PS1360 LONG NON‐CODING RNA NEAT1 TARGETING TRIGGERS ANTI‐TUMOR ACTIVITY AND RESULTS IN CHEMO‐SENSITIZING EFFECT IN MULTIPLE MYELOMA CELLS
Authors: E. Taiana, V.K. Favasuli, D. Ronchetti, K. Todoerti, F. Pelizzoni, M. Manzoni, M. Barbieri, I. Silvestris, N. Platonova, R. Chiaramonte, N. Amodio, P. Tassone, L. Agnelli, A. Neri
Journal: HemaSphere (2019)

Background: Multiple myeloma (MM) is a fatal malignant proliferation of antibody‐secreting bone marrow plasma cells (PCs) characterized by high genomic instability. The discovery of long non‐coding RNAs (lncRNAs), for which the biological role and therapeutic potential remain open questions, has added a further layer of complexity to the pathobiology of the disease. NEAT1 is a lncRNA located at 11q13, transcribed in two different isoforms, retained in the nucleus where it forms the core structural component of the paraspeckle sub‐organelles. Aims: Our recent work reported a significant overexpression of NEAT1 in MM as compared to normal control and its putative involvement in different mechanisms of cellular stress response. Based on these data, the present study was aimed at characterizing the biological role of NEAT1 in MM cells in order to evaluate whether its targeting could represent a promising strategy for novel anti‐MM therapeutic options. Methods: qRT‐PCR has been used to evaluate NEAT1 expression level in a panel of different hematological cell lines by the use of two distinct couples of primers, able to amplify either both isoforms or selectively the long variant of NEAT1. To investigate the specific role played by NEAT1 in MM, we silenced NEAT1 in NCI‐H929 and AMO‐1 cell lines by using the gimnotyc delivery of LNA‐gapmeR; efficiency of silencing was evaluated by qRT‐PCR and RNA‐FISH. Proliferation, cell cycle and apoptosis were investigated by BrdU incorporation assay and FACS analysis, respectively. Gene expression profiling upon NEAT1 silencing was investigated by GeneChip ® Human Gene 2.0 ST array by the use of Affimetrix platform. Results: Our study demonstrated that NEAT1 expression level is significantly higher in MM cells with respect to other hematological malignancies. NEAT1 silencing was able to antagonize MM cell proliferation, as suggested by a significant decrease in the number of growing cells, and to affect cell cycle with an increased percentage of sub G0/G1 phase events. Furthermore, NEAT1 deprivation was able to trigger apoptosis in vitro as revealed by the increase of Annexin+/7AAD+ cells and of cleaved PARP, Casp3 and Casp7 fractions. Induction of apoptosis and reduction of cell viability upon NEAT1 silencing were also confirmed on purified CD138+ MM primary cells. By transcriptome analyses, we found that, in both NCI‐H929 and AMO‐1, NEAT1 targeting down‐regulated genes involved in DNA repair processes. Finally, we found that NEAT1 silencing had a synergistic effect in MM cells when combined with proteasome inhibitors. Furthermore, our data indicated an anti‐proliferative and pro‐apoptotic effect of NEAT1 silencing in vivo in xenograft mouse model. Summary/Conclusion: Overall, our study investigating the pathogenic role of NEAT1 in MM provided novel important insights concerning the NEAT1‐dependent regulation of MM growth and proliferation. We also provided preliminary evidence that a LNA‐gapmeR NEAT1‐targeting strategy may represent a potential therapeutic approach for MM treatment.