Daunorubicin Activates NFκB and Induces κB-dependent Gene Expression in HL-60 Promyelocytic and Jurkat T Lymphoma Cells

The anthracycline antibiotic, daunorubicin, can induce programmed cell death (apoptosis) in cells. Recent work suggests that this event is mediated by ceramide via enhanced ceramide synthase activity. Since the generation of ceramide has been directly linked with the activation of the transcription factor, NFκB, this was investigated as a novel target for the action of daunorubicin. Here we describe how treatment of HL-60 promyelocytes and Jurkat T lymphoma cells with daunorubicin results in the activation of the transcription factor NFκB. The effect of daunorubicin was evident following 1–2 h treatment, which was in contrast to the time course of activation obtained with the cytokine, tumor necrosis factor, where NFκB activation was detected within minutes of cellular stimulation. Activated complexes were shown to contain predominantly p50 and p65/RelA subunit components. Daunorubicin also induced IκB degradation and increased the expression of an NFκB-linked reporter gene. In addition, the drug was found to strongly potentiate the ability of tumor necrosis factor to induce an NFκB-linked reporter gene, suggesting a synergy between these two agents in this response. These events were sensitive to the iron chelator, deferoxamine mesylate (desferal), and the anti-oxidant and metal chelator pyrrolidine dithiocarbamate. A structurally related compound, mitoxantrone, which, unlike daunorubicin, is unable to undergo redox cycling in cells, also activated NFκB in a pyrrolidine dithiocarbamate-sensitive manner. A specific inhibitor of ceramide synthase, fumonisin B1, had no effect on daunorubicin induced NFκB activation at a range of concentrations previously reported to block apoptosis induced by this drug. However, this agent could inhibit increases in ceramide induced by daunorubicin, in addition to blocking ceramide synthase activity from HL-60 cells which was activated in response to daunorubicin treatment. These data therefore suggest that the effect of daunorubicin on NFκB is unlikely to involve ceramide, but may involve reactive oxygen species generated as a result of endogenous cellular processes rather than reductive metabolism of the drug. As NFκB may be involved in apoptosis, this effect may be an important aspect of the cellular responses to this agent. The anthracycline antibiotic, daunorubicin, can induce programmed cell death (apoptosis) in cells. Recent work suggests that this event is mediated by ceramide via enhanced ceramide synthase activity. Since the generation of ceramide has been directly linked with the activation of the transcription factor, NFκB, this was investigated as a novel target for the action of daunorubicin. Here we describe how treatment of HL-60 promyelocytes and Jurkat T lymphoma cells with daunorubicin results in the activation of the transcription factor NFκB. The effect of daunorubicin was evident following 1–2 h treatment, which was in contrast to the time course of activation obtained with the cytokine, tumor necrosis factor, where NFκB activation was detected within minutes of cellular stimulation. Activated complexes were shown to contain predominantly p50 and p65/RelA subunit components. Daunorubicin also induced IκB degradation and increased the expression of an NFκB-linked reporter gene. In addition, the drug was found to strongly potentiate the ability of tumor necrosis factor to induce an NFκB-linked reporter gene, suggesting a synergy between these two agents in this response. These events were sensitive to the iron chelator, deferoxamine mesylate (desferal), and the anti-oxidant and metal chelator pyrrolidine dithiocarbamate. A structurally related compound, mitoxantrone, which, unlike daunorubicin, is unable to undergo redox cycling in cells, also activated NFκB in a pyrrolidine dithiocarbamate-sensitive manner. A specific inhibitor of ceramide synthase, fumonisin B1, had no effect on daunorubicin induced NFκB