Abstract 4747: NSD2 mutation drives oncogenic programming in mantle cell lymphoma

Background: NSD2, a histone methyltransferase, is an oncoprotein first characterized by its overexpression in multiple myeloma (MM). NSD2 mutations within the catalytic SET domain are found in acute lymphoblastic leukemia (ALL) and mantle cell lymphoma (MCL). We previously demonstrated that NSD2 p.E1099K mutation caused an imbalance of H3K36me2/H3K27me3 and drove glucocorticoid resistance in ALL. NSD2 mutations, especially p.E1099K and p.T1150A, were identified in 10-15% of cases of MCL and are enriched in patients who relapse from targeted therapies such as ibrutinib. However, the activity of NSD2 mutations in MCL remains unexplored. Aim: To demonstrate the role of NSD2 mutations in MCL progression due to aberrant chromatin modification. Methods: We created isogenic MCL cell lines by knock-in NSD2 p.E1099K mutation into Z138 and Jeko-1 cell lines using CRISPR/Cas9 gene editing. We then determined the effect of the mutation on H3K36me2/H3K27me3 levels and biological activities including cell growth (IncuCyte), apoptosis (Annexin V/PI Staining), and cell cycle (BrdU incorporation). We determined transcriptome (RNA-Seq) and histone modification profiles (ChIP-Seq) in isogenic Z138 cell lines. Finally, we integrated analysis of RNA-Seq of human patients and our human MCL cell lines to comprehensively disclose the epigenetic landscape in MCL with NSD2 mutation. Results: We successfully created isogenic Z138 cell lines with heterozygous and homozygous NSD2 p.E1099K mutation and a Jeko-1 cell line with heterozygous NSD2 p.E1099K mutation. Insertion of NSD2 p.E1099K by CRISPR/Cas9 gene editing led to a striking increase of H3K36me2 and concomitant decrease of H3K27me3 in both Z138 and Jeko-1 cell lines. NSD2 mutation significantly increased cellular growth with enhanced S phase entry, decreased number of cells in G0/G1 phase and decreased spontaneous apoptosis. RNA-Seq analysis demonstrated striking changes in gene expression with 1794 genes upregulated and 1492 genes downregulated in NSD2 mutant MCL cells. Among them, anti-apoptotic genes BCL2 and BCL2L2 were upregulated while pro-apoptotic genes BAX, BID, and BIK were downregulated in NSD2 mutant cells, which was consistent with the biological phenotypes. Surprisingly, CCND1, CCNE1, CCNE2, TP53, and CDKN2C (p21) were downregulated while CDKN2D, CDKL3, and CDKL5 were upregulated in NSD2 mutant cells. Altered gene expression in isogenic Z138 cells were compared with patient expression profiles, with gene ontology revealing significant overlap and enrichment of cell adhesion, neural pathways, and evidence of activated signaling. Aberrant histone modification H3K27ac contributed to many of differentially expressed genes pattern. Conclusions: The NSD2 mutation led to increased tumor cell growth but decreased apoptosis due to the dysregulation of epigenetic landscape and transcriptome, suggesting an oncogenic reprogramming driven by an activated NSD2 mutation in MCL. Citation Format: Jianping Li, Marta Kulis, Alberto Riva, Heidi Casellas Román, Daphne Dupere-Richer, Amin Sobh, Charlotte Leonie Kaestner, Richard L. Bennett, Inaki Martin, Jonathan D. Licht. NSD2 mutation drives oncogenic programming in mantle cell lymphoma. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4747.