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)

Expression of the bcl-2 gene becomes deregulated in many non-Hodgkin lymphomas as the result of t(14;18) chromosomal translocations. Because bcl-2 regulates the survival of cells, and because its over-expression is associated with cellular resistance to killing by chemotherapeutic drugs and gamma-irradiation, this gene and its mRNA and protein products represent ideal targets for designing novel therapeutic strategies for the treatment of cancer. Here we describe the effects of an 18-mer phosphodiester oligonucleotide that is complementary to the first 6 codons of the bcl-2 mRNA's open reading frame. When tested for inhibition of in vitro protein synthesis using RNAse-H-supplemented reticulocyte lysates and RNA prepared by in vitro transcription of a human bcl-2 cDNA, the bcl-2 antisense (AS) oligomer completely abolished Bcl-2 protein production at 10 microM, but had no effect on the in vitro translation of a chicken bcl-2 RNA that contained three mismatches relative to the oligomer binding site on the human bcl-2 RNA. A control 18-mer having the same base composition as the AS oligomer but with scrambled order (SC) was not inhibitory. Addition of AS and SC oligomers to cultures of a NIH-3T3 fibroblast cell line that had been stably infected with a recombinant retrovirus containing the same human bcl-2 cDNA used for in vitro transcription/translation experiments revealed concentration-dependent reductions in the relative levels of the 26-kD human Bcl-2 protein (as determined by immunoblotting) by the AS but not by the SC oligomer. Similar results were obtained when AS and SC oligomers were applied to a t(14;18)-containing lymphoma cell line SU-DHL-4 that was cultured in low-serum media. When used at 200 microM, the bcl-2 AS oligomer produced 84-95% reductions in Bcl-2 protein levels in SU-DHL-4 cells but had relatively little effect on the levels of other mitochondrial control proteins, suggesting that the inhibitory effects were specific. Treatment of SU-DHL-4 cells with AS oligomer lead to essentially complete loss of bcl-2 mRNA from cells within 1 day of addition to cultures, but presumably because of the long half-life of the Bcl-2 protein (approximately 14 h), commensurate reductions in Bcl-2 protein levels did not occur until 3 days.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Investigations of antisense oligonucleotides targeted against bcl-2 RNAs. 840 Aug 1

This study was designed to assess the efficacy of a new antimelanoma therapeutic strategy that relies on the use of a c-myc antisense 15-mer phosphorothioate oligodeoxynucleotide ([S]ODN), in combination with cisplatin (cis-diamminedichloroplatinum; DDP), which is currently used in the clinical management of melanoma patients. Proliferation and colony formation of melanoma cells were both inhibited by the DDP/c-myc antisense [S]ODN combination to a greater extent than that observed with either agent alone. Inhibition was most effective when DDP was followed by c-myc antisense [S]ODNs. Cell cycle flow cytometric analysis of cells exposed to the two agents either alone or in combination demonstrated that (a) c-myc antisense [S]ODNs induced an accumulation of cells in S phase and apoptosis in a fraction of the cells, detectable at day 5 after the beginning of treatment; (b) DDP induced a block in G2-M phase detectable at day 1, which was partially recovered, and apoptosis similar in extent to that induced by c-myc antisense [S]ODNs; and (c) DDP and c-myc antisense [S]ODNs together induced arrest in G2-M phase, which was maximum at day 3, i.e., delayed as compared to the block induced by DDP. The combination induced a higher percentage of apoptosis, evident at day 3 from the start of treatment, that correlated with a marked reduction in Bcl-2 expression. Mice bearing human melanoma xenografts and treated sequentially with DDP and c-myc antisense [S]ODNs showed a higher inhibition of tumor growth, reduction in the number of lung metastases, and increase in life span compared with those treated with either agent alone. Together, these data lend support to the development of anticancer therapies involving oncogene-targeted antisense ODNs and conventional antineoplastic drugs.
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PMID:c-myc antisense oligodeoxynucleotides enhance the efficacy of cisplatin in melanoma chemotherapy in vitro and in nude mice. 944 6

