Difluoromethylornithine Induces Apoptosis through Regulation of AP-1 Signaling via JNK Phosphorylation in Epithelial Ovarian Cancer.
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ABSTRACT:
SUBMITTER: Hwang WY
PROVIDER: S-EPMC8508876 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Background:It has been demonstrated that bufadienolides exert potent anti-cancer activity in various tumor types. However, the mechanisms that underlie their anti-cancer properties remain unclear. Yes-associated protein, a key effector of Hippo signaling, functions as a transcription coactivator, plays oncogenic and tumor suppressor roles under different conditions. Here, we report that arenobufagin (ABF), a representative bufadienolide, induced breast cancer MCF-7 cells to undergo apoptosis, which occurred through the JNK-mediated multisite phosphorylation of YAP. Methods:Cytotoxicity was examined using an MTT assay. ABF-induced apoptosis was measured with a TUNEL assay and Annexin V-FITC/PI double staining assay. Western blotting, immunofluorescence, qRT-PCR and coimmunoprecipitation were employed to assess the expression levels of the indicated molecules. Lose-of-function experiments were carried out with siRNA transfection and pharmacological inhibitors. ABF-induced phosphopeptides were enriched with Ti4+-IMAC chromatography and further subjected to reverse-phase nano-LC-MS/MS analysis. Results:ABF significantly reduced the viability of MCF-7 cells and increased the percentage of early and late apoptotic cells in a concentration- and time-dependent manner. Following ABF treatment, YAP accumulated in the nucleus and bound to p73, which enhanced the transcription of the pro-apoptotic genes Bax and p53AIP1. YAP knock-down significantly attenuated ABF-induced apoptotic cell death. Importantly, we found that the mobility shift of YAP was derived from its phosphorylation at multiple sites, including Tyr357. Moreover, mass spectrometry analysis identified 19 potential phosphorylation sites in YAP, with a distribution of 14 phosphoserine and 5 phosphothreonine residues. Furthermore, we found that the JNK inhibitor SP600125 completely diminished the mobility shift of YAP and its phosphorylation at Tyr357, the binding of YAP and p73, the transcription of Bax and p53AIP1 as well as the apoptosis induced by ABF. These data indicate that ABF induced YAP multisite phosphorylation, which was associated with p73 binding, and that apoptosis was mediated by the JNK signaling pathway. Conclusions:Our data demonstrate that ABF suppresses MCF-7 breast cancer proliferation by triggering the pro-apoptotic activity of YAP, which is mediated by JNK signaling-induced YAP multisite phosphorylation as well as its association with p73. The present work not only provides additional information on the use of ABF as an anti-breast cancer drug, but also offers evidence that the induction of the tumor suppressor role of YAP may be a therapeutic strategy.
| S-EPMC6299615 | biostudies-literature
Project description:The genome of the human immunodeficiency virus type 1 (HIV-1) encodes the canonical retroviral proteins, as well as additional accessory proteins that enhance the expression of viral genes, the infectivity of the virus and the production of virions. The accessory Viral Protein U (Vpu), in particular, enhances viral particle production, while also promoting apoptosis of HIV-infected human T lymphocytes. Some Vpu effects rely on its interaction with the ubiquitin-proteasome protein degradation system, but the mechanisms responsible for its pro-apoptotic effects in vivo are complex and remain largely to be elucidated.We took advantage of the Drosophila model to study the effects of Vpu activity in vivo. Expression of Vpu in the developing Drosophila wing provoked tissue loss due to caspase-dependent apoptosis. Moreover, Vpu induced expression of the pro-apoptotic gene reaper, known to down-regulate Inhibitor of Apoptosis Proteins (IAPs) which are caspase-antagonizing E3 ubiquitin ligases. Indeed, Vpu also reduced accumulation of Drosophila IAP1 (DIAP1). Though our results demonstrate a physical interaction between Vpu and the proteasome-addressing SLIMB/?-TrCP protein, as in mammals, both SLIMB/?TrCP-dependent and -independent Vpu effects were observed in the Drosophila wing. Lastly, the pro-apoptotic effect of Vpu in this tissue was abrogated upon inactivation of the c-Jun N-terminal Kinase (JNK) pathway. Our results in the fly thus provide the first functional evidence linking Vpu pro-apoptotic effects to activation of the conserved JNK pathway.
