An 111In-labelled bis-ruthenium(ii) dipyridophenazine theranostic complex: mismatch DNA binding and selective radiotoxicity towards MMR-deficient cancer cells

Martin R. Gill*, Michael G. Walker, Sarah Able, Ole Tietz, Abirami Lakshminarayanan, Rachel Anderson, Rod Chalk, Afaf H. El-Sagheer, Tom Brown, Jim A. Thomas, Katherine A. Vallis

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Theranostic radionuclides that emit Auger electrons (AE) can generate highly localised DNA damage and the accompanying gamma ray emission can be used for single-photon emission computed tomography (SPECT) imaging. Mismatched DNA base pairs (mismatches) are DNA lesions that are abundant in cells deficient in MMR (mismatch mediated repair) proteins. This form of genetic instability is prevalent in the MMR-deficient subset of colorectal cancers and is a potential target for AE radiotherapeutics. Herein we report the synthesis of a mismatch DNA binding bis-ruthenium(ii) dipyridophenazine (dppz) complex that can be radiolabelled with the Auger electron emitting radionuclide indium-111 (111In). Greater stabilisation accompanied by enhanced MLCT (metal to ligand charge-transfer) luminescence of both the bis-Ru(dppz) chelator and non-radioactive indium-loaded complex was observed in the presence of a TT mismatch-containing duplex compared to matched DNA. The radioactive construct [111In]In-bisRu(dppz) ([111In][In-2]4+) targets cell nuclei and is radiotoxic towards MMR-deficient human colorectal cancer cells showing substantially less detrimental effects in a paired cell line with restored MMR function. Additional cell line studies revealed that [111In][In-2]4+ is preferentially radiotoxic towards MMR-deficient colorectal cancer cells accompanied by increased DNA damage due to 111In decay. The biodistribution of [111In][In-2]4+ in live mice was demonstrated using SPECT. These results illustrate how a Ru(ii) polypyridyl complex can incorporate mismatch DNA binding and radiometal chelation in a single molecule, generating a DNA-targeting AE radiopharmaceutical that displays selective radiotoxicity towards MMR-deficient cancer cells and is compatible with whole organism SPECT imaging.

Original languageEnglish
Pages (from-to)8936-8944
Number of pages9
JournalChemical Science
Volume11
Issue number33
DOIs
Publication statusPublished - 7 Sep 2020
Externally publishedYes

Bibliographical note

Copyright the Royal Society of Chemistry 2020. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.

Fingerprint Dive into the research topics of 'An <sup>111</sup>In-labelled bis-ruthenium(ii) dipyridophenazine theranostic complex: mismatch DNA binding and selective radiotoxicity towards MMR-deficient cancer cells'. Together they form a unique fingerprint.

Cite this