Exp Mol Med.  2007 Apr;39(2):195-204.

Differential promoter methylation may be a key molecular mechanism in regulating BubR1 expression in cancer cells

• Park HY
• Jeon YK
• Shin HJ
• Kim IJ
• Kang HC
• Jeong SJ
• Chung DH
• Lee CW

Abstract

The BubR1 mitotic-checkpoint protein monitors proper attachment of microtubules to kinetochores, and links regulation of chromosome-spindle attachment to mitotic-checkpoint signaling. Thus, disruption of BubR1 activity results in a loss of checkpoint control, chromosomal instability caused by a premature anaphase, and/or the early onset of tumorigenesis. The mechanisms by which deregulation and/or abnormalities of BubR1 expression operate, however, remain to be elucidated. In this study, we demonstrate that levels of BubR1 expression are significantly increased by demethylation. Bisulfite sequencing analysis revealed that the methylation status of two CpG sites in the essential BubR1 promoter appear to be associated with BubR1 expression levels. Associations of MBD2 and HDAC1 with the BubR1 promoter were significantly relieved by addition of 5-aza-2'-deoxycytidine, an irreversible DNA methyltransferase inhibitor. However, genomic DNA isolated from 31 patients with colorectal carcinomas exhibited a +84A/G polymorphic change in approximately 60% of patients, but this polymorphism had no effect on promoter activity. Our findings indicate that differential regulation of BubR1 expression is associated with changes in BubR1 promoter hypermethylation patterns, but not with promoter polymorphisms, thus providing a novel insight into the molecular regulation of BubR1 expression in human cancer cells.

Keyword

Bub1 spindle checkpoint protein; colorectal neoplasms; DNA methylation; polymorphism, genetic

MeSH Terms

Azacitidine/pharmacology
Base Sequence
Cell Line, Tumor
*DNA Methylation/drug effects
DNA Mutational Analysis
DNA-Binding Proteins/metabolism
*Gene Expression Regulation, Neoplastic/drug effects
Hela Cells
Histone Deacetylases/metabolism
Humans
Jurkat Cells
Molecular Sequence Data
Neoplasms/*genetics/*pathology
Polymorphism, Genetic/drug effects
Promoter Regions, Genetic/drug effects/*genetics
Protein Binding/drug effects
Protein Kinases/*genetics
Protein-Serine-Threonine Kinases
Transcription, Genetic/drug effects