Effect of Actinomycin D and Cycloheximide on Epstein-Barr Virus Early Antigen Induction in Lymphoblastoid Cells

Yamamoto, Naoki; Mueller-Lantzsch, N.; Hausen, Harald zur

doi:10.1099/0022-1317-51-2-255

Cited by 20 publications

(13 citation statements)

References 18 publications

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“…As we had previously observed the upregulation of PUMA, NOXA and BAX mRNA, we initially hypothesised that this could be mediated by the upregulation of pro-apoptotic genes at the mRNA level. However, we were surprised to find that a transcription inhibitor (Yamamoto et al, 1980), although effectively blocking IP6-induced upregulation of gene expression ( Figure 3B), did not protect cells from the effects of IP6 ( Figure 3A). As protein expression can be modulated by post-transcriptional events including mRNA export, mRNA translation and proteasome-mediated protein degradation, it remained possible that the ratio of pro-apoptotic to antiapoptotic proteins could shift in response to IP6 independently of mRNA transcription and actinomycin D. Indeed, PC3 cells in which protein translation was blocked using cycloheximide were significantly protected from the effects of IP6 (Figure 3C).…”

Section: Discussionmentioning

confidence: 99%

“…As IP6 treatment could lead to protein upregulation independently of transcription, we next assessed the efficacy of IP6 in PC3 cells where protein production was blocked using cycloheximide (50 mg ml À1 , 4 h pre-treatment). Figure 3C shows that a continuous treatment with the translation inhibitor cycloheximide (Yamamoto et al, 1980), starting 4 h before treatment with IP6, significantly protected from IP6- )-and ethanol-pre-treated PC3 cells were treated with increasing doses of IP6 for 24 h and metabolic activity was measured using WST-1. Data represent an average of three independent experiments performed in three to six replicates.…”

Section: Protein Synthesis Is Important For Ip6-induced Cytotoxicitymentioning

confidence: 99%

“…To gain an overall appreciation for this, we compared the efficacy of IP6 in PC3 cells pre-treated (4h) with an inhibitor of mRNA transcription (Yamamoto et al, 1980) or vehicle (DMSO). Figure 3A shows that continuous treatment with actinomycin D, starting 4 h before the addition of IP6 (for 24 h), did not modulate PC3 cell sensitivity to IP6.…”

Section: Protein Synthesis Is Important For Ip6-induced Cytotoxicitymentioning

confidence: 99%

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Enhanced killing of androgen-independent prostate cancer cells using inositol hexakisphosphate in combination with proteasome inhibitors

et al. 2008

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Effective treatments for androgen-independent prostate cancer (AIPCa) are lacking. To address this, emerging therapeutics such as proteasome inhibitors are currently undergoing clinical trials. Inositol hexakisphosphate (IP6) is an orally non-toxic phytochemical that exhibits antitumour activity against several types of cancer including PCa. We have previously shown that treatment of PC3 cells with IP6 induces the transcription of a subset of nuclear factor-kB (NF-kB)-responsive and pro-apoptotic BCL-2 family genes. In this study, we report that although NF-kB subunits p50/p65 translocate to the nucleus of PC3 cells in response to IP6, inhibition of NF-kBmediated transcription using non-degradable inhibitor of kB (IkB)-a does not modulate IP6 sensitivity. Treatment with IP6 also leads to increased protein levels of PUMA, BIK/NBK and NOXA between 4 and 8 h of treatment and decreased levels of MCL-1 and BCL-2 after 24 h. Although blocking transcription using actinomycin D does not modulate PC3 cell sensitivity to IP6, inhibition of protein translation using cycloheximide has a significant protective effect. In contrast, blocking proteasome-mediated protein degradation using MG-132 significantly enhances the ability of IP6 to reduce cellular metabolic activity in both PC3 and DU145 AIPCa cell lines. This effect of combined treatment on mitochondrial depolarisation is particularly striking and is also reproduced by another proteasome inhibitor (ALLN). The enhanced effect of combined MG132/IP6 treatment is almost completely inhibited by cycloheximide and correlates with changes in BCL-2 family protein levels. Altogether these results suggest a role for BCL-2 family proteins in mediating the combined effect of IP6 and proteasome inhibitors and warrant further pre-clinical studies for the treatment of AIPCa.

