[Demethylation of the gamma-synuclein gene CpG island in colorectal cancer and its clinical significance].
OBJECTIVE
To explore the relationship between gamma-synuclein gene expression and CpG island demethylation in colorectal cancer(CRC), and the relationship between the demethylation and clinicopathological factors of CRC.


METHODS
The expression of gamma-synuclein mRNA was examined in 30 pairs of tumor tissues and tumor-matched non-neoplastic adjacent tissues(NNAT) by RT-PCR. CRC cell lines including COLO205, LoVo, and SW480 were used and treated with a demethylating agent, 5-aza-2'-deoxycytidine(5-aza-C). Before and after the treatment, the expression of gamma-synuclein mRNA in the cells was determined by RT-PCR, and bisulfite sequencing PCR was also used to analyze methylation status of CpG island. The methylation status of gamma-synuclein was then examined in 67 CRC samples and 30 NNAT samples by nested methylation-specific PCR (NMSP) and real time methylation-specific PCR(real-time MSP). The relationship between the demethylation of gamma-synuclein in CRC and clinicopathological factors was analyzed.


RESULTS
The mean gamma-synuclein mRNA expression was 0.66+/-0.34 in CRC samples, which was much higher than 0.45+/-0.26 in NNAT samples(P=0.011). 5-aza-C could induce expression and demethylation of gamma-synuclein in COLO205, LoVo and SW480 cells. gamma-Synuclein gene was demethylated in 80.0%(24/30) of the CRC samples and 50.0%(15/30) of the NNAT samples. The demethylated status of gamma-synuclein was much higher in CRC samples than that in NNAT samples(P=0.030), and was significantly correlated with clinical stage, lymph node involvement, and distant metastasis of CRC(P<0.05).


CONCLUSIONS
The upregulation of gamma-synuclein expression in CRC is primarily attributed to the demethylation of CpG island, which may be used as a marker for prognosis.
Ye
Qing
Q
Department of General Surgery, Ruijin Hospital, Shanghai Minimally Invasive Surgery Center, Shanghai Institute of Digestive Surgery, Shanghai Jiaotong University School of Medicine, Shanghai 200025, China.
Feng
Bo
B
Peng
Yuan-fei
YF
Cai
Qu
Q
Chen
Xue-hua
XH
Yu
Bei-qin
BQ
Ma
Jun-jun
JJ
Lu
Ai-guo
AG
Li
Jian-wen
JW
Wang
Ming-liang
ML
Liu
Bing-ya
BY
Zheng
Min-hua
MH
D045744:Cell Line, Tumor; D015179:Colorectal Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology*; D018899:CpG Islands; D019175:DNA Methylation; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D011379:Prognosis; D012333:RNA, Messenger / Q000235:genetics; D051845:gamma-Synuclein / Q000235:genetics* / Q000378:metabolism
D012333:RNA, Messenger; D051845:gamma-Synuclein