Abstract 5158: The H3K9 demethyltransferase gene JMJD1C has tumor suppressor functions in multiple myeloma

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Abstract Increasing evidence points towards the importance of epigenetic changes in the pathogenesis of multiple myeloma (MM). The biochemical modifications that govern epigenetics are DNA methylation, and post-translational modifications of histone proteins. Histone methylation is catalyzed by histone methyltransferases (HMT) and histone demethylases (HDMT). The purpose of our study was to interrogate genomics data to identify HMT or HDMT genes that are altered in MM. We mined copy number, gene expression and whole genome sequencing data generated as part of the Multiple Myeloma Research Consortium Genomics Initiative. Collectively, the datasets converged on numerous alterations involving histone methylation of lysine 9 (H3K9). One of these genes, the HDMT JMJD1C, was downregulated in approximately 25% of MM samples examined and was associated with worst clinical outcome. We validated these data by quantitative RT-PCR and by immunohistochemistry (IHC) on a tissue microarray (TMA) consisting of over 60 MM samples. Next we demonstrated a negative correlation between JMJD1C expression and H3K9 methylation by IHC and western blot in 6/10 HMCL and in over 60% of clinical samples examined on the TMA. To study the direct effects of JMJD1C on H3K9 methylation and determine the functional significance, we generated a knockout isogenic cell line pair in KMS11 MM cells using zinc finger nuclease technology. JMJD1C depletion resulted in an increase in H3K9 mono- and dimethylation as demonstrated by western blot and immunofluorescence, confirming its association to H3K9 methylation. H3K9 trimethylation was unaffected by JMJD1C depletion. Differential gene expression analysis demonstrated defects in cell cycle and G2/M transition. Most notably, NEK2, Cyclin B, CDC20, PLK1 and TTK were among genes upregulated in response to JMJD1C depletion. Accordingly, we assessed cell growth using CellTiter-Glo® and demonstrated increased cell growth in JMJD1C-depleted cells. We also demonstrated a more pronounced G2/M peak by FACS. DNA methylation analysis using the HumanMethylation 450K BeadChip showed global hypomethylation in response to JMJD1C loss, a phenotype indicative of myeloma progression. Results to date validate the H3K9 demethylase activity of JMJD1C, and suggest a tumor suppressive function, which may be lost in MM. Data demonstrate a novel biological and molecular understanding of JMJD1C, pointing us to therapeutic vulnerabilities in MM. Studies are ongoing to further characterize the genomic, epigenomic and functional significance of JMJD1C in MM. Citation Format: Danielle DiPerna, Gerald C. Gooden, Brooke Hjelm, Sara Nasser, Janine LoBello, Aprill Watanabe, Bodour Salhia. The H3K9 demethyltransferase gene JMJD1C has tumor suppressor functions in multiple myeloma. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5158. doi:10.1158/1538-7445.AM2014-5158