Investigation of autophagy as a survival factor for chronic myeloid leukaemia

RC0254 Neoplasms. Tumors. Oncology (including Cancer)

Karvela, Maria ; Holyoake, Tessa

University:University of Glasgow

Department:Institute of Cancer Sciences

关键词: Chronic myeloid leukaemia, tyrosine kinase inhibitors, autophagy, stem cells;   

Others  :  http://theses.gla.ac.uk/4271/7/2013KarvelaPhD.pdf

来源: University of Glasgow

【 摘 要 】

Tyrosine kinase inhibitors (TKIs) have revolutionised the treatment of chronic myeloidleukemia (CML), however, fail to cure the disease due to the persistence of a refractoryfraction of stem/progenitor cells. Autophagy is a recycling mechanism utilised by the cellas a survival mechanism under stressful conditions, and its induction has been suggested tohave a cytoprotective role in cancer cells.In this study we demonstrate that autophagy is triggered in CML upon TKI-mediatedinhibition of BCR-ABL, and protects from cell death. In order to evaluate if specificautophagy inhibition enhances TKI effects, we stably transduced primary CMLstem/progenitor cells with a vector carrying a short-hairpin against the key autophagy geneATG7. Knock-down of basal ATG7/autophagy levels in CML stem/progenitor cellsinhibited by approximately 50% the survival of the cells in a clonogenic assay, andreduced by 75% their erythroid differentiation potential. Furthermore, ATG7 knock-downenhanced the effects of TKIs imatinib (IM; 1st), dasatinib (DAS; 2nd), nilotinib (NIL; 2nd)and ponatinib (PON; 3rd generation), reducing by 92-98% the survival of these cells in aclonogenic assay. In contrast, ATG7 knock-down in normal stem cells, with or withoutTKI treatment, did not have a significant effect on survival and proliferation.ATG7 was also knocked-down in final disease stage, blast crisis (BC), patient-derivedK562 and KCL22 cell lines. Both cell lines appeared to depend significantly on autophagyfor survival as indicated by high apoptosis levels (70-100%) after ATG7 knock-down.Interestingly, ATG7 knock-down cells appeared to be more differentiated compared to thecontrol (scrambled shRNA).Our findings suggest a role for basal autophagy in the survival, differentiation decisionsand clonogenicity of CML cells, and support the combined use of autophagy inhibitionwith TKIs for the eradication of CML stem/progenitor cells. This could be partiallyattributed to a bypass of the differentiation block upon autophagy inhibition, whichfacilitates TKI-targeting. We underline the necessity for the development of specificautophagy inhibitors that in combination with TKIs could potentially eradicate the fractionof persistent CML stem/progenitor cells and offer a curative option for CML patients.