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)

Bortezomib, a proteasome inhibitor, shows substantial anti-tumor activity in a variety of tumor cell lines, is in phase I, II, and III clinical trials and has recently been approved for the treatment of patients with multiple myeloma. The sequence of events leading to apoptosis following proteasome inhibition by bortezomib is unclear. Bortezomib effects on components of the mitochondrial apoptotic pathway were examined: generation of reactive oxygen species (ROS), alteration in the mitochondrial membrane potential (Delta psi m), and release of cytochrome c from mitochondria. With human H460 lung cancer cells, bortezomib exposure at 0.1 microM showed induction of apoptotic cell death starting at 24 h, with increasing effects after 48-72 h of treatment. After 3-6 h, an elevation in ROS generation, an increase in Delta psi m, and the release of cytochrome c into the cytosol, were observed in a time-dependent manner. Co-incubation with rotenone and antimycin A, inhibitors of mitochondrial electron transport chain complexes I and III, or with cyclosporine A, an inhibitor of mitochondrial permeability transition pore, resulted in inhibition of bortezomib-induced ROS generation, increase in Delta psi m, and cytochrome c release. Tiron, an antioxidant agent, blocked the bortezomib-induced ROS production, Delta psi m increase, and cytochrome c release. Tiron treatment also protected against the bortezomib-induced PARP protein cleavage and cell death. Benzyloxycarbonyl-VAD-fluoromethyl ketone, an inhibitor of pan-caspase, did not alter the bortezomib-induced ROS generation and increase in Delta psi m, although it prevented bortezomib-induced poly(ADP-ribose) polymerase cleavage and apoptotic death. In PC-3 prostate carcinoma cells (with overexpression of Bcl-2), a reduction of bortezomib-induced ROS generation, Delta psi m increase was correlated with cellular resistance to bortezomib and the attenuation of drug-induced apoptosis. The transient transfection of wild type p53 in p53 null H358 cells caused stimulation of the bortezomib-induced apoptosis but failed to enhance ROS generation and Delta psi m increase. Thus ROS generation plays a critical role in the initiation of the bortezomib-induced apoptotic cascade by mediation of the disruption of Delta psi m and the release of cytochrome c from mitochondria.
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PMID:Reactive oxygen species generation and mitochondrial dysfunction in the apoptotic response to Bortezomib, a novel proteasome inhibitor, in human H460 non-small cell lung cancer cells. 1282 77

Bortezomib is a proteasome inhibitor for the treatment of relapsed/refractory multiple myeloma (MM). Mechanisms of resistance to Bortezomib are undefined. Myeloid cell leukemia-1 (Mcl-1) is an antiapoptotic protein, which protects tumor cells against spontaneous and chemotherapy-induced apoptosis. In MM, specific downregulation of Mcl-1 induces apoptosis. Here, we examined the role of Mcl-1 in Bortezomib- and doxorubicin-induced apoptosis. We demonstrate that Bortezomib, but not doxorubicin, triggers caspase-dependent generation of a 28 kDa Mcl-1-fragment, in several MM cell lines, including MM.1S cells. Conversely, transient transfection of MM.1S cells with a previously reported 28 kDa Mcl-1(128-350) fragment, but not with the Mcl-1(1-127) fragment, induces apoptosis. Therefore, both downregulation of full-length antiapoptotic Mcl-1, as well as Bortezomib-induced generation of Mcl-1(128-350) cleaved protein, contribute to MM cell apoptosis. To verify further these findings, we next compared effects triggered by Bortezomib, doxorubicin and melphalan in Mcl-1(wt/wt) and Mcl-1(Delta/null) murine embryonic fibroblasts (MEFs). Our results show that Bortezomib, but not doxorubicin or melphalan, triggers Mcl-1 cleavage in Mcl-1(wt/wt), but not Mcl-1(Delta/null) MEFs and induces sub-G(1) phase cells; caspase-3 and -9, and PARP cleavage as well as morphological signs of apoptosis. Taken together, these results support an important role of Mcl-1 and a Mcl-1 fragment in Bortezomib-induced cell death in general, and in MM in particular. To prevent relapse of MM in patients treated with Bortezomib, we therefore recommend the combination of Bortezomib with agents that induce MM cell death independent of Mcl-1.
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PMID:A pivotal role for Mcl-1 in Bortezomib-induced apoptosis. 1765 83

