TY - JOUR
T1 - CBFβ-SMMHC, expressed in M4eo acute myeloid leukemia, reduces p53 induction and slows apoptosis in hematopoietic cells exposed to DNA-damaging agents
AU - Britos-Bray, Martin
AU - Ramirez, Manuel
AU - Cao, Wangsen
AU - Wang, Xinping
AU - Liu, P. Paul
AU - Civin, Curt I.
AU - Friedman, Alan D.
PY - 1998/12/1
Y1 - 1998/12/1
N2 - CBFβ-SMMHC is expressed in M4Eo acute myeloid leukemia (AML) as a result of inv(16), but how it contributes to leukemogenesis is unknown. p53 mutations are rare in de novo AML, but they are common in many malignancies. Expression of CBFβ-SMMHC in Ba/F3 cells reduced p53 induction in response to ionizing radiation or etoposide 3- to 4-fold. However, p53 induction was normal in Ba/F3 cells expressing a CBFβ-SMMHC variant that does not interfere with DNA binding by CBF, indicating that a CBF genetic target regulates p53 induction. The p53 gene may be regulated by CBF, because p53 mRNA levels were reduced by CBFβ-SMMHC. Reduced p53 induction was not caused by slowed cell proliferation, a consequence of CBFβ-SMMHC expression, because p53 was induced similarly in control cultures and in cultures propagated in 10-fold less interleukin-3 (IL-3). CBFβ-SMMHC did not slow apoptosis resulting from IL-3 withdrawal, where p53 induction is minimal, but slowed apoptosis in Ba/F3 cells exposed to 10 Gy of ionizing radiation or 3 to 8 μg/mL etoposide, providing 2-fold protection at 6 or 18 hours. Inhibition of apoptosis was temporary, because all the cells exposed to these doses ultimately died, and clonal survival assays performed using 0.04 μg/mL etoposide did not show protection by CBFβ-SMMHC. p21 levels were increased in cells subjected to DNA damage, regardless of CBFβ-SMMHC expression and attenuated p53 induction. Bcl-2, bcl-x(L), bcl-x(S), and bax levels were unaffected by CBFβ-SMMHC. Attenuated p53 induction may contribute to leukemogenesis by CBFβ-SMMHC by slowing apoptosis via a p21-independent mechanism.
AB - CBFβ-SMMHC is expressed in M4Eo acute myeloid leukemia (AML) as a result of inv(16), but how it contributes to leukemogenesis is unknown. p53 mutations are rare in de novo AML, but they are common in many malignancies. Expression of CBFβ-SMMHC in Ba/F3 cells reduced p53 induction in response to ionizing radiation or etoposide 3- to 4-fold. However, p53 induction was normal in Ba/F3 cells expressing a CBFβ-SMMHC variant that does not interfere with DNA binding by CBF, indicating that a CBF genetic target regulates p53 induction. The p53 gene may be regulated by CBF, because p53 mRNA levels were reduced by CBFβ-SMMHC. Reduced p53 induction was not caused by slowed cell proliferation, a consequence of CBFβ-SMMHC expression, because p53 was induced similarly in control cultures and in cultures propagated in 10-fold less interleukin-3 (IL-3). CBFβ-SMMHC did not slow apoptosis resulting from IL-3 withdrawal, where p53 induction is minimal, but slowed apoptosis in Ba/F3 cells exposed to 10 Gy of ionizing radiation or 3 to 8 μg/mL etoposide, providing 2-fold protection at 6 or 18 hours. Inhibition of apoptosis was temporary, because all the cells exposed to these doses ultimately died, and clonal survival assays performed using 0.04 μg/mL etoposide did not show protection by CBFβ-SMMHC. p21 levels were increased in cells subjected to DNA damage, regardless of CBFβ-SMMHC expression and attenuated p53 induction. Bcl-2, bcl-x(L), bcl-x(S), and bax levels were unaffected by CBFβ-SMMHC. Attenuated p53 induction may contribute to leukemogenesis by CBFβ-SMMHC by slowing apoptosis via a p21-independent mechanism.
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U2 - 10.1182/blood.v92.11.4344
DO - 10.1182/blood.v92.11.4344
M3 - Article
C2 - 9834241
AN - SCOPUS:0032217051
SN - 0006-4971
VL - 92
SP - 4344
EP - 4352
JO - Blood
JF - Blood
IS - 11
ER -