benzyloxycarbonylleucyl-leucyl-leucine-aldehyde and Pancreatic-Neoplasms
benzyloxycarbonylleucyl-leucyl-leucine-aldehyde has been researched along with Pancreatic-Neoplasms* in 16 studies
Other Studies
16 other study(ies) available for benzyloxycarbonylleucyl-leucyl-leucine-aldehyde and Pancreatic-Neoplasms
Article | Year |
---|---|
CSN6 inhibition suppresses pancreatic adenocarcinoma metastasis via destabilizing the c-Fos protein.
Deubiquitinase (DUB) can reverse the ubiquitin signal, and participate in virtually all aspects of cancer progression. Thus, DUB represents an attractive target for development of anticancer drugs. However, little is known about DUB which can be used as drug targets. Here, we found that the constitutive photomorphogenic 9 (COP9) signalosome complex subunit 6 (COPS6/CSN6), a DUB belongs to JAMM/MPN domain-associated metallopeptidases(JAMMs) class, was highly expressed in pancreatic adenocarcinoma(PAAD) tissues. High expression of CSN6 was associated with tumor TNM stage and metastasis in PAAD patients. Moreover, we demonstrated that CSN6 promoted invasion and metastasis through regulating forkhead box protein A1 (FOXA1) in PAAD cells. Re-expression of FOXA1 rescued the decreased invasion and metastasis caused by CSN6 knockdown, whereas inhibition of FOXA1 alleviated the pro-metastasis effect induced by CSN6 overexpression. Further, CSN6 regulated the expression of FOXA1 via c-Fos in PAAD cells. Mechanistically, CSN6 stabilized c-Fos protein by binding to it and decreasing its ubiquitination. Our work identified CSN6 as a targeting-permissible deubiquitinase, and CSN6 inhibition maybe a potential treatment strategy for PAAD. Topics: Adaptor Proteins, Signal Transducing; Adenocarcinoma; Aged; Cell Line, Tumor; Cell Movement; Cell Proliferation; COP9 Signalosome Complex; Female; Gene Expression Regulation, Neoplastic; Hepatocyte Nuclear Factor 3-alpha; Humans; Leupeptins; Lymphatic Metastasis; Male; Middle Aged; Neoplasm Staging; Pancreatic Neoplasms; Proteasome Endopeptidase Complex; Proto-Oncogene Proteins c-fos; RNA, Small Interfering; Signal Transduction; Survival Analysis; Ubiquitin; Ubiquitination; Xenograft Model Antitumor Assays | 2020 |
Construction of a circRNA-miRNA-mRNA network to explore the pathogenesis and treatment of pancreatic ductal adenocarcinoma.
Many studies focusing on circular RNAs (circRNAs) have recently been published. However, a large number of circRNAs remain to be explored. This study was designed to discover new circRNAs and investigate their potential roles in the pathogenesis of pancreatic ductal adenocarcinoma (PDAC).. A combination of gene chip analysis and bioinformatic methods was utilized to reveal new circRNAs and their possible mechanisms in PDAC. A circRNA-miRNA-mRNA network was established based on the results of differential analyses and interaction predictions. Promising drugs for treating PDAC were determined by connectivity map (CMap) analysis.. Expression profile data were collected from the Gene Expression Omnibus database, and integration of differentially expressed circRNAs (DECs) from two gene chips using the RobustRankAggreg method revealed 10 DECs. The microRNA (miRNA) response elements of these 10 DECs were predicted. The predicted miRNAs and differentially expressed miRNAs were intersected, and 12 overlapping miRNAs were acquired. Next, 2908 miRNA target mRNAs and 1187 differentially expressed genes (DEGs) in PDAC were identified and combined, revealing 118 overlapping mRNAs. A protein-protein interaction network was constructed with the 118 mRNAs, and four hub genes (CDH1, SERPINE1, IRS1 and FYN) were identified. Using Gene Expression Profiling Interactive Analysis, survival analyses were conducted for the four hub genes, and SERPINE1 and FYN were found to be significantly associated with PDAC patient survival. Functional enrichment analysis indicated that these four hub genes are closely associated with certain cancer-related biological functions and pathways. In addition, CMap analysis based on the four hub genes was performed to screen potential therapeutic agents for PDAC, and three bioactive chemicals (celastrol, 5109870 and MG-132) were discovered.. The results of this study further our understanding of the pathogenesis and treatment of PDAC from the perspective of the circRNA-related competing endogenous RNA network. Topics: Antineoplastic Agents; Carcinoma, Pancreatic Ductal; Computational Biology; Gene Expression Profiling; Gene Expression Regulation, Neoplastic; Gene Regulatory Networks; HL-60 Cells; Humans; Imidazoles; Leupeptins; MicroRNAs; Oligonucleotide Array Sequence Analysis; Pancreatic Neoplasms; Pentacyclic Triterpenes; Phosphorylation; Protein Interaction Maps; RNA, Circular; RNA, Messenger; Software; Treatment Outcome; Triterpenes | 2020 |
Apigenin: Selective CK2 inhibitor increases Ikaros expression and improves T cell homeostasis and function in murine pancreatic cancer.
