MDS-MSC Derived Exosomes Promote MDS Cells Malignant Proliferation through RIG-1/Isgs Pathway Via RN7SL1

The interactions between bone marrow stem cells (BM-MSCs) and myelodysplastic syndromes (MDS) cells perform a crucial role in MDS pathogenesis by secreting cytokines ,growth factors, and exosomes. Although BM-MSCs induced growth of MDS cells has been studied, the role of exosomes from MDS-derived MSC (MDS-MSC-EXO) in this action remains unclear. In our study, we investigate the effect of MDS-MSC-EXO on the viability, proliferation, migration, cellular apoptosis of MDS cell lines, such as MDS-L and SKM-1. Our data identified that MDS-MSC-EXO can promote proliferation, migration, and decrease cell apoptosis. Both LR-MDS-MSC and HR-MDS-MSC-derived exosomes increased MDS cell growth.Exosomes mediate local cell-to-cell communication by transferring mRNAs, miRNAs, and proteins. In our study, we found that MDS-MSC-EXO expressed higher unshielded RN7SL1,an endogenous RNA normally shielded by RNA binding proteins SRP9/14, than that from health controls (HC-MSC-EXO). MDS cloned cells expressed higher retinoic acid inducible gene-I (RIG-I) and interferon-stimulated genes (ISGs), such as ISG15, IFIT1 and IFITM1, which are the receptor and effector molecules of RN7SL1. Both MDS-MSC-EXO and exogenous RN7SL1 can promote MDS cloned cells proliferation and stimulate ISGs expression by activating RIG-1. RIG-I inhibitor can block this effect. We demonstrate that MDS-MSC may promote MDS cloned cell proliferation through RIG-ISGs signal activated by exosomes-derived RN7SL1. Overall, our studies provide new insights that MSC-EXO functions the crucial roles in mediating the progression of MDS via RIG-1/ISGs activation, and demonstrate novel targets of RN7SL1 to the pathogenesis of MDS.This study will provide new ideas for MDS treatment in the aspect of microenvironment.