Recent Submissions

  • Ectopic HOXB4 overcomes the inhibitory effect of tumor necrosis factor-{alpha} on Fanconi anemia hematopoietic stem and progenitor cells.

    Milsom, Michael D; Schiedlmeier, Bernhard; Bailey, Jeff; Kim, Mi-Ok; Li, Dandan; Jansen, Michael; Ali, Abdullah Mahmood; Kirby, Michelle; Baum, Christopher; Fairbairn, Leslie J; Williams, David A; Children's Hospital Boston and Harvard Stem Cell Institute, MA, USA. (2009-05-21)
    Ectopic delivery of HOXB4 elicits the expansion of engrafting hematopoietic stem cells (HSCs). We hypothesized that inhibition of tumor necrosis factor-alpha (TNF-alpha) signaling may be central to the self-renewal signature of HOXB4. Because HSCs derived from Fanconi anemia (FA) knockout mice are hypersensitive to TNF-alpha, we studied Fancc(-/-) HSCs to determine the physiologic effects of HOXB4 on TNF-alpha sensitivity and the relationship of these effects to the engraftment defect of FA HSCs. Overexpression of HOXB4 reversed the in vitro hypersensitivity to TNF-alpha of Fancc(-/-) HSCs and progenitors (P) and partially rescued the engraftment defect of these cells. Coexpression of HOXB4 and the correcting FA-C protein resulted in full correction compared with wild-type (WT) HSCs. Ectopic expression of HOXB4 resulted in a reduction in both apoptosis and reactive oxygen species in Fancc(-/-) but not WT HSC/P. HOXB4 overexpression was also associated with a significant reduction in surface expression of TNF-alpha receptors on Fancc(-/-) HSC/P. Finally, enhanced engraftment was seen even when HOXB4 was expressed in a time-limited fashion during in vivo reconstitution. Thus, the HOXB4 engraftment signature may be related to its effects on TNF-alpha signaling, and this pathway may be a molecular target for timed pharmacologic manipulation of HSC during reconstitution.
  • Retrovirally-mediated genetic correction of mesenchymal stem cells from patients affected by mucopolysaccharidosis type II (Hunter Syndrome)

    Corradi-Perini, Carla; Southgate, Thomas D; Besley, Guy T N; Cooper, Alan; Deakin, Jon A; Wraith, J Ed; Fairbairn, Leslie J; Wynn, Robert F; Bellantuono, Ilaria; Stem Cell Research Group, Royal Manchester Children's Hospital, Manchester. (2008)
  • Hypoxia response element-driven cytosine deaminase/5-fluorocytosine gene therapy system: a highly effective approach to overcome the dynamics of tumour hypoxia and enhance the radiosensitivity of prostate cancer cells in vitro.

    Marignol, Laure; Foley, Ruth; Southgate, Thomas D; Coffey, Mary; Hollywood, Donal; Lawler, Mark; Department of Haematology and Academic Unit of Clinical and Molecular Oncology, Institute of Molecular Medicine, St James's Hospital and Trinity College Dublin, Dublin, Ireland. marignol@tcd.ie (2009-02)
    BACKGROUND: We proposed to exploit hypoxia-inducible factor (HIF)-1alpha overexpression in prostate tumours and use this transcriptional machinery to control the expression of the suicide gene cytosine deaminase (CD) through binding of HIF-1alpha to arrangements of hypoxia response elements. CD is a prodrug activation enzyme, which converts inactive 5-fluorocytosine to active 5-fluorouracil (5-FU), allowing selective killing of vector containing cells. METHODS: We developed a pair of vectors, containing either five or eight copies of the hypoxia response element (HRE) isolated from the vascular endothelial growth factor (pH5VCD) or glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (pH8GCD) gene, respectively. The kinetics of the hypoxic induction of the vectors and sensitization effects were evaluated in 22Rv1 and DU145 cells in vitro. RESULTS: The CD protein as selectively detected in lysates of transiently transfected 22Rv1 and DU145 cells following hypoxic exposure. This is the first evidence of GAPDH HREs being used to control a suicide gene therapy strategy. Detectable CD levels were sustained upon reoxygenation and prolonged hypoxic exposures. Hypoxia-induced chemoresistance to 5-FU was overcome in both cell lines treated with this suicide gene therapy approach. Hypoxic transfectants were sensitized to prodrug concentrations that were ten-fold lower than those that are clinically relevant. Moreover, the surviving fraction of reoxygenated transfectants could be further reduced with the concomitant delivery of clinically relevant single radiation doses. CONCLUSIONS: This strategy thus has the potential to sensitize the hypoxic compartment of prostate tumours and improve the outcome of current therapies.