Pancreatic cancer (PC) evades immune destruction by favoring the development of regulatory T cells (Tregs) that inhibit effector T cells. The transcription factor Ikaros is critical for lymphocyte development, especially T cells. We have previously shown that downregulation of Ikaros occurs as a result of its protein degradation by the ubiquitin-proteasome system in our Panc02 tumor-bearing (TB) mouse model. Mechanistically, we observed a deregulation in the balance between Casein Kinase II (CK2) and protein phosphatase 1 (PP1), which suggested that increased CK2 activity is responsible for regulating Ikaros' stability in our model. We also showed that this loss of Ikaros expression is associated with a significant decrease in CD4+ and CD8+ T cell percentages but increased CD4+CD25+ Tregs in TB mice. In this study, we evaluated the effects of the dietary flavonoid apigenin (API), on Ikaros expression and T cell immune responses. Treatment of splenocytes from naïve mice with (API) stabilized Ikaros expression and prevented Ikaros downregulation in the presence of murine Panc02 cells in vitro, similar to the proteasome inhibitor MG132. In vivo treatment of TB mice with apigenin (TB-API) improved survival, reduced tumor weights and prevented splenomegaly. API treatment also restored protein expression of some Ikaros isoforms, which may be attributed to its moderate inhibition of CK2 activity from splenocytes of TB-API mice. This partial restoration of Ikaros expression was accompanied by a significant increase in CD4+ and CD8+ T cell percentages and a reduction in Treg percentages in TB-API mice. In addition, CD8+ T cells from TB-API mice produced more IFN-γ and their splenocytes were better able to prime allogeneic CD8+ T cell responses compared to TB mice. These results provide further evidence that Ikaros is regulated by CK2 in our pancreatic cancer model. More importantly, our findings suggest that API may be a possible therapeutic agent for stabilizing Ikaros expression and function to maintain T cell homeostasis in murine PC. Topics: Animals; Apigenin; Casein Kinase II; Cell Line, Tumor; Down-Regulation; Female; Homeostasis; Ikaros Transcription Factor; Leupeptins; Lymphocyte Culture Test, Mixed; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Pancreatic Neoplasms; Proteasome Inhibitors; Protein Phosphatase 1; T-Lymphocytes; Tumor Suppressor Proteins | 2017 |
Chidamide Inhibits Aerobic Metabolism to Induce Pancreatic Cancer Cell Growth Arrest by Promoting Mcl-1 Degradation.
