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Synergy is achieved by complementation with Apo2L/TRAIL and actinomycin D in Apo2L/TRAIL-mediated apoptosis of prostate cancer cells: role of XIAP in resistance.

Abstract

BACKGROUND

Tumors have an inherent immunogenicity that can be exploited by immunotherapy. However, often tumors develop mechanisms that render them resistant to most immunologic cytotoxic effector mechanisms. This study examines the underlying mechanism of resistance to Apo2L/TRAIL (tumor necrosis factor-related apoptosis-inducing ligand)-mediated apoptosis.

METHODS

We studied prostate tumor cell lines for their sensitivity to Apo2L/TRAIL-mediated apoptosis in the presence and absence of the sensitizing agent actinomycin D (Act D). Apoptosis was determined by flow cytometry and signaling for apoptosis by Western blot.

RESULTS

Treatment with subtoxic concentrations of Act D significantly sensitizes the tumor cells (CL-1, DU-145, and PC-3 prostate tumor cells) to Apo2L/TRAIL-mediated apoptosis. The cytotoxicity of Act D-sensitized prostate tumor cells was a result of synergistic activation of caspases (caspase-3, -9, and -8), detectable after 6 hr of treatment. Treatment with Apo2L/TRAIL alone, although it was insufficient to induce apoptosis, resulted in the loss of mitochondrial membrane potential and release of cytochrome c from the mitochondria into the cytoplasm in the absence of significant caspases activation. These findings suggested that a major apoptosis resistance factor blocking the Apo2L/TRAIL apoptotic signaling events is present downstream of the mitochondrial activation. The expression of receptors and anti-apoptotic proteins were examined in Act D-sensitized CL-1 cells. The earliest and the most pronounced change induced by Act D was down-regulation of X-linked inhibitor of apoptosis (XIAP) and up-regulation of Bcl-xL/-xS proteins. The role of XIAP in resistance was demonstrated by overexpression of Smac/DIABLO, which inhibited inhibitors of apoptosis (IAPs) and sensitized the cells to Apo2L/TRAIL. Apo2L/TRAIL receptors (DR4, DR5, DcR1, and DcR2), c-FLIP, Bcl-2, and other IAP members (c-IAP1 and c-IAP2) were marginally affected at later times in the cells sensitized by Act D.

CONCLUSION

This study suggests that the combination of Act D-induced down-regulation of XIAP (Signal I) and Apo2L/TRAIL-induced release of cytochrome c (Signal II) leads to the reversal of resistance to Apo2L/TRAIL-mediated apoptosis in the tumor cells. The sensitization of tumor cells to Apo2L/TRAIL by Act D is of potential clinical application in the immunotherapy of drug/Apo2L/TRAIL refractory tumors.

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  • Authors+Show Affiliations

    ,

    Department of Microbiology, Immunology, and Molecular Genetics, UCLA School of Medicine and Jonsson Comprehensive Cancer Center, University of California, Los Angeles, California 90095-1747, USA.

    ,

    Source

    The Prostate 53:4 2002 Dec 01 pg 286-99

    MeSH

    Apoptosis
    Apoptosis Regulatory Proteins
    Carrier Proteins
    Caspase 3
    Caspase 8
    Caspase 9
    Caspases
    Cytochrome c Group
    Dactinomycin
    Drug Synergism
    Enzyme Activation
    Humans
    Intracellular Signaling Peptides and Proteins
    Male
    Membrane Glycoproteins
    Membrane Potentials
    Mitochondria
    Mitochondrial Proteins
    Prostatic Neoplasms
    Proteins
    Receptors, TNF-Related Apoptosis-Inducing Ligand
    Receptors, Tumor Necrosis Factor
    Recombinant Proteins
    TNF-Related Apoptosis-Inducing Ligand
    Tumor Cells, Cultured
    Tumor Necrosis Factor-alpha
    X-Linked Inhibitor of Apoptosis Protein

    Pub Type(s)

    Journal Article
    Research Support, U.S. Gov't, Non-P.H.S.
    Research Support, U.S. Gov't, P.H.S.

