[Phenol butyrate inhibits cell cycle of leukemia cell lines through up-regulation of p21WAF1/CIP1 gene].
OBJECTIVE
To elucidate effects of histone deacetylase inhibitors on cell cycle of leukemia cell lines and investigate its molecular mechanisms.


METHODS
Kasumi-1, U937 and NB4 cell lines were exposed to a histone deacetylase inhibitor, phenyl butyrate (PB), for 24, 48 and 72 hrs. Cells were harvested for cell cycle analysis by flow cytometry. Gene expression of p21WAF1/CIP1, a cyclin-dependent kinase inhibitor, was determined by semi-quantitative reverse transcriptase polymerase chain reaction (semi-quantitative RT-PCR). Promoter activity of p21WAF1/CIP1 was determined by luciferase-reporter assay in 293T cell line.


RESULTS
PB inhibited cell cycle of Kasumi-1, U937 and NB4 cell lines, showing G(0)/G(1) phase arrest and S-phase fraction reduction with a dose and time dependent manner. After Kasumi-1, U937 or NB4 cells exposed to 3 mmol/L PB for 72 hrs, G(0)/G(1)-phase fraction was increased by 42.03%, 44.36% and 26.82%, and S-phase fraction was decreased by 31.86%, 38.9% and 26.77%, respectively. After Kasumi-1, U937 and NB4 cell lines exposed to PB, the expression of p21WAF1/CIP1 gene was increased by (2.06 +/- 0.27), (2.78 +/- 0.40) and (1.78 +/- 0.20) times at its maximum, respectively. PB could stimulate p21WAF1/CIP1 promoter activity (by luciferase-reporter assay) and the effect was dose dependent. The promoter activity was increased by 5.74 times after the cells exposed to 3 mmol/L PB for 48 hrs. PB stimulating p21WAF1/CIP1 promoter activity was mainly mediated by a 101 base pairs fragment upstream of transcription start site.


CONCLUSIONS
PB could inhibit cell cycle of leukemia cell lines. The effects were mainly through up-regulation of p21WAF1/CIP1 expression.
Wei
Hui
H
State Key Laboratory of Experimental Hematology, Institute of Hematology and Blood Diseases Hospital, CAMS & PUMC, Tianjin 300020, China.
Liu
Xiang-rong
XR
Lin
Dong
D
Rao
Qing
Q
Lin
Yue-hui
YH
Wang
Min
M
Wang
Jian-xiang
JX
D002453:Cell Cycle / Q000187:drug effects*; D002460:Cell Line; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000235:genetics* / Q000378:metabolism; D005434:Flow Cytometry; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D007938:Leukemia / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D010654:Phenylbutyrates / Q000494:pharmacology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D020298:U937 Cells; D015854:Up-Regulation / Q000187:drug effects
D050759:Cyclin-Dependent Kinase Inhibitor p21; D010654:Phenylbutyrates