Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

Drug resistance is a well recognized problem in cancer therapy. Despite the current dogma that drug resistance is always an obstacle for treatment, here I show that it provides opportunities for selective protection of non-resistant cells with killing of drug-resistant cancer cells. According to the proposed 'two-drug' strategy, the first drug should be ineffective against a target drug-resistant cell (ie the drug is a substrate of MRP or Pgp pumps). In addition, it must be cytostatic but not cytotoxic. The second drug, which is applied in sequence, must be a cycle-dependent apoptotic drug to which the target cell is not cross-resistant. Thus, low doses of adriamycin, etoposide and actinomycin D, used as the first drugs, were cytostatic to parental HL60 cells. Therefore, these drugs precluded Bcl-2/Raf-1 phosphorylation, PARP cleavage and cell death which are otherwise induced by paclitaxel, a mitosis-selective apoptotic drug for HL60 cells. In contrast, HL60/ADR cells which express MRP, a transporter which pumps out the first drugs from a cell, were insensitive to the first drugs and therefore readily underwent apoptosis following the second drug. This strategy also allowed a selective killing of HL60/TX cells which express MDR-1, with the only difference being that the second drug, paclitaxel, was substituted for epothilones, non-Pgp substrates. Lack of protection by the first drug, a Pgp substrate, resulted in HL60/TX killing by the second drug, whereas parental HL-60 cells were fully protected. Therefore, drug resistant cells can be selectively killed by a combination of drugs not killing sensitive cells. Lack of toxicity against normal cells will be clinically translated in reduction of adverse side-effects of chemotherapy against drug-resistant malignancies.
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PMID:Drug-resistance enables selective killing of resistant leukemia cells: exploiting of drug resistance instead of reversal. 1060 25

We investigated the in vitro growth inhibitory and apoptotic effects of clinically achievable concentrations of As(2)O(3) (0.5 to 2.0 micromol/L) against human myeloid leukemia cells known to be resistant to a number of apoptotic stimuli. These included chronic myelocytic leukemia (CML) blast crisis K562 and HL-60/Bcr-Abl cells, which contain p210 and p185 Bcr-Abl, respectively, and HL-60 cell types that overexpress Bcl-2 (HL-60/Bcl-2), Bcl-x(L) (HL-60/Bcl-x(L)), MDR (HL-60/VCR), or MRP (HL-60/AR) protein. The growth-inhibitory IC(50) values for As(2)O(3) treatment for 7 days against all these cell types ranged from 0.8 to 1.5 micromol/L. Exposure to 2 micromol/L As(2)O(3) for 7 days induced apoptosis of all cell types, including HL-60/Bcr-Abl and K562 cells. This was associated with the cytosolic accumulation of cyt c and preapoptotic mitochondrial events, such as the loss of inner membrane potential (DeltaPsim) and the increase in reactive oxygen species (ROS). Treatment with As(2)O(3) (2 micromol/L) generated the activities of caspases, which produced the cleavage of the BH3 domain containing proapoptotic Bid protein and poly (ADP-ribose) polymerase. Significantly, As(2)O(3)-induced apoptosis of HL-60/Bcr-Abl and K562 cells was associated with a decline in Bcr-Abl protein levels, without any significant alterations in the levels of Bcl-x(L), Bax, Apaf-1, Fas, and FasL. Although As(2)O(3 )treatment caused a marked increase in the expression of the myeloid differentiation marker CD11b, it did not affect Hb levels in HL-60/Bcr-Abl, K562, or HL-60/neo cells. However, in these cells, As(2)O(3 )potently induced hyper-acetylation of the histones H3 and H4. These findings characterize As(2)O(3) as a growth inhibiting and apoptosis-inducing agent against a variety of myeloid leukemia cells resistant to multiple apoptotic stimuli.
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PMID:Arsenic induces apoptosis of multidrug-resistant human myeloid leukemia cells that express Bcr-Abl or overexpress MDR, MRP, Bcl-2, or Bcl-x(L). 1064 17

