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Therapeutic potential and molecular mechanism of a novel, potent, nonpeptide, Smac mimetic SM-164 in combination with TRAIL for cancer treatment.

ABSTRACT: Smac mimetics are being developed as a new class of anticancer therapies. Because the single-agent activity of Smac mimetics is very limited, rational combinations represent a viable strategy for their clinical development. The combination of Smac mimetics with TNF-related apoptosis inducing ligand (TRAIL) may be particularly attractive because of the low toxicity of TRAIL to normal cells and the synergistic antitumor activity observed for the combination. In this study, we have investigated the combination synergy between TRAIL and a potent Smac mimetic, SM-164, in vitro and in vivo and the underlying molecular mechanism of action for the synergy. Our study shows that SM-164 is highly synergistic with TRAIL in vitro in both TRAIL-sensitive and TRAIL-resistant cancer cell lines of breast, prostate, and colon cancer. Furthermore, the combination of SM-164 with TRAIL induces rapid tumor regression in vivo in a breast cancer xenograft model in which either agent is ineffective. Our data show that X-linked IAP (XIAP) and cellular IAP 1 (cIAP1), but not cIAP2, work in concert to attenuate the activity of TRAIL; SM-164 strongly enhances TRAIL activity by concurrently targeting XIAP and cIAP1. Moreover, although RIP1 plays a minimal role in the activity of TRAIL as a single agent, it is required for the synergistic interaction between TRAIL and SM-164. This study provides a strong rationale to develop the combination of SM-164 and TRAIL as a new therapeutic strategy for the treatment of human cancer.

SUBMITTER: Lu J

PROVIDER: S-EPMC3091962 | biostudies-literature | 2011 May

REPOSITORIES: biostudies-literature

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Therapeutic potential and molecular mechanism of a novel, potent, nonpeptide, Smac mimetic SM-164 in combination with TRAIL for cancer treatment.

Lu Jianfeng J McEachern Donna D Sun Haiying H Bai Longchuan L Peng Yuefeng Y Qiu Su S Miller Rebecca R Liao Jinhui J Yi Han H Liu Meilan M Bellail Anita A Hao Chunhai C Sun Shi-Yong SY Ting Adrian T AT Wang Shaomeng S

Molecular cancer therapeutics 20110303 5

Smac mimetics are being developed as a new class of anticancer therapies. Because the single-agent activity of Smac mimetics is very limited, rational combinations represent a viable strategy for their clinical development. The combination of Smac mimetics with TNF-related apoptosis inducing ligand (TRAIL) may be particularly attractive because of the low toxicity of TRAIL to normal cells and the synergistic antitumor activity observed for the combination. In this study, we have investigated the ...[more]

PMID: 21372226

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Project description:Purposeinhibitors of apoptosis proteins (IAPs) have been shown to contribute to resistance of neoplastic cells to chemotherapy and to biologic antineoplastic agents. Consequently, new agents are being developed targeting this family of proteins. In a panel of bladder cancer cell lines, we evaluated a Smac mimetic that antagonizes several IAPs for its suitability for bladder cancer therapy. Experimental design: A panel of seven bladder cancer cell lines were evaluated for sensitivity to the Smac mimetic compound-A alone, TRAIL alone, chemotherapy alone, compound-A plus TRAIL, and compound-A plus chemotherapy by DNA fragmentation analysis. IAP levels and caspase activation were examined by western blotting. Release of caspase-3 from X-linked inhibitor of apoptosis protein (XIAP), the most effective IAP, was assessed by immunoprecipitation and western blotting. Finally, siRNA knockdown of XIAP was correlated with the sensitivity of cells to apoptosis induced by compound-A plus TRAIL by DNA fragmentation and western blotting.Resultssingle-agent compound-A had little effect, but compound-A augmented TRAIL- and chemotherapy-induced apoptosis. Immunoblotting showed that combination treatment with compound-A and TRAIL resulted in cleavage of procaspase-3 and procaspase-7, activation of which irreversibly commits cells to apoptosis. Immunoprecipitation of XIAP showed displacement of active caspase-3 fragments from XIAP, supporting the proposed mechanism of action. Furthermore, siRNA-mediated silencing of XIAP similarly sensitized these cells to apoptosis.Experimental designa panel of seven bladder cancer cell lines were evaluated for sensitivity to the Smac mimetic compound-Alone, TRAIL alone, Chemotherapy alone, compound-A plus TRAIL and compound-A plus chemotherapy by DNA fragmentation analysis. IAP levels and caspase activation were examined by western blotting. Release of caspase-3 from X-linked inhibitor of apoptosis protein (XIAP), the most effective IAP, was assessed by immunoprecipitation and western blotting. Finally siRNA knockdown of XIAP was correlated with the sensitivity of cells to apoptosis induced by compound-A plus TRAIL by DNA fragmentation and western blotting.Conclusionour results suggest that targeting of XIAP with the Smac mimetic compound-A has the potential to augment the effects of a variety of chemotherapeutic and biologic therapies in bladder cancer.

Dataset Information

Therapeutic potential and molecular mechanism of a novel, potent, nonpeptide, Smac mimetic SM-164 in combination with TRAIL for cancer treatment.

Publications

Therapeutic potential and molecular mechanism of a novel, potent, nonpeptide, Smac mimetic SM-164 in combination with TRAIL for cancer treatment.

Similar Datasets

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