Pancreatic cancer is a fatal malignancy worldwide and urgently requires valid therapies. Previous research showed that the HDAC inhibitor chidamide is a promising anti-cancer agent in pancreatic cancer cell lines. In this study, we elucidate a probable underlying anti-cancer mechanism of chidamide involving the degradation of Mcl-1. Mcl-1 is frequently upregulated in human cancers, which has been demonstrated to participate in oxidative phosphorylation, in addition to its anti-apoptotic actions as a Bcl-2 family member. The pancreatic cancer cell lines BxPC-3 and PANC-1 were treated with chidamide, resulting in Mcl-1 degradation accompanied by induction of Mcl-1 ubiquitination. Treatment with MG132, a proteasome inhibitor reduced Mcl-1 degradation stimulated by chidamide. Chidamide decreased O2 consumption and ATP production to inhibit aerobic metabolism in both pancreatic cancer cell lines and primary cells, similar to knockdown of Mcl-1, while overexpression of Mcl-1 in pancreatic cancer cells could restore the aerobic metabolism inhibited by chidamide. Furthermore, chidamide treatment or Mcl-1 knockdown significantly induced cell growth arrest in pancreatic cancer cell lines and primary cells, and Mcl-1 overexpression could reduce this cell growth inhibition. In conclusion, our results suggest that chidamide promotes Mcl-1 degradation through the ubiquitin-proteasome pathway, suppressing the maintenance of mitochondrial aerobic respiration by Mcl-1, and resulting in inhibition of pancreatic cancer cell proliferation. Our work supports the claim that chidamide has therapeutic potential for pancreatic cancer treatment. Topics: Aminopyridines; Benzamides; Cell Cycle Checkpoints; Cell Line, Tumor; Gene Knockdown Techniques; Humans; Leupeptins; Myeloid Cell Leukemia Sequence 1 Protein; Oxidative Phosphorylation; Oxygen Consumption; Pancreatic Neoplasms; Proteasome Endopeptidase Complex; Proteolysis; Ubiquitin | 2016 |
Synergistic antitumor effects of radiation and proteasome inhibitor treatment in pancreatic cancer through the induction of autophagy and the downregulation of TRAF6.
Ninety percent of human pancreatic cancer is characterized by activating K-RAS mutations. TRAF6 is an oncogene that plays a vital role in K-RAS-mediated oncogenesis. We investigated the synergistic effect of combining ionizing radiation (IR) and proteasome inhibitor (MG132). Furthermore, following combined treatment with IR and MG132, we analyzed the expression of TRAF6 and the mechanism of human pancreatic cancer cell death in vitro and in an orthotopic pancreatic cancer mouse model. The combined treatment groups displayed synergistic cell killing effects and induced endoplasmic reticulum stress in human pancreatic cancer cells. The combined treatment groups were characterized by enhanced cytotoxicity, which resulted from increased autophagy induction through the inhibition of TRAF6. Significantly reduced cytotoxicity was observed following MG132 and IR treatment of MIA PaCa-2 cells pre-treated with 3-MA (an autophagy inhibitor). Down-regulation of TRAF6 led to a significant increase in apoptosis and autophagy. In an orthotopic xenograft model of SCID mice, combination MG132 and IR therapy resulted in a significant increase in the tumor growth delay time and a decreased tumor tissue expression of TRAF6. IR combined with a proteasome inhibitor or TRAF6 inhibition could represent a new therapeutic strategy for human pancreatic cancer. Topics: Animals; Apoptosis; Autophagy; Cell Line, Tumor; Cell Proliferation; Cell Survival; Combined Modality Therapy; Down-Regulation; Endoplasmic Reticulum Stress; Humans; Leupeptins; Mice; Mice, SCID; Neoplasm Transplantation; Pancreatic Neoplasms; Proteasome Inhibitors; RNA Interference; RNA, Small Interfering; TNF Receptor-Associated Factor 6; Transplantation, Heterologous | 2015 |
Oxidative inhibition of Hsp90 disrupts the super-chaperone complex and attenuates pancreatic adenocarcinoma in vitro and in vivo.