Peripheral T-cell lymphomas (PTCL) are usually characterized by aggressive clinical behaviour and poor clinical outcome, but their biological background has not been extensively investigated to date, due to their low incidence, about 10% of all non-Hodgkin's lymphoma cases in Western countries, and also to the paucity of specific molecular-genetic abnormalities. Neverthless, there is increasing biological and clinical evidence that primary nodal PTCL should be considered separately from extra-nodal cases, but little is known about biological factors of possible clinical and prognostic impact. This immunohistochemical study has analysed the expression of p53, Mdm2, p21(WAF1), BCL-2 and p-glycoprotein (MDR-1 gene product) in a series of 45 cases of nodal peripheral T-cell lymphomas (PTCL) with 'high-grade' histology. The immunohistochemical findings were then correlated with proliferative activity and clinical outcome. p53 was over-expressed in 13 cases (28.9%). p53 positive cases showed significantly higher proliferative activity (p<0.01), more frequent expression of Bcl-2 (p<0.01) and less frequent expression of p21(WAF1) than p53 negative cases. Mdm2 and p-glycoprotein were expressed in 4/13 (30.8%) and 8/13 (61.5%) p53 positive cases respectively, and in none (0%) of the p53 negative cases (p<0.01). Analysis of the survival curves showed that p53 positive cases were associated with a significantly poorer clinical outcome than p53 negative cases, in terms of both overall survival (p=0.0032) and event-free survival (p=0.0004). Furthermore, multivariate analysis showed that p53 expression was the most important independent prognostic variable. These findings indicate that p53 over-expression identifies a subset of nodal PTCL cases with a distinctive biological profile (higher proliferative activity, less frequent expression of p21(WAF1) and more frequent expression of Bcl-2, Mdm2 and p-glycoprotein than p53 negative cases) and poor clinical outcome. The immunohistochemical analysis of p53 expression is a simple, rapid and low-cost method which may provide information of potential clinical and prognostic value in nodal peripheral T-cell lymphomas.
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PMID:p53 over-expression identifies a subset of nodal peripheral T-cell lymphomas with a distinctive biological profile and poor clinical outcome. 1167 35

P-glycoprotein (P-gp) is a 170-kDa glycoprotein encoded by the MDR-1 gene. In tumor cells overexpression of P-gp is associated with resistance to chemotherapy-induced apoptosis. P-gp is also expressed on cells of the immune system; however, its role in lymphocyte physiology remains unclear. Therefore, in this investigation, we examined a possible role of P-gp in the survival of in vitro activated peripheral blood mononuclear cells (MNCs). MNCs were activated with anti-CD3 monoclonal antibody (mAb) for 96 hr in the presence or absence of anti-P-gp mAb or isotype control and examined for apoptosis by TUNEL assay. Activation of caspase was determined by colorimetric assay. Activated lymphocytes (96 hr) are resistant to apoptosis. However, anti-P-gp mAb-induced apoptosis in anti-CD3 activated MNC. Induction of apoptosis was associated with increased expression of CD95L; activation of caspase 3, however, did not affect the expression of Bcl-2 and Bcl-xL. Furthermore, both recombinant Fas-Fc fusion protein, a blocker of CD95-CD95L interactions, and Z-DEVD-FMK, a cell-permeable caspase 3 inhibitor, reversed anti-P-gp-induced apoptosis. These data demonstrate that anti-P-gp mAb promotes apoptosis in activated T lymphocytes by up-regulating CD95L expression and via CD95-CD95L interactions and suggest a possible role of P-gp in lymphocyte survival.
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PMID:Anti-P-glycoprotein antibody-induced apoptosis of activated peripheral blood lymphocytes: a possible role of P-glycoprotein in lymphocyte survival. 1181 87

AIM:To compare the expression level of Fas gene and Bcl-2 gene in gastric cancer cells SGC7901 and gastric cancer MDR (multidrug resistant) cells SGC7901/VCR,to transduce Fas cDNA and Bcl-2 antisense nucleic acid into SGC7901/VCR cells respectively, and to observe the expression of two genes in transfectants and non-transfectants as well as their drug sensitivity.METHODS:Eukaryotic expression vector pBK-Fas cDNA and pDOR-anti Bcl-2 were constructed and transfected into SGC7901/VCR cells by lipofectamine,respectively.Northern blot and Western blot were used to detect the expression of mRNA and protein in SGC7901/VCR and SGC7901 cells and transfectants, and drug sensitivity of transfectants for VCR, CDDP and 5-FU was analyzed with MTT assay.RESULTS:After gene transfection, 80 for Fas and 120 for antisense Bcl-2 drug-resistant clones were selected from 2 X10(5) cells, transfection rate being 0.04% and 0.06%. Two clones of SGC7901 Fas/VCR cells and SGC7901 anti Bcl-2/VCR cells were randomly selected for further incubation. Hybridization results showed that the expression level of Fas mRNA and protein in SGC7901/VCR cells was much lower,but that of Bcl-2 mRNA and protein was higher than that in SGC7901 cells. The expression of Fas mRNA and protein in SGC7901 Fas/VCR cells was higher,and of Bcl-2 mRNA and protein was lower in SGC7901 anti Bcl-2/VCR cells than that in non-transfectants. MTT assay showed that transfectants were more sensitive to VCR, CDDP, 5-FU than non-transfectants. CONCLUSION:Bcl-2 gene displayed high expression while Fas gene had low expression in drug resistant gastric cancer cells. Expression of Bcl-2 protein was effectively blocked in SGC7901 anti Bcl-2/VCR cells by gene transfection. In contrast, the expression of Fas mRNA and protein in SGC7901 Fas/VCR cells increased. Fas gene and Bcl-2 antisense nucleic acid transfection sensitized drug resistant gastric cancer cells to chemotherapeutic drugs. These results suggest cell apoptosis plays an important role in the mechanism of MDR, and enhancing apoptosis might reverse MDR.
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PMID:Transduction of Fas gene or Bcl-2 antisense RNA sensitizes cultured drug resistant gastric cancer cells to chemotherapeutic drugs. 1181 36

