[The re-expression of p15(INK4B) gene in leukemia cells induced by in vitro DNA methyltransferase and histone deacetylase inhibition].
OBJECTIVE
To explore the possibility of re-expression of silenced p15(INK4B) gene in leukemia cells by 5-Aza-2'-deoxycytidine (CdR), a DNA methyltransferase inhibitor, and sodium butyrate (SB), a histone deacetylase inhibitor.


METHODS
A myeloid leukemia cell line, KG1a and two primary cultured leukemia cells isolated from bone marrow of AML-M(2) and MDS-RAEB-T patients were chosen as the experimental target. The methylation pattern of p15(INK4B) gene was analyzed with restriction endonucleases combined with PCR technique. The expression level of mRNA and protein was detected by RT-PCR technique and Western blot.


RESULTS
All detected leukemia cells showed a hypermethylated promoter region of p15(INK4B) gene with complete or partial loss of expression of mRNA and protein. Either CdR or SB induced weak expression of p15(INK4B) with a dose dependent effect. Combined low dose of CdR (0.5 micro mol/L) and SB (0.5 mmol/L) increased the expression level of p15(INK4B) significantly. The synergistic effect of the two drugs was significantly stronger than that of any drug of high dose alone.


CONCLUSIONS
Hypermethylated and silenced p15(INK4B) gene could be re-expressed by synergy of CdR and SB.
Ren
Limin
L
Department of Hematology, The First Hospital of Peking University, Beijing 100034, China.
Du
Hongling
H
Zhu
Qiang
Q
Shi
Yongjin
Y
Chen
Hua
H
Wu
Shulan
S
D001374:Azacitidine / Q000031:analogs & derivatives* / Q000494:pharmacology; D018797:Cell Cycle Proteins / Q000096:biosynthesis* / Q000235:genetics; D050762:Cyclin-Dependent Kinase Inhibitor p15; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000096:biosynthesis* / Q000235:genetics; D019175:DNA Methylation; D000077209:Decitabine; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D015870:Gene Expression / Q000187:drug effects*; D056572:Histone Deacetylase Inhibitors; D006801:Humans; D066298:In Vitro Techniques; D007938:Leukemia / Q000473:pathology; D008780:Methyltransferases / Q000037:antagonists & inhibitors*; D014407:Tumor Cells, Cultured; D025521:Tumor Suppressor Proteins
C493966:CDKN2B protein, human; D018797:Cell Cycle Proteins; D050762:Cyclin-Dependent Kinase Inhibitor p15; D019941:Cyclin-Dependent Kinase Inhibitor p16; D004791:Enzyme Inhibitors; D056572:Histone Deacetylase Inhibitors; D025521:Tumor Suppressor Proteins; D000077209:Decitabine; D008780:Methyltransferases; D001374:Azacitidine