The Hodgkin cells and Reed-Sternberg cells (HRS) of classical Hodgkin lymphoma (CHL) are derived from germinal center B cells. The pathogenesis of CHL is unclear but constitutive activation of NFkappaB may contribute. Proteasome inhibition aimed at inhibiting NFkappaB has been shown to result in apoptosis in HRS cells. Here we investigated the effects of bortezomib, a proteasome inhibitor, in HRS cells with a combination of functional assays and gene expression profiling (GEP). Exposure of KMH2 and L428 cells to bortezomib resulted in inhibition of proliferation and induction of apoptosis. Gene expression analysis of KMH2 cells by oligonucleotide cDNA microarrays showed that a limited set of genes were differentially expressed involving several key cellular pathways including cell cycle and apoptosis. Among them, the caspase 8 inhibitor cFLIP was down-regulated and confirmed by Q-PCR. Given the evidence that cFLIP in HRS cells contribute to cells' insensitive to death receptor-mediated apoptosis, we combined bortezomib and TRAIL. This combination caused further down-regulation of cFLIP protein and increased apoptosis in CHL cells demonstrated by PARP p85 immunohistochemistry and immunoblotting. Such apoptotic effects were inhibited by caspase inhibitor z-VAD-FMK, confirming the pro-apoptotic effects of bortezomib and TRAIL are caspase-dependent. Bortezomib has no detectable effect on expression of TRAIL receptor DR4/DR5 in these two cell lines. Tissue microarray analysis of primary Hodgkin lymphomas displayed that 82% cases (95/116) expressed cFLIP in Reed-Sternberg cells. The discovery of apoptotic pathways that can be manipulated by proteasome inhibition provides rationale for the combination of bortezomib and agents such as TRAIL in CHL treatment.
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PMID:Bortezomib induces caspase-dependent apoptosis in Hodgkin lymphoma cell lines and is associated with reduced c-FLIP expression: a gene expression profiling study with implications for potential combination therapies. 1765 39

EWS-Fli1 plays important roles in oncogenesis of Ewing's family tumors (EFTs). We have reported that EWS-Fli1 inhibits p21(waf1/cip1) and p27(kip1) expressions, which are degraded by the ubiquitin-proteasome pathway. Bortezomib efficiently up-regulated p21(waf1/cip1) and p27(kip1) expression, and induced apoptosis accompanied by the expression of cleaved-PARP, DR4 and activated caspase-8 in EFT cells. Since most EFTs deaths result from the tumor being resistant to chemotherapeutic drugs, the effects of novel anti-tumor reagents on drug-resistant tumors were next investigated. The results demonstrated that the drug-resistant EFT clones were cross-resistant to bortezomib probably due to the over-expression of the efflux pumps, P-glycoprotein and MRP1. We further investigated whether the efflux pump inhibitors would modulate the effects of bortezomib. The combination of P-gp-specific or MRP1-specific inhibitors could enhance the anti-tumor effects of bortezomib on the drug-resistant clones. These data suggest that bortezomib might be a substrate of P-gp and MRP1. Although bortezomib would be effective on the primary EFTs, it is necessary to pay attention to the resistance to bortezomib in clinical trials for the advanced cases. The combination of bortezomib and the efflux pump inhibitors might be a promising method as a novel molecular target therapy for advanced EFTs.
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PMID:The mechanism of cross-resistance to proteasome inhibitor bortezomib and overcoming resistance in Ewing's family tumor cells. 1778 11

Our recent study demonstrated that a novel proteasome inhibitor NPI-0052 triggers apoptosis in multiple myeloma (MM) cells, and importantly, that is distinct from bortezomib (Velcade) in its chemical structure, effects on proteasome activities, and mechanisms of action. Here, we demonstrate that combining NPI-0052 and bortezomb induces synergistic anti-MM activity both in vitro using MM cell lines or patient CD138(+) MM cells and in vivo in a human plasmacytoma xenograft mouse model. NPI-0052 plus bortezomib-induced synergistic apoptosis is associated with: (1) activation of caspase-8, caspase-9, caspase-3, and PARP; (2) induction of endoplasmic reticulum (ER) stress response and JNK; (3) inhibition of migration of MM cells and angiogenesis; (4) suppression of chymotrypsin-like (CT-L), caspase-like (C-L), and trypsin-like (T-L) proteolytic activities; and (5) blockade of NF-kappaB signaling. Studies in a xenograft model show that low dose combination of NPI-0052 and bortezomib is well tolerated and triggers synergistic inhibition of tumor growth and CT-L, C-L, and T-L proteasome activities in tumor cells. Immununostaining of MM tumors from NPI-0052 plus bortezomib-treated mice showed growth inhibition, apoptosis, and a decrease in associated angiogenesis. Taken together, our study provides the preclinical rationale for clinical protocols evaluating bortezomib together with NPI-0052 to improve patient outcome in MM.
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PMID:Combination of proteasome inhibitors bortezomib and NPI-0052 trigger in vivo synergistic cytotoxicity in multiple myeloma. 1800 97