Pancreatic cancer is almost always fatal, in part because of its delayed diagnosis, poor prognosis, rapid progression and chemoresistance. Oncogenic proteins are stabilized by the Hsp90, making it a potential therapeutic target. We investigated the oxidative stress-mediated dysfunction of Hsp90 and the hindrance of its chaperonic activity by a carbazole alkaloid, mahanine, as a strategic therapeutic in pancreatic cancer. Mahanine exhibited antiproliferative activity against several pancreatic cancer cell lines through apoptosis. It induced early accumulation of reactive oxygen species (ROS) leading to thiol oxidation, aggregation and dysfunction of Hsp90 in MIAPaCa-2. N-acetyl-L-cysteine prevented mahanine-induced ROS accumulation, aggregation of Hsp90, degradation of client proteins and cell death. Mahanine disrupted Hsp90-Cdc37 complex in MIAPaCa-2 as a consequence of ROS generation. Client proteins were restored by MG132, suggesting a possible role of ubiquitinylated protein degradation pathway. Surface plasmon resonance study demonstrated that the rate of interaction of mahanine with recombinant Hsp90 is in the range of seconds. Molecular dynamics simulation showed its weak interactions with Hsp90. However, no disruption of the Hsp90-Cdc37 complex was observed at an early time point, thus ruling out that mahanine directly disrupts the complex. It did not impede the ATP binding pocket of Hsp90. Mahanine also reduced in vitro migration and tube formation in cancer cells. Further, it inhibited orthotopic pancreatic tumor growth in nude mice. Taken together, these results provide evidence for mahanine-induced ROS-mediated destabilization of Hsp90 chaperone activity resulting in Hsp90-Cdc37 disruption leading to apoptosis, suggesting its potential as a specific target in pancreatic cancer. Topics: Acetylcysteine; Adenocarcinoma; Adenosine Triphosphate; Alkaloids; Animals; Antineoplastic Agents; Apoptosis; Carbazoles; Cell Cycle Proteins; Cell Line, Tumor; Cell Movement; Cell Proliferation; Cell Survival; Chaperonins; HSP90 Heat-Shock Proteins; Humans; Leupeptins; Mice; Mice, Nude; Oxidative Stress; Pancreatic Neoplasms; Reactive Oxygen Species; Sulfhydryl Compounds | 2013 |
Noxa/Mcl-1 balance influences the effect of the proteasome inhibitor MG-132 in combination with anticancer agents in pancreatic cancer cell lines.
Pancreatic cancer progresses aggressively and owing to chemoresistance responds poorly to chemotherapy. Thus, there is an urgent need to understand the mechanisms of cancer cell resistance to generate effective strategies to circumvent intrinsic chemoresistance in this tumour indication. In this study, three pancreatic cancer cell lines, MIA PaCa-2, MDAPanc-3 and AsPC-1, were treated with the proteasome inhibitor MG-132 together with camptothecin, doxorubicin or paclitaxel, and cytotoxicity was measured using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The combination of MG-132 and camptothecin at a ratio of 5 : 1 gave the most promising results and enhanced cytotoxicity compared with the single compounds in MIA PaCa-2 cells. The increase was shown to be due to enhanced caspase-3 activity resulting in apoptosis. Moreover, this combination upregulated the levels of the proapoptotic protein Noxa and reduced the levels of the antiapoptotic protein Mcl-1, as demonstrated by western blotting. In contrast, the combination of MG-132 with doxorubicin also induced increased cytotoxicity, but apoptosis was decreased. The lack of an enhanced apoptosis induction could be correlated with high levels of Mcl-1 in response to the combined treatment with MG-132 and doxorubicin. Thus, the results indicate that regulation of the antiapoptotic and proapoptotic Bcl-2 family members Noxa and Mcl-1 is predicative of the effectiveness of the combination of MG-132 with different anticancer agents on apoptosis induction in pancreatic cancer cells. Topics: Antineoplastic Agents; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Camptothecin; Caspase 3; Caspase 7; Cell Line, Tumor; Doxorubicin; Humans; Leupeptins; Myeloid Cell Leukemia Sequence 1 Protein; NF-kappa B; Paclitaxel; Pancreatic Neoplasms; Proteasome Inhibitors; Proto-Oncogene Proteins c-bcl-2 | 2012 |
SIRT1 inhibits proliferation of pancreatic cancer cells expressing pancreatic adenocarcinoma up-regulated factor (PAUF), a novel oncogene, by suppression of β-catenin.
