Search

Multiple myeloma is an incurable malignancy with marked clinical and genetic heterogeneity. The cytogenetic abnormality t(4;14) (p16.3;q32.3) confers aggressive behavior in multiple myeloma. Recently, essential oncogenic drivers in a wide range of cancers have been shown to be controlled by super-enhancers (SE). We used chromatin immunoprecipitation sequencing of the active enhancer marker histone H3 lysine 27 acetylation (H3K27ac) to profile unique SEs in t(4;14)-translocated multiple myeloma. The histone chaperone HJURP was aberrantly overexpressed in t(4;14)-positive multiple myeloma due to transcriptional activation by a distal SE induced by the histone lysine methyltransferase NSD2. Silencing of HJURP with short hairpin RNA or CRISPR interference of SE function impaired cell viability and led to apoptosis. Conversely, HJURP overexpression promoted cell proliferation and abrogated apoptosis. Mechanistically, the NSD2/BRD4 complex positively coregulated HJURP transcription by binding the promoter and active elements of its SE. In summary, this study introduces SE profiling as an efficient approach to identify new targets and understand molecular pathogenesis in specific subtypes of cancer. Moreover, HJURP could be a valuable therapeutic target in patients with t(4;14)-positive myeloma. SIGNIFICANCE: A super-enhancer screen in t(4;14) multiple myeloma serves to identify genes that promote growth and survival of myeloma cells, which may be evaluated in future studies as therapeutic targets. Published version The work was supported by the National Research Foundation Singapore and the Singapore Ministry of Education under its Research Centres of Excellence initiative (to W.J. Chng), the NMRC Clinician Scientist Investigator award (to W.J. Chng), the RNA Biology Center at CSI Singapore, NUS, from funding by the Singapore Ministry of Education’s Tier 3 grants, grant number MOE2014-T3–1-006 (to W.J. Chng), the National Natural Science Foundation of China (grant no. 82000212 to Y. Jia), Natural Science Foundation of Zhejiang Province (grant no. LQ21H160022 to Y. Jia), Medical Health Science and Technology Project of Zhejiang Provincial Health Commission (grant no. 2021RC003 to Y. Jia). Y. Jia also thanks the China Scholarship Council (grant no. 201706320167) for financial support to visit National University of Singapore.

Multiple myeloma is an incurable malignancy with marked clinical and genetic heterogeneity. The cytogenetic abnormality t(4;14) (p16.3;q32.3) confers aggressive behavior in multiple myeloma. Recently, essential oncogenic drivers in a wide range of cancers have been shown to be controlled by super-enhancers (SE). We used chromatin immunoprecipitation sequencing of the active enhancer marker histone H3 lysine 27 acetylation (H3K27ac) to profile unique SEs in t(4;14)-translocated multiple myeloma. The histone chaperone

Background Multiple myeloma (MM) is an incurable malignancy characterized by complex heterogeneous cytogenetic abnormalities. Defined as large clusters of cis-acting enhancers, super-enhancers (SEs) could promote oncogenic transcription to which cancer cells highly addicted. Structural maintenance of chromosome 4 (SMC4) is a core subunit of condensin complexes, which contributes to chromosome condensation and segregation. Here, we identified SMC4 as a novel SE-associated oncogene of myeloma cells, whose functional roles in MM remain largely elusive. Methods We performed H3K27ac ChIP-seq and RNA-seq on primary MM patient samples, MM cell lines, normal CD138+ plasma cell and lymphoma cell lines as the controls, then the ROSE analysis was used to annotate SEs and their associated genes. THZ1 as a transcriptional CDK7 inhibitor was used to further filter THZ1-responsive genes. Combined analysis of THZ1-sensitive and SE-associated gene uncovered a number of promising MM oncogenes as SMC4. The public data mining, RNA interference, CRISPR/Cas9 gene editing system, overexpression and a variety of cellular functional assays were performed to determine the oncogenic effects of SMC4 on MM malignant. Transcriptome analysis with SMC4 silencing and overexpression, and the underlying molecular mechanism of SMC4 oncogenic role in MM are ongoing. Results We have demonstrated SMC4 as one of the SE-associated genes specific to MM patient samples and cell lines. SMC4 was related to myelomagenesis with increased expression from MGUS, SMM to MM cases, and overexpression of SMC4 predicted poor overall survival of MM patients, suggesting its clinical relevance. SMC4 silencing in MM cells suppressed cell proliferation and lead to cell apoptosis. Repression of the SMC4-SE region also led to impairment of cell viability and cell growth, consistent with an oncogenic function. Conclusion In summary, our integrative approached by combing H3H27ac ChIP-seq, RNA-seq and THZ1-sensitive transcripts identified the landscape of SEs and novel oncogenic transcripts as SMC4 in MM. Mapping these acquired SEs and their associated genes may provide novel insight into understanding MM biology, and SMC4 may serve as novel therapeutic targets in MM. Citation Format: Yunlu Jia, Jianbiao Zhou, Tze-King Tan, Tae-Hoon Chung, Yongxia Chen, Enfan Zhang, Zhen Cai, Takaomi Sanda, Wee-Joo Chng. Superenhancer-drvien SMC4 promote cell growth and proliferation in multiple myeloma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2956.