A Targeted Toxin Based on a Binding Module of Non-Immunoglobulin Scaffold as a New Agent for Theranostics

The aim of the investigation was to create multifunctional antitumor protein agent DARPin-mCherry-PE40 possessing both diagnostic and therapeutic properties.

Materials and Methods. The experiments were carried out on human cell lines of breast adenocarcinoma SK-BR-3. Chinese hamster ovarian cell line CHO-K1 was used as a control. Genetic engineering methods, metal chelate affinity chromatography, confocal microscopy and spectrophotometric MTT test were used to perform the experiments.

Results. A multifunctional targeted anticancer protein agent DARPin-mCherry-PE40 consisting of targeted HER2-specific non-immunoglobulin module DARPin, an imaging module mCherry and cytotoxic module based on a fragment of Pseudomonas exotoxin A (PE40) has been created. Using HER2-positive cells it was shown in vitro that all three domains of the recombinant protein retained their functional qualities — high affinity for HER2 antigen, ability to fluorescence, and cytotoxicity.

Conclusion. The ability of the targeted antitumor agent DARPin-mCherry-PE40 selectively stains HER2-positive cells and highly selective cytotoxicity against these cells make this targeted recombinant protein DARPin-mCherry-PE40 a perspective theranostic agent for the diagnosis and treatment of HER2-positive human tumors.

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Proshkina G.M., Stremovskiy O.A., Sibrikova D.V., Ryabova A.V., Deyev S.M. A Targeted Toxin Based on a Binding Module of Non-Immunoglobulin Scaffold as a New Agent for Theranostics. Sovremennye tehnologii v medicine 2016; 8(4): 7, https://doi.org/10.17691/stm2016.8.4.01