Abstract 2871: Global reduction of H3K4me3 improves chemotherapeutic efficacy for pediatric ependymomas

Background Ependymomas (EPNs) are the third most common brain tumor in children. These tumors are resistant to available chemotherapeutic treatments, therefore new effective targeted therapeutics must be identified. Increasing evidence shows epigenetic alterations including histone posttranslational modifications (PTMs), are associated with malignancy, chemotherapeutic resistance and prognosis for pediatric EPNs. In this study we examined histone PTMs in EPNs and identified potential targets to improve chemotherapeutic efficacy. Methods Global histone H3 lysine 4 trimethylation (H3K4me3) levels were detected in pediatric EPN tumor samples with immunohistochemistry and immunoblots. Candidate genes conferring therapeutic resistance were profiled in pediatric EPN tumor samples with micro-array. Promoter H3K4me3 occupancy was examined for two candidate genes, CCND1 and ERBB2, with chromatin-immunoprecipitation coupled with real-time PCR (ChIP-PCR). These methods and MTS assay were used to verify a relationship between H3K4me3 levels and CCND1 and ERBB2, and to investigate cell viability in response to chemotherapeutic drugs in primary cultured pediatric EPN cells. Results H3K4me3 levels positively correlate with WHO grade malignancy in pediatric EPNs and are associated with progression free survival in patients with posterior fossa group A EPNs (PF-EPN-A). Reduction of H3K4me3 by silencing its methyltransferase SETD1A, in primary cultured EPN cells, increased cell response to chemotherapy. Conclusions Our results support the development of a novel treatment that targets H3K4me3 to increase chemotherapeutic efficacy in pediatric PF-EPN-A tumors. Key words: promoter, H3K4me3, human SETD1A, chemotherapy, pediatric ependymoma Citation Format: Guifa Xi, Nitin Wadhwani, Rintaro Hashizume, Barbara Mania-Farnell, Marcelo Bento Soares, Charles D. James, Tadanori Tomita. Global reduction of H3K4me3 improves chemotherapeutic efficacy for pediatric ependymomas [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2871.