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: EC:2.4.2.30 (PARP)
13,611 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Expression and function of the TRAIL apoptotic pathway was investigated in normal and malignant breast epithelial cells. Glutathione-S-transferase (GST)-TRAIL extracellular domain fusion proteins were produced to analyze TRAIL-induced apoptosis. Only GST-TRAIL constructs containing regions homologous to the Fas self-association and ligand binding domains could induce apoptosis. GST-TRAIL induced significant (>90%) apoptosis in just one of eight normal and one of eight malignant breast cell lines. All other lines were relatively resistant to TRAIL-induced apoptosis. Activating TRAIL receptors DR4 and DR5 were expressed in all normal and malignant breast cell lines. The inhibitory receptor TRID was highly expressed in one of four normal and two of seven malignant breast cell lines. DR4, DR5, or TRID expression did not correlate with sensitivity to TRAIL-induced apoptosis. Incubation of cell lines with doxorubicin or 5-fluorouracil significantly augmented TRAIL-induced apoptosis in most breast cell lines. By fractional inhibition analysis, the toxicity of the combination of TRAIL and doxorubicin or 5-fluorouracil was synergistic compared with either agent alone. In contrast, melphalan and paclitaxel augmented TRAIL-induced apoptosis in few cell lines, and methotrexate did not augment it in any cell line. Augmentation of TRAIL-induced apoptosis by doxorubicin or 5-fluorouracil was mediated through caspase activation. This was evidenced by the fact that chemotherapy agents that synergized with TRAIL (e.g., doxorubicin) themselves caused cleavage of caspase-3 and poly(ADP-ribose) polymerase (PARP), and their toxicity was blocked by the caspase inhibitor Z-Val-Ala-Asp(OMe)-CH2 (ZVAD-fmk). The combination of TRAIL and doxorubicin caused significantly greater caspase-3 and PARP cleavage, and the combined toxicity also was inhibited by ZVAD-fmk. In contrast, chemotherapy agents that did not augment TRAIL-induced apoptosis (e.g., methotrexate) caused minimal caspase-3 and PARP cleavage by themselves, and their toxicity was not inhibited by ZVAD-fmk. These drugs also did not increase caspase-3 or PARP cleavage when combined with TRAIL. In summary, few breast cell lines are sensitive to TRAIL-induced apoptosis, and no difference in sensitivity is found between normal and malignant cell lines. Treatment with chemotherapy provides an approach to sensitize breast cancer cells to TRAIL-induced apoptosis.
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PMID:Chemotherapy augments TRAIL-induced apoptosis in breast cell lines. 997 25

The synthetic retinoid 6-[3-(1-adamantyl)-4-hydroxyphenyl]-2-naphthalene carboxylic acid (CD437) induces apoptosis in several types of cancer cell. CD437 inhibited the growth of both androgen-dependent and -independent human prostate carcinoma (HPC) cells in a concentration-dependent manner by rapid induction of apoptosis. CD437 was more effective in killing androgen-independent HPC cells such as DU145 and PC-3 than the androgen-dependent LNCaP cells. The caspase inhibitors Z-VAD-FMK and Z-DEVD-FMK blocked apoptosis induced by CD437 in DU145 and LNCaP cells, in which increased caspase-3 activity and PARP cleavage were observed, but not in PC-3 cells, in which CD437 did not induce caspase-3 activation and PARP cleavage. Thus, CD437 can induce either caspase-dependent or caspase-independent apoptosis in HPC cells. CD437 increased the expression of c-Myc, c-Jun, c-Fos, and death receptors DR4, DR5 and Fas. CD437's potency in apoptosis induction in the different cell lines was correlated with its effects on the expression of oncogenes and death receptors, thus implicating these genes in CD437-induced apoptosis in HPC cells. However, the importance and contribution of each of these genes in different HPC cell lines may vary. Because CD437 induced the expression of DR4, DR5 and Fas, we examined the effects of combining CD437 and tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) and Fas ligand, respectively, in HPC cells. We found synergistic induction of apoptosis, highlighting the importance of the modulation of these death receptors in CD437-induced apoptosis in HPC cells. This result also suggests a potential strategy of using CD437 with TRAIL for treatment of HPC. Oncogene (2000) 19, 4513 - 4522.
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PMID:Implication of multiple mechanisms in apoptosis induced by the synthetic retinoid CD437 in human prostate carcinoma cells. 1100 24