activation at a range of concentrations previously reported to block apoptosis induced by this drug. However, this agent could inhibit increases in ceramide induced by daunorubicin, in addition to blocking ceramide synthase activity from HL-60 cells which was activated in response to daunorubicin treatment. These data therefore suggest that the effect of daunorubicin on NFκB is unlikely to involve ceramide, but may involve reactive oxygen species generated as a result of endogenous cellular processes rather than reductive metabolism of the drug. As NFκB may be involved in apoptosis, this effect may be an important aspect of the cellular responses to this agent. The anthracycline antibiotic, daunorubicin, is widely used in cancer chemotherapy with proven therapeutic benefit in the treatment of a variety of neoplasia (1Calabresi P. Chabner B.A. Gilman A.G. Rall T.W. Nies A.S. Taylor P. Pharmacological Basis of Therapeutics. 8th Ed. Pergamon Press, New York1990: 1202-1263Google Scholar). Although its mechanism of anti-tumor action is uncertain, DNA is believed to be a primary target (2Powis G. Powis G. Prough R.A. Metabolism and Action of Anti-cancer Drugs. Taylor and Francis Ltd., London1987: 211-246Google Scholar). Its ability to cause strand scission may be mediated by stabilizing a cleavable complex between DNA and the enzyme, topoisomerase II, and/or oxygen radicals arising from redox cycling following its bioreduction. Additionally, bioreduction products and reactive oxygen species have been associated with anthracycline induced alkylation of cellular macromolecules, DNA intercalation and cross-linking, lipid peroxidation, and cell membrane damage (2Powis G. Powis G. Prough R.A. Metabolism and Action of Anti-cancer Drugs. Taylor and Francis Ltd., London1987: 211-246Google Scholar). Irrespective of the initial insult, anthracyclines, along with a variety of agonists, ultimately activate the event of programmed cell death or apoptosis in cells (3Barry M.A. Behnke C.A. Eastman A. Biochem. Pharmacol. 1990; 40: 2353-2362Crossref PubMed Scopus (914) Google Scholar). Their ability to induce this pathway may be a mechanism underlying their therapeutic efficacy in certain tumor types. The development of the apoptotic morphology is well defined; however, signaling pathways that may act as primary mediators of apoptosis and growth suppression are poorly characterized (4Steller H. Science. 1995; 267: 1445-1449Crossref PubMed Scopus (2429) Google Scholar). Some of those relevant to the cytotoxic action of chemotherapeutic drugs include the triggering of CD95/CD95-L interaction resulting in a type of autocrine suicide (5Friesen C. Herr I. Krammer P.H. Debatin K-M. Nature Med. 1996; 2: 574-577Crossref PubMed Scopus (952) Google Scholar), and the activation of effector molecules such as interleukin-1 converting enzyme-like proteases (6Kaufmann S.H. Desnoyers S. Ottaviano Y. Davidson N.E. Poirier G.G. Cancer Res. 1993; 53: 3976-3985PubMed Google Scholar). Recent studies suggest that the neutral lipid ceramide may also play a role in mediating drug-induced apoptosis (7Bose R. Verheij M. Haimovitz-Friedman A. Scotto K. Fuks Z. Kolesnick R. Cell. 1995; 82: 405-414Abstract Full Text PDF PubMed Scopus (784) Google Scholar, 8Jaffrezou J-P. Levade T. Bettaieb A. Andrieu N. Bezombes C. Maestre N. Vermeersch S. Rousse A. Laurent G. EMBO J. 1996; 15: 2417-2424Crossref PubMed Scopus (351) Google Scholar). Ceramide is a putative second messenger which can also be generated following the activation of distinct sphingomyelinase activities in response to a range of extracellular agents including TNF-α, 1The abbreviations used are: TNF, tumor necrosis factor; PDTC, pyrrolidine dithiocarbamate; ROS, reactive oxygen species; NFκB, nuclear factor κB; 1The abbreviations used are: TNF, tumor necrosis factor; PDTC, pyrrolidine dithiocarbamate; ROS, reactive oxygen species; NFκB, nuclear factor κB; growth factor, and 1995; Full Text PDF PubMed Scopus Google Scholar). A role in growth and suppression is by its