Overexpression of Bcl-2 is a potential mechanism for chemoresistance in acute leukemia and has been associated with unfavorable clinical outcome. We hypothesized that down-regulation of Bcl-2 would restore chemosensitivity in leukemic cells. To test this hypothesis, we performed a phase 1 study of G3139 (Genasense, Genta, Berkeley Heights, NJ), an 18-mer phosphorothioate Bcl-2 antisense, with fludarabine (FL), cytarabine (ARA-C), and granulocyte colony-stimulating factor (G-CSF) (FLAG) salvage chemotherapy in patients with refractory or relapsed acute leukemia. Twenty patients with refractory or relapsed acute myeloid leukemia (AML) or acute lymphoblastic leukemia (ALL) were enrolled. G3139 was delivered by continuous infusion on days 1 to 10. FLAG chemotherapy was administered on days 5 to 10. Common side effects of this combination included fever, nausea, emesis, electrolyte imbalance, and fluid retention that were not dose limiting. Plasma pharmacokinetics of G3139 demonstrated steady-state concentration (Css) within 24 hours. Of the 20 patients, 9 (45%) had disease response, 6 (5 AML, 1 ALL) with complete remission (CR) and 3 (2 AML and 1 ALL) with no evidence of disease but failure to recover normal neutrophil and/or platelet counts or to remain in remission for at least 30 days (incomplete remission). Bcl-2 mRNA levels were down-regulated in 9 of the 12 (75%) evaluable patients. This study demonstrates that G3139 can be administered safely with FLAG chemotherapy and down-regulate its target, Bcl-2. The encouraging clinical and laboratory results justify the current plans for a phase 3 study in previously untreated high-risk AML (ie, age at least 60 years).
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PMID:Phase 1 and pharmacodynamic studies of G3139, a Bcl-2 antisense oligonucleotide, in combination with chemotherapy in refractory or relapsed acute leukemia. 1239 93

Although attempts have been made to treat undifferentiated thyroid carcinoma using multidisciplinary therapeutic procedures including surgery, radiotherapy, and chemotherapy, the prognosis of undifferentiated thyroid carcinoma remains quite poor. New approaches to increase the sensitivity of patients to anticancer drugs and radiation will be needed to improve the survival rate for undifferentiated thyroid carcinoma. We examined the effect of Bcl-2 antisense oligonucleotide on drug-sensitivity in association with apoptosis in the 8305C undifferentiated thyroid carcinoma cell line. The drug sensitivity was evaluated by MTT assay for 48 h, while apoptosis was assessed according to the formation of internucleosomal DNA ladders. The Bcl-2 antisense was introduced into 8305C cells by using a 18-mer phosphorothioate oligonucleotide by lipopolyamine-mediated transfection twice for 12 h. The expression of apoptosis genes was assessed by Western blotting. The 8305C cells were sensitive to adriamycin (ADM), mitomycin (MMC), docetaxel (TXT), and paclitaxel (TXL), showing mean IC50 values of 0.72, 1.1, 1.3, and 4.1 microM, respectively. In contrast, the 8305C cells were resistant to cisplatin (CDDP) and 5-fluorouracil (5-FU), with mean IC50 values of 42.0 and 48.0 microM, respectively. Treatment with Bcl-2 antisense suppressed the protein level of Bcl-2 in 8305C cells in a dose-dependent manner up to 1.0 microM. Drug-sensitivity was increased by pretreatment with Bcl-2 antisense as assessed by the IC50 (x-fold): 0.48 (1.5-fold) in ADM; 0.42 (2.6-fold) in MMC, 0.56 (2.3-fold) in TXT, 1.5 (2.7-fold) in TXL, 8.6 (4.9-fold) in CDDP, and 25.0 (1.9-fold) in 5-FU, respectively. The increased drug-sensitivity was associated with the induction of apoptosis-related proteins, Fas, caspase 8, cytochrome c, caspase 3, and to subsequent apoptosis, as determined by the formation of internucleosomal DNA ladders and PARP in the treated cells. Susceptibility in apoptotic cell death following treatment with anticancer drugs was associated with induction of apoptosis-related genes in undifferentiated thyroid carcinoma cells, and induction of apoptosis was enhanced by pretreatment with Bcl-2 antisense oligonucleotide. These results imply a potential new strategy targeting an antiapoptotic protein, Bcl-2, by its antisense oligonucleotide for enhancement of chemotherapeutic efficacy in undifferentiated thyroid carcinomas.
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PMID:Effect of Bcl-2 antisense oligonucleotide on drug-sensitivity in association with apoptosis in undifferentiated thyroid carcinoma. 1273 25

