Aberrant promoter hypermethylation of the CHFR gene in oral squamous cell carcinomas.
Recent studies have shown that promoter hypermethylation of tumor suppressor genes is an important factor in carcinogenesis of several human organs. The purpose of this study was to examine the methylation status of CHFR, a novel cell cycle regulatory gene, in both primary oral cancer tumors and the adjacent normal mucosa, and to clarify the relation between the methylation status and expression of the CHFR-related chromosomal passenger protein Aurora-A. The methylation status of the CHFR gene was examined by the methylation-specific PCR (MSP) in 49 primary oral squamous cell carcinomas (OSCC) and 6 OSCC cell lines. In 13 cases, the adjacent normal oral mucosal tissues were also examined. Normal oral mucosa from 18 healthy volunteers was used as the control. The mRNA level of Aurora-A and CHFR in OSCC cell lines was investigated by real-time RT PCR and the protein expression of Aurora-A in certain tumor samples was confirmed by immunohistochemistry. Aberrant promoter methylation of the CHFR gene was detected in 34.7% (17 of 49) of OSCC cases. As for the 13 OSCC cases with paired cancerous and adjacent normal tissues, promoter hypermethylation of the CHFR gene was detected in 46.1% (6 of 13) of the cancerous tissues. In contrast, promoter hypermethylation of the CHFR gene was recognized in only 7.7% (1 of 13) of the surrounding normal mucosa. No hypermethylation of the CHFR gene was detected in healthy volunteers. Only one OSCC cell line shows hypermethylation of the CHFR gene with concurrently silenced mRNA expression, however, Aurora-A was expressed abundantly in all cell lines. Furthermore, there is no significant relationship between methylation status of the CHFR gene and Aurora-A protein expression in OSCC. Hypermethylation of the CHFR gene was detected in a certain part of OSCC cases whereas it had very low frequency in adjacent normal oral tissues. Although further study is needed, Aurora-A gene expression seems to be independent from methylation status of the CHFR gene in OSCC.
Department of Oral and Maxillofacial Sciences, Graduate School of Medicine, Gifu University, Gifu 501-1194, Japan.
Seiji
S
Baba
Akira
A
Hara
Keizo
K
Kato
Nguyen Khanh
NK
Long
Yuichiro
Y
Hatano
Masashi
M
Kimura
Yukio
Y
Okano
Yasuhiro
Y
Yamada
Toshiyuki
T
Shibata
D000368:Aged; D000369:Aged, 80 and over; D064127:Aurora Kinases; D015153:Blotting, Western; D002294:Carcinoma, Squamous Cell / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D018797:Cell Cycle Proteins / Q000235:genetics* / Q000378:metabolism; D045744:Cell Line, Tumor; D019175:DNA Methylation; D004273:DNA, Neoplasm / Q000235:genetics; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D020868:Gene Silencing; D006801:Humans; D008297:Male; D008875:Middle Aged; D009061:Mouth Mucosa / Q000378:metabolism / Q000473:pathology; D009062:Mouth Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D009363:Neoplasm Proteins / Q000235:genetics* / Q000378:metabolism; D009367:Neoplasm Staging; D000075223:Poly-ADP-Ribose Binding Proteins; D011379:Prognosis; D011401:Promoter Regions, Genetic / Q000235:genetics*; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D044767:Ubiquitin-Protein Ligases
D018797:Cell Cycle Proteins; D004273:DNA, Neoplasm; D009363:Neoplasm Proteins; D000075223:Poly-ADP-Ribose Binding Proteins; D012333:RNA, Messenger; C412002:CHFR protein, human; D044767:Ubiquitin-Protein Ligases; D064127:Aurora Kinases; D017346:Protein Serine-Threonine Kinases