PT - JOURNAL ARTICLE AU - Pattamadilok, J. AU - Huapai, N. AU - Rattanatanyong, P. AU - Vasurattana, A. AU - Triratanachat, S. AU - Tresukosol, D. AU - Mutirangura, A. TI - LINE- 1 hypomethylation level as a potential prognostic factor for epithelial ovarian cancer AID - 10.1136/ijgc-00009577-200807000-00015 DP - 2008 Jul 01 TA - International Journal of Gynecologic Cancer PG - 711--717 VI - 18 IP - 4 4099 - http://ijgc.bmj.com/content/18/4/711.short 4100 - http://ijgc.bmj.com/content/18/4/711.full SO - Int J Gynecol Cancer2008 Jul 01; 18 AB - A genome-wide hypomethylation is a common and crucial event in cancer. This study was to evaluate common epithelial ovarian cancer (EOC) if long interspersed element-1 (LINE-1) repetitive sequences methylation levels are progressively decreased during multistage carcinogenesis and there are the correlation between LINE-1 methylation levels and clinicopathologic characteristics. A total of 59 pairs of microdissected EOC tissues obtained from patients with EOC were examined for the methylation levels of LINE-1 repetitive sequences by a COBRALINE-1 (combined bisulfite restriction analysis of LINE-1) PCR protocol. The methylation levels were correlated with clinicopathologic parameters to determine the potential role of global hypomethylation as a prognostic marker for EOC. The LINE-1 methylation levels of 59 EOCs, 34.87 ± 7.39%, were lower than in representative normal ovarian tissues (46.89 ± 8.31%; 95% CI: 9.42–14.62; P< 0.001, paired-two-tailed t test). A decrease in the LINE-1 level of methylation was correlated with histological subtypes, higher FIGO and advanced tumor grade. Patients with greater hypomethylation (i.e., a methylation level ≤ 34.87%) had poorer mean overall survival (P= 0.003) and a lower mean progression-free interval (P< 0.001). Therefore, progressive decrease in LINE-1 methylation level is a common and important epigenetic process in ovarian multistep carcinogenesis. Moreover, the COBRALINE-1 method has the potential to be used as a tumor marker for EOC.