Abstract LB-87: Methylated-mediated repression of ZNF154 in ovarian cancer is associated with poor overall survival

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Abstract Objectives: Epigenetic gene regulation plays an important role in the development of cancer. We previously found that Zinc Finger Protein 154 (ZNF154), a Krüppel family zinc finger protein, is ubiquitously methylated in a large panel of ovarian cancer cell lines but is unmethylated in normal cells. The objectives of this study were to determine the relevance of ZNF154 methylation to mRNA expression and relationship to clinical outcome in primary epithelial ovarian cancers. Methods: Genomic DNA from 85 ovarian cancers (53 serous, 13 clear cell, 11 endometrioid and 8 mucinous) along with 4 fallopian tube and 4 ovarian surface epithelium specimens was bisulfite modified (Zymo EZ DNA Methylation kit) followed by generation of Illumina Infinium 450k Methylation Beadchip data for >485,000 CpG sites, given as β-values (scale, 0-1, where 1 is completely methylated). Bisulfite pyrosequencing was used to validate array results. ZNF154 mRNA expression was quantified using real time RT-PCR following treatment of 5 ovarian cancer cell lines and 2 immortalized OSE controls with 5µM 5-aza-2′ deoxycytidine (DAC) for 72h. Mann-Whitney U tests were used for group comparisons, Pearson correlation for continuous variables and the Kaplan-Meier method for overall survival. Results: Methylation of ZNF154 was significantly higher in cancers versus normal tissues (average β=0.51 versus β=0.09, respectively; p<0.0001). Methylation values obtained by pyrosequencing strongly correlated with array β-values (R=0.94; p=1.31e-40). ZNF154 mRNA expression was lower in ovarian cancer versus normal cells (p=0.015). Following DAC treatment, ZNF154 expression increased an average 8.01-fold (p=0.0499) while methylation levels decreased up to 20% (p=0.028) compared to mock treated controls. Stage III-IV serous cancers with higher (N=25) versus lower (N=22) ZNF154 methylation had 66 months decreased median overall survival (p=0.032). Conclusions: ZNF154 is ubiquitously methylated in primary ovarian cancers but not in normal cells and expression of ZNF154 is at least partially regulated by DNA methylation. In addition, increased methylation of ZNF154 is associated with poor clinical outcome for advanced stage serous cancers. Our results suggest that ZNF154 methylation status may have utility as a biomarker and also as a tool for prognostic prediction. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr LB-87. doi:1538-7445.AM2012-LB-87