Adoptive T cell therapy to treat cancer in combination with re-directing specificity through T cell receptor (TCR) gene transfer, represents an effective therapeutic option. However, reduced effector responses due to the immunosuppressive tumour microenvironment and insufficient long-term engraftment of transferred cells represent two potential limitations. Tumours often employ mechanisms to inhibit T cell responses including secretion of TGFβ and depleting the tumour microenvironment of amino acids. The main aim of this PhD project was to develop a strategy to enhance T cell function for tumour therapy. The mammalian target of rapamycin (mTOR) pathway regulates CD8 T cell differentiation such that high mTOR activation leads to enhanced effector whilst low mTOR activation leads to increased T cell memory formation. Two retrovirus constructs have been designed whereby one expresses the positive mTOR regulator Rheb and the other expresses the negative mTOR regulator Pras40. Rheb transduction into CD8 T cells resulted in enhanced activation of mTOR, increased effector functions and partial resistance to TGFβ and low arginine concentrations. Pras40 overexpression led to a decrease in the activation of mTOR and reduced effector functions. Rheb transduced CD8 T cells expanded efficiently upon antigen encounter in vivo, followed by pronounced T cell contraction. Pras40 transduced T cells were unable to expand in vivo, but persisted at low numbers and acquired a central memory phenotype. Tumour bearing mice treated with TCR re-directed CD8 T cells transduced with Rheb showed improved tumour protection. Pras40 overexpression resulted in the loss of the protective function of TCR re-directed T cells. Together, the data show that gene transfer can be used to regulate mTOR activity in T cells. Enhancing mTOR activity led to improved tumour control despite reducing memory formation. Permanent mTOR inhibition, on the other hand, preserved some memory characteristcs of T cells but deteriorated their tumour protective functions.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:602911 |
| Date | January 2014 |
| Creators | Zech, M. H. |
| Publisher | University College London (University of London) |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://discovery.ucl.ac.uk/1420953/ |
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