Because we found in a recent study that pancreatic adenocarcinoma up-regulated factor (PAUF), a novel oncogene, induces a rapid proliferation of pancreatic cells by up-regulation of β-catenin, we postulated that β-catenin might be a target molecule for pancreatic cancer treatment. We thus speculated whether SIRT1, known to target β-catenin in a colon cancer model, suppresses β-catenin in those pancreatic cancer cells that express PAUF (Panc-PAUF). We further evaluated whether such suppression would lead to inhibition of the proliferation of these cells. The ectopic expression of either SIRT1 or resveratrol (an activator of SIRT1) suppressed levels of β-catenin protein and its transcriptional activity in Panc-PAUF cells. Conversely, suppression of SIRT1 expression by siRNA enhanced β-catenin expression and transcriptional activity. SIRT1 mutant analysis showed that nuclear localization of SIRT1 is not required for reduction of β-catenin. Treatment with MG132, a proteasomal inhibitor, restored β-catenin protein levels, suggesting that SIRT1-mediated degradation of β-catenin requires proteasomal activity. It was reported that inhibition of GSK-3β or Siah-1 stabilizes β-catenin in colon cancer cells, but suppression of GSK-3β or Siah-1 using siRNA in the presence of resveratrol instead diminished β-catenin protein levels in Panc-PAUF cells. This suggests that GSK-3β and Siah-1 are not involved in SIRT1-mediated degradation of β-catenin in the cells. Finally, activation of SIRT1 inhibited the proliferation of Panc-PAUF cells by down-regulation of cyclin-D1, a target molecule of β-catenin. These results suggest that SIRT1 activation may be a therapeutic strategy for treatment of pancreatic cancer cells that express PAUF via the down-regulation of β-catenin. Topics: beta Catenin; Cell Line, Tumor; Cell Nucleus; Cell Proliferation; Cyclin D1; Gene Expression Regulation, Neoplastic; HEK293 Cells; Humans; Intercellular Signaling Peptides and Proteins; Lectins; Leupeptins; Oncogenes; Pancreatic Neoplasms; Proteasome Endopeptidase Complex; Proteolysis; Sirtuin 1 | 2012 |
Proteasome inhibitor MG132 inhibits angiogenesis in pancreatic cancer by blocking NF-kappaB activity.
Since angiogenesis enables solid tumors, including pancreatic cancer (PaCa), to grow and metastasize, the development of anti-angiogenic agents is currently one of the urgent issues. Proteasome inhibitors are well known for inhibiting nuclear factor-kappa B (NF-kappaB) activity in various cancer cells, but little is known about their biologic mechanisms against angiogenesis in PaCa. We divided human PaCa cell lines into high-angiogenic (BxPC-3 and SW 1990) and low-angiogenic (MIA PaCa-2 and Capan-2) groups. The high-angiogenic PaCa cell lines constitutively expressed high NF-kappaB activity and produced high levels of vascular endothelial growth factor (VEGF) and interleukin 8 (IL-8). The conditioned media from BxPC-3 significantly enhanced both proliferation of and tube formation by human umbilical vein endothelial cells (HUVECs) and these enhancements were significantly inhibited by the proteasome inhibitor MG132 treatment. Collectively, MG132 blocked PaCa-derived VEGF and IL-8 production through inhibition of NF-kappaB activity. Thus, proteasome inhibitors may prove beneficial as anti-angiogenic therapy for PaCa. Our studies show that MG132, a proteasome inhibitor, significantly blocked pancreatic-cancer-associated angiogenesis through inhibition of NF-kappaB and NF-kappaB-dependent proangiogenic gene products VEGF and IL-8. Topics: Antineoplastic Agents; Cell Division; Cell Line, Tumor; Cell Survival; Cysteine Proteinase Inhibitors; Endothelium, Vascular; Humans; In Vitro Techniques; Interleukin-8; Leupeptins; Neovascularization, Pathologic; NF-kappa B; Pancreas; Pancreatic Neoplasms; Umbilical Veins; Vascular Endothelial Growth Factor A | 2010 |
Characterization of BAG3 cleavage during apoptosis of pancreatic cancer cells.
