NSD2 interacts with SMARCA2 and regulates expression of oncogenes CCND1 and PRL3 in t(4;14) multiple myeloma

Recurrent chromosomal translocations are central to the pathogenesis of multiple myeloma (MM), with t(4;14) translocation being the second-most common and associated with poor prognosis. The nuclear receptor-binding SET domain 2 (NSD2) is overexpressed as a result of the translocation and has been suggested to be the primary oncogenic factor in t(4;14) MM. However, the detailed oncogenic mechanism of NSD2 in MM is still not completely understood. To address the relevant pathways downstream of NSD2 that contributes to myelomagenesis, SILAC-based mass-spectrometry analysis was used to determine NSD2-interacting proteins. We identified 74 proteins and in silico analysis showed that one of them, SMARCA2, interacts with NSD2. Comparison of SMARCA2 expression across MM cell lines with different translocation statuses showed that SMARCA2 was highly expressed in t(4;14) MM cells but not in non-t(4;14) MM cells. SMARCA2 knockdown in t(4;14) MM cells showed reduced cell growth and capacity to form colonies. We further investigated how NSD2 and SMARCA2 regulate the expressions of key myeloma genes, such as PRL3 and CCND1. This study reveals a spectrum of NSD2-interacting proteins involved in different biological pathways, indicating the importance of NSD2 in t(4;14) MM. The interaction between NSD2 and SMARCA2 in regulating the expression of CCND1 and PRL3 suggests the potential of SMARCA2 as a novel therapeutic target for t(4;14) MM. KMS11 cells were treated with shRNAs for 96 h. Total RNA was extracted by using the Qiagen miRNeasy Mini kit (Germany). Sequencing library was generated with 1 ug of total RNA using the TruSeq RNA Sample Prep Kit v2 (Illumina) according to manufacturer’s protocol.