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Project description:Forkhead transcription factor (Foxo3a) is a downstream effector of JNK-induced tumor suppression. However, it is not clear whether the caveolin-1 (CAV1)-mediated JNK/Foxo3a pathway is involved in cancer cell apoptosis. We found that cordycepin upregulates CAV1 expression, which was accompanied by JNK phosphorylation (p-JNK) and subsequent Foxo3a translocation into the nucleus, resulting in the upregulation of Bax protein expression. Furthermore, we found that CAV1 overexpression upregulated p-JNK, whereas CAV1 siRNA downregulated p-JNK. Additionally, SP600125, a specific JNK inhibitor, significantly increased Foxo3a phosphorylation, which downregulated Foxo3a translocation into the nucleus, indicating that CAV1 mediates JNK regulation of Foxo3a. Foxo3a siRNA downregulated Bax protein and attenuated A549 apoptosis, indicating that the CAV1-mediated JNK/Foxo3a pathway induces the apoptosis of A549 lung cancer cells. Cordycepin significantly decreased tumor volume in nude mice. Taken together, these results indicate that cordycepin promotes CAV1 upregulation to enhance JNK/Foxo3a signaling pathway activation, inducing apoptosis in lung cancer cells, and support its potential as a therapeutic agent for lung cancer.
| S-EPMC5355338 | biostudies-literature
Project description:OBJECTIVE:Epithelial ovarian cancer (EOC) cells are known to be resistant to apoptosis through a mechanism that may involve alteration in their redox balance. NADPH oxidase is a major source of intracellular superoxide, which is converted to the less toxic product by superoxide dismutase (SOD). Superoxide contributes to hypoxia inducible factor (HIF)-1? stabilization. We sought to determine the effects of inhibiting the generation of intracellular reactive oxygen species (ROS) on apoptosis of EOC cells. METHODS:Diphenyleneiodonium (DPI), an irreversible ROS inhibitor, was used to inhibit the generation of ROS in EOC cell lines, SKOV-3 and MDAH-2774, followed by assessment of apoptosis, NADPH oxidase, SOD3 and HIF-1? expression. A combination of immunohistochemistry, immunoprecipitation/western blot, and real-time RT-PCR were utilized to evaluate the expression of these enzymes in EOC cells as well as normal ovarian tissue and ovarian cancer tissue specimens. RESULTS:DPI treatment significantly induced apoptosis in both EOC cell lines as evident by increased caspase-3 activity and TUNEL assay. Additionally, both EOC cell lines were found to express NADPH oxidase, HIF-1?, and SOD3, which were highly sensitive to DPI treatment. DPI treatment resulted in reduced NADPH oxidase, SOD3 and HIF-1? levels. Furthermore, ovarian cancer tissues were found to manifest higher NADPH oxidase levels as compared to normal ovarian tissues. CONCLUSIONS:These data suggest that lowering oxidative stress, possibly through the inhibition of NADPH oxidase, induces apoptosis in ovarian cancer cells and may serve as a potential target for cancer therapy.
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Project description:Neutral sphingomyelinase (nSMase) activation in response to environmental stress or inflammatory cytokine stimuli generates the second messenger ceramide, which mediates the stress-induced apoptosis. However, the signaling pathways and activation mechanism underlying this process have yet to be elucidated. Here we show that the phosphorylation of nSMase1 (sphingomyelin phosphodiesterase 2, SMPD2) by c-Jun N-terminal kinase (JNK) signaling stimulates ceramide generation and apoptosis and provide evidence for a signaling mechanism that integrates stress- and cytokine-activated apoptosis in vertebrate cells. An nSMase1 was identified as a JNK substrate, and the phosphorylation site responsible for its effects on stress and cytokine induction was Ser-270. In zebrafish cells, the substitution of Ser-270 for alanine blocked the phosphorylation and activation of nSMase1, whereas the substitution of Ser-270 for negatively charged glutamic acid mimicked the effect of phosphorylation. The JNK inhibitor SP600125 blocked the phosphorylation and activation of nSMase1, which in turn blocked ceramide signaling and apoptosis. A variety of stress conditions, including heat shock, UV exposure, hydrogen peroxide treatment, and anti-Fas antibody stimulation, led to the phosphorylation of nSMase1, activated nSMase1, and induced ceramide generation and apoptosis in zebrafish embryonic ZE and human Jurkat T cells. In addition, the depletion of MAPK8/9 or SMPD2 by RNAi knockdown decreased ceramide generation and stress- and cytokine-induced apoptosis in Jurkat cells. Therefore the phosphorylation of nSMase1 is a pivotal step in JNK signaling, which leads to ceramide generation and apoptosis under stress conditions and in response to cytokine stimulation. nSMase1 has a common central role in ceramide signaling during the stress and cytokine responses and apoptosis.