For the treatment of ovarian cancer, gene therapy is increasingly viewed as the fourth therapeutic concept (in addition to surgery, chemotherapy, and irradiation). Many approaches that use viral and nonviral delivery systems have been employed to introduce genes into tumor cells, thus changing their malignant phenotype. The development of tissue-specific promoters has enhanced the specificity of adenoviral transduction, the most commonly used transfer method. Phase I clinical trials (targeting p53, BRCA1, Her2/neu, Bcl-2, MDR, EIA, and HSV-TK genes) have been performed to test the relative safety of different strategies. Further studies are needed to evaluate the effectiveness of these treatments. New studies must evaluate gene therapy alone and in combination with cytostatic regimens because preclinical studies have shown the chemosensitizing effects of several target genes. The increasing knowledge about the genetic background of ovarian cancer will provide many targets for novel gene therapy approaches.
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PMID:Gene therapy of ovarian cancer. 1211 82

Advances in molecular and cell biology have led to further understanding of the mechanisms of malignant growth and metastasis in human breast cancer cells. Initiation and progression of breast cancer results from mutations and the abnormal expression of many genes that control cellular proliferation, differentiation, invasion, metastasis and sensitivity to therapy (chemotherapy and radiation therapy). Inhibition of host immunity also plays a role in breast cancer progression. Many genes have been selected as targets for antisense therapy, including HER-2/neu, PKA, TGF-alpha, EGFR, TGF-beta, IGFIR, P12, MDM2, BRCA, Bcl-2, ER, VEGF, MDR, ferritin, transferrin receptor, IRE, C-fos, HSP27, C-myc, C-raf and metallothionein genes. The strategy behind antisense therapy is the development of specific therapeutic agents that aim to correct the mutations and abnormal expression of cellular genes in breast tumour cells by decreasing gene expression, inducing degradation of target mRNA and causing premature termination of transcription. Many in vitro and in vivo studies have investigated the therapeutic efficacy of oligonucleotides and antisense RNAs. These studies have demonstrated specific inhibition of tumour cell growth by antisense therapy and have shown synergistic inhibitory effects between antisense oligonucleotides or antisense RNA and conventional chemotherapeutic drugs used in the treatment of breast cancer. Antisense oligonucleotides have been modified to improve their ability to penetrate cells, bind to gene sequences and downregulate target gene function. Many delivery systems for antisense RNA and antisense oligonucleotides have been developed, including virus vectors (retrovirus, adenovirus and adeno-associate virus) and liposomes, to carry the antisense RNA or oligonucleotides through the cell membrane into the cytoplasm and nucleus of the tumour cells. However, in order to determine their feasibility antisense therapies need to be further investigated to determine their antitumour activity, pharmacokinetics and toxicity in breast cancer patients.
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PMID:Gene targets of antisense therapies in breast cancer. 1222 74

We investigated the possibility of the proapoptotic lipid ceramide as an indicator of chemoresistance in leukemia. Doxorubicin (DOX) increased the ceramide level and apoptosis in drug-sensitive HL-60 cells but not in drug-resistant HL-60/ADR cells, under the condition that the uptake of DOX was not different between the two cell lines. In addition, exogenous N-acetylsphingosine (C2-ceramide) enhanced DOX-induced apoptosis in HL-60/ADR cells without affecting the expression of multidrug resistant-1 protein (MDR 1) and the uptake of DOX. A lower level of ceramide with higher activities of glucosylceramide synthase (GCS) and sphingomyelin synthase (SMS) was detected in HL-60/ADR cells than in HL-60 cells. In contrast, HL-60/GCS cells, overexpressing GCS, significantly inhibited DOX-induced ceramide increase and apoptosis. These observations suggest the involvement of ceramide regulation in drug resistance of leukemia cells. In vivo, the level of ceramide was lower in chemoresistant leukemia patients (6.4 +/- 1.8 pmol/nmol phosphate; n = 14) than in chemosensitive patients (9.5 +/- 2.7 pmol/nmol phosphate; n = 9), and the activities of GCS and SMS were more than 2-fold higher in chemoresistant leukemia cells than in chemosensitive cells. MDR-1 protein was faintly expressed in one of four chemoresistant patients, but Bcl-2 were clearly detected in four patients. Therefore, it is suggested that a decrease of the ceramide level via activation of GCS and SMS is associated with the chemoresistant condition in leukemia, probably in relation to Bcl-2 but not to MDR-1 expression.
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PMID:Possible role of ceramide as an indicator of chemoresistance: decrease of the ceramide content via activation of glucosylceramide synthase and sphingomyelin synthase in chemoresistant leukemia. 1253 95

