Treatment of cells with etoposide, a topoisomerase inhibitor that induces doublestrand dna breaks in noncycling cells, showed that the drug induced apoptosis. The therapeutic effects of etoposide vp16, a widely used anticancer agent, on hscs apoptosis and liver fibrosis resolution are still unclear. In addition, vp16 markedly induced apoptosis in panc1 cells in the same manner, which was confirmed by annexin v and pi staining. Effects of vp16 on cell cycle and apoptosis in panc1 cells. Molecular cell article starpap control of bik expression and apoptosis is regulated by nuclear pipkia and pkcd signaling weimin li,1,4 rakesh s. It is also used for hemophagocytic lymphohistiocytosis. It is still unclear, however, if the induction of autophagic processes by etoposide causes cell death or plays a prosurvival function. Etoposide is a commonly used drug in testicular cancer chemotherapy. Apoptosis vs necrosis necrosis is the uncontrolled pathological cell death. That is, this pi3kinase functions in a pathway that prevents apoptosis. This cascade proceeds by coupling dna damage to p53 phosphorylation through the action of dnapk. Caspases are a family of cysteine proteases that are essentially involved in the apoptotic pathway.
Signaling crosstalk of fhit, p53, and p38 in etoposide. A read is counted each time someone views a publication summary such as the title, abstract, and list of authors, clicks on a figure, or views or downloads the fulltext. During camptothecin and etoposide vp16induced apoptosis in hl60 cells, the expression level of cell death receptor3 dr3, cell death receptor4 dr4, and fas remained mostly unchanged, whereas the expression of silencers of death domain sodd and flice inhibitory proteins, inhibitors of the cell death receptor signaling pathways, decreased substantially. The supernatant was then diluted twofold with 50 mm. The mechanism by which vp16 initiates the intracellular apoptotic pathway is not well understood. In contrast with apoptosis, cleanup of cell debris by phagocytes of the immune system is generally more difficult. Normally when something goes wrong in a cell, it is quickly destroyed via apoptosis. Reynolds, and alan eastman2 department of pharmacology. Essential role of caspase8 in p53p73dependent apoptosis. Distinct pathways of apoptosis triggered by fty720. In the present study, we investigated the molecular mechanisms of vp16induced apoptosis in panc1 cells and the change of markers of cscs. Apparently, in jurkat cells, etoposide can induce caspase8 processing and apoptosis in a cd95independent fashion. A small molecule that induces intrinsic pathway apoptosis. However, growing evidence exist that many cancer cells are resistant to its apoptotic effects.
Activation of the er stress signaling pathway leads to the lx2 cell apoptosis induced by vp16. The overexpression of bcl2 gene prevented fty720 and etoposidemediated apoptosis, but not fasmediated apoptosis. Etoposide induces g2m arrest and apoptosis in neural. Etoposide induces apoptosis via the mitochondrial and.
A classic example is antifas mab treatment to induce the extrinsic pathway in fas receptorbearing jurkat cells. These data define a sequence of biochemical events that mediates the apoptosis induced by etoposide. The translocation of bax to the mitochondria induces the mpt. Sustained activation of the jnk cascade and apoptosis by rapamycin are suppressed by wildtype p53, in which the cells are arrested in the g 1 phase 34. Using the apoptosis marker array, we observed that ppip5k1 overexpression resulted in decreased basal levels of multiple components of the death receptor pathway i. Original article role of wnt1induciblesignaling pathway. In addition, mitochondria were demonstrated to play a critical role in fty720triggered cell death, suggesting that this drug has a potent anticancer activity. Etoposide treatment induces proteolytic cleavage of various apoptosisrelated proteins including caspases, iap, and parp. M etoposide for 5 hours serve as a positive control for activated apoptotic cascades. Inhibiting the mtor pathway synergistically enhances. Molecular mechanisms of etoposide pubmed central pmc. Etoposide induced apoptosis in a concentration and timedependent manner, but no signs of preceding maturation or gcsf rescue were detected. Erk pathway is well documented for apoptosis induced by dnadamaging agents, such as etoposide 1215, doxorubicin,1620, uv and gamma irradiation 21.