Bortezomib (VELCADE), formerly known as PS-341, is a novel dipeptide boronic acid proteasome inhibitor with in vitro and in vivo anti-tumor activity. Bortezomib has been approved for the treatment of multiple myeloma and mantle cell lymphoma. In this report, we examined the sensitivity of cell lines derived from Ewing's sarcoma-family of tumors (ESFT) to Bortezomib. Five ESFT-derived cell lines, TC-71, TC-32, SK-N-MC, A4573 and GRIMES, were highly sensitive to Bortezomib (IC(50) = 20 to 50 nM), and underwent cell cycle arrest and apoptosis following drug treatment. Bortezomib-induced apoptosis was associated with activation of caspase 3, cleavage of PARP and induction of p27 and p21 expression. Moreover, Bortezomib exhibited synergistic activity against the TC-71 and TC-32 cell lines when combined with TRAIL. Our results suggest that Bortezomib might be a useful agent for treatment of ESFT, when used alone or in combination with TRAIL.
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PMID:Proteasome inhibitor Bortezomib induces cell cycle arrest and apoptosis in cell lines derived from Ewing's sarcoma family of tumors and synergizes with TRAIL. 1822 18

This study investigated the biological significance of the inhibition of fatty acid synthase (FAS) in multiple myeloma (MM) using the small molecule inhibitor Cerulenin. Cerulenin triggered growth inhibition in both MM cell lines and MM patient cells, and overcame the survival and growth advantages conferred by interleukin-6, insulin-like growth factor-1, and bone marrow stromal cells. It induced apoptosis in MM cell lines with only modest activation of caspase -8, -9, -3 and PARP; moreover, the pan-caspase inhibitor Z-VAD-FMK did not inhibit Cerulenin-induced apoptosis and cell death. In addition, treatment of MM cells with Cerulenin primarily up-regulated apoptosis-inducing factor/endonuclease G, mediators of caspase-independent apoptosis. Importantly, Cerulenin induced endoplasmic reticulum stress response via up-regulation of the Grp78/IRE1alpha/JNK pathway. Although the C-Jun-NH(2)-terminal kinase (JNK) inhibitor SP600215 blocked Cerulenin-induced cytotoxicity, it did not inhibit apoptosis and caspase cleavage. Furthermore, Cerulenin showed synergistic cytotoxic effects with various agents including Bortezomib, Melphalan and Doxorubicin. Our results therefore indicate that inhibition of FAS by Cerulenin primarily triggered caspase-independent apoptosis and JNK-dependent cytotoxicity in MM cells. This report demonstrated that inhibition of FAS has anti-tumour activity against MM cells, suggesting that it represents a novel therapeutic target in MM.
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PMID:Fatty acid synthase is a novel therapeutic target in multiple myeloma. 2071 68

