Abstract: Objective To investigate the effect of curcumin on reversion-inducing-cysteine-rich protein with kazal motifs (RECK) gene expression and methylation, and then analyzed the possible mechanism. Methods nasopharyngeal carcinoma cell line CNE-1 was cultured in vitro, and stimulated by 1, 10 and 30 μmol/L curcumin for 48h, expression of RECK and DNA methyltransferases 1 (DNMT1) gene mRNA and protein were detected by Western blot and real-time PCR, respectively. RECK methylation was determined by HPLC chromatographic and mass spectrometric methods. Cell proliferation was assessed by MTT assay, and the DNA-binding activity of nuclear factor Sp1 was detected by EMSA. Results The expression level of RECK was very low in unstimulated cells, and 1~30μmol/L could decrease the protein and mRNA level (P<0.05). 30μmol/L of curcumin could decrease the promoter methylation level to 31% of the basal level (P<0.01), and the global DNA methylation level and the methylation activity of the nuclear extract were also decreased about 39% (P<0.01) and 71.6% (P<0.01), respectively. Western blot showed that curcumin could also decrease the protein and mRNA level of DNMT1 (P<0.05), and survival rate (P<0.05). In addition, the DNA-binding activity of Sp1 was decreased after curcumin treatment, as demonstrated by EMSA. Conclusion Curcumin inhibits CNE-1 cells growth by up regulation of RECK gene expression and down regulation of the its methylation.

Key words: nasopharyngeal carcinoma, reversion-inducing-cysteine-rich protein with kazal motifs, methylation, Curcumin