| S-EPMC4291487 | biostudies-literature
Project description:Developing new anticancer agents against ovarian cancer is an urgent medical need. MPT0G066, a novel synthetic arylsulfonamide compound, was shown to inhibit cell growth and decrease viability in human ovarian cancer cells. MPT0G066 induced arrest of the cell cycle at the multipolyploidy (MP) phase in SKOV3 and at the G2/M phase in A2780 cells, while increasing the proportion of cells in the subG1. Additionally, MPT0G066 induced c-Jun-NH2 terminal kinase (JNK) activation, influenced cell cycle regulatory and Bcl-2 family proteins, which triggered intrinsic apoptotic pathways through cleavage of caspase-3, -7, -9, and poly-(ADP-ribose) polymerase (PARP). Flow cytometry analysis of p-glycoprotein (p-gp) function showed that MPT0G066 was not a substrate of p-gp. Additionally, it was shown that MPT0G066 could decrease cell viability in multiple-drug-resistant human ovarian cancer cells. Furthermore, the combination of MPT0G066 and cisplatin presented a synergistic cytotoxic effect against ovarian cancer cell lines in vitro. MPT0G066 also significantly suppressed the growth of ovarian carcinoma and potentiated the antineoplastic effects of cisplatin in vivo. In conclusion, these findings indicate that MPT0G066 can be a potential anticancer agent against ovarian cancer that worthy of further development.
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Project description:Colorectal carcinoma (CRC) is the third most common malignant tumor pathology worldwide. Despite progress in surgical procedures and therapy options, CRC is still a considerable cause of cancer-related mortality. In this study, we tested the antitumor effects of shikonin in CRC and tried to identify its potential mechanism. The potential target, molecular mechanism as well as in vitro and in vivo antitumor effects of shikonin in CRC cells were determined by an integrative protocol including quantitative proteomics, RT-PCR, western blotting, RNA interference and overexpression, apoptosis and autophagy assays, etc. Galectin-1 was a potential target of shikonin from the iTRAQ-based proteomic analysis in shikonin-treated SW620 cell. The overexpression and RNA silencing of galectin-1 in two CRC cells suggested that the shikonin sensitivity was correlation to galectin-1 levels. The ROS accumulation induced by shikonin was important to the formation of galectin-1 dimers. Dimer galectin-1 was found to be associated with the activation of JNK and downstream apoptosis or autophagy. Moreover, through functional in vitro studies, we showed that differences in galectin-1 level affected tumor cell proliferation, migration, and invasion. In summary, shikonin induced CRC cells apoptosis and autophagy by targeting galectin-1 and JNK signaling pathway both in vitro and in vivo, which suggested a potential novel therapy target for CRC.