Etoposide is a commonly used chemotherapy agent with a broad range of antitumor activity. Sclc is a typical example of tumor entity where trail monotherapy is not efficient. The synergistic interaction of rapamycin and etoposide was lower when the cjun pathway was suppressed by a cjun nterminal kinase inhibitor. The role of atm ataxiatelangiectasia mutated in the. A group of intracellular proteases called caspases are responsible for the deliberate disassembly of the cell into apoptotic bodies during apoptosis. Total cell extracts from jurkat cells treated with 25. Our data suggest the importance of caspase8mediated positive feedback amplification in the p53p73dependent apoptosis induced by etoposide in hnscc cells. Vp16 inhibited the growth of cells in a dose and timedependent manner. Synergistic induction of apoptosis in human leukemia t. A protease pathway for the repair of topoisomerase iidna covalent complexes j biol chem 2006 281. Doxorubicin is a key adjuvant drug for breast cancer treatment. To determine whether higher concentrations of etoposide may be inducing apoptosis through the transcriptiondependent actions of p53, we used the small molecule inhibitor pft pft. Likewise, a cell that does not express a necessary receptor cannot be induced to undergo apoptosis by the extrinsic pathway.
This effect was associated with upregulation of phosphorylated cjun and downregulation of bclxl. Molecular cell article university of wisconsinmadison. Smyth research division, the peter maccallum cancer centre, st. The course of etoposideinduced apoptosis from damage to dna. The intrinsic signaling pathway for programmed cell death involves nonreceptormediated intracellular signals, inducing activities in the mitochondria that initiate apoptosis. Both differentiation and caspase2 but not 3mediated apoptosis were. Etoposide, and antifas antibody in human tlymphoma cell.
The course of etoposideinduced apoptosis from damage to dna and p53 activation to mitochondrial release of cytochromec. In addition, blocking of cd95 receptor function with a specific antibody does not inhibit etoposideinduced apoptosis. Our findings suggested that the jnk pathway has a key role in the synergistic induction of apoptosis by the treatment of ovarian cancer cells with rapamycin and etoposide together. The role of atm ataxia telangiectasia mutated in the mitochondrial pathway of apoptosis background ataxiatelangiectasia ataxiatelangiectasia at is a primary immunodeficiency disorder that occurs in an estimated 1 in 40,000 to 1 in 300,000 births leaderman, 2000. Biochemical events lead to characteristic cell changes and death.
At is characterized by progressive cerebellar ataxia, the loss of balance. Based on these results, we next explored the effect of inhibition of the akt survival pathway in enhancing etoposideinduced apoptosis. The response is both time and concentration dependent, suggesting that multiple pathways play a role in triggering the caspase3 activation. It is known that high etoposide concentrations can trigger caspasemediated apoptosis which mainly occurs through the cytocrome ccaspase 9 pathway wang et al. We investigated whether caspase3 was involved in apoptosis induced by vp16 in panc1 cells. However, the molecular pathways that activate germ cell apoptosis in response to etoposide are poorly understood.
Atra and etoposideinduced apoptosis were both mediated through the caspase pathway and were partially blocked with the general caspase inhibitor zvadfmk. Hergenrother1, 1department of chemistry, university of illinois at urbana. Apoptosis is one of the checks and balances built into the cell cycle. Caspases 8, 9 and 3 are situated at pivotal junctions in apoptosis pathways. The aim of this study was to evaluate the participation of p73, a member of the p53 family, in apoptosis induced by etoposide in male germ cells. Etoposide is a wellknown trigger of apoptotic pathways but recent findings suggest its involvement in autophagic pathways as well. A cell cycle analysis of u937 cells treated with 0. The topoisomerase inhibitors camptothecin and etoposide. Two pathways of apoptosis induced with alltrans retinoic. The activation of p53 by etoposide resulted in the upregulation of the proapoptotic protein bax, a result that was prevented by the protein synthesis inhibitor cycloheximide. Camptothecin and etoposideinduced apoptosis in human. Trail is considered as a promising anticancer agent, because of its ability to induce apoptosis in cancer but not in most normal cells. Andrews place, east melbourne 3002, victoria, australia apoptosis plays an important role in cell and tissue homeostasis and in growth control.
Accordingly, inhibition of this kinase by wortmannin potentiates apoptotic cell death. Etoposide induces apoptosis in activated human hepatic. Rapamycin dramatically enhanced apoptosis induced by etoposide and the expression of cleaved caspase 9. These changes include blebbing, cell shrinkage, nuclear fragmentation, chromatin condensation, chromosomal dna fragmentation, and global vague mrna decay. A potential synergistic effect of perifosine and etoposide on cell death was evaluated in doseresponse studies. Significant increases in the proteolysis of cell death substrates and dna fragmentation further verified a caspase 3mediated sensitization in doxorubicin and etoposideinduced apoptosis. Etoposide and teniposide, the epipodophyllotoxins, stabilize the doublestranded dna cleavage normally catalyzed by topoisomerase ii topo ii and inhibit faithful religation of dna breaks 1,2. The components of the apoptotic signalling network. The addition of igfi markedly inhibited etoposideinduced apoptosis in a concentrationdependent manner. Etoposide vp16, an antitumor agent, is a topoisomerase ii inhibitor that causes dna damage. Etoposide induces cell death via mitochondrialdependent. This effect is enhanced by addition of rapamycin which inhibits the mtor pathway. We demonstrated that doxorubicin and etoposide markedly sensitized sclc cells.
