LONG NON-CODING RNA MALAT1 WAS ASSOCIATED WITH PROGRESSION OF MULTIPLE MYELOMA AND INDUCED BY CELLULAR STRESS

Background: Recent transcriptome-wide analyses have revealed an overwhelming amount of transcribed, but not translated, non-coding RNAs capable of influencing diverse cellular processes such as proliferation, apoptosis, and motility. Long non-coding RNA (lncRNAs), which are commonly defined as transcripts u003e200 nt in length, have emerged as a class of key regulatory RNA. LncRNAs are deregulated in diverse human cancers and associated with disease progression; however, little is known about its role in multiple myeloma (MM). To elucidate the role of lncRNAs in MM, we studied the expression patterns of several well-known lncRNAs in the plasma cells of MM, MGUS and plasmacytoma patients and the function in MM cell lines in vitro . Moreover, to reveal the distinct lncRNA signature comprehensively, we performed next-generation sequencing-based RNA sequencing. Methods: CD138+ plasma cells from bone marrow (BM) mononuclear cells were obtained from 110 MM patients, 48 MGUS patients, 19 control subjects and 1 patient with extramedullary plasmacytoma of the liver and analyzed after obtaining informed consent from all the patients. The expression levels of lncRNAs MALAT1, ANRIL, HOTAIR, HOTTIP, and XIST were determined by a RQ-PCR analysis. RNase H-activating LNA™ GapmeR antisense oligonucleotides were used to knockdown lncRNA in vitro in MM cell lines. The cell lines were then treated with bortezomib, MG132, doxorubicin and hypoxic conditions to evaluate the effects of cytotoxic stress on the lncRNA expression. This study was approved by the IRB of Gunma University Hospital in accordance with the Declaration of Helsinki. Results: A significant higher level of MALAT1 expression was observed in BM plasma cells of MM patients (4.49) compared to MGUS patients (1.51) and control subjects (0.55) (p Conclusion: Significant upregulation of lncRNAs MALAT1 and ANRIL might be associated with MM progression. Given that MALAT1 is associated with lung cancer metastasis, MALAT1 might be strongly associated with extramedullary plasmacytoma formation due to its high expression in liver plasmacytoma. Genotoxic and ER stress induced by therapeutic drugs might upregulate MALAT1 expression, leading to extramedullary extension, which is a recent problem in MM treatment. Determining the distinct lncRNA signature of MM is a current important issue to clarify the molecular mechanisms underlying MM progression for the development of novel therapies. Disclosures No relevant conflicts of interest to declare.