Caspases are a conserved family of cell death proteases that cleave intracellular substrates at Asp residues to modify their function and promote apoptosis. In this report, we identify BAG3 as a novel caspases substrate. Here, we show that one of these BAG proteins, BAG3, is cleaved during apoptosis. BAG3 cleavage is inhibited by several different caspase inhibitors. The analysis of BAG3 cleavage by recombinant caspase proteins shows that BAG3 is efficiently cleaved by caspase-3, to a smaller extent by caspases-1 and -8, and relatively inefficient by caspase-9. Cleavage of the BAG3 protein occurs in the C-terminal part of the protein majorly at Asp347 (KEVD347 downward arrow S) in vitro and in pancreatic cancer SW1990 and PANC-1 cells undergoing apoptosis. We also demonstrate that unlike cleavage of Bcl-2 and Bcl-XL, cleaved form of BAG3 does not result in pro-apoptotic fragments, however, cleavage of BAG3 lead to loss its per se anti-apoptotic property. This novel regulation of BAG3 may have important implications for its role in apoptosis. Topics: Adaptor Proteins, Signal Transducing; Apoptosis; Apoptosis Regulatory Proteins; Aspartic Acid; Caspase Inhibitors; Caspases; Cell Line, Tumor; Cysteine Proteinase Inhibitors; Etoposide; Humans; Leupeptins; Mutation; Pancreatic Neoplasms; Peptide Fragments; Protein Processing, Post-Translational; Protein Structure, Tertiary; Recombinant Proteins; Staurosporine; Time Factors; Transfection; Tumor Necrosis Factor-alpha; Ultraviolet Rays | 2010 |
Intracellular zinc increase inhibits p53(-/-) pancreatic adenocarcinoma cell growth by ROS/AIF-mediated apoptosis.
We show that treatment with non-toxic doses of zinc in association to the ionophore compound pyrrolidine dithiocarbamate (PDTC) inhibits p53(-/-) pancreatic cancer cell growth much more efficiently than gemcitabine, the gold standard chemotherapeutic agent for pancreatic cancer. Both the metal chelator N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine and the radical scavenger N-acetyl-l-cysteine are able to recover cell growth inhibition by Zn/PDTC, demonstrating that this effect depends on the increased levels of intracellular zinc and of reactive oxygen species (ROS). Zn/PDTC treatment induces a strong apoptotic cell death that is associated to ROS-dependent nuclear translocation of the mitochondrial factor AIF, but not to the regulation of apoptotic genes and caspase activation. Primary fibroblasts are more resistant than pancreatic cancer cells to Zn/PDTC treatment and exhibit a lower basal and Zn/PDTC-induced enhancement of intracellular zinc. We show that Zn/PDTC induces p53 proteasomal degradation and that the proteasome inhibitor MG132 further increases fibroblast growth inhibition by Zn/PDTC, suggesting that p53 degradation plays an important role in fibroblast resistance to Zn/PDTC. Topics: Adenocarcinoma; Apoptosis; Apoptosis Inducing Factor; Caspases; Cell Line, Tumor; Cell Nucleus; Cell Proliferation; Drug Screening Assays, Antitumor; Enzyme Activation; Ethylenediamines; Fibroblasts; Humans; Intracellular Space; Leupeptins; Mitochondria; Models, Biological; Pancreatic Neoplasms; Protein Transport; Pyrrolidines; Reactive Oxygen Species; Thiocarbamates; Tumor Suppressor Protein p53; Zinc | 2009 |
Geminin is overexpressed in human pancreatic cancer and downregulated by the bioflavanoid apigenin in pancreatic cancer cell lines.
