Building de novo signaling pathways for multi-stage smart delivery systems in cancer

Lead Research Organisation: Imperial College London
Department Name: Dept of Chemistry

Abstract

It has now been established that relapse of prostate cancers can be significantly mitigated by
targeting and inhibiting the androgen receptor in tumours. Critical to this process is the delivery of
corresponding inhibitory peptides but to date this has proved problematic. This is because direct
exposure of protein to the carcinoma environment leads to rapid breakdown through protease
driven action. Here, we propose to develop a unique multi-stage vesicle delivery system, which
differs substantially from previous philosophies as it does not rely on disassembly of the vesicle for
release of its cargo but instead capitalizes upon the construction of the first de novo
mechanosensitive signalling pathway inside artificial cells (ACs) and communication
between real cells and artificial cells. This will be achieved by constructing multi-layered vesicle
machines that are capable of transducing signals from the environment (prostate cancer cells) to
the surface of an AC and then onto the inner lumen of the AC inside through a series of user-
defined protein-protein interactions. These do not require direct protein-protein contacts and are
instead mediated through the recently discovered phenomenon of membrane mediated protein-
protein interactions. As the signal propagates into the AC from the cancer it triggers the opening of
embedded large-pore channels in different layers of the AC, allowing onboard therapeutic agents to
be released in bursts or different agents to be released in series. The channels are based around
the mechanically sensitive channels of large conductance (MscL). MscL has shown a robust and
readily overexpressed (~mg) membrane channel protein that exhibits a wide range of large pores
(up to 40Å) whose size range can be carefully controlled. Once it is embedded in a lipid bilayer, it
has been shown to be sensitive (and opens) to membrane asymmetry (figure 1). One method of
generating asymmetry is to use phospholipase A1 or A2 (PLA). PLA rapidly alters phospholipid
structure by converting them into lysophospholipid (single chained) and the concomitant free fatty
acid, which generates asymmetry when only acting from one side of the bilayer. We have previously
demonstrated that through this asymmetry generation, it is possible to engineer MscL-PLA
communication in analogue and digital format (Charalambous et al. JACS, 2012), a phenomenon
we aim to exploit in this project as it is now well understood that PLA is aberrantly expressed by a
wide variety of tumour cells including prostate cancer cells. The function of the resultant ACs will
depend on the delicate interplay of lipid-lipid, lipid-protein and membrane mediated protein-protein
interactions and new platform technologies for fabricating multi-layered vesicle constructs.

Publications

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Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/S023518/1 01/10/2019 31/03/2028
2268913 Studentship EP/S023518/1 01/10/2019 30/09/2023 Matthew Allen