    Language

    eng

    PubMed ID

    12430140

    Citation

    Ng, Chuen-Pei, et al. "Synergy Is Achieved By Complementation With Apo2L/TRAIL and Actinomycin D in Apo2L/TRAIL-mediated Apoptosis of Prostate Cancer Cells: Role of XIAP in Resistance." The Prostate, vol. 53, no. 4, 2002, pp. 286-99.
    Ng CP, Zisman A, Bonavida B. Synergy is achieved by complementation with Apo2L/TRAIL and actinomycin D in Apo2L/TRAIL-mediated apoptosis of prostate cancer cells: role of XIAP in resistance. Prostate. 2002;53(4):286-99.
    Ng, C. P., Zisman, A., & Bonavida, B. (2002). Synergy is achieved by complementation with Apo2L/TRAIL and actinomycin D in Apo2L/TRAIL-mediated apoptosis of prostate cancer cells: role of XIAP in resistance. The Prostate, 53(4), pp. 286-99.
    Ng CP, Zisman A, Bonavida B. Synergy Is Achieved By Complementation With Apo2L/TRAIL and Actinomycin D in Apo2L/TRAIL-mediated Apoptosis of Prostate Cancer Cells: Role of XIAP in Resistance. Prostate. 2002 Dec 1;53(4):286-99. PubMed PMID: 12430140.
    * Article titles in AMA citation format should be in sentence-case
    TY - JOUR T1 - Synergy is achieved by complementation with Apo2L/TRAIL and actinomycin D in Apo2L/TRAIL-mediated apoptosis of prostate cancer cells: role of XIAP in resistance. AU - Ng,Chuen-Pei, AU - Zisman,Amnon, AU - Bonavida,Benjamin, PY - 2002/11/14/pubmed PY - 2002/12/20/medline PY - 2002/11/14/entrez SP - 286 EP - 99 JF - The Prostate JO - Prostate VL - 53 IS - 4 N2 - BACKGROUND: Tumors have an inherent immunogenicity that can be exploited by immunotherapy. However, often tumors develop mechanisms that render them resistant to most immunologic cytotoxic effector mechanisms. This study examines the underlying mechanism of resistance to Apo2L/TRAIL (tumor necrosis factor-related apoptosis-inducing ligand)-mediated apoptosis. METHODS: We studied prostate tumor cell lines for their sensitivity to Apo2L/TRAIL-mediated apoptosis in the presence and absence of the sensitizing agent actinomycin D (Act D). Apoptosis was determined by flow cytometry and signaling for apoptosis by Western blot. RESULTS: Treatment with subtoxic concentrations of Act D significantly sensitizes the tumor cells (CL-1, DU-145, and PC-3 prostate tumor cells) to Apo2L/TRAIL-mediated apoptosis. The cytotoxicity of Act D-sensitized prostate tumor cells was a result of synergistic activation of caspases (caspase-3, -9, and -8), detectable after 6 hr of treatment. Treatment with Apo2L/TRAIL alone, although it was insufficient to induce apoptosis, resulted in the loss of mitochondrial membrane potential and release of cytochrome c from the mitochondria into the cytoplasm in the absence of significant caspases activation. These findings suggested that a major apoptosis resistance factor blocking the Apo2L/TRAIL apoptotic signaling events is present downstream of the mitochondrial activation. The expression of receptors and anti-apoptotic proteins were examined in Act D-sensitized CL-1 cells. The earliest and the most pronounced change induced by Act D was down-regulation of X-linked inhibitor of apoptosis (XIAP) and up-regulation of Bcl-xL/-xS proteins. The role of XIAP in resistance was demonstrated by overexpression of Smac/DIABLO, which inhibited inhibitors of apoptosis (IAPs) and sensitized the cells to Apo2L/TRAIL. Apo2L/TRAIL receptors (DR4, DR5, DcR1, and DcR2), c-FLIP, Bcl-2, and other IAP members (c-IAP1 and c-IAP2) were marginally affected at later times in the cells sensitized by Act D. CONCLUSION: This study suggests that the combination of Act D-induced down-regulation of XIAP (Signal I) and Apo2L/TRAIL-induced release of cytochrome c (Signal II) leads to the reversal of resistance to Apo2L/TRAIL-mediated apoptosis in the tumor cells. The sensitization of tumor cells to Apo2L/TRAIL by Act D is of potential clinical application in the immunotherapy of drug/Apo2L/TRAIL refractory tumors. SN - 0270-4137 UR - https://www.unboundmedicine.com/medline/citation/12430140/Synergy_is_achieved_by_complementation_with_Apo2L/TRAIL_and_actinomycin_D_in_Apo2L/TRAIL_mediated_apoptosis_of_prostate_cancer_cells:_role_of_XIAP_in_resistance_ L2 - https://doi.org/10.1002/pros.10155 DB - PRIME DP - Unbound Medicine ER -