Universität zu Köln

Heß, Felix Alexander ORCID: 0009-0007-1883-3608 (2026). Development of a Multi-Modular siRNA Carrier System for Epidermal Growth Factor Receptor Specific Delivery. PhD thesis, Universität zu Köln.

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Abstract

Long non-coding RNAs (lncRNAs) transcribed from pericentromeric satellite repeats III (HSat3) are involved in stress-responsive splicing mechanisms and the preservation of genome stability. Elevated levels of HSat3 RNA have been observed across various cancer types, as well as under heat stress conditions and chemotherapeutic induced cytotoxic stress. Clinically, increased expression of satellite RNAs is detectable in mul-tiple cancer tissues. Additionally, induction of murine major Satellites has been shown to accelerate tumour onset in mice, resulting in reduced survival rates. Moreover, HSat3 transcripts are linked with the resistance to the topoisomerase 2a (TOP2A) in-hibitor etoposide in non-small cell lung cancer (NSCLC). Recently, novel regulators of HSat3 expression have been discovered. When combined with etoposide, these agents can reverse therapy resistance and effectively inhibit cell proliferation. However, achieving tumor-specific delivery of such agents remains challenging. Therefore, this project aims to develop a receptor-targeted, multi-modular siRNA delivery system to address this issue. Since compound development depends on the effectiveness of its development platform, this work is divided into two parts: Establishing a new com-pound development platform (Section One) and developing an siRNA delivery system targeting epidermal growth factor receptor (EGFR) (Section Two). The initial section demonstrates the successful development of a sensitive dual fluorescence-based assay called FluoroDetect. The assay is designed to evaluate small interfering RNAs (siRNAs), antisense oligonucleotides (ASOs), and RNA-binding compounds. Assay results can be obtained using fluorescence microscopy, plate readers, or flow cytometry, enabling quantification of knockdown efficiency. Consequently, the FluoroDetect assay serves as a valuable tool for screening nucleic acid drug candidates and aids in optimizing and quantifying nucleic acid delivery in therapies. The second section outlines the devel-opment of an aptamer-siRNA conjugate against HSat3 RNA utilizing solid-phase synthe-sis, in vitro transcription, and hybrid approaches. All drug candidates were assessed using in vitro cell culture models. The final nucleic-acid based conjugate successfully targets EGFR positive cells and is incorporated into the cells, but faces limitations re-lated to endosomal escape. In sum, in this thesis I was able to develop tools for NA-based compound selections and provide first steps towards a HSat3-directed aptamer treatment.

Item Type:	Thesis (PhD thesis)
Creators:	Creators Email ORCID ORCID Put Code Heß, Felix Alexander derfelixhess@yahoo.de https://orcid.org/0009-0007-1883-3608 UNSPECIFIED
URN:	urn:nbn:de:hbz:38-804361
Date:	2026
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Zentrum für Molekulare Medizin
Subjects:	Chemistry and allied sciences Life sciences Technology (Applied sciences) Medical sciences Medicine
Uncontrolled Keywords:	Keywords Language lncRNA English HSat3 English ASO English siRNA English FluoroDetect English RNA Aptamer English EGFR English Therapy English Cancer English Drug Development English
Date of oral exam:	9 March 2026
Referee:	Name Academic Title Stripecke, Renata Prof. Dr. Neundorf, Ines Prof. Dr.
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/80436