Role of the C-terminal actin binding domain in BCR/ABL-mediated survival and drug resistance.
Philadelphia chromosome-positive, chronic myeloid leukaemia (CML) stem and progenitor cells have a survival and growth advantage compared with their normal counterparts. The mechanisms through which the BCR/ABL protein tyrosine kinase (PTK) induces these effects and the important domains within this protein are not fully defined. The F- and G-actin binding region of the BCR/ABL C-terminus may be important in BCR/ABL-mediated events, and we have investigated this by expressing a C-terminus deletion mutant of the temperature-sensitive BCR/ABL PTK, in a haemopoietic progenitor cell line, which models the chronic phase of CML. The truncated BCR/ABL PTK displayed similar levels of PTK activity when compared with wild type and activation of second messenger formation (in the form of sn-1,2-diacylglycerol) remains intact. On fibronectin substrata, localisation of the protein to the periphery of the cell was, however, dependent on the C-terminus of BCR/ABL PTK. Deletion of the C-terminus reversed both BCR/ABL-mediated apoptotic suppression and drug resistance although the progenitor cells did retain a proliferative advantage at low concentrations of growth factor. These results demonstrated that the C-terminal actin-binding domain of BCR/ABL is important for some of BCR/ABL PTK-mediated leukaemogenic effects.
Faculty of Life Sciences, University of Manchester, Christie Hospital, Withington, Manchester, UK.
N
N
Underhill-Day
A
A
Pierce
S E
SE
Thompson
D
D
Xenaki
A D
AD
Whetton
P J
PJ
Owen-Lynch
D000199:Actins / Q000235:genetics* / Q000378:metabolism; D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D002454:Cell Differentiation / Q000235:genetics; D002455:Cell Division / Q000235:genetics; D045744:Cell Line, Tumor; D003001:Cloning, Molecular / Q000379:methods; D003561:Cytarabine / Q000494:pharmacology; D019008:Drug Resistance, Neoplasm / Q000235:genetics; D005455:Fluorescent Antibody Technique / Q000379:methods; D016044:Fusion Proteins, bcr-abl / Q000032:analysis / Q000235:genetics*; D006801:Humans; D006918:Hydroxyurea / Q000494:pharmacology; D007377:Interleukin-3 / Q000378:metabolism; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000201:enzymology / Q000235:genetics* / Q000401:mortality; D008055:Lipids / Q000032:analysis; D008954:Models, Biological; D014411:Neoplastic Stem Cells / Q000187:drug effects / Q000502:physiology; D011505:Protein-Tyrosine Kinases / Q000235:genetics* / Q000378:metabolism; D013696:Temperature
D000199:Actins; D000970:Antineoplastic Agents; D007377:Interleukin-3; D008055:Lipids; D003561:Cytarabine; D011505:Protein-Tyrosine Kinases; D016044:Fusion Proteins, bcr-abl; D006918:Hydroxyurea