The tumor necrosis factor (TNF) related apoptosis-inducing ligand (TRAIL or Apo2L) and its receptors are members of the tumor necrosis factor superfamily. TRAIL triggers apoptosis by binding to its two proapoptotic receptors DR4 and DR5, a process which is negatively regulated by binding of TRAIL to its two decoy receptors TRID and TRUNDD. Here, we show that TRAIL effectively induces apoptosis in H460 human non-small-cell lung carcinoma cells via cleavage of caspases 8, 9, 7, 3, and BID, release of cytochrome c from the mitochondria, and cleavage of poly (ADP-ribose) polymerase (PARP). However, overexpression of Bcl2 blocked TRAIL-induced apoptosis in H460 cells, which correlated with the Bcl2 protein levels. Importantly, the release of cytochrome c and cleavage of caspase 7 triggered by TRAIL were considerably blocked in Bcl2 overexpressing cells as compared to vector control cells. Moreover, inhibition of TRAIL-mediated cytochrome c release and caspase 7 activation by Bcl2 correlated with the inability of PARP to be cleaved and the inability of the Bcl2 transfectants to undergo apoptosis. Thus, these results suggest that Bcl2 can serve an anti-apoptotic function during TRAIL-dependent apoptosis by inhibiting the release of cytochrome c and activation of caspase 7, thereby blocking caspase 7-dependent cleavage of cellular substrates.
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PMID:Overexpression of BCL2 blocks TNF-related apoptosis-inducing ligand (TRAIL)-induced apoptosis in human lung cancer cells. 1116 90

The tumor necrosis factor-related apoptosis-inducing ligand (TRAIL, Apo-2L) is a recently characterized member of the family of programmed cell death-inducing ligands that includes TNF-alpha and CD95L (FasL). It is well known that TRAIL binds to the death signaling receptors, DR4 and DR5, and initiates the TRAIL death pathway. Activation of this pathway, mediated through a caspase cascade, causes apoptosis. In this study, we hypothesized that oxidative stress facilitates TRAIL-induced apoptosis by promoting caspase activity through cytochrome c release from mitochondria. Human colorectal carcinoma CX-1 cells were treated with various concentrations of TRAIL (12.5-200 ng/ml) and/or sodium nitroprusside (SNP; 0.03-1 mM) for 12 h. SNP, a nitric oxide donor, which had little toxic effect by itself, enhanced TRAIL-induced cytotoxicity. For example, TRAIL-induced apoptosis (200 ng/ml) was increased by a factor of 2.5-fold in the presence of 1 mM SNP. The combined treatment also caused an increase in cytochrome c release, caspase-3 activity, and PARP cleavage. Overexpression of Bcl-2 completely blocked the SNP-promoting effects, but only moderately inhibited TRAIL-induced apoptosis. Similar results were observed in the presence of hydrogen peroxide or peroxynitrite. Taken together, the present studies suggest that SNP enhances TRAIL-induced cytotoxicity by facilitating the mitochondria-mediated caspase signal transduction pathway.
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PMID:Sodium nitroprusside enhances TRAIL-induced apoptosis via a mitochondria-dependent pathway in human colorectal carcinoma CX-1 cells. 1131 91

TRAIL, Tumor necrosis factor-related apoptosis-inducing ligand), a member of the TNF family, is known to be cytotoxic for a high proportion of tumor cell lines. However, successful application of TRAIL in tumor therapy may depend on finding other agents that can potentiate its antitumor effects. The present study showed that the cytostatic/cytotoxic TRAIL activity against U937 cells could be significantly augmented by proteasome inhibitor PSI, as revealed by MTT assay. Increased cytostatic/cytotoxic effect on U937 cells by TRAIL/PSI combined treatment was caused by apoptosis, as shown by an increased PARP cleavage rate. TRAIL/PSI did not affect the level of mRNA expression for TRAIL receptors (DR4, DR5, DcR1) and other apoptosis signal transduction molecules (TRADD, caspase-8).
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PMID:Augmented pro-apoptotic effects of TRAIL and proteasome inhibitor in human promonocytic leukemic U937 cells. 1139 70

