Chromosome translocations that disrupt the Mixed Lineage Leukaemia (MLL) gene are associated with a unique subset of acute myelogenous and lymphoblastic leukaemias. MLL translocations are most prevalent in infant leukaemia, where they comprise 80% of cases of acute lymphoblastic leukaemia and 60% of cases in acute myeloid leukaemia. To identify transcriptional target genes required for the immortalisation, previous work in our laboratory involved generating constitutively and conditionally immortalised primary mouse haematopoietic progenitor cells. Global gene expression analysis, upon loss of MLL-fusion protein, identified a number of genes that were differentially expressed. This project aims to investigate the importance of two differentially expressed genes, Msi2 and Ruvbl2, in MLL-fusion mediated leukaemogenesis. To examine the efficacy of targeting Ruvbl2 and Msi2 in leukaemia elimination in vivo, shRNA inducible models were generated for the human leukaemic cell line, THP1 and murine MLL-ENL leukaemic cells. While targeting Msi2 had no significant impact on leukaemia progression in vivo, inhibiting RUVBL2 function significantly delayed leukaemia onset. RUVBL2 is a member of the AAA+ family of DNA helicases and plays an important role in diverse cellular processes. RUVBL2 was inhibited either via shRNA-mediated knockdown or through the expression of a dominant-negative mutant form of RUVBL2, and its inhibition resulted in a marked increase in apoptosis, reduction in colony formation and a block in cell cycle. In parallel, while expression of dominant-negative RUVBL2 induced apoptosis in mouse MLL-ENL leukaemic cells, it had a relatively mild impact on normal haematopoietic progenitor colony formation in vitro. Further experiments indicated that RUVBL2 functioned mainly through influencing the transcriptional activity of c-MYC. Taken together, our data suggest that a potential therapeutic window exists for targeting RUVBL2 function in MLL-rearranged leukaemia.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:631826 |
| Date | January 2014 |
| Creators | Zhao, L. |
| 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/1432505/ |
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