing Bcl-2, where expression of Bcl-2 has been shown to correlate with a lower proliferative index in tumors.
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PMID:Bcl-2 expression delays mammary tumor development in dimethylbenz(a)anthracene-treated transgenic mice. 1059 64

In breast cancer, mutations located in the zinc-binding functional domains of the p53 gene have been reported to predict a worse prognosis and a worse response to treatment with doxorubicin, compared with mutations in other parts within exons 5-8 of the gene. Similarly, mutations in residues of p53 that directly contact DNA have been associated with a poor prognosis. To investigate whether these specific p53 mutations are associated with differences in the rate of apoptosis and/or mitosis, or expression of the anti-apoptotic Bcl-2 protein, these parameters were evaluated in 89 invasive breast cancers with a confirmed p53 mutation in exons 5-8 and in 99 tumours without a p53 mutation in exons 5-8. Neither mutations located in the zinc-binding functional domains nor mutations in residues that directly contact DNA were associated with alterations in mitotic or apoptotic activity. However, compared with the wild-type p53 tumours, both apoptotic and mitotic indices showed an approximately two-fold increase in the mutant p53 group ( p< 0. 001). The presence of a p53 mutation was also associated with the presence of tumour necrosis ( p< 0.001), high tumour grade ( p< 0. 001) and low expression of Bcl-2 ( p< 0.001). Our data support the concept that in invasive breast carcinoma, loss of p53 function is involved in enhanced proliferation rather than decreased apoptosis and that the resulting acceleration of cell turnover may enhance clonal evolution and tumour progression.
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PMID:Mutations in exons 5-8 of the p53 gene, independent of their type and location, are associated with increased apoptosis and mitosis in invasive breast carcinoma. 1062 50

Medical oncologists are increasingly interested in identifying reliable prognostic factors for breast cancer in order to distinguish subsets of breast cancer patients and to optimize therapeutic approaches. Among them, the p53 tumor suppressor gene and bcl2 protein continue to be extensively studied, but their role remains to be defined. Moreover the mechanism of action by which they affect cell kinetics has to be clarified, particularly with respect to the balance between cell proliferation and apoptosis. We studied 138 operable breast cancer patients in order to verify the relationships of p53 and bcl2 proteins with better known clinicopathological features and their impact on the clinical outcomes of relapse-free survival (RFS) and overall survival (OS). Our data indicated a significant relationship between bcl2 expression and steroid receptor positive status, wild-type p53 and low proliferative index. Mutant p53 accumulation was found to be related to the absence of steroid receptors and high proliferation. Both were significant markers of better prognosis in univariate analysis. Multivariate analysis confirmed the favorable impact of bcl2 on both RFS and OS. On the contrary, we failed to observe any prognostic role for p53 status. We describe herein an independent favorable prognostic impact for patients with positive bcl2 expression that appears to be worthy of larger confirmatory study. On the contrary, our series seems to confirm the decreasing prognostic relevance of p53 in clinical practice.
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PMID:Bcl2, p53 and clinical outcome in a series of 138 operable breast cancer patients. 1065 Aug 10

Epidemiology shows a clear correlation between chronic infection with the hepatitis B virus (HBV) and development of hepatocellular carcinoma (HCC). The potential role of the transactivating hepatitis B virus X protein (HBx) in transformation by HBV is controversial. Here we report that HBx suppresses transformation of primary rat embryo fibroblasts (REFs). Cooperating oncogenes like c-Ha-ras and c-myc transform REF very efficiently but cotransfection with HBx suppressed transformation of REFs down to 5%. Similarly, transfection of HBx together with the cooperating oncogenes Ha-ras and SV40 LTAg or c-Ha-ras and mutant p53 reduced the number of foci to 13%. Comparable results were obtained with HBx in the context of the whole HBV. Suppression of focus formation in REF could be partly relieved by cotransfection of apoptosis inhibitors Bcl-2 or E1B. However, cotransfection of apoptosis inhibitors crmA and p35 did not influence the proapoptotic functions of HBx. Thus, HBx may specifically activate the Bcl-2 sensitive pathway leading to apoptosis. Experiments with 13 HBx linker scanning mutants revealed that the domains necessary for HBx dependent transactivation overlap with the domains needed for the apoptotic/growth arrest functions of HBx.
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PMID:Induction of apoptosis by the transactivating domains of the hepatitis B virus X gene leads to suppression of oncogenic transformation of primary rat embryo fibroblasts. 1071 5

Cisplatin is in common use in ovarian cancer therapy, although it is also implicated in cytotoxicity in normal tissue. We have examined the effect of cisplatin alone and in combination with theophylline, a phoshodiesterase inhibitor, on modulation of Bcl-2/Bax expression and induction of apoptosis in human granulosa cells transformed by stable transfection with mutant p53 plus Ha-ras. Theophylline elicited cell death only at relatively high concentrations with an EC50 of 200 microg/ml. Cisplatin exerted its lethal effect with an EC50 of 7 microM. In the presence of 15 or 50 microg/ml of theophylline (in the range used against asthma in humans), the EC50 for cisplatin was reduced to 2 microM or 1.2 microM, respectively. Using fluorescence-activated cell sorting analysis of DNA stained cells and the terminal deoxy-nucleotide tranferase-mediated dUTP nick end-labeling method, we found that even at concentrations of 0. 3 and 1 microM cisplatin, theophylline at 15 and 50 microg/ml increased the incidence of apoptosis in these cells by 3-5-fold, while theophylline alone induced extremely low apoptosis. Neither drug had any measurable effect on Bax protein expression. In contrast Bcl-2 protein expression levels were markedly reduced by theophylline and cisplatin in a dose-dependent manner. The combination of theophylline and cisplatin resulted in a further dramatic reduction in Bcl-2, under-scoring the pronounced synergy of these two drugs. These observations suggest that suppression of Bcl-2 expression may play an important role in mediating the synergistic effect of cisplatin and theophylline on induction of apoptosis in ovarian cancer cells.
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PMID:Theophylline and cisplatin synergize in down regulation of BCL-2 induction of apoptosis in human granulosa cells transformed by a mutated p53 (p53 val135) and Ha-ras oncogene. 1089 29

A prospective study was carried out on ten patients with prostate cancer. The TNM stage, Gleason's grade, general clinical status and, serum PSA level were all registered by the time of diagnosis. Total androgen blockade (TAB) was performed. Serum PSA control and general clinical examination re-biopsy was performed on average 107 days after the start of the therapy. The pre- and post treatment histology included HE and Tunel reaction to show apoptotic cells, as well as p53, bcl2 and Ki67 immunostaining. Clinical improvement of the disease, manifested by regression or by steady state was observed in all ten patients. An increase of apoptotic index, and a decrease of mitotic index was detected in most cases. The serum PSA level decreased in all patients. Ki67, bcl2 and mutant p53 were strongly expressed in tumor cells of patients in whom Gleason's grade was 7 or higher and decreased markedly in all cases upon therapy. Data obtained by repeated biopsy in the course of TAB therapy are indicators of the effectiveness of TAB, like changes in serum PSA, and may be considered as predictive factors.
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PMID:Follow-up of prostate carcinoma patients treated with total androgen blockade by repeated map-biopsy. 1099 42


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