Role of Hsp-70 in triptolide-mediated cell death of neuroblastoma

Mara B Antonoff; Rohit Chugh; Steven J Skube; Vikas Dudeja; Daniel Borja-Cacho; Kimberly A Clawson; Selwyn M Vickers; Ashok K Saluja

doi:10.1016/j.jss.2010.04.047

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Role of Hsp-70 in triptolide-mediated cell death of neuroblastoma

Journal article

Peer reviewed

Role of Hsp-70 in triptolide-mediated cell death of neuroblastoma

Mara B Antonoff, Rohit Chugh, Steven J Skube, Vikas Dudeja, Daniel Borja-Cacho, Kimberly A Clawson, Selwyn M Vickers and Ashok K Saluja

The Journal of surgical research, Vol.163(1), pp.72-78

09/01/2010

DOI: 10.1016/j.jss.2010.04.047

PMID: 20638672

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Abstract

Our recent work demonstrated that treatment of neuroblastoma with triptolide causes apoptotic cell death in vitro and decreases tumor size in vivo. Triptolide therapy has been associated with reduced expression of Hsp-70, suggesting a mechanism of cell killing involving Hsp-70 inhibition. The principal objective of this study was to investigate the role of Hsp-70 in triptolide-mediated cell death in neuroblastoma. Neuroblastoma cells were transfected with Hsp-70-specific siRNA. Viability, caspase activity, and phosphatidylserine externalization were subsequently measured. An orthotopic, syngeneic murine tumor model was developed, and randomized mice received daily injections of triptolide or vehicle. At 21 d, mice were sacrificed. Immunohistochemisty was used to characterize Hsp-70 levels in residual tumors, and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) was performed to identify cells undergoing apoptosis. Targeted silencing of Hsp-70 with siRNA significantly decreased cellular viability, augmented caspase-3 activity, and resulted in increased annexin-V staining. These effects parallel those findings obtained following treatment with triptolide. Residual tumors from triptolide-treated mice showed minimal staining with Hsp-70 immunohistochemistry, while control tumors stained prominently. Tumors from treated mice demonstrated marked staining with the TUNEL assay, while control tumors showed no evidence of apoptosis. Use of siRNA to suppress Hsp-70 expression in neuroblastoma resulted in apoptotic cell death, similar to the effects of triptolide. Residual tumors from triptolide-treated mice expressed decreased levels of Hsp-70 and demonstrated significant apoptosis. These findings support the hypothesis that Hsp-70 inhibition plays a significant role in triptolide-mediated neuroblastoma cell death.

Animals

Antineoplastic Agents, Alkylating - pharmacology

Antineoplastic Agents, Alkylating - therapeutic use

Apoptosis - drug effects

Cell Line, Tumor

Diterpenes - pharmacology

Diterpenes - therapeutic use

Drug Evaluation, Preclinical

Epoxy Compounds - pharmacology

Epoxy Compounds - therapeutic use

Gene Silencing

HSP70 Heat-Shock Proteins - genetics

HSP70 Heat-Shock Proteins - metabolism

Humans

Mice

Neuroblastoma - drug therapy

Neuroblastoma - metabolism

Phenanthrenes - pharmacology

Phenanthrenes - therapeutic use

RNA, Small Interfering

Details

Title: Subtitle: Role of Hsp-70 in triptolide-mediated cell death of neuroblastoma
Creators: Mara B Antonoff - University of Minnesota
Rohit Chugh - University of Minnesota
Steven J Skube - University of Minnesota
Vikas Dudeja - University of Minnesota
Daniel Borja-Cacho
Kimberly A Clawson - University of Minnesota
Selwyn M Vickers - University of Minnesota
Ashok K Saluja - University of Minnesota
Resource Type: Journal article
Publication Details: The Journal of surgical research, Vol.163(1), pp.72-78
DOI: 10.1016/j.jss.2010.04.047
PMID: 20638672
NLM abbreviation: J Surg Res
ISSN: 0022-4804
eISSN: 1095-8673
Grant note: R01 CA124723 / NCI NIH HHS
Language: English
Date published: 09/01/2010
Academic Unit: Anatomy and Cell Biology; Surgery
Record Identifier: 9985244574002771

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