Single-chain antibody/activated BID chimeric protein effectively suppresses HER2-positive tumor growth

BH3-interacting domain death agonist (BID) is a crucial element in death signaling pathways and is recognized as an intracellular link connecting the intrinsic mitochondrial apoptotic and extrinsic death receptor–mediated apoptotic pathways. Herein, we describe experiments conducted with a fusion pr...

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Published in:Molecular cancer therapeutics 2008-07, Vol.7 (7), p.1890-1899
Main Authors: Qiu, Xiu-Chun, Xu, Yan-Ming, Wang, Fang, Fan, Qing-Yu, Wang, Li-Feng, Ma, Bao-An, Jia, Lin-Tao, Zhao, Jing, Meng, Yan-Ling, Yao, Li-Bo, Chen, Si-Yi, Yang, An-Gang
Format: Article
Language:English
Subjects:
Animals
Antibodies
Antibodies, Neoplasm - pharmacology
Apoptosis
Apoptosis Inducing Factor - metabolism
BH3 Interacting Domain Death Agonist Protein - pharmacology
Cell Death - drug effects
Cell Line, Tumor
Cell Proliferation - drug effects
Cell Surface Molecules
Cercopithecus aethiops
COS Cells
Cytochromes c - metabolism
Gene Therapy
Human
Humans
Mice
Mice, Inbred BALB C
Mice, Nude
Neoplasms - immunology
Neoplasms - pathology
Peptides - chemistry
Protein Structure, Tertiary
Receptor, ErbB-2 - metabolism
Recombinant Fusion Proteins - pharmacology
Transduction, Genetic
Xenograft Model Antitumor Assays
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Summary:BH3-interacting domain death agonist (BID) is a crucial element in death signaling pathways and is recognized as an intracellular link connecting the intrinsic mitochondrial apoptotic and extrinsic death receptor–mediated apoptotic pathways. Herein, we describe experiments conducted with a fusion protein, which was generated by fusing a human epidermal growth factor receptor-2 (HER2)–specific single-chain antibody with domain II of Pseudomonas exotoxin A and the truncated active BID (tBID). These experiments extend our previous work on several other immuno-proapoptotic proteins. Specifically, by excluding cells with undetectable HER2, we showed that the secreted immuno-tBID molecule selectively recognized and killed HER2-overexpressing tumor cells in vitro by attacking their mitochondria and inducing their apoptotic death. This apoptosis could only be inhibited partially by caspase pan-inhibitor zVAD and mitochondrial protector TAT-BH4. Subsequently, we transferred the immuno-tbid gene into BALB/c athymic mice bearing HER2-positive tumors together with other immuno-proapoptotic proteins using i.m. injections of liposome-encapsulated vectors. The expression of the immuno-tbid gene suppressed tumor growth and prolonged animal survival significantly. We also shortened the translocation domain of Pseudomonas exotoxin A II to only 10–amino acid sequence, which were crucial for furin cleavage. The new recombinant molecule retained the translocation efficiency and the ability of specific killing HER2-positive tumor cells. Our data showed that, compared with the toxins employed before, the chimeric immuno-tBID molecule can not only specifically recognize HER2-positive tumor cells but also certainly induce apoptosis even in the presence of zVAD and TAT-BH4, thereby suggesting an alternative approach to treating HER2/ neu -positive tumors. [Mol Cancer Ther 2008;7(7):1890–9]
ISSN:1535-7163
1538-8514
DOI:10.1158/1535-7163.MCT-07-2235