Pancreatic adeniocarcinoma is among the deadliest of human cancers. Apigenin, an antitumor flavonoid, inhibits pancreatic cancer cell proliferation in vitro. Geminin is a recently identified novel protein that plays a critical role in preventing abnormal DNA replication by binding to and inhibiting the essential replication factor Cdt1. Microarray analysis identified geminin to be downregulated in pancreatic cancer cells treated with apigenin. Therefore, we investigated the effects of apigenin on geminin expression and other proteins involved in replication (Cdc6, Cdt1, and MCM7) in pancreatic cancer cell lines CD18 and S2013. Real time RT-PCR and western blotting analysis showed that geminin expression is downregulated by apigenin at both mRNA and protein levels. Furthermore, treatment of cells with proteosome inhibitor MG132 reversed the downregulation of geminin by apigenin, supporting our hypothesis that the degradation pathway is another mechanism by which apigenin affects geminin expression. Apigenin treatment also resulted in downregulation of Cdc6 at both mRNA and protein levels. However, Cdt1 and MCM7 expression was not affected in apigenin-treated cells. The effect of apigenin treatment on geminin promoter activity was measured by transient transfection of Hela cells with a reporter gene, demonstrating that apigenin inhibited geminin promoter activity. Geminin expression was also evaluated in human pancreatic tissue (n = 15) by immunohistochemistry and showed that geminin is overexpressed in human pancreatic cancer compared to normal adjacent pancreatic tissue. In conclusion, our studies demonstrated that geminin is overexpressed in human pancreatic cancer and downregulated by apigenin which may contribute to the antitumor effect of this natural flavonoid. Topics: Apigenin; Biological Products; Cell Cycle Proteins; Cell Line, Tumor; Down-Regulation; Geminin; Gene Expression Regulation, Neoplastic; Humans; Leupeptins; Nuclear Proteins; Pancreatic Neoplasms; Promoter Regions, Genetic; Proteasome Endopeptidase Complex; Proteasome Inhibitors; RNA, Messenger | 2008 |
The proteasome inhibitor MG132 induces apoptosis in human pancreatic cancer cells.
The ubiquitin-proteasome system plays a critical role in the regulation of programmed cell death. Proteasome inhibitors induce apoptosis in various cancer cells and have antitumor effects in murine tumor models. In the present study, we investigated whether the cell-permeable proteasome inhibitor MG132 (carbobenzoxyl-L-leucyl-L-leucyl-L-leucinal) reduced the growth of a human pancreatic cancer cell line through induction of apoptosis in vitro. The effects of MG132 (0.125-1.000 microM) on the growth of the human pancreatic cancer cell line BxPC-3 were analyzed by cell count and MTT assay. Apoptosis was determined by FACS analysis after annexin V and propidium iodide staining and the enrichment of intracellular nucleosomes. The proteasome inhibitor MG132 decreased cell growth of the human pancreatic cancer cell line BxPC-3 in a dose- and time-dependent manner. This effect was at least in part mediated by the induction of apoptosis. A combination therapy with standard cytotoxic agents and proteasome inhibitors could potentially be a novel therapeutic strategy in treatment of pancreatic cancer. Topics: Apoptosis; Cell Line, Tumor; Cell Proliferation; Cell Survival; Cysteine Proteinase Inhibitors; Dose-Response Relationship, Drug; Flow Cytometry; Humans; Leupeptins; Nucleosomes; Pancreatic Neoplasms; Time Factors | 2005 |
Glial cell line-derived neurotrophic factor enhances nuclear factor-kappaB activity and invasive potential in human pancreatic cancer cells.
The invasive potential is increased by glial cell line-derived neurotrophic factor (GDNF) in human pancreatic cancer cell lines. We researched whether the signaling pathway activated by GDNF correlates with the nuclear factor-kappaB (NF-kappaB) in human pancreatic cancer cell lines and whether the inhibition of NF-kappaB activity is associated with suppression of invasive potential.. Proliferation of human pancreatic cancer cell lines (BxPC-3 and MIA PaCa-2) was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays (MTT assay). NF-kappaB activity was examined by dual luciferase assay and electrophoretic mobility shift assay. In addition, to investigate the invasive potential, an in vitro invasion assay was performed.. Proliferation of both cell lines was decreased by a proteasome inhibitor, MG132, in a dose-dependent manner, but proliferation of control and IkappaBalphaM vector-transfected BxPC-3 cells was similar. The invasion cell number and the NF-kappaB activity were increased by GDNF stimulation. However, in the presence of MG132 or IkappaBalphaM, which blocks the nuclear localization of NF-kappaB, both were significantly suppressed. Furthermore, reduced activity of both remained unchanged by GDNF stimulation.. These results indicate that GDNF promotes NF-kappaB activation and that the latter is involved in the invasive potential of human pancreatic cancer cells. Topics: Cell Division; Cell Line, Tumor; Collagen; Drug Combinations; Gene Expression Regulation, Neoplastic; Genes, Reporter; Glial Cell Line-Derived Neurotrophic Factor; Humans; I-kappa B Proteins; Laminin; Leupeptins; Luciferases; Neoplasm Invasiveness; Neoplasm Proteins; Nerve Growth Factors; NF-kappa B; NF-KappaB Inhibitor alpha; Pancreatic Neoplasms; Proteoglycans; Recombinant Fusion Proteins; Recombinant Proteins; Signal Transduction; Transcriptional Activation; Transfection | 2004 |
Inhibition of NF-kappaB sensitizes human pancreatic carcinoma cells to apoptosis induced by etoposide (VP16) or doxorubicin.
