Browsing by Author "Zhu, Fen"

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    EGR1 addiction in diffuse large B cell lymphoma
    (American Association for Cancer Research, 2021) Kimpara, Shuichi; Lu, Li; Hoang, Nguyet M.; Zhu, Fen; Bates, Paul D.; Daenthanasanmak, Anusara; Zhang, Shanxiang; Yang, David T.; Kelm, Amanda; Liu, Yunxia; Li, Yangguang; Rosiejka, Alexander; Kondapelli, Apoorv; Bebel, Samantha; Chen, Madelyn; Waldmann, Thomas A.; Capitini, Christian M.; Rui, Lixin; Pathology and Laboratory Medicine, School of Medicine
    Early growth response gene (EGR1) is a transcription factor known to be a downstream effector of B-cell receptor signaling and Janus kinase 1 (JAK1) signaling in diffuse large B-cell lymphoma (DLBCL). While EGR1 is characterized as a tumor suppressor in leukemia and multiple myeloma, the role of EGR1 in lymphoma is unknown. Here we demonstrate that EGR1 is a potential oncogene that promotes cell proliferation in DLBCL. IHC analysis revealed that EGR1 expression is elevated in DLBCL compared with normal lymphoid tissues and the level of EGR1 expression is higher in activated B cell-like subtype (ABC) than germinal center B cell-like subtype (GCB). EGR1 expression is required for the survival and proliferation of DLBCL cells. Genomic analyses demonstrated that EGR1 upregulates expression of MYC and E2F pathway genes through the CBP/p300/H3K27ac/BRD4 axis while repressing expression of the type I IFN pathway genes by interaction with the corepressor NAB2. Genetic and pharmacologic inhibition of EGR1 synergizes with the BRD4 inhibitor JQ1 or the type I IFN inducer lenalidomide in growth inhibition of ABC DLBCL both in cell cultures and xenograft mouse models. Therefore, targeting oncogenic EGR1 signaling represents a potential new targeted therapeutic strategy in DLBCL, especially for the more aggressive ABC DLBCL. IMPLICATIONS: The study characterizes EGR1 as a potential oncogene that promotes cell proliferation and defines EGR1 as a new molecular target in DLBCL, the most common non-Hodgkin lymphoma.
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    PRMT5 is upregulated by B-cell receptor signaling and forms a positive-feedback loop with PI3K/AKT in lymphoma cells
    (Springer, 2019-05-23) Zhu, Fen; Guo, Hui; Bates, Paul D.; Zhang, Shanxiang; Zhang, Hui; Nomie, Krystle J.; Li, Yangguang; Lu, Li; Seibold, Kaitlyn R.; Wang, Fangyu; Rumball, Ian; Cameron, Hunter; Hoang, Nguyet M.; Yang, David T.; Xu, Wei; Zhang, Liang; Wang, Michael; Capitini, Christian M.; Rui, Lixin; Pathology and Laboratory Medicine, School of Medicine
    PRMT5, which regulates gene expression by symmetric dimethylation of histones and non-histone target proteins, is overexpressed and plays a pathogenic role in many cancers. In diffuse large B cell lymphoma (DLBCL), the mechanisms of PRMT5 dysregulation and its role in lymphomagenesis remain largely unknown. Here we demonstrate that B cell receptor (BCR) signaling regulates PRMT5 expression in DLBCL cells. Immunohistochemical analysis reveals elevated levels of PRMT5 expression in DLBCL cases and in germinal center (GC) B cells when compared to naive B cells. PRMT5 can be induced in naive B cells by BCR stimulation. We discovered that BTK-NF-κB signaling induces PRMT5 transcription in activated B cell-like (ABC) DLBCL cells while BCR downstream PI3K-AKT-MYC signaling upregulates PRMT5 expression in both ABC and GCB DLBCL cells. PRMT5 inhibition inhibits the growth of DLBCL cells in vitro and patient derived xenografts. Genomic and biochemical analysis demonstrate that PRMT5 promotes cell cycle progression and activates PI3K-AKT signaling, suggesting a feedback regulatory mechanism to enhance cell survival and proliferation. Co-targeting PRMT5 and AKT by their specific inhibitors is lethal to DLBCL cell lines and primary cancer cells. Therefore, this study provides a mechanistic rationale for clinical trials to evaluate PRMT5 and AKT inhibitors for DLBCL.