In recent studies, we and others showed that autophagy is critical to estrogen receptor positive (ER+) breast cancer cell survival and the development of antiestrogen resistance. Consequently, new approaches are warranted for targeting autophagy in breast cancer cells undergoing antiestrogen therapy. Because crosstalk has been demonstrated between the autophagy- and proteasome-mediated pathways of protein degradation, this study investigated how the proteasome inhibitor bortezomib affects autophagy and cell survival in antiestrogen-treated ER+ breast cancer cells. Bortezomib, at clinically achievable doses, induced a robust death response in ER+, antiestrogen-sensitive and antiestrogen-resistant breast cancer cells undergoing hormonal therapy. Cleavage of PARP and lamin A was detectable as a read-out of cell death, following bortezomib-induced mitochondrial dysfunction. Prior to induction of cell death, bortezomib-treated cells showed high levels of light chain 3 (LC3) and p62, two protein markers for autophagy. The accumulation of these proteins was due to bortezomib-mediated blockade of long-lived protein turnover during macroautophagy. This novel action of bortezomib was linked to its blockade of cathepsin-L activity, which is required for autolysosomal-mediated protein turnover in ER+ breast cancer cells. Further, bortezomib-treated breast cancer cells showed induction of the unfolded protein response, with upregulation of CH OP and GRP78. Bortezomib also induced high levels of the pro-apoptotic protein BNIP3. Knockdown of CH OP and/or BNIP3 expression via RNAi targeting significantly attenuated the death-promoting effects of bortezomib. Thus, bortezomib inhibits prosurvival autophagy, in addition to its known function in blocking the proteasome, and is cytotoxic to hormonally treated ER+ breast cancer cells. These findings indicate that combining a proteasome inhibitor like bortezomib with antiestrogen therapy may have therapeutic advantage in the management of early-stage breast cancer.
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PMID:Bortezomib blocks the catabolic process of autophagy via a cathepsin-dependent mechanism, affects endoplasmic reticulum stress and induces caspase-dependent cell death in antiestrogen-sensitive and resistant ER+ breast cancer cells. 2011 Jul 75

Neuroblastoma (NB), the most frequent solid tumor of early childhood, is diagnosed as a disseminated disease in >60% of cases, and several lines of evidence support the resistance to apoptosis as a prerequisite for NB progression, and new treatment modalities or potent drugs are further needed. Bortezomib owns a substantial cytotoxicity through regulating degradation of protein associated with cell cycle control and tumor growth. The involvement of bortezomib in neuroblastoma is largely unkown. The aim of this study was to investigate the effects and mechanisms of bortezomib on human neuroblastoma CHP126 cells. Our results indicated that bortezomib inhibits proliferation of neuroblastoma cells in a time- and dose- dependent manner, and the concentration that caused 50% inhibition of CHP126 cells growth was 11.25 nM. Furthermore, bortezomib-induced proliferation inhibition results from massive cell death characterized by apoptosis. Besides, the NFkappaB pathway was not involved in bortezomib treatment in neuroblastoma CHP126 cells, bortezomib-driven apoptotic events were associated with promoting p21 and Bax expression and down-regulating Bcl-2 expression. Ultimately, caspase-3 was activated and the cleavage of PARP was induced. Above all, our data revealed that bortezomib triggered apoptosis by enhancing the caspase 3 activation and/or modulating the Bax/Bcl-2 balance, and also provided preliminary data for further researches of bortezomib on pediatric neuroblastoma.
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PMID:Bortezomib induces apoptosis in human neuroblastoma CHP126 cells. 2038 43

The proteasome inhibitor bortezomib (B) has been shown to enhance gemcitabine (G) effects against pancreatic ductal adenocarcinoma (PDAC). Endothelial monocyte activating polypeptide II (EMAP, E) is an antiendothelial and antiangiogenic cytokine. We tested the combination effects of bortezomib, gemcitabine and EMAP in experimental PDAC. Bortezomib inhibited the in vitro proliferation of PDAC and endothelial cells, with additive effects in combination with gemcitabine or EMAP. Bortezomib induced apoptosis as observed by PARP-1 cleavage; it also increased the expression of p21 (>27-fold) and p27 (>2.5-fold), with additive effects in combination with gemcitabine and EMAP. Bortezomib caused a decrease in the expression of the antiapoptotic protein Bcl-2, and an increase in the proapoptotic protein Bax and in p53. Bortezomib had no effect on the intracellular levels of full length or mature EMAP. An in vivo murine xenograft model showed extended survival in all combination groups except B + E compared with control or monotherapy, but no benefit of B + E + G over E + G. The relative local tumor growth compared to controls after bortezomib, EMAP, gemcitabine, B + G, E + G or B + E + G was 92, 52, 48, 36, 18 and 35%, respectively. Our results show that in vitro bortezomib had an antiproliferative and proapoptotic effect, and it's combination with gemcitabine and EMAP increased these effects. In vivo, bortezomib had no antitumor effect by itself, enhanced gemcitabine effects in combination, but failed to further significantly improve the E + G combination benefit. The potential value of proteasome inhibition in experimental therapy approaches for PDAC appears to relate primarily to the combination with the cytotoxic drug rather than with the antiendothelial agent.
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PMID:Combination effects of bortezomib with gemcitabine and EMAP II in experimental pancreatic cancer. 2058 50


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