4-iodo-6-phenylpyrimidine and Multiple-Myeloma

Multiple myeloma (MM) remains an incurable cancer characterized by accumulation of malignant plasma cells in the bone marrow (BM). The mechanism underlying MM homing to BM is poorly elucidated.. The clinical significance of migration inhibitory factor (MIF) expression was examined by analyzing six independent gene expression profile databases of primary MM cells using the Student's t test and Kaplan-Meier test. Enzyme-linked immunosorbent assay was used to examine MIF expression. In vivo bioluminescent imaging was used to determine MM cell localization and treatment efficacy in human MM xenograft mouse models, with three to four mice per group. MM cell attachment to BM stromal cells (BMSCs) was monitored by cell adhesion assay. MIF regulation of the expression of adhesion molecules was determined by chromatin immunoprecipitation (ChIP) assay. Statistical tests were two-sided.. High levels of MIF were detected in MM BM (MIF level in BM plasma: healthy = 10.72 ± 5.788 ng/mL, n = 5; MM = 1811 ± 248.7 ng/mL, n = 10; P < .001) and associated with poor survival of patients (Kaplan-Meier test for MM OS: 87 MIF(high) patients, 86 MIF(low) patients, P = .02). Knocking down MIF impaired MM cell adhesion to BMSCs in vitro and led to formation of extramedullary tumors in SCID mice. MIF acted through surface receptor CXCR4 and adaptor COPS5 to regulate the expression of adhesion molecules ALCAM, ITGAV, and ITGB5 on MM cells. More importantly, MIF-deficient MM cells were sensitive to chemotherapy in vitro when cocultured with BMSCs and in vivo. MIF inhibitor 4-IPP sensitized MM cells to chemotherapy.. MIF is an important player and a novel therapeutic target in MM. Inhibiting MIF activity will sensitize MM cells to chemotherapy.

Topics: Activated-Leukocyte Cell Adhesion Molecule; Animals; Antigens, Differentiation, B-Lymphocyte; Antineoplastic Agents, Alkylating; Apoptosis; Autocrine Communication; Bone Marrow; Bortezomib; Cell Adhesion; Cell Line, Tumor; Chemotaxis; Coculture Techniques; COP9 Signalosome Complex; Drug Resistance, Neoplasm; Female; Gene Expression; Gene Knockdown Techniques; Heterografts; Histocompatibility Antigens Class II; Humans; Intracellular Signaling Peptides and Proteins; Intramolecular Oxidoreductases; Macrophage Migration-Inhibitory Factors; Melphalan; Mesenchymal Stem Cells; Mice; Mice, SCID; Multiple Myeloma; Neoplasm Transplantation; Peptide Hydrolases; Plasma Cells; Pyrimidines; Receptors, CXCR4; RNA, Messenger

Tumor-associated macrophages (TAM) are important components of the multiple myeloma (MM) microenvironment that support malignant plasma cell survival and resistance to therapy. It has been proposed that macrophages (MØ) retain the capacity to change in response to stimuli that can restore their antitumor functions. Here, we investigated several approaches to reprogram MØ as a novel therapeutic strategy in MM. First, we found tumor-limiting and tumor-supporting capabilities for monocyte-derived M1-like MØ and M2-like MØ, respectively, when mixed with MM cells, both in vitro and in vivo. Multicolor confocal microscopy revealed that MM-associated MØ displayed a predominant M2-like phenotype in the bone marrow of MM patient samples, and a high expression of the pro-M2 cytokine macrophage migration inhibitory factor (MIF). To reprogram the protumoral M2-like MØ present in MM toward antitumoral M1-like MØ, we tested the pro-M1 cytokine granulocyte-macrophage colony-stimulating factor (GM-CSF) plus blockade of the M2 cytokines macrophage colony-stimulating factor or MIF. The combination of GM-CSF plus the MIF inhibitor 4-iodo-6-phenyl-pyrimidine achieved the best reprogramming responses toward an M1 profile, at both gene and protein expression levels, as well as remarkable tumoricidal effects. Furthermore, this combined treatment elicited MØ-dependent therapeutic responses in MM xenograft mouse models, which were linked to upregulation of M1 and reciprocal downregulation of M2 MØ markers. Our results reveal the therapeutic potential of reprogramming MØ in the context of MM.

Topics: Animals; Cell Differentiation; Cellular Reprogramming Techniques; Disease Models, Animal; Granulocyte-Macrophage Colony-Stimulating Factor; Humans; Macrophage Migration-Inhibitory Factors; Macrophages; Mice; Microscopy, Confocal; Multiple Myeloma; Pyrimidines; Xenograft Model Antitumor Assays