The transcription factor NF-kappaB has anti-apoptotic properties and may confer chemoresistance to cancer cells. Here, we describe human pancreatic carcinoma cell lines that differ in the responsiveness to the topoisomerase-2 inhibitors VP16 (20 microM) and doxorubicin (0.3 microM): Highly sensitive T3M4 [corrected] and PT45-P1 cells, and Capan-1 and A818-4 cells that were almost resistant to both anti cancer drugs. VP16, but not doxorubicin, transiently induced NF-kappaB activity in all cell lines, whereas basal NF-kappaB binding was nearly undetectable in T3M4 [corrected] and PT45-P1 cells, but rather high in Capan-1 and A818-4 cells, as demonstrated by gel-shift and luciferase assays. Treatment with various NF-kappaB inhibitors (Gliotoxin, MG132 and Sulfasalazine), or transfection with the IkappaBalpha super-repressor, strongly enhanced the apoptotic effects of VP16 or doxorubicin on resistant Capan-1 and 818-4 cells. Our results indicate that under certain conditions the resistance of pancreatic carcinoma cells to chemotherapy is due to their constitutive NF-kappaB activity rather than the transient induction of NF-kappaB by some anti-cancer drugs. Blockade of basal NF-kappaB activity by well established drugs efficiently reduces chemoresistance of pancreatic cancer cells and offers the potential for improved therapeutic strategies. Topics: Antineoplastic Agents; Carcinoma; DNA-Binding Proteins; Doxorubicin; Drug Resistance; Etoposide; Gliotoxin; Humans; I-kappa B Proteins; Leupeptins; NF-kappa B; NF-KappaB Inhibitor alpha; Pancreatic Neoplasms; Sulfasalazine | 2001 |
Effects of arachidonic and docosahexaenoic acids on secretion and degradation of bile salt-dependent lipase in AR4-2J cells.
In this study we demonstrated that two polyunsaturated fatty acids, arachidonic acid (AA, n-6) and docosahexaenoic acid (DHA, n-3), modulate the secretion of bile salt-dependent lipase (BSDL) by pancreatic AR4-2J cells. The effects of AA and DHA were also compared with that of the monounsaturated fatty acid, oleic acid (OA). Our results showed that the chronic treatment of cells with AA or DHA, that did not affect the biosynthesis rate of BSDL, similarly decreased the amount of secreted BSDL and perturbed the intracellular partitioning of the enzyme, whereas OA had no effect. Particularly, AA and DHA induced the retention of the enzyme in microsomes and lowered its content in the cell cytosol. We have further shown that AA treatment decreased the ubiquitination of the protein, and consequently diminished its export toward the cytosol, a result that might explain the retention of BSDL in microsomes and correlated with membrane phospholipids alteration. The retained protein was further degraded by a nonproteasomal pathway that likely involves ATP-dependent endoplasmic reticulum proteases. These findings concerning the regulation of the pancreatic BSDL secretion by two polyunsaturated acids, AA and DHA, might be of physiological importance in the plasmatic and cellular cholesterol homeostasis. Topics: Adenosine Triphosphate; Animals; Arachidonic Acid; Bile Acids and Salts; Blotting, Western; Cytosol; Docosahexaenoic Acids; Leupeptins; Lipase; Lipid Metabolism; Microsomes; Oleic Acid; Pancreatic Neoplasms; Rats; Tritium; Tumor Cells, Cultured; Ubiquitin | 2001 |