Bi-specific Aptamers mediating Tumour Cell Lysis.
[Ph.D. Thesis], (2011)
Dissertation Achim Boltz -
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|Item Type:||Ph.D. Thesis|
|Title:||Bi-specific Aptamers mediating Tumour Cell Lysis|
The aim of the work presented herein is the development of bi-specific DNA aptamers simultaneously binding to tumour cell overexpressed receptor tyrosine kinase c-Met and Fcγ receptor IIIα (CD16α) on Natural Killer (NK) cells to mediate specific tumour cell lysis. Comparable antibody-dependent cellular cytotoxicity (ADCC) plays a pivotal role in antibody-based tumour therapies. Tumour-bound therapeutic antibodies recruit Natural Killer cells via their Fc receptors and induce specific lysis of tumour cells. In comparison to therapeutic monoclonal antibodies, potential advantages of aptamers are a facile selection, cost-effective and uniform synthesis as well as no to low immunogenicity. CD16α specific DNA aptamers were isolated by SELEX (systematic evolution of ligands by exponential enrichment) that bound with both high specificity and affinity (6 – 195 nM) to recombinant and NK cell expressed CD16α. Selected c-Met specific DNA aptamers showed high affinity (91 pM and 11 nM) and specificity to recombinant and cellular presented target protein as well. Two aptamers of each selection were optimised and coupled applying linkers of varying compositions and lengths to yield 24 constructs. Bi-specific aptamers that retained suitable binding properties and displayed simultaneous binding were applied in functional ADCC assays. Five bi-specific aptamers mediated cellular cytotoxicity dependent on aptamer and effector cell concentration. Displacement of a bi-specific aptamer from CD16α by the competing antibody 3G8 reduced aptamer-dependent cytotoxicity and hence confirmed the proposed mode of action. A bi-specific aptamer mediated specific lysis of human gastric and lung tumour cells, GTL-16 and EBC-1, respectively. These results represent the first gain of an effector function by coupling of two distinct aptamers to generate an anti-tumour effective molecule. A facile exchange of the tumourspecific aptamer to target other surface tumour markers could broaden the concept of aptamer-dependent cellular cytotoxicity to therapies of further tumour species.
|Uncontrolled Keywords:||Krebs, ADCC, bi-spezifisch, Aptamer, CD16, c-Met, HGF-R, Cancer, therapeutic, bi-specific|
|Classification DDC:||600 Technik, Medizin, angewandte Wissenschaften > 610 Medizin, Gesundheit
500 Naturwissenschaften und Mathematik > 570 Biowissenschaften, Biologie
Fachbereich Chemie > Biochemie
|Date Deposited:||11 May 2011 11:30|
|Last Modified:||07 Dec 2012 12:00|
|Referees:||Kolmar, Prof. Dr. Harald|
|Refereed:||12 April 2011|
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