Currently assigned research projects
PK/PD modelling of PR104A and its active metabolites
PR104A and Nitro-CBI glucosides and galactosides for targeting tumour necrosis with
armed Clostridia
PPG project jointly with Stanford University
Gamma H2AX response to TPZ analogues
New Zealand Cancer Society project aimed at finding biomarkers for cell damage caused
by hypoxia active drugs
Spatially-resolved pharmacokinetic/pharmacodynamic (PK/PD) modelling of a lead nitroCBI
hypoxia-activated prodrug
Option specialisation: Cancer Biology and Therapeutics
Hypoxic regions have been identified in many tumours leading to resistance to radiotherapy.
This has lead to the development of many classes of drugs that are selectively activated
under hypoxic conditions to a cytotoxic species. NitroCBIs are prodrugs derived
from natural antibiotics and are the most potent hypoxia-activated cytotoxins developed
to date.
Enzymatic reductive metabolism of the nitro prodrug to an aminoCBI (effector) form
occurs selectively under hypoxia; the effector then binds to the minor groove of
DNA and alkylates the N3 of adenine: a highly damaging lesion. Since its action
is cytotoxic the prodrug must be able to diffuse to the target hypoxic tumour cells
and the effector must be able to diffuse to and kill surrounding cells. However,
the cells in hypoxic regions are generally the ones most distant from the blood
supply. Consequently, the ability of the prodrug and its effector to diffuse through
tumour tissue is critical in determining its clinical utility.
This project will use the multicellular layers (MCL), a novel tissue culture technique
developed in our laboratory, to investigate the diffusion of the prodrug and the
effector. This technique has recently been validated for one class of hypoxia-activated
prodrugs by showing that it well predicts in vivo anti-tumour activity. MCL are
grown on tissue culture inserts and are used to separate two sides of a diffusion
chamber. Drug is added to the compartment on one side and its diffusion into the
other compartment is measured by taking samples and analysing these with an existing
sensitive triple quadrupole mass spectrometry method. Separate experiments in stirred
cell suspensions will be used to relate cell killing to define the PD model; experiments
are in progress to determine the plasma PK. The experimentally determined PK/PD
parameters will be used to extend our three dimensional spatially-resolved model
to this class of drugs and simulations will be used to compare predicted in vivo
killing to that determined experimentally in other projects.
Skills to be gained by the student:
- human tumour cell culture
- preparation and characterisation of drug
solutions
- clonogenic assays of cell killing under aerobic and hypoxic
conditions
- determination of drug uptake and metabolism by cells LC/MS/MS
(HPLC with on-line triple quadrupole mass spectrometry) for quantitation of
parent and metabolites
- data analysis and quantitative modelling.
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Research project on offer
BSc (Hons) Biomedical Science projects on offer
Information on the structure and process of the BSc (Hons) in Biomedical Science programme
Ascorbate transport and HIF-1 regulation in tumours
Option specialisation: Cancer Biology and Therapeutics
Upregulation of the hypoxia-inducible transcription factor HIF-1 in hypoxic regions
of tumours is considered to facilitate tumour cell survival in this hostile environment.
Hypoxic cells are refractory to radiation and to many cytotoxic drugs, so elimination
of these cells is an important goal in cancer research. Recent studies have demonstrated
that the HIF-1 response is strongly inhibited by ascorbic acid (vitamin C) in cell
culture; ascorbate acts as a cofactor for the proline and asparagine hydroxylases
responsible for marking HIF-1 for proteosomal degradation. This leads to the hypothesis
that the stabilisation of HIF-1 in hypoxic regions of tumours requires both oxygen
and ascorbate deficiency. However, it is not currently known whether ascorbate diffuses
efficiently into hypoxic regions of tumours or whether its concentration gradient
is steep enough to exacerbate HIF-1 stabilisation.
We will test this by evaluating the transport of ascorbate through tumour tissue,
using an in vitro model (multicellular layer cultures, MCL) developed by us. We
will compare MCL grown from four different human tumour cell lines, and will measure
flux of ascorbate through the MCLs under aerobic and hypoxic conditions. The transport
parameters will be used to model ascobate concentration profiles in tumour microvascular
networks. The effect of high concentrations of ascorbate on HIF-1 levels in hypoxic
MCLs will then be tested using MCLs of different thicknesses.
This project will provide training in:
- tumour cell culture (including the MCLtumour cell culture (including the MCL model)
- bioanalysis of
ascorbate using (LC/MS/MS or electrochemical detection)
- immunohistochemistry and mathematical modelling. (A background in advanced mathematics
is not required).
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