PB1650 CSRP2 PROMOTES THE PROLIFERATION AND CELL CYCLE PROGRESSION OF HUMAN B-CELL LYMPHOMA RAMOS CELLS VIA ACTIVATION OF THE ERK-CREB PATHWAY
Authors: S. Wang, L. Yang, K. Liu, Y. Liu
Journal: HemaSphere (2019)

Background: Cysteine and glycine-rich protein 2(CSRP2) is a member of the CSRP family of genes, encoding a group of LIM domain proteins, which may be involved in regulatory processes important for development and cellular differentiation. In our previous study, we found that CSRP2 was widely overexpressed in B-cell acute lymphoblastic leukemia (B-ALL) and correlated with poor survival in B-ALL patients with normal karyotype. Functional analyses indicated CSRP2 promoted cell proliferation, cell cycle progression and chemotherapy resistance in B-ALL. Like B-ALL, B-cell lymphoma is also characterized by clonal expansion of developmentally-arrested B-cell precursors. Our previous studies have found that CSRP2 is highly expressed in the lymphoma cell line Maver, and low in Ramos. So far, the roles of CSRP2 in B-cell lymphoma and the underlying mechanism remain blank and are open to study. Aims: To explore the effects of CSRP2 on the biological behavior of B-cell lymphoma and its potential mechanism. Methods: Lentiviral vector-mediated gene overexpression was used to construct CSRP2-overexpression Ramos cell models, and RQ-PCR (real-time fluorescent quantitative reverse transcription-polymerase chain reaction) and western blot were then used to verify CSRP2 overexpression. The cell proliferation and colony formation were detected by CCK-8 and colony formation assay. The cell apoptosis and cell cycle were analyzed by flow cytometry and western blot. The sensitivity to chemotherapy agents was assessed by CCK-8. Nude mice were used to evaluate cell proliferation in vivo. Western blot and immunohistochemistry technology were used to determine the protein level of the signaling pathway. Results: CSRP2-overexpression Ramos cells were successfully constructed and verified by RQ-PCR and western blot. CSRP2-overexpression markedly increased cell proliferation, cell-cycle progression, in vitro colony formation, and increased resistance to chemotherapy. In mouse model, CSRP2-overexpression significantly increased cell proliferation in vivo. CSRP2-overexpression promoted cell cycle progression through regulating cell-cycle related protein (upregulating p53 and downregulating cyclin D1 and CDK4) while had no effects on cell apoptosis-related protein (cleaved PARP). CSRP2 overexpression activated ERK1/2 and CREB signaling pathway in vitro and in vivo. The inhibitor of CREB signaling pathway (KG-501) reversed the effects of CSRP2 overexpression on cell proliferation and cell cycle progression. The inhibition rate of 25 μM KG-501 on cell proliferation in the control group and CSRP2-overexpression group was 75% and 91%, respectively, suggesting that KG-501 inhibited proliferation in CSRP2-overexpression cells more significantly. Summary/Conclusion: CSRP2 promoted cell proliferation, cell-cycle progression and resistance to chemotherapy in B-cell lymphoma Ramos cells at least partially through activating ERK-CREB pathway. CSRP2 and its related signaling pathways had the potential to be novel approaches to targeted therapy of B cell lymphoma.