ability to induce cell apoptosis, or cell 1995; Full Text PDF PubMed Scopus Google Scholar), a role has been in certain cell K. A K. T.W. M. J. Med. 1995; PubMed Scopus Google Scholar). In a daunorubicin was shown to ceramide in cells following of the ceramide synthase (7Bose R. Verheij M. Haimovitz-Friedman A. Scotto K. Fuks Z. Kolesnick R. Cell. 1995; 82: 405-414Abstract Full Text PDF PubMed Scopus (784) Google Scholar). of this by the fumonisin B1, apoptosis induced by daunorubicin. The of ceramide may a signaling mechanism by which apoptotic events are induced by this drug. The generation of ceramide following activation of sphingomyelinase has been linked with apoptosis, but also with the activation of NFκB Z. M. Kolesnick J. 1993; Full Text PDF PubMed Google Scholar). transcription factor has been in the of which for mediators of the and responses T. PubMed Scopus Google Scholar). The complex a in the of a variety of to the NFκB in and These a in the the which DNA nuclear and of the inhibitor IκB or T. PubMed Scopus Google Scholar). of these have distinct DNA and may to activate specific of R. J. J. 1995; Full Text Full Text PDF PubMed Scopus Google Scholar). In cells, the NFκB is in the by with and can be from this complex by a variety of A for NFκB activation is as of IκB by specific activated for degradation T. Cell. 1996; Full Text Full Text PDF PubMed Scopus Google Scholar). the nuclear of activated NFκB to expression is The signaling pathways to NFκB activation are poorly A of have been in the of the a T. Cell. 1996; Full Text Full Text PDF PubMed Scopus Google Scholar). at two specific and on is to to its and degradation by the NFκB and the K. S. G. Science. 1995; 267: PubMed Scopus Google Scholar). these undergo in response to a variety of T. S. EMBO J. 1995; PubMed Scopus Google suggesting that pathways on the putative IκB In addition to ceramide as an of a has been reactive oxygen species act as second in this event K. M. Biochem. Pharmacol. 1995; PubMed Scopus Google Scholar). to this is on the ability of to activate NFκB R. P. EMBO J. PubMed Scopus Google and the of such as and and pyrrolidine which is also a metal chelator, on NFκB activation R. P. EMBO J. PubMed Scopus Google Scholar, R. J. Med. PubMed Scopus Google Scholar, P. P. 1995; 2: Full Text PDF PubMed Scopus Google Scholar, P. 1995; PubMed Scopus Google Scholar). The between ceramide and in signaling activation or apoptotic events is 15: Full Text PDF PubMed Scopus Google 1996; Full Text PDF PubMed Scopus Google Scholar). In a for NFκB by and T. PubMed Scopus Google Scholar), ceramide generation of an event which to the activation of this transcription work the of and ceramide in response to daunorubicin (2Powis G. Powis G. Prough R.A. Metabolism and Action of Anti-cancer Drugs. Taylor and Francis Ltd., London1987: 211-246Google Scholar, R. Verheij M. Haimovitz-Friedman A. Scotto K. Fuks Z. Kolesnick R. Cell. 1995; 82: 405-414Abstract Full Text PDF PubMed Scopus (784) Google Scholar), we investigated the effect of this agent on NFκB have found that daunorubicin NFκB activation in HL-60 promyelocytes and Jurkat T cells by a suggesting the of ROS, and activated ceramide The of this for apoptosis is HL-60 and Jurkat T cells obtained from the of were in in with and and obtained from was a from Ltd., was also a from was from and the to the were from A and were from was from to the of NFκB and and the inhibitor were from NFκB was also from to the p50 subunit of NFκB was a from were from cells in of growth were in at a of and at in a of cells were with and for and for to the addition of drug were by the addition of and nuclear or cell were as previously J. 1995; Full Text Full Text PDF PubMed Scopus Google Scholar). were the with as The of activated NFκB complexes was following of cells C. Cell. Full Text PDF PubMed Scopus Google with a NFκB of a reporter a from treatment in from cells were for activity as previously Biochem. J. 1993; PubMed Scopus Google Scholar). was by for NFκB was by the a the which had