The IMiDs targets IKZF-1/3 and IRF4 as novel negative regulators of NK cell-activating ligands expression in multiple myeloma

Abstract

// Cinzia Fionda 1 , Maria Pia Abruzzese 1 , Alessandra Zingoni 1 , Francesca Cecere 1 , Elisabetta Vulpis 1 , Giovanna Peruzzi 2 , Alessandra Soriani 1 , Rosa Molfetta 1 , Rossella Paolini 1 , Maria Rosaria Ricciardi 3 , Maria Teresa Petrucci 3 , Angela Santoni 1,4,* and Marco Cippitelli 1,* 1 Department of Molecular Medicine, Istituto Pasteur-Fondazione Cenci Bolognetti, Sapienza University of Rome, Rome, Italy 2 Istituto Italiano di Tecnologia, CLNS@Sapienza, Sapienza University of Rome, Rome, Italy 3 Division of Hematology, Department of Cellular Biotechnologies and Hematology, Sapienza University of Rome, Rome, Italy 4 Istituto Mediterraneo di Neuroscienze Neuromed, Pozzilli, Italy * These authors have contributed equally to this work Correspondence to: Marco Cippitelli, email: // Angela Santoni, email: // Keywords : IMiDs, multiple myeloma, natural killer, NKG2DLs, DNAM-1Ls Received : May 13, 2015 Accepted : June 14, 2015 Published : June 23, 2015 Abstract Immunomodulatory drugs (IMiDs) have potent anti-tumor activities in multiple myeloma (MM) and are able to enhance the cytotoxic function of natural killer (NK) cells, important effectors of the immune response against MM. Here, we show that these drugs can enhance the expression of the NKG2D and DNAM-1 activating receptor ligands MICA and PVR/CD155 in human MM cell lines and primary malignant plasma cells. Depletion of cereblon (CRBN) by shRNA interference strongly impaired upregulation of these ligands and, more interestingly, IMiDs/CRBN-mediated downregulation of the transcription factors Ikaros (IKZF1), Aiolos (IKZF3) and IRF4 was critical for these regulatory mechanisms. Indeed, shRNA knockdown of IKZF1 or IKZF3 expression was both necessary and sufficient for the upregulation of MICA and PVR/CD155 expression, suggesting that these transcription factors can repress these genes; accordingly, the direct interaction and the negative role of IKZF1 and IKZF3 proteins on MICA and PVR/CD155 promoters were demonstrated. Finally, MICA expression was enhanced in IRF4-silenced cells, indicating a specific suppressive role of this transcription factor on MICA gene expression in MM cells. Taken together, these findings describe novel molecular pathways involved in the regulation of MICA and PVR/CD155 gene expression and identify the transcription factors IKZF-1/IKZF-3 and IRF4 as repressors of these genes in MM cells.