TY - JOUR
T1 - C/EBPα inactivation in FAK-overexpressed HL-60 cells impairs cell differentiation
AU - Hashimoto, Ken Ichiro
AU - Sonoda, Yoshiko
AU - Yamakado, Masakazu
AU - Funakoshi-Tago, Megumi
AU - Yoshida, Naomi
AU - Rokudai, Akiko
AU - Aizu-Yokota, Eriko
AU - Kasahara, Tadashi
N1 - Funding Information:
This study was supported by grants from the Ministry of Education, Science and Culture (14572066 and 16390024) and High-Tech Research Center Project for Private Universities from MEXT (2004–2008).
PY - 2006/7
Y1 - 2006/7
N2 - We previously demonstrated that focal adhesion kinase (FAK)-overexpressed (HL-60/FAK) cells have marked resistance against various apoptotic stimuli such as oxidative stress, ionizing radiation and TNF-receptor-induced ligand (TRAIL) compared with vector-transfected (HL-60/Vect) cells. Here, we show that HL-60/FAK cells are highly resistant to all-trans retinoic acid (ATRA)-induced differentiation, whereas original HL-60 or HL-60/Vect cells are sensitive. Treatment with ATRA at 1 μM for 5 days markedly inhibited the proliferation and increased the expression of differentiation markers (CD38, CD11b) in HL-60/Vect cells, but showed no such effect in HL-60/FAK cells. Electrophoretic mobility shift assay (EMSA) using an oligonucleotide for the c/EBP consensus binding sequence showed that c/EBPα was activated in ATRA-treated HL-60/Vect cells but not in HL-60/FAK cells, indicating that c/EBPα activation by ATRA was impaired in HL-60/FAK cells. In addition, the association of retinoblastoma protein (pRb) and c/EBPα after treatment with ATRA was seen in HL-60/Vect cells but not in HL-60/FAK cells. Further, hyperphosphorylation of pRb was observed in HL-60/FAK cells. Finally, the introduction of FAK siRNA into HL-60/FAK cells resulted in the recovery of sensitivity to ATRA-induced differentiation, confirming that the inhibition of HL-60/FAK differentiation resulted from both the induction of pRb hyperphosphorylation and the inhibition of association of pRb and c/EBPα.
AB - We previously demonstrated that focal adhesion kinase (FAK)-overexpressed (HL-60/FAK) cells have marked resistance against various apoptotic stimuli such as oxidative stress, ionizing radiation and TNF-receptor-induced ligand (TRAIL) compared with vector-transfected (HL-60/Vect) cells. Here, we show that HL-60/FAK cells are highly resistant to all-trans retinoic acid (ATRA)-induced differentiation, whereas original HL-60 or HL-60/Vect cells are sensitive. Treatment with ATRA at 1 μM for 5 days markedly inhibited the proliferation and increased the expression of differentiation markers (CD38, CD11b) in HL-60/Vect cells, but showed no such effect in HL-60/FAK cells. Electrophoretic mobility shift assay (EMSA) using an oligonucleotide for the c/EBP consensus binding sequence showed that c/EBPα was activated in ATRA-treated HL-60/Vect cells but not in HL-60/FAK cells, indicating that c/EBPα activation by ATRA was impaired in HL-60/FAK cells. In addition, the association of retinoblastoma protein (pRb) and c/EBPα after treatment with ATRA was seen in HL-60/Vect cells but not in HL-60/FAK cells. Further, hyperphosphorylation of pRb was observed in HL-60/FAK cells. Finally, the introduction of FAK siRNA into HL-60/FAK cells resulted in the recovery of sensitivity to ATRA-induced differentiation, confirming that the inhibition of HL-60/FAK differentiation resulted from both the induction of pRb hyperphosphorylation and the inhibition of association of pRb and c/EBPα.
KW - Differentiation
KW - FAK
KW - Granulocyte
KW - c/EBP
KW - pRb
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U2 - 10.1016/j.cellsig.2005.08.014
DO - 10.1016/j.cellsig.2005.08.014
M3 - Article
C2 - 16226872
AN - SCOPUS:33645099380
SN - 0898-6568
VL - 18
SP - 955
EP - 963
JO - Cellular Signalling
JF - Cellular Signalling
IS - 7
ER -