previously been with as J. 1995; Full Text Full Text PDF PubMed Scopus Google Scholar). of nuclear was with at for as previously J. 1995; Full Text Full Text PDF PubMed Scopus Google Scholar). NFκB complexes were on and following the subunit of activated NFκB was where from cells were with to and subunit on for to the addition of A was in studies were at where and type NFκB were for their ability to block of activated complexes to type NFκB of cell were by and was as previously J. 1995; Full Text Full Text PDF PubMed Scopus Google Scholar). was used at a of The were by to the Ceramide was by the as (7Bose R. Verheij M. Haimovitz-Friedman A. Scotto K. Fuks Z. Kolesnick R. Cell. 1995; 82: 405-414Abstract Full Text PDF PubMed Scopus (784) Google Scholar), with In following cell were with of h at were and in of (7Bose R. Verheij M. Haimovitz-Friedman A. Scotto K. Fuks Z. Kolesnick R. Cell. 1995; 82: 405-414Abstract Full Text PDF PubMed Scopus (784) Google Scholar). The was by the addition of by of was as following at for The of ceramide was by with a generated with of ceramide type activity was in HL-60 as previously (7Bose R. Verheij M. Haimovitz-Friedman A. Scotto K. Fuks Z. Kolesnick R. Cell. 1995; 82: 405-414Abstract Full Text PDF PubMed Scopus (784) Google Scholar). In cells were following drug treatment and in of by a membrane was in a as (7Bose R. Verheij M. Haimovitz-Friedman A. Scotto K. Fuks Z. Kolesnick R. Cell. 1995; 82: 405-414Abstract Full Text PDF PubMed Scopus (784) Google with as The was by the addition of the was to for h at and by with an of The concentrations were on those reported to activity to be (7Bose R. Verheij M. Haimovitz-Friedman A. Scotto K. Fuks Z. Kolesnick R. Cell. 1995; 82: 405-414Abstract Full Text PDF PubMed Scopus (784) Google Scholar), with as (7Bose R. Verheij M. Haimovitz-Friedman A. Scotto K. Fuks Z. Kolesnick R. Cell. 1995; 82: 405-414Abstract Full Text PDF PubMed Scopus (784) Google Scholar), to was an of HL-60 and Jurkat T cells with the anthracycline antibiotic, daunorubicin, in the activation of NFκB, which was and A data obtained with HL-60 cells, where activation of NFκB is by the of The activation was from to h and was to h was in contrast to that with TNF, where the activation of NFκB was within minutes of cellular of daunorubicin were to those previously reported to induce apoptosis in this cell (7Bose R. Verheij M. Haimovitz-Friedman A. Scotto K. Fuks Z. Kolesnick R. Cell. 1995; 82: 405-414Abstract Full Text PDF PubMed Scopus (784) Google Scholar), with activation at and at These concentrations also that reported for ceramide induced by this drug (7Bose R. Verheij M. Haimovitz-Friedman A. Scotto K. Fuks Z. Kolesnick R. Cell. 1995; 82: 405-414Abstract Full Text PDF PubMed Scopus (784) Google Scholar). for and are shown in for A was in Jurkat T cells where activation could be detected at and a at daunorubicin. The of activated complexes was by studies in which NFκB the of a had no effect at concentrations of specific subunit in activated NFκB complexes the of p50 and to a p65/RelA as by enhanced of complexes following Although complexes were with a with the of this subunit in the complex HL-60 cells with daunorubicin at which in NFκB activation were for degradation of the inhibitor a event in the activation of this transcription factor T. PubMed Scopus Google Scholar). A degradation of this inhibitor was which was In of the for a was to degradation to the of this which is a for its degradation K. S. G. Science. 