Proteins of the Bcl-2 family share one or several Bcl-2 homology (BH) regions and behave as pro- or anti-apoptotic proteins. Prosurvival members such as Bcl-2 and Bcl-X(L) are supposed to preserve mitochondrial outer membrane integrity, thus preventing the release of soluble apoptogenic molecules. Pro-apoptotic members include BH3-only proteins that act as sensors of cellular damage and initiate the death process and Bax-like proteins that act downstream of BH3-only proteins to permeabilise the mitochondrial outer membrane. Whether BH3-only proteins directly activate Bax-like proteins or prevent prosurvival members of the family from inhibiting Bax-like proteins or both remains a matter of controversy. Expression of these proteins is altered in various human tumours and this abnormal expression may contribute to oncogenesis and tumour cell resistance to anticancer drug-induced cell death. Based on these observations, prosurvival proteins are attractive intracellular targets for inducing tumour cell death or sensitising tumour cells to death induced by chemotherapeutic drugs. The use of 18-mer antisense oligonucleotides (G3139 or Genasense) targeting the first six codons of bcl-2 mRNA is currently developed in clinics with phase I studies demonstrating that thrombocytopenia may be the main dose-limiting side effect. This strategy, that efficiently decreases Bcl-2 protein expression in some tumour cells, is currently tested in phase II and phase III trials. Alternative approaches to achieve the functional knock-out of Bcl-2 include the use of either peptides mimicking the BH3 domain of Bcl-2-related proteins or more stable, non peptidic BH3 mimetics and the pharmacological modulation of the post-translational modifications of the protein.
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PMID:Bcl-2 proteins: targets and tools for chemosensitisation of tumor cells. 1276 75

A P-ethoxy oligonucleotide (oligo), 20 bases long and specific for the translation initiation site of human Bcl-2 mRNA, was incorporated into liposomes to increase its intracellular delivery. This oligo selectively inhibited Bcl-2 protein expression and induced growth inhibition in t(14;18)-positive transformed follicular lymphoma (FL) cell lines. We studied the inhibitory effects of shorter liposomal P-ethoxy oligos (7, 9, 11 or 15 mer) in order to determine the activity of different oligo chain lengths targeted to the same Bcl-2 mRNA. At 12 microM, all the oligos inhibited the growth of a FL cell line. We compared the 7-mer oligo with the 20-mer oligo. The two oligos inhibited Bcl-2 protein expression similarly: 66% and 60% for the 7- and 20-mer, respectively. The uptake and retention of both oligos were also very similar. Our results indicate that the Bcl-2 inhibitory activity is maintained with P-ethoxy antisense oligos ranging from 7 to 20 bases.
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PMID:Cellular pharmacology of P-ethoxy antisense oligonucleotides targeted to Bcl-2 in a follicular lymphoma cell line. 1473 53

Two sets of 20-mer phosphorothioate-modified oligodeoxynucleotide DNAs (sODN) and 21-mer or 22-mer small interfering RNAs (siRNAs), targeted to the same coding sites in raf-1 mRNA, were compared for their abilities to reduce the amount of endogenously expressed Raf-1 protein in T24 cells. The amount of Raf-1 protein was monitored by careful quantitation of Western blots. We found that the siRNAs were somewhat less effective than the S-ODNs in reducing the Raf-1 protein level 20 hours after a 4-hour transfection. The siRNA duplexes were characterized by circular dichroism (CD) spectra, and melting temperatures (Tm) were obtained for the siRNA duplexes and DNA x RNA hybrids formed by the S-ODNs. The S-ODNs differed in their effectiveness, the S-ODN that formed the more stable hybrid being the more effective in reducing the Raf-1 protein level, but the two siRNAs were equally effective despite a difference in Tm of about 20 degrees C. Finally, the siRNAs and S-ODNs had a comparable nonspecific effect on a nontargeted (Bcl-2) protein. Our data add to others in the literature that show it can be difficult to select siRNAs that are more effective than antisense ODNs in downregulating endogenously expressed proteins.
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PMID:The reduction of Raf-1 protein by phosphorothioate ODNs and siRNAs targeted to the same two mRNA sequences. 1500 Aug 22