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Project description:Paclitaxel (PTX) has previously been used to treat tumours of various tissue origins, such as lung, breast, ovarian, prostate cancers and leukemia. PTX-induced apoptosis is associated with p38 mitogen-activated protein kinase (p38 MAPK), extracellular signal-regulated kinase (ERK), nuclear factor-kappa B (NF-?B) and c-Jun N-terminal kinase or stress-activated protein kinase (JNK/ SAPK) pathways. Transforming growth factor-beta-activated kinase 1 (TAK1) and TAK1-binding protein 1 (TAB1) play an important role in cell apoptosis through the p38, ERK, NF-?B and JNK signal transduction pathways. To investigate the role of TAK1 in PTX-induced cell apoptosis, we treated HEK293 and 8305C cells with 0-20 µM PTX for 6, 12 or 24 h. To investigate whether TAK1 can cooperate with PTX for cancer treatment, we transfected cells with TAK1, TAB1 or control plasmid and treated them with PTX (3-10 µM) for 9-24 h. Apoptosis rates were analysed by flow cytometry (Annexin V/PI). Endogenous TAK1 and TAB1, caspase-7 cleavage, poly ADP-ribose polymerase (PARP) cleavage, Bcl-xL level, phospho-p44/42, phospho-JNK and phospho-p38 were detected by western blot. We show that in HEK293 and 8305C cells, PTX enhanced the endogenous TAK1/TAB1 level and induced cell apoptosis in a dose- and time-dependent manner. Upon TAK1 overexpression in HEK293 cells treated with PTX, apoptosis rate, JNK phosphorylation and PARP cleavage increased contrary to heat-shocked or untreated cells. CRISPR editing of the tak1 gene upon PTX treatment resulted in lower phospho-JNK and PARP cleavage levels than in cells transfected with the control or the TAK1- or TAB1 + TAK1-containing plasmids. TAK1-K63A could not induce JNK phosphorylation or PARP cleavage. We conclude that PTX induces HEK293 and 8305C cell apoptosis through the TAK1-JNK activation pathway, potentially highlighting TAK1's role in chemosensitivity.
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Project description:Bovine mammary epithelial cells (MAC-Ts) are a common cell line for the study of mammary epithelial inflammation; these cells are used to mechanistically elucidate molecular underpinnings that contribute to bovine mastitis. Bovine mastitis is the most prevalent form of disease in dairy cattle that culminates in annual losses of two billion dollars for the US dairy industry. Thus, there is an urgent need for improved therapeutic strategies. Histone deacetylase (HDAC) inhibitors are efficacious in rodent models of inflammation, yet their role in bovine mammary cells remain unclear. HDACs have traditionally been studied in the regulation of nucleosomal DNA, in which deacetylation of histones impact chromatin accessibility and gene expression. Using MAC-T cells stimulated with tumor necrosis factor ? (TNF-?) as a model for mammary cell inflammation, we report that inhibition of HDACs1 and 2 (HDAC1/2) attenuated TNF-?-mediated inflammatory gene expression. Of note, we report that HDAC1/2-mediated inflammatory gene expression was partly regulated by c-Jun N-terminal kinase (JNK) and extracellular signal-regulated kinase (ERK) phosphorylation. Here, we report that HDAC1/2 inhibition attenuated JNK and ERK activation and thus inflammatory gene expression. These data suggest that HDACs1 and 2 regulate inflammatory gene expression via canonical (i.e., gene expression) and noncanonical (e.g., signaling dependent) mechanisms. Whereas, further studies using primary cell lines and animal models are needed. Our combined data suggest that HDAC1/2-specific inhibitors may prove efficacious for the treatment of bovine mastitis.
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Project description:Myelodysplastic syndromes (MDS) are a diverse group of malignant clonal hematopoietic stem cell disorders characterized by ineffective hematopoiesis, dysplastic cell morphology in one or more hematopoietic lineages, and a risk of progression to acute myeloid leukemia (AML). Approximately 50% of MDS patients respond to current FDA-approved drug therapies but a majority of responders relapse within 2-3 years. There is therefore a compelling need to identify potential new therapies for MDS treatment. We utilized the MDS-L cell line to investigate the anticancer potential and mechanisms of action of a plant-derived compound, Withaferin A (WFA), in MDS. WFA was potently cytotoxic to MDS-L cells but had no significant effect on the viability of normal human primary bone marrow cells. WFA also significantly reduced engraftment of MDS-L cells in a xenotransplantation model. Through transcriptome analysis, we identified reactive oxygen species (ROS)-activated JNK/AP-1 signaling as a major pathway mediating apoptosis of MDS-L cells by WFA. We conclude that the molecular mechanism mediating selective cytotoxicity of WFA on MDS-L cells is strongly associated with induction of ROS. Therefore, pharmacologic manipulation of redox biology could be exploited as a selective therapeutic target in MDS.
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