1995; 267: PubMed Scopus Google Scholar). the concentrations of daunorubicin degradation was of Jurkat T cells with a reporter NFκB of a reporter gene, the of daunorubicin on expression were Daunorubicin induced expression of activity in a a previously shown to activate NFκB, activity was increased that induced complexes were In addition, daunorubicin and were found to in this response a of which was with a of daunorubicin a in in a synergy suggests that and daunorubicin activated NFκB by as was previously from the time of activation for these two A and investigated the mechanism by which daunorubicin NFκB. In cells with the metal and also has anti-oxidant activation was as by a to activated the response by with no at was the inhibitor of the two at concentrations the response by at and were also found to inhibit the in expression the mechanism of NFκB activation involved redox cycling of daunorubicin. this we used a related mitoxantrone, which undergo redox cycling Cancer Pharmacol. PubMed Scopus Google Scholar, Cancer Pharmacol. PubMed Scopus Google Scholar). was found to be as an of NFκB in HL-60 as daunorubicin with an effect evident from In addition, was found to inhibit this with blocking the response induced by and These results that activation of NFκB by daunorubicin involved the generation of via endogenous cellular processes rather than redox cycling of the drug we the effect of a specific ceramide synthase fumonisin B1, for its ability to block NFκB activation at a range of concentrations previously reported to block apoptosis induced by this drug (7Bose R. Verheij M. Haimovitz-Friedman A. Scotto K. Fuks Z. Kolesnick R. Cell. 1995; 82: 405-414Abstract Full Text PDF PubMed Scopus (784) Google Scholar). to inhibit NFκB activation at concentrations no of activation was However, treatment of HL-60 cells with daunorubicin and for h increased ceramide as shown in with a effect was by fumonisin with ceramide to that in cells. treatment of HL-60 cells with daunorubicin for h was found to ceramide synthase activity than fumonisin this to which was with its ability to act as a inhibitor a where of ceramide synthase was found to increases in ceramide in cells in response to daunorubicin (7Bose R. Verheij M. Haimovitz-Friedman A. Scotto K. Fuks Z. Kolesnick R. Cell. 1995; 82: 405-414Abstract Full Text PDF PubMed Scopus (784) Google Scholar). However, data that this was involved in NFκB activation therefore that increases in ROS, generated by endogenous cellular but ceramide synthase were mediating the effect of daunorubicin on NFκB activation and In this we the that daunorubicin, an anthracycline antibiotic, NFκB. The of this effect was in of its In this is that the of the NFκB complex its R. J. J. 1995; Full Text Full Text PDF PubMed Scopus Google Scholar), to activation or the of which has been with p50 H. M. M. M. J. Med. 1995; PubMed Scopus Google Scholar). activation of specific of on activated or their in cell and are to and are the of NFκB complexes T. PubMed Scopus Google Scholar), to of the of in activated complexes from cells the of and p50 which the NFκB The ability of these activated complexes to was in a reporter where treatment of cells with daunorubicin activity from a NFκB-linked reporter in a manner. in with the of NFκB activation T. PubMed Scopus Google Scholar), IκB and degradation was at concentrations which those shown to activate NFκB and the role of and as second in NFκB In this NFκB is to be an transcription factor K. M. Biochem. Pharmacol. 1995; PubMed Scopus Google and daunorubicin can be to a (2Powis G. Powis G. Prough R.A. Metabolism and Action of Anti-cancer Drugs. Taylor and Francis Ltd., London1987: 211-246Google which in which to The of daunorubicin is by a of cellular including the and (2Powis G. Powis G. Prough R.A. Metabolism and Action of Anti-cancer Drugs. Taylor and Francis Ltd., London1987: 211-246Google Scholar). The resulting is reactive and in the of to the with of are generated its in oxygen species have previously been in the mechanism of NFκB activation in response to and K. M. Biochem. Pharmacol. 