Convergent biochemical and genetic evidence suggests that the formation of alpha-synuclein (alpha-syn) protein deposits is an important and, probably, seminal step in the development of Parkinson's disease (PD), dementia with Lewy bodies (DLB) and multiple system atrophy (MSA). It has been reported that transgenic animals overexpressing human alpha-syn develop lesions similar to those found in the brain in PD, together with a progressive loss of dopaminergic cells and associated abnormalities of motor function. Inhibiting and/or reversing alpha-syn self-aggregation could, therefore, provide a novel approach to treating the underlying cause of these diseases. We synthesized a library of overlapping 7-mer peptides spanning the entire alpha-syn sequence, and identified amino acid residues 64-100 of alpha-syn as the binding region responsible for its self-association. Modified short peptides containing alpha-syn amino acid sequences from part of this binding region (residues 69-72), named alpha-syn inhibitors (ASI), were found to interact with full-length alpha-syn and block its assembly into both early oligomers and mature amyloid-like fibrils. We also developed a cell-permeable inhibitor of alpha-syn aggregation (ASID), using the polyarginine peptide delivery system. This ASID peptide was able to inhibit the DNA damage induced by Fe(II) in neuronal cells transfected with alpha-syn(A53T), a familial PD-associated mutation. ASI peptides without this delivery system did not reverse levels of Fe(II)-induced DNA damage. Furthermore, the ASID peptide increased (P<0.0005) the number of cells stained positive for Bcl-2, while significantly (P<0.05) decreasing the percentage of cells stained positive for BAX. These short peptides could serve as lead compounds for the design of peptidomimetic drugs to treat PD and related disorders.
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PMID:A strategy for designing inhibitors of alpha-synuclein aggregation and toxicity as a novel treatment for Parkinson's disease and related disorders. 1518 Sep 68

Complexes (lipoplexes) between cationic liposomes and single-strand oligodeoxynucleotides (ODN) are potential delivery systems for antisense therapy. The nanometer-scale morphology of these assemblies is relevant to their transfection efficiency. In this work the monocationic lipid dioleoyloxytrimethylammoniumpropane, the neutral "helper" lipid cholesterol, and an 18-mer anti-bcl2 ODN were combined at different ratios. The lipoplexes formed were characterized for the quantity of ODN bound, for the degree of lipid mixing, and for their size. The nanostructure of the system was examined by cryogenic-temperature transmission electron microscopy, augmented by small-angle x-ray scattering. Addition of ODN to cationic liposomes induced both liposome aggregation and the formation of a novel condensed lamellar phase. This phase is proposed to be stabilized by anionic single-strand ODN molecules intercalated between cationic bilayers. The proportion of cholesterol present apparently did not affect the nature of lipoplex microstructure, but changed the interlamellar spacing.
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PMID:Nanostructure of cationic lipid-oligonucleotide complexes. 1524 Apr 93

G3139 is an antisense Bcl-2 phosphorothioate oligonucleotide that has been combined with DTIC in a phase III clinical trial in melanoma. However, its actual mechanism of action in melanoma is controversial. Treatment of 518A2 melanoma cells with either G3139 or G4126 (a two-base mismatch) and then with light-activated DTIC caused these cells (but not SK-Mel-30 or 346.1 cells) to be protected against the cytotoxic effects of DTIC. This cytoprotection was not recapitulated with a phosphodiester congener of G3139 nor with a small interfering RNA (siRNA) also targeted to the Bcl-2 mRNA. Administering the drugs in reverse order also did not produce cytoprotection, and an 18- mer phosphorothioate homopolymer of thymidine was also inactive. Subsequently, it was discovered that gemcitibine and cis-platinum also induced cytoprotection to DTIC in this cell line, suggesting that the cytoprotection is a stress response to chemical proapoptotic stress. Cytoprotection was completely inhibited by O(6)-benzylguanine, an inhibitor of O(6)-guanosine alkyltransferase (OGAT) activity. However, a direct assay of OGAT activity demonstrated that 518A2 melanoma cells are essentially completely devoid of it, either basally or induced. The cytoprotection may thus be caused by a chemical stress-induced increase in mismatch repair activity.
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PMID:518A2 melanoma cells are protected by G3139 and other antineoplastic agents against the cytotoxic effects of DTIC. 1620 8


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