Study on 5-aza-2"-deoxycytidine Induces Syk Gene Promoter Demethylation in Nasopharyngeal Carcinoma Cell Lines

Abstract: The nasopharyngeal carcinoma cell lines， CNE-1， CNE-2 and the non-cancerous immortalized nasopharyngeal epithelial cell lines NP-69 were treated with 5 μmol/L 5-aza-2'-deoxycytidine (5-aza-CdR) in vitro. BS-PCR， Q-RT-PCR， Western blot were used to detect Syk promoter methylation and the level of Syk mRNA and protein. This study purposed to investigate the effect of 5-aza-CdR on the degree of promoter methylation and the expression of spleen tyrosine kinase (Syk) in nasopharyngeal carcinoma cell lines. It suggests that the mRNA and protein level of Syk in the two nasopharyngeal carcinoma cell lines were significantly lower than in NP-69 cell line (P<0.01)， and shows negative relation with the methylation level of Syk promoter. The promoter methylation level of Syk gene was significantly decreased and the expression of Syk mRNA and protein were up-regulated (P<0.05) after treatment with 5-aza-CdR in the cell lines of CNE-1 and CNE-2， which was not observed in NP- 69 cell line (P>0.05). Compared with poorly differentiated nasopharyngeal carcinoma cell line， well-differentiated nasopharyngeal carcinoma cell line was more sensitive to 5-aza-CdR (P<0.01). Taken together， Syk promoter methylation directly leads to the decreased expression of Syk in nasopharyngeal carcinoma cell lines. 5-aza-CdR induces the demethylation of the Syk promoter， restores the expression of Syk both in mRNA and protein levels. Meanwhile， the cytotoxicity of 5-aza-CdR did not affect the transcriptional activity of Syk gene in nasopharyngeal epithelial cells. Moreover， the different sensitivity of nasopharyngeal carcinoma cell lines to 5-aza-CdR was related with the methylation of Syk promoter.

CSTR: 32200.14.cjcb.2012.09.0003