miR-22 suppresses DNA ligase III addiction in multiple myeloma
Multiple myeloma (MM) is a hematologic malignancy characterized by high genomic instability. Here we provide evidence that hyper-activation of DNA ligase III (LIG3) is crucial for genomic instability and survival of MM cells. LIG3 mRNA expression in MM patients correlates with shorter survival and even increases with more advanced stage of disease. Knockdown of LIG3 impairs MM cells viability in vitro and in vivo, suggesting that neoplastic plasmacells are dependent on LIG3-driven repair. To investigate the mechanisms involved in LIG3 expression, we investigated the post-transcriptional regulation. We identified miR-22-3p as effective negative regulator of LIG3 in MM. Enforced expression of…
Selective targeting of IRF4 by synthetic microRNA-125b-5p mimics induces anti-multiple myeloma activity in vitro and in vivo
Interferon regulatory factor 4 (IRF4) is an attractive therapeutic target in multiple myeloma (MM). We here report that expression of IRF4 mRNA inversely correlates with microRNA (miR)-125b in MM patients. Moreover, we provide evidence that miR-125b is downregulated in TC2/3 molecular MM subgroups and in established cell lines. Importantly, constitutive expression of miR-125b-5p by lentiviral vectors or transfection with synthetic mimics impaired growth and survival of MM cells and overcame the protective role of bone marrow stromal cells in vitro. Apoptotic and autophagy-associated cell death were triggered in MM cells on miR-125b-5p ectopic expression. Importantly, we found that the anti-…
Bortezomib Induces Anti–Multiple Myeloma Immune Response Mediated by cGAS/STING Pathway Activation
Abstract The proteasome inhibitor bortezomib induces apoptosis in multiple myeloma cells and has transformed patient outcome. Using in vitro as well as in vivo immunodeficient and immunocompetent murine multiple myeloma models, we here show that bortezomib also triggers immunogenic cell death (ICD), characterized by exposure of calreticulin on dying multiple myeloma cells, phagocytosis of tumor cells by dendritic cells, and induction of multiple myeloma–specific immunity. We identify a bortezomib-triggered specific ICD gene signature associated with better outcome in two independent cohorts of patients with multiple myeloma. Importantly, bortezomib stimulates multiple myeloma cell immunogen…
Gabarap Loss Mediates Immune Escape in High Risk Multiple Myeloma
Abstract Immune therapies including CAR T cells and bispecific T cell engagers are demonstrating remarkable efficacy in relapsed refractory myeloma (MM). In this context, we have recently shown that proteasome inhibitor bortezomib (BTZ) results in immunogenic cell death (ICD) and in a viral mimicry state in MM cells, allowing for immune recognition of tumor cells. Induction of a robust anti-MM immune response after BTZ was confirmed both in vitro and in vivo: treatment of 5TGM1 MM cells with BTZ induced tumor regression associated with memory immune response, confirmed by ELISPOT of mouse splenocytes. We have confirmed the obligate role of calreticulin (CALR) exposure in phagocytosis and th…
Inhibition of miR-21 restores RANKL/OPG ratio in multiple myeloma-derived bone marrow stromal cells and impairs the resorbing activity of mature osteoclasts.
// Maria Rita Pitari 1 , Marco Rossi 1 , Nicola Amodio 1 , Cirino Botta 1 , Eugenio Morelli 1 , Cinzia Federico 1 , Annamaria Gulla 1 , Daniele Caracciolo 1 , Maria Teresa Di Martino 1 , Mariamena Arbitrio 2 , Antonio Giordano 3, 4 , Pierosandro Tagliaferri 1 , Pierfrancesco Tassone 1, 4 1 Department of Experimental and Clinical Medicine and T. Campanella Cancer Center, Magna Graecia University, S. Venuta University Campus, Catanzaro, Italy 2 ISN-CNR, Roccelletta di Borgia, Catanzaro, Italy 3 Department of Human Pathology and Oncology, University of Siena, Siena, Italy 4 Sbarro Institute for Cancer Research and Molecular Medicine, Center for Biotechnology, College of Science and Technology,…
A 13 mer LNA-i-miR-221 Inhibitor Restores Drug Sensitivity in Melphalan-Refractory Multiple Myeloma Cells.
Abstract Purpose: The onset of drug resistance is a major cause of treatment failure in multiple myeloma. Although increasing evidence is defining the role of miRNAs in mediating drug resistance, their potential activity as drug-sensitizing agents has not yet been investigated in multiple myeloma. Experimental Design: Here we studied the potential utility of miR-221/222 inhibition in sensitizing refractory multiple myeloma cells to melphalan. Results: miR-221/222 expression inversely correlated with melphalan sensitivity of multiple myeloma cells. Inhibition of miR-221/222 overcame melphalan resistance and triggered apoptosis of multiple myeloma cells in vitro, in the presence or absence of…
MiR-29b antagonizes the pro-inflammatory tumor-promoting activity of multiple myeloma-educated dendritic cells
Dendritic cells (DCs) have a key role in regulating tumor immunity, tumor cell growth and drug resistance. We hypothesized that multiple myeloma (MM) cells might recruit and reprogram DCs to a tumor-permissive phenotype by changes within their microRNA (miRNA) network. By analyzing six different miRNA-profiling data sets, miR-29b was identified as the only miRNA upregulated in normal mature DCs and significantly downregulated in tumor-associated DCs. This finding was validated in primary DCs co-cultured in vitro with MM cell lines and in primary bone marrow DCs from MM patients. In DCs co-cultured with MM cells, enforced expression of miR-29b counteracted pro-inflammatory pathways, includin…