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Section: Discussionmentioning

confidence: 99%

Section: Protein Synthesis Is Important For Ip6-induced Cytotoxicitymentioning

confidence: 99%

Section: Protein Synthesis Is Important For Ip6-induced Cytotoxicitymentioning

confidence: 99%

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Enhanced killing of androgen-independent prostate cancer cells using inositol hexakisphosphate in combination with proteasome inhibitors

et al. 2008

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“…Endogenous or silent retrovirus genomes were activated by 5AZcd, and activation of the Epstein-Barr virus (EBV) genome or the herpes simplex virus thymidine kinase gene has been detected in cells treated with 5AZcd or iododeoxyuridine (IUdR) (Gerber, 1972;Groudine et al, 1981;Glough et al, 1982;Jaenisch et al, 1985;Niwa et al, 1983;Yamamoto et al, 1980). The effect of these reagents on cell differentiation or viral gene activation may be correlated with a fluctuation of 2-5AS levels, although it is also possible that the enzyme activity may be due to non-specific gene activation.…”

mentioning

confidence: 99%

Induction of Oligo-2',5'-adenylate Synthetase in Human Lymphoid Cells Treated with 5-Azacytosine and 5-Iododeoxyuridine

Fujii

Oguma

1986

Journal of General Virology

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“…The transcription of these genes is independent on de novo protein synthesis in superinfected Raji cells [28]. but not in TPA plus »-buty rate-treated P3HR-1 cells [29][30][31], Once cells enter the lytic phase, EBV early protein synthesis is induced, fol lowed by replication of viral DNA and subsequent synthe sis of EBV late proteins. The present study has demon strated that EBV DNA amplification in superinfected Raji cells is suppressed by SNAP without affecting EBV early protein synthesis required for progeny EBV DNA replication.…”

Section: Introductionmentioning

confidence: 99%

Nitric Oxide Inhibits Epstein-Barr Virus DNA Replication and Activation of Latent EBV

Kawanishi

1995

Intervirology

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Nitric oxide (NO), a mediator of biological functions, has antimicrobial activity against a variety of pathogens including viruses. Effects of NO donors on EBV replication in two EBV lytic systems, Raji cells infected with P3HR-1 virus and P3HR-1 cells activated with TPA plus n-butyrate, were studied. S-nitroso-N-acetylpenicillamine (SNAP), which generates NO when placed in an aqueous solution, and 3-morpholinosydnonimine (SIN-1), which liberates NO and O₂, resulting in the formation of peroxynitrite, were used as NO donors. Immunoprecipitation analysis showed that in superinfected Raji cells, SNAP inhibited EBV late protein synthesis but not EBV early protein expression. Analysis of the structure of EBV DNA termini demonstrated that SNAP suppressed the amplification of EBV DNA in superinfected Raji cells at a dose which did not affect synthesis of EBV early proteins required for EBV DNA replication. In TPA plus n-butyrate-treated P3HR-1 cells, SNAP inhibited synthesis of both early and late proteins of EBV. Northern blot analysis of RNA expressed in TPA plus n-butyrate-treated P3HR-1 cells demonstrated that expression of EBV immediate-early mRNAs coded from BZLF1 and BRLF1 genes was inhibited by SNAP. SIN-1 showed no or little effect on EBV replication in both cell systems. Cell viability and cellular protein synthesis were not affected by either NO donor under the conditions used. These findings suggest that NO prevents EBV replication by inhibiting EBV DNA amplification during the lytic phase of the life cycle as well as by blocking activation of the latent EBV genome. The mechanism for inhibiting of EBV replication by NO was discussed in relation to the role of NO in EBV latency in vivo.

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Effect of Actinomycin D and Cycloheximide on Epstein-Barr Virus Early Antigen Induction in Lymphoblastoid Cells

Cited by 20 publications

References 18 publications

Enhanced killing of androgen-independent prostate cancer cells using inositol hexakisphosphate in combination with proteasome inhibitors

Enhanced killing of androgen-independent prostate cancer cells using inositol hexakisphosphate in combination with proteasome inhibitors

Induction of Oligo-2',5'-adenylate Synthetase in Human Lymphoid Cells Treated with 5-Azacytosine and 5-Iododeoxyuridine

Nitric Oxide Inhibits Epstein-Barr Virus DNA Replication and Activation of Latent EBV

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