Strategies to enhance efficacy of nucleotide therapeutics for targeted cancer therapy
Nominating Supervisor: Prof. Katherine Vallis
Second Supervisor: Prof. Tom Brown
Oligonucleotide (ON) drugs hold promise in cancer medicine as they offer exquisitely precise inhibition of DNA and RNA targets. However, the introduction of ON-based agents into clinical practise has been held back by poor penetration of the plasma membrane and, therefore, limited internalisation into target cells. Most ON therapeutics enter cells through endocytic pathways but may then become entrapped in endosomes, preventing interaction with their intended molecular target. Cell-penetrating peptides (CPPs) such as Tat have the potential to enhance the cellular delivery of many types of non-permeant biomolecules1,2 including nucleic acids and some also possess endosomal escape properties.
We have recently shown that multimeric arrays of linear and cyclic CPPs more efficiently promote cell uptake of pharmacons than monomers and that structural modifications influence mechanisms of interaction with the cell membrane and escape from endosomes.
In this project two approaches to multimeric CPP-assisted transport of ONs will be explored: covalent conjugation and non-covalent co-delivery. Initial work will centre on CPP-mediated internalisation of nucleotide therapeutics designed to inhibit telomerase through sequence-specific binding of the hTR RNA template2 and successful methods will be expanded to other DNA or RNA cancer targets.
The aims of the project are to (1) to synthesise novel covalently linked CPP-ON macromolecules, (2) to explore the structure-activity relationships of multimeric CPP constructs, (3) to evaluate a panel of CPP-ON combinations in in vitro and in vivo cancer models with, initially, telomerase inhibition as the functional readout, and (4) to investigate the potential for efficient delivery of raidolabelled ONs for ON-mediated targeted radionuclide therapy of cancer.
Although the emphasis will be on ONs, effective CPP constructs are likely to have broad applications for drug delivery in cancer medicine.
This is an interdisciplinary project that includes aspects of cancer biology, radiation biology and nucleotide and peptide chemistry. It will involve training in aspects of advanced site-specific conjugation chemistry on bio-macromolecules, state of the art purification and chemical analysis of conjugates, as well as radiochemistry using diagnostic and therapeutic radionuclides. Furthermore, this project will utilize in vitro cancer models with the prospect of advancing to in vivo models, advanced microscopy including confocal live cell imaging, radiobiology assays and molecular and cell biology.
Bavelaar BM, et al. Front Pharmacol, 9, 996, 2018.
Cornelissen B, et al. Cancer Res. 71, 4539-4549, 2011.
Jackson MR, et al. Cancer Res, 79, 4627-4649, 2019.