title: Aberrant expression and demethylation of gamma-synuclein in colorectal cancer, correlated with progression of the disease.
abstract: Recent evidence suggests that gamma-synuclein is abnormally expressed in a high percentage of tumor tissues of diversified cancer types, but rarely expressed in tumor-matched non-neoplastic adjacent tissues (NNAT). The molecular mechanism of CpG island demethylation may underlie aberrant gamma-synuclein expression. To fully understand the roles of aberrant gamma-synuclein expression and demethylation in the development of colorectal cancer (CRC), we examined the expression and methylation status of gamma-synuclein in 67 CRC samples, 30 NNAT samples, and five CRC cell lines as well. By using reverse transcription-polymerase chain reaction (RT-PCR), western blot, and immunohistochemistry analyses, gamma-synuclein expression was detected in both HT-29 and HCT116 cells, and was much higher in CRC samples than in NNAT samples (P < 0.05). The demethylating agent, 5-aza-2 cent-deoxycytidine, can induce re-expression of gamma-synuclein in COLO205, LoVo, and SW480 cells. Unmethylated gamma-synuclein alleles were detected in HT-29, HCT116, and LoVo cells by nested methylation-specific PCR, and the demethylated status of gamma-synuclein was much higher in CRC samples than in NNAT samples by real-time quantitative methylation-specific PCR (P < 0.05). The results of genomic bisulfite DNA sequencing further confirmed that the aberrant gamma-synuclein expression in CRC was primarily attributed to the demethylation of CpG island. The protein expression and demethylation status of gamma-synuclein in 67 CRC samples correlated with clinical stage, lymph node involvement, and distant metastasis. These findings suggest an involvement of aberrant gamma-synuclein expression and demethylation in progression of CRC, especially in advanced stages.
authors.affiliation: Department of General Surgery, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China.
authors.forename: Qing
authors.initials: Q
authors.lastname: Ye
authors.forename: Min-Hua
authors.initials: MH
authors.lastname: Zheng
authors.forename: Qu
authors.initials: Q
authors.lastname: Cai
authors.forename: Bo
authors.initials: B
authors.lastname: Feng
authors.forename: Xue-Hua
authors.initials: XH
authors.lastname: Chen
authors.forename: Bei-Qin
authors.initials: BQ
authors.lastname: Yu
authors.forename: Ya-Bo
authors.initials: YB
authors.lastname: Gao
authors.forename: Jun
authors.initials: J
authors.lastname: Ji
authors.forename: Ai-Guo
authors.initials: AG
authors.lastname: Lu
authors.forename: Jian-Wen
authors.initials: JW
authors.lastname: Li
authors.forename: Ming-Liang
authors.initials: ML
authors.lastname: Wang
authors.forename: Bing-Ya
authors.initials: BY
authors.lastname: Liu
mesh_terms: D045744:Cell Line, Tumor; D015179:Colorectal Neoplasms / Q000235:genetics* / Q000473:pathology*; D019175:DNA Methylation; D018450:Disease Progression; D015972:Gene Expression Regulation, Neoplastic; D045325:HCT116 Cells; D019073:HT29 Cells; D006801:Humans; D007150:Immunohistochemistry; D009367:Neoplasm Staging; D012189:Retrospective Studies; D051845:gamma-Synuclein / Q000235:genetics* / Q000378:metabolism*
chemical_list: D051845:gamma-Synuclein