Histone deacetylase inhibitors (HDACIs) are a new class of chemotherapeutic drugs able to induce tumor cell apoptosis and/or cell cycle arrest; however, the molecular mechanisms underpinning their anticancer effects are poorly understood. Herein, we assessed the apoptotic pathways activated by three HDACIs, suberoylanilide hydroxamic acid, oxamflatin, and depsipeptide. We determined that all three drugs induced the accumulation of cells with a 4n DNA content and apoptosis mediated by the intrinsic apoptotic pathway. HDACI-induced mitochondrial membrane damage and apoptosis were inhibited by overexpression of Bcl-2, but not by the polycaspase inhibitor N-tert-butoxy-carbonyl-Val-Ala-Asp-fluoromethylketone (zVAD-fmk). Moreover, induction of a G(1)-S checkpoint through overexpression of p16(INK4A) or suppression of de novo protein synthesis also inhibited HDACI-induced cell death. Proteolytic cleavage of caspase-2, which is poorly inhibited by zVAD-fmk, was concomitant with HDACI-induced death; however, full processing of caspase-2 to the p19 active form was blocked by Bcl-2. Whereas all three drugs induce the activation of the proapoptotic Bcl-2 protein Bid upstream of mitochondrial membrane disruption, Bid cleavage in response to depsipeptide was significantly attenuated by zVAD-fmk. Suberoylanilide hydroxamic acid and oxamflatin could kill both P-glycoprotein (P-gp)(+) MDR cells and their P-gp(-) counterparts, whereas depsipeptide was shown to be a substrate for P-gp and was less effective in killing P-gp(+) cells. These data provide insight into the functional profile of three HDACIs and are important for the development of more rational approaches to chemotherapy, where information regarding the genetic profile of the tumor is matched with the functional profile of a given chemotherapeutic drug to promote favorable clinical responses.
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PMID:Novel mechanisms of apoptosis induced by histone deacetylase inhibitors. 1290 19

BPR0L075 is a novel synthetic compound discovered through research to identify new microtubule inhibitors. BPR0L075 inhibits tubulin polymerization through binding to the colchicine-binding site of tubulin. Cytotoxic activity of BPR0L075 in a variety of human tumor cell lines has been ascertained, with IC(50) values in single-digit nanomolar ranges. As determined by flow cytometry, human cervical carcinoma KB cells are arrested in G(2)-M phases in a time-dependent manner before cell death occurs. Terminal deoxynucleotidyl transferase-mediated nick end labeling assay indicates that cell death proceeds through an apoptotic pathway. Additional studies indicate that the effect of BPR0L075 on cell cycle arrest is associated with an increase in cyclin B1 levels and a mobility shift of Cdc2 and Cdc25C. The changes in Cdc2 and Cdc25C coincide with the appearance of phosphoepitopes recognized by a marker of mitosis, MPM-2. Furthermore, phosphorylated forms of Bcl-2, perturbed mitochondrial membrane potential, and activation of the caspase-3 cascade may be involved in BPR0L075-induced apoptosis. Notably, several KB-derived multidrug-resistant cell lines overexpressing P-gp170/MDR and MRP are resistant to vincristine, paclitaxel, and colchicine but not to BPR0L075. Moreover, BPR0L075 shows potent activity against the growth of xenograft tumors of the gastric carcinoma MKN-45, human cervical carcinoma KB, and KB-derived P-gp170/MDR-overexpressing KB-VIN10 cells at i.v. doses of 50 mg/kg in nude mice. These findings indicate BPR0L075 is a promising anticancer compound with antimitotic activity that has potential for management of various malignancies, particularly for patients with drug resistance.
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PMID:BPR0L075, a novel synthetic indole compound with antimitotic activity in human cancer cells, exerts effective antitumoral activity in vivo. 1523 74


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