TY - JOUR
T1 - BCR-ABL fails to inhibit apoptosis in U937 myelomonocytic cells expressing a carboxyl-terminal truncated STAT5
AU - Ahmed, M.
AU - Dusanter-Fourt, I.
AU - Dugray, A.
AU - Dubrez, L.
AU - Novault, S.
AU - Bonnet, M. L.
AU - Gisselbrecht, S.
AU - Varet, B.
AU - Solary, E.
AU - Vainchenker, W.
AU - Turhan, A. G.
N1 - Funding Information:
Keywords: BCR-ABL, inhibition of apoptosis, U937 Cells, carboxyl-terminalt runcated STATS, myelo-monocytic cells Work supported by grants from the Association de Recherche sur le Cancer (ARC), la Ligue Nationale Contre le Cancer, INSERM and Institut Gustave Roussy.
PY - 2001/1/1
Y1 - 2001/1/1
N2 - Recent experimental data suggest that one of the major effects of BCR-ABL gene expression in hematopoietic cells is the inhibition of apoptosis. Although the exact mechanisms of this phenomenon are not clear, it is thought to be related to the fact that BCR-ABL induces several signalling pathways also activated by growth factors. In order to determine the anti-apoptotic role of BCR-ABL in a hematopoietic cell line and to by-pass the influence of cytokine-dependence, BCR-ABL gene was expressed in the autonomously growing myelomonocytic U937 cell line using retroviral vectors. There was no resistance to apoptosis induced by either serum deprivation or different doses of etoposide in any U937 clones expressing BCR-ABL protein. In addition to serum deprivation and etoposide, BCR-ABL-expressing clones were not protected from apoptosis induced by TNF, ceramide-C2 and FAS-cross-linking. BCL2 expression was absent in U937 cells and BAX levels were identical between Neo and BCR-ABL clones. To further investigate the mechanisms of this phenomenon, band-shift assays were performed to detect activation of STAT molecules. No constitutive activation of STATs was detected in either NeoR or BCR-ABL-U937 cells, although both IFN-γ and GM-CSF activated STAT1 and STAT5, respectively, with similar kinetics in both NeoR and BCR-ABL-U937 cells. In addition, the GM-CSF-induced-STAT5 activation was found to be weakened in all clones expressing BCR-ABL. In both control NeoR and BCR-ABL-transfected clones, band-shift assays revealed the presence of an abnormal truncated STAT5 recognized only by an anti- N-terminal but not by an anti-C-Terminal STAT5 antibody. These findings suggest a possible link between the absence of anti-apoptotic potential of BCR-ABL and abnormalities of the STAT5 pathway, including, absence of constitutive activation of STAT5, inhibition of GM-CSF-induced STAT5 activation and expression of a carboxyl-terminal-truncated STAT5.
AB - Recent experimental data suggest that one of the major effects of BCR-ABL gene expression in hematopoietic cells is the inhibition of apoptosis. Although the exact mechanisms of this phenomenon are not clear, it is thought to be related to the fact that BCR-ABL induces several signalling pathways also activated by growth factors. In order to determine the anti-apoptotic role of BCR-ABL in a hematopoietic cell line and to by-pass the influence of cytokine-dependence, BCR-ABL gene was expressed in the autonomously growing myelomonocytic U937 cell line using retroviral vectors. There was no resistance to apoptosis induced by either serum deprivation or different doses of etoposide in any U937 clones expressing BCR-ABL protein. In addition to serum deprivation and etoposide, BCR-ABL-expressing clones were not protected from apoptosis induced by TNF, ceramide-C2 and FAS-cross-linking. BCL2 expression was absent in U937 cells and BAX levels were identical between Neo and BCR-ABL clones. To further investigate the mechanisms of this phenomenon, band-shift assays were performed to detect activation of STAT molecules. No constitutive activation of STATs was detected in either NeoR or BCR-ABL-U937 cells, although both IFN-γ and GM-CSF activated STAT1 and STAT5, respectively, with similar kinetics in both NeoR and BCR-ABL-U937 cells. In addition, the GM-CSF-induced-STAT5 activation was found to be weakened in all clones expressing BCR-ABL. In both control NeoR and BCR-ABL-transfected clones, band-shift assays revealed the presence of an abnormal truncated STAT5 recognized only by an anti- N-terminal but not by an anti-C-Terminal STAT5 antibody. These findings suggest a possible link between the absence of anti-apoptotic potential of BCR-ABL and abnormalities of the STAT5 pathway, including, absence of constitutive activation of STAT5, inhibition of GM-CSF-induced STAT5 activation and expression of a carboxyl-terminal-truncated STAT5.
KW - BCR-ABL
KW - Carboxyl-terminal truncated STATS
KW - Inhibition of apoptosis
KW - Myelomonocytic cells
KW - U937 cells
UR - http://www.scopus.com/inward/record.url?scp=0034908521&partnerID=8YFLogxK
U2 - 10.3109/10428190109064601
DO - 10.3109/10428190109064601
M3 - Article
C2 - 11699409
AN - SCOPUS:0034908521
SN - 1042-8194
VL - 42
SP - 445
EP - 455
JO - Leukemia and Lymphoma
JF - Leukemia and Lymphoma
IS - 3
ER -