TRAIL (TNF-related apoptosis-inducing ligand) induces apoptosis in susceptible cells by binding to death receptors 4 (DR4) and 5 (DR5). TRAIL preferentially induces apoptosis in transformed cells and the identification of mechanisms by which TRAIL-induced apoptosis can be enhanced may lead to novel cancer chemotherapeutic strategies. Here we show that reovirus infection induces apoptosis in cancer cell lines derived from human breast, lung and cervical cancers. Reovirus-induced apoptosis is mediated by TRAIL and is associated with the release of TRAIL from infected cells. Reovirus infection synergistically and specifically sensitizes cancer cell lines to killing by exogenous TRAIL. This sensitization both enhances the susceptibility of previously resistant cell lines to TRAIL-induced apoptosis and reduces the amount of TRAIL needed to kill already sensitive lines. Sensitization is not associated with a detectable change in the expression of TRAIL receptors in reovirus-infected cells. Sensitization is associated with an increase in the activity of the death receptor-associated initiator caspase, caspase 8, and is inhibited by the peptide IETD-fmk, suggesting that reovirus sensitizes cancer cells to TRAIL-induced apoptosis in a caspase 8-dependent manner. Reovirus-induced sensitization of cells to TRAIL is also associated with increased cleavage of PARP, a substrate of the effector caspases 3 and 7.
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PMID:Caspase 8-dependent sensitization of cancer cells to TRAIL-induced apoptosis following reovirus-infection. 1168 70

Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) is one of the latest members of the TNF superfamily known to induce apoptosis in a wide variety of tumor cells. Some cell types, however, are quite resistant to TRAIL. We investigated the effect of ectopic expression of Bcl-2 and Bcl-xL on TRAIL-induced apoptosis in human acute myelogenous leukemia HL-60 cells. We found that HL-60 cells, which express TRAIL receptors (also called death receptor, DR) DR4, DR5, and Dc (decoy) R2, are highly sensitive to TRAIL-induced cytotoxicity. Greater than 90% killing occurred within 24 h of TRAIL treatment. The expression of Bcl-2 and Bcl-xL, however, completely abolished the TRAIL-induced cytotoxic effects. Treatment of HL-60 cells with TRAIL induced caspase-8 activation within 2-4 h, but no activation could be seen in Bcl-2-expressing or Bcl-xL-expressing cells. TRAIL also induced cleavage of BID, which was also abolished by Bcl-2 and Bcl-xL. Similarly, TRAIL activated caspase-3 and caspase-7 in control cells but not in cells expressing Bcl-2 or Bcl-xL. Cleavage of the caspase-3 substrate poly(ADP-ribose) polymerase (PARP), was abrogated by ectopic expression of Bcl-2 and Bcl-xL. Inhibition of caspases by the pan-caspase inhibitor, benzyloxycarbonyl-valine-alanine-aspartate-fluoromethylketone (zVAD-fmk) abolished the TRAIL-induced apoptosis. Overall, these results indicate that TRAIL-induced apoptosis involves activation of caspase-8, caspase-7, caspase-3, and BID cleavage, and Bcl-2 and Bcl-xL prevents TRAIL-induced apoptosis by abrogating caspase activation and BID cleavage.
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PMID:Ectopic expression of Bcl-2 and Bcl-xL inhibits apoptosis induced by TNF-related apoptosis-inducing ligand (TRAIL) through suppression of caspases-8, 7, and 3 and BID cleavage in human acute myelogenous leukemia cell line HL-60. 1191 10

Tumor necrosis factor-related apoptosis inducing ligand (TRAIL/Apo2L) can induce receptor-mediated apoptosis in prostate cancer cell lines that have been co-treated with the chemotherapeutic agent doxorubicin (Voelkel-Johnson C, et al. Cancer Gene Therapy 2002; 9:164-172). In this study, we report that pretreatment with doxorubicin is sufficient to sensitize cells to TRAIL. To identify possible targets of doxorubicin, we analyzed levels of several Bcl-2 family members, TRAIL receptors and the anti-apoptotic protein c-FLIP. Doxorubicin did not affect steady state levels of Bax, Bcl-2 and Bcl-X(L) in the majority of the prostate cancer cell lines. TRAIL receptor mRNAs (DR4, DR5, and DcR2) were induced by doxorubicin but these changes were not reflected at the protein level. In contrast, in response to doxorubicin, levels of c-FLIP, particularly FLIP(S), decreased in all cell lines tested. The decrease in c-FLIP(S) correlated with onset and magnitude of caspase-8 and PARP cleavage in PC3 cells. In two TRAIL resistant cell lines, DU145 and LNCaP, treatment with TRAIL alone resulted in processing of c-FLIP(L) and initiated abortive caspase-8 proteolysis. TRAIL treatment did not affect levels of c-FLIP(S) in Du145 and LNCaP cells and did not result in PARP cleavage. Therefore, our results suggest that doxorubicin- mediated down regulation of c-FLIP(S) predisposes cells to TRAIL-induced apoptosis.
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PMID:Doxorubicin pretreatment sensitizes prostate cancer cell lines to TRAIL induced apoptosis which correlates with the loss of c-FLIP expression. 1249 82

