Insulin growth factor binding protein-3 (IGFBP-3) has been postulated to be a mediator of growth suppression signal.In our previous study, IGFBP-3 was found as an invasion suppressor gene in ovarian endometrioid carcinoma (EC) (Oncogene Oncogene 2008,2 7;213 7-47).Since promoter methylation can silence gene expression, we investigated whether hypermethylation of the IGFBP-3 promoter is involved in the loss of IGFBP-3 expression in ovarian EC.By methylation-specific PCR assay, IGFBP-3 promoter was found methylated in the higher invasive ovarian cancer cell line OVTW59-P4, compared with the lower invasive P0 cell line.After treatment with DNA methyltransferase inhibitor 5-aza-2-deoxycytidine, P4 showed restoration of IGFBP-3 expression.Methylation status correlated with IGFBP-3 rnRNA and protein levels.By bisulfite genomic DNA sequencing, the hyprermethylated CpG sites were found focused at the-210,-206,-183 and-179 sites of p53 consensus binding sequence in IGFBP-3 promoter region.