[Effect of MLL-AF9 fusion gene silence of acute monocytic leukemia cell line THP-1 on cyclin-dependent kinase inhibitor p27 expression].
OBJECTIVE
To explore the effect of MLL-AF9 fusion gene silence on p27 expression and transcription regulation in THP-1 cells.


METHODS
Small interference RNA (siRNA) fragments targeting THP-1 cells specific MLL-AF9 fusion gene were designed and constructed, and transfected into THP-1 by lipofectamine. Flow cytometry was used to detect siRNA transfection efficiency. The level of MLL-AF9 mRNA expression was examined by RT-PCR and the expression of MLL-AF9 and p27 protein was detected by Western blot. Chromatin immunoprecipitation (ChIP) assay was used to confirm whether MLL-AF9 binds to the p27 promoter in THP-1 cell.


RESULTS
SiRNA transfection efficiency was (69.1 +/- 1.8)%. The level of p27 expression was up-regulated at both mRNA [(0.84 +/- 0.12) vs (0.35 +/- 0.03) of control group] and protein levels after MLL-AF9 expression was significantly inhibited in siRNA-transfected cells (0.31 +/- 0.07) compared with that in the controls (1.25 +/- 0.13) (P<0.01). MLL-AF9 fusion protein bond to DNA fragment of p27 gene promoter region in THP-1 cell.


CONCLUSIONS
MLL-AF9 fusion gene silence up-regulates p27 gene expression, and the mechanism maybe the recovery of p27 gene expression due to MLL-AF9 fusion protein binding to p27 promoter.
Li
Lei
L
Institute of Hematology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China.
Liu
Ling-bo
LB
Wang
Li
L
Zou
Ping
P
D045744:Cell Line, Tumor; D050760:Cyclin-Dependent Kinase Inhibitor p27 / Q000235:genetics / Q000378:metabolism*; D050939:Gene Fusion; D006801:Humans; D007948:Leukemia, Monocytic, Acute / Q000235:genetics / Q000473:pathology*; D051788:Myeloid-Lymphoid Leukemia Protein / Q000235:genetics*; D015514:Oncogene Proteins, Fusion / Q000235:genetics*; D034622:RNA Interference; D014162:Transfection
C474558:MLL-AF9 fusion protein, human; D015514:Oncogene Proteins, Fusion; D050760:Cyclin-Dependent Kinase Inhibitor p27; D051788:Myeloid-Lymphoid Leukemia Protein