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) has been shown to exert potent cytotoxic activity against many tumor cells but not normal cells. However, some tumor cells are resistant to TRAIL, and it has not been determined how this occurs. In the present study, we obtained three subgroups of Jurkat clones with TRAIL-sensitive, -partial resistant and -resistant phenotypes. We found that most TRAIL-resistant and -partial resistant clones expressed low levels of DR5, whereas most TRAIL-sensitive clones expressed high levels of Death Receptor (DR5). However, there were clones with a range of different TRAIL-sensitivities that had similar levels of DR5 expression. The expression levels of DR4 and the decoy receptors, DcR1 and DcR2, did not correlate with TRAIL sensitivities. We also compared the subgroups in terms of the expression of Fas-associated death domain protein (FADD), the levels of activation of Receptor Interacting Protein (RIP) and caspases, and cleavage of Poly (ADP-Ribose)Polymerase (PARP). Basal expression levels of FADD were not significantly different among the subgroups. After treatment with TRAIL, both TRAIL-sensitive and partial resistant clones showed high levels of activation of caspase-3, caspase-8, RIP and PARP. Relative basal level and induced level of Phosphoprotein over Expressed in Diabetes/Phosphoprotein Enriched in Astrocytes (PED/PEA-15) after TRAIL treatment were compared in the clones. Basal levels of PED/PEA-15 expression were similar among sensitive, partial resistant and resistant clones. TRAIL did not change the PED/PEA-15 level in the clones. In addition, transduction and expression of the dominant negative form of the I-kBalpha gene did not change TRAIL-sensitivities. Our results showed that the expression levels of DR5, the activation levels of caspase-8, -3 and RIP were critical factors in determining TRAIL-sensitivities in Jurkat cells. The results of our study also suggest that cells with different TRAIL-sensitivities arise through multiple mechanisms even within a single cell line.
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PMID:Analysis of the phenotypes of Jurkat clones with different TRAIL-sensitivities. 1270 64

Because apoptosis is deregulated in most cancers, apoptosis-modulating approaches offer an attractive opportunity for clinical therapy of many tumors, including that of the prostate. LNCaP-derived C4-2 human prostate cancer cells are quite resistant to treatment with Apo2 ligand (Apo2L) or tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), when using a nontagged, Zn-bound recombinant trimeric version that is devoid of any exogeneous sequences and therefore least likely to be immunogenic in human patients and that has been optimized for maximum efficacy and minimum toxicity. When combined with the topoisomerase I inhibitor CPT-11 (irinotecan), Apo2L/TRAIL exhibits enhanced apoptotic activity in C4-2 cells cultured in vitro as well as xenografted as tumors in vivo. Apoptosis both in vitro and in vivo was characterized by two major molecular events. First, apoptosis induction was accompanied by changes in expression levels of the Bcl-2 family genes and their products. However, whereas combination treatment applied to in vitro cell culture was characterized by a significant up-regulation and activation of Bax and down-regulation of Bcl-xL, the treatment applied to tumors induced Bak and Bcl-xS, whereas Bcl-omega and Bcl-xL were down-regulated. Because there are multiple members of the Bcl-2 family (24 members to date), these data indicate that, under different biological conditions, different proteins may be responsible for activating apoptosis and provide evidence for a differential regulation of the multidomain Bcl-2 protein-encoding genes, bax and bak. Increased Bax expression led to its activation, translocation to the mitochondria, and release of cytochrome c. In addition, this combination treatment induced apoptosis through potent activation of caspase-8 and the proapoptotic protein Bid, resulting in activation of effector caspase-3 and cleavage of its cellular target protein, poly(ADP-ribose) polymerase (PARP), events blocked by the pan-caspase inhibitor N-tert-butoxy-carbonyl-Val-Ala-Asp-fluoro methylketone (zVAD-fmk). Activation of multiple caspases and PARP cleavage were also observed in the C4-2 tumors treated with doses resulting in effective tumor control at 42 days after Apo2L/TRAIL plus CPT-11 treatment. Down-regulation of Bax by small interference (RNA) (siRNA) in C4-2 cells significantly prevented PARP cleavage and apoptosis. Strikingly, similar experiments in cells stably expressing a dominant-negative death receptor DR5 led to complete ablation of PARP cleavage and apoptosis, indicating the essential role of both mitochondrial and receptor-mediated apoptotic pathways. Our data indicate that the combined treatment of Apo2L/TRAIL and CPT-11 achieves tumor control in prostate cancer tumors through regulation of Bcl-2 family proteins and potent activation of caspases.
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PMID:Apoptosis induction in prostate cancer cells and xenografts by combined treatment with Apo2 ligand/tumor necrosis factor-related apoptosis-inducing ligand and CPT-11. 1290 54


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