Detailed methylation patterns and protein expression profiles of MGMT in colorectal carcinoma surgical margins.
OBJECTIVE
Molecular margin analysis is considered more sensitive in detecting preneoplastic lesions and residual cancer cells than conventional histological margin examination. Hence, we examined MGMT expression profile and methylation status in histologically negative margins of colorectal cancer patients.


METHODS
This study included 24 colorectal tumor tissues and corresponding negative surgical margin tissues. MGMT promoter methylation patterns were analyzed by using methylation-specific oligonucleotide microarray. In addition, MGMT protein expression was analyzed by immunohistochemistry. MGMT clinical significance was evaluated together with other well-known clinicopathological factors.


RESULTS
Extensive MGMT promoter methylation was observed in tumor tissues; a moderate methylation level was found in surgical margin tissues and little or no methylation was observed in the normal control. There was a trend towards longer overall survival for those patients with negative MGMT immunostaining in surgical margins.


CONCLUSIONS
MGMT expression negative in surgical margin tissues indicates longer overall survival for colorectal tumor patients.
Zhang
Dingdong
D
State Key Laboratory of Bioelectronics, Southeast University, Nanjing 210096, China.
Bai
Yunfei
Y
Wang
Yan
Y
Luo
Junfeng
J
Ge
Qinyu
Q
Qiao
Yingjuan
Y
Jia
Chao
C
Lu
Zuhong
Z
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001483:Base Sequence; D001706:Biopsy / Q000379:methods; D002277:Carcinoma / Q000235:genetics* / Q000378:metabolism / Q000401:mortality / Q000601:surgery; D015179:Colorectal Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000401:mortality / Q000601:surgery; D019175:DNA Methylation; D005260:Female; D020869:Gene Expression Profiling; D006801:Humans; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D019853:O(6)-Methylguanine-DNA Methyltransferase / Q000235:genetics* / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D016019:Survival Analysis
D019853:O(6)-Methylguanine-DNA Methyltransferase