Etoposideinduced apoptosis in human hl60 cells is associated with intracellular acidification1 michael a. Distinct pathways of apoptosis triggered by fty720, etoposide. Wnt1induciblesignaling pathway protein 1, lung adenocarcinoma, a549, etoposide, apoptosis introduction lung cancer is the second most common cancer in both men and women, accounting for approximately 15% of all newly diagnosed can. For example, when skin cells are damaged by ultraviolet radiation i. Based on their structure and mechanism of action, topoisomerases are. There are many causes of necrosis including injury, infection, cancer. We find that etoposide does not induce cd95 ligand expression at the mrna level.
Ppip5k1 suppresses etoposidetriggered apoptosis art. Etoposide induces apoptosis via the mitochondrial and caspasedependent pathways and in noncancer stem cells in panc1 pancreatic cancer cells article in oncology reports 306 october 20. Stimuli for the intrinsic pathway include viral infections or damage to the cell by toxins, free radicals, or radiation. Reconstitution of caspase 3 sensitizes mcf7 breast cancer. Doxorubicin and etoposide sensitize small cell lung. After a genotoxic insult, in the early phases of apoptosis, cytocrome c is released from the mitochondria into the cytoplasm and binds to apoptotic protease activating factor 1. The course of etoposideinduced apoptosis from damage to. Etoposide induces cell death via mitochondrialdependent actions of. Treatment with pes, which inhibits the mitochondrial arm of the p53 pathway inhibited etoposideinduced cell death at all concentrations tested. Phosphorylation of smac by akt promotes the caspase. In the p53independent pathway the cell cycle block induced by dna.
Etoposide induces apoptosis via the mitochondrial and caspase. Thus, the protective effect of wortmannin against cell killing by etoposide in the present study must reflect inhibition of a proapoptotic pi3kinase rather than inhibition of an anti. The long latent phase and lack of synchrony after treatment of k562 cells with 17. Extrinsic apoptosis pathways inge verbrugge, ricky w. Activation of the caspase3 pathway is a hallmark of apoptosis and can be used in cellular assays to quantify activators and inhibitors of the death cascade. Etoposide induces apoptosis in activated human hepatic stellate. Doxorubicin and etoposide are active chemotherapeutic agents used in clinical oncology. In our previous studies, it was shown that vp16 induces sphase accumulation and g2m arrest, eventually resulting in apoptosis, through p53related pathway in the. Treatment of mefs with an inhibitor of p53, pifithrin. In p53 knockdown cells, inhibition of p38 induced fhit expression and apoptosis. The activation of hepatic stellate cells hscs plays a vital role in the progression of liver fibrosis, and the induction of hscs apoptosis may attenuate or reverse fibrogenesis. Etoposide, sold under the brand name etopophos among others, is a chemotherapy medication used for the treatments of a number of types of cancer including testicular cancer, lung cancer, lymphoma, leukemia, neuroblastoma, and ovarian cancer.
In the future, epigenetical changes of the etoposide pathway might have a great role in diagnostics, prognostics and personalized medicine. The data showed that activity of caspase3 increased significantly in a dose and timedependent manner in the cells treated with vp16. Apoptosis is a tightly regulated and at the same time highly efficient cell death program which requires the interplay of a multitude of factors. Apoptosis is delayed in k562 cells even after treatment with higher doses of etoposide. Anderson1,2, 1department of pharmacology 2molecular and cellular pharmacology program school of medicine and public health, university of wisconsinmadison, madison, wi 53706, usa.
Erk pathway in the induction of apoptosis see table 1 for details. Pes inhibits etoposideinduced apoptosis and cell cycle checkpoint. Wnt1induciblesignaling pathway protein 1, lung adenocarcinoma, a549, etoposide, apoptosis introduction lung cancer is the second most common cancer in both men and women, accounting for approximately 15% of all newly diagnosed cancers 1, 2. Mvr hampshire 037553835 abstract apoptosis is a pathway of cell death characterized by internucleosomal digestion of genomic dna.
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