1995; PubMed Scopus Google Scholar, R. P. EMBO J. PubMed Scopus Google Scholar). have been from studies of signaling events with and metal R. P. EMBO J. PubMed Scopus Google Scholar, R. J. Med. PubMed Scopus Google Scholar, P. 1995; PubMed Scopus Google Scholar), and the of such as and P. P. 1995; 2: Full Text PDF PubMed Scopus Google Scholar). the mechanism of NFκB activation by daunorubicin, were which which has and metal and previously has been shown to inhibit the activation of NFκB mediated by R. J. Med. PubMed Scopus Google Scholar). inhibitor deferoxamine (desferal), can with the of oxygen in radicals generated in the of of by iron PubMed Scopus Google Scholar). NFκB activation and The with at concentrations may be to has previously been shown to the growth of daunorubicin to cells (2Powis G. Powis G. Prough R.A. Metabolism and Action of Anti-cancer Drugs. Taylor and Francis Ltd., London1987: 211-246Google Scholar), suggesting that in in the growth of this for in the effect of daunorubicin from time course studies where NFκB activation was with that obtained with the cytokine, TNF, with enhanced nuclear complexes detected 1–2 h However, this time course for NFκB activation is to that by in and cells A. Biochem. PubMed Google Scholar, S. M. J. J. 1995; Full Text Full Text PDF PubMed Scopus Google Scholar), suggesting that a signaling pathway for NFκB activation be mediated by agents which directly we found that daunorubicin and could in the of a reporter gene. The for this is but suggests that agents activate NFκB by as was also from time course the can activate NFκB in a time course which that previously by S. M. J. J. 1995; Full Text Full Text PDF PubMed Scopus Google and has been that DNA damage a signaling event from that by which of NFκB complexes in the the A effect may be with NFκB A of which have also been shown to activate NFκB for TNF, and can also induce DNA strand in cells Y. Y. H. N. T. 1995; Google Scholar). is that this damage may be a for the activation of specific NFκB as has been previously S. M. J. J. 1995; Full Text Full Text PDF PubMed Scopus Google Scholar). Although daunorubicin may have been the of which activated NFκB, was also that endogenous cellular processes were for we a related compound, mitoxantrone, which, structurally to daunorubicin, undergo redox cycling Cancer Pharmacol. PubMed Scopus Google Scholar, Cancer Pharmacol. PubMed Scopus Google Scholar). was with the of the ability of but such as the cause of which is to be generation via redox cycling (1Calabresi P. Chabner B.A. Gilman A.G. Rall T.W. Nies A.S. Taylor P. Pharmacological Basis of Therapeutics. 8th Ed. Pergamon Press, New York1990: 1202-1263Google Scholar). was found to be as at NFκB as daunorubicin, and was to by that the mechanism of NFκB activation by daunorubicin involved generation of ROS, redox cycling of the but cellular events activated by the to The of the as is the for of NFκB which are sensitive to studies have the role of redox cycling in cytotoxic with than the daunorubicin in this Cancer Pharmacol. PubMed Scopus Google Scholar). therefore that redox cycling may be for or NFκB activation induced by such is a of DNA strand Cancer Pharmacol. PubMed Scopus Google Scholar). this has been in mediating its cytotoxic Cancer Pharmacol. PubMed Scopus Google Scholar), may also be a signaling event to NFκB to that for daunorubicin. The time course of NFκB activation by daunorubicin that reported in a for ceramide induced by this drug (7Bose R. Verheij M. Haimovitz-Friedman A. Scotto K. Fuks Z. Kolesnick R. Cell. 1995; 82: 405-414Abstract Full Text PDF PubMed Scopus (784) Google Scholar). (7Bose R. Verheij M. Haimovitz-Friedman A. Scotto K. Fuks Z. Kolesnick R. Cell. 1995; 82: 405-414Abstract Full Text PDF PubMed Scopus (784) Google Scholar), a fumonisin B1, which is a specific inhibitor of ceramide synthase, to that this activity was for ceramide However, in fumonisin block NFκB result that ceramide generated apoptotic by this drug was for NFκB is an of this event Z. M. Kolesnick J. 1993; Full Text PDF PubMed Google Scholar). however, to that where fumonisin to inhibit NFκB increases in ceramide induced by daunorubicin in HL-60 were In addition, fumonisin ceramide synthase activity in from HL-60 cells. results from a which that daunorubicin increases ceramide in cells an of ceramide synthase activity (7Bose R. Verheij M. Haimovitz-Friedman A. Scotto K. Fuks Z. Kolesnick R. Cell. 1995; 82: 405-414Abstract Full Text PDF PubMed Scopus (784) Google Scholar). In has been shown that daunorubicin neutral sphingomyelinase activity and that this is for the ceramide in response to relevant of daunorubicin J-P. Levade T. Bettaieb A. Andrieu N. Bezombes C. Maestre N. Vermeersch S. Rousse A. Laurent G. EMBO J. 1996; 15: 2417-2424Crossref PubMed Scopus (351) Google Scholar). in to the by (7Bose R. Verheij M. Haimovitz-Friedman A. Scotto K. Fuks Z. Kolesnick R. Cell. 1995; 82: 405-414Abstract Full Text PDF PubMed Scopus (784) Google Scholar), to by fumonisin of apoptosis induced by daunorubicin. The for these is In increases in ceramide were by fumonisin B1, that ceramide synthase is the for such As was with of daunorubicin that we increases in ceramide and ceramide synthase was that the NFκB activation evident at of daunorubicin was mediated via an in ceramide as a result of sphingomyelinase have from that ceramide was unlikely to be important in the effect of daunorubicin on NFκB. is with that ceramide is unlikely to be an important for of NFκB such as Science. 1996; PubMed Scopus Google Scholar). the of ceramide synthase in the apoptotic effect of daunorubicin. of this agent used to induce the are to be therapeutic concentrations (5Friesen C. Herr I. Krammer P.H. Debatin K-M. Nature Med. 1996; 2: 574-577Crossref PubMed Scopus (952) Google and in the the that a related induced apoptosis via (5Friesen C. Herr I. Krammer P.H. Debatin K-M. Nature Med. 1996; 2: 574-577Crossref PubMed Scopus (952) Google which daunorubicin has been shown to activate sphingomyelinase R. P. M. A. R. J. Med. PubMed Scopus Google Scholar). The range of daunorubicin in was in with that reported to induce apoptosis (7Bose R. Verheij M. Haimovitz-Friedman A. Scotto K. Fuks Z. Kolesnick R. Cell. 1995; 82: 405-414Abstract Full Text PDF PubMed Scopus (784) Google and the therapeutic concentrations for the related (5Friesen C. Herr I. Krammer P.H. Debatin K-M. Nature Med. 1996; 2: 574-577Crossref PubMed Scopus (952) Google Scholar), the of The role of ceramide synthase in the of apoptosis by daunorubicin therefore as that is involved in NFκB is to that increased expression of by NFκB in response to daunorubicin may be involved in be a role in the of apoptosis G. A. H. M. R. PubMed Scopus Google Scholar). Its expression has been shown to be in response to and NFκB complexes H. M. M. M. J. Med. 1995; PubMed Scopus Google and studies are with the that its be related to apoptotic R. M. J. Y. Cancer Res. Google Scholar). has also been that which is in the NFκB may in the activation of a of death where its expression was shown to with the of apoptosis C. N. J. Cell. 1993; Full Text PDF PubMed Scopus Google Scholar). chemotherapeutic agents have been shown to activate NFκB. the has been reported to activate NFκB, via neutral sphingomyelinase J. Full Text PDF PubMed Google Scholar). to daunorubicin, was also found to induce NFκB-linked expression at a which with its ability to activate this transcription The DNA has been shown to activate NFκB I. M. G. J. 1993; Full Text PDF PubMed Google Scholar, M. G. I. J. 1995; Full Text Full Text PDF PubMed Scopus Google by a novel mechanism enhanced nuclear of in cells I. M. G. J. 1993; Full Text PDF PubMed Google Scholar). NFκB activation be a mechanism for is also however, that NFκB activation an response. has been in in cells from in or in cells where NFκB is enhanced apoptosis in response to a range of agents including daunorubicin Science. 1996; PubMed Scopus Google Scholar, A.S. Science. 1996; PubMed Scopus Google Scholar, T. Science. 1996; PubMed Scopus Google Scholar). In addition, the by apoptosis S. 1995; PubMed Scopus Google Scholar). enhanced is associated with expression of certain in the and NFκB may play a role in the expression of such as has been J. M. J. 1995; Full Text Full Text PDF PubMed Scopus Google Scholar). A in the between apoptosis and NFκB could therefore cells or and the of a between activation and apoptotic or may important on anthracycline to the NFκB p50 subunit was by M. P. and R. for