Abstract
Abstract Multiple myeloma (MM), characterized by the uncontrolled proliferation of malignant plasma cells, occurs mainly in the elderly population. Recurrent chromosomal translocations are central to the pathogenesis of MM, with t(4;14) being the second most common and associated with poor prognosis. The histone methyltransferase (HMTase) NSD2 is overexpressed in MM due to the t(4;14) translocation and has been suggested to play an important tumorigenic role in t(4;14) MM. However, the detailed molecular mechanism or signaling pathways describing how deregulation of NDS2 contributes to MM cell growth and survival are still uncertain. In this study, stable isotope labeling of amino acid in cell culture (SILAC)-based mass spectrometry analysis was used to determine NSD2-interacting proteins. Mass spectrometry analysis indicated that there were 75 proteins identified in the immunoprecipitation of NSD2 protein complexes. Gene ontology (GO) enrichment analysis showed that these proteins were enriched in processes related to chromatin organization, RNA processing and translation. Five high potential MMSET-interacting proteins from the most enriched functions were selected and verified by Immunoprecipitation and Western blot assays. The results indicated that there were interactions between NSD2 and SMARCA2, topoisomerase IIa, ADAR1, DDX5 and RPS6. In silico analysis with STRING database showed that SMARCA2 interacts with NSD2. SMARCA2 is the ATPase subunit of the SWI/SNF chromatin remodeling complex, which harnesses the energy from ATP to remodel the position of nucleosomes, making the DNA accessible during transcription, replication and DNA repair. Double immunofluorescence showed NSD2 and SMARCA2 co-localized in the cell nucleus. SMARCA2 was knocked down (KD) by shRNAs in t(4;14) MM cells. CellTiter-Glo Luminescent Cell Viability Assay (CTG assay) indicated that SMARCA2 KD by shRNA reduced t(4;14) MM cell growth. SMARCA2 KD also significantly inhibited the capacity to form colonies in t(4;14) MM cells on methylcellulose colony formation assay. Inhibiting SMARCA2 with active DNA-dependent ATPase A domain inhibitor (ADAADi) also reduced t(4;14) MM cell growth. In addition, SMARCA2 KD reduced cell cycle S phase. Western blot analysis showed downregulation of PRL3 and CCND1 protein level upon NSD2 or SMARCA2 KD. This study reveals a protein-protein interaction between NSD2 and SMARCA2. SMARCA2 KD showed SMARCA2 might be a novel therapeutic target for t(4;14) MM. Citation Format: Jing Yuan Chooi, Zhigang Xie, Hannah Lee-Foon Swa, Jayantha Gunaratne, Dennis Kappei, Wee Joo Chng. Identification of functional proteins interacting with NSD2 in multiple myeloma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2499.
Published Version
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