Purpose: To determine the in vivo and in vitro antiangiogenic power of lenalidomide, a "lead compound" of IMiD immunomodulatory drugs in bone marrow (BM) endothelial cells (EC) of patients with multiple myeloma (MM) in active phase (MMEC).Experimental Design: The antiangiogenic effect in vivo was studied using the chorioallantoic membrane (CAM) assay. Functional studies in vitro (angiogenesis, "wound" healing and chemotaxis, cell viability, adhesion, and apoptosis) were conducted in both primary MMECs and ECs of patients with monoclonal gammopathies (MGUS) of undetermined significance (MGEC) or healthy human umbilical vein endothelial cells (HUVEC). Real-time reverse transcriptase PCR, Western blotting, and differential proteomic analysis were used to correlate morphologic and biological EC features with the lenalidomide effects at the gene and protein levels.Results: Lenalidomide exerted a relevant antiangiogenic effect in vivo at 1.75 mmol/L, a dose reached in interstitial fluids of patients treated with 25 mg/d. In vitro, lenalidomide inhibited angiogenesis and migration of MMECs, but not of MGECs or control HUVECs, and had no effect on MMEC viability, apoptosis, or fibronectin-and vitronectin-mediated adhesion. Lenalidomide-treated MMECs showed changes in VEGF/VEGFR2 signaling pathway and several proteins controlling EC motility, cytoskeleton remodeling, and energy metabolism pathways.Conclusions: This study provides information on the molecular mechanisms associated with the antimigratory and antiangiogenic effects of lenalidomide in primary MMECs, thus giving new avenues for effective endothelium-targeted therapies in MM.
SummaryAdult neurogenesis requires the precise control of neuronal versus astrocyte lineage determination in neural stem cells. While microRNAs (miRNAs) are critically involved in this step during development, their actions in adult hippocampal neural stem cells (aNSCs) has been unclear. As entry point to address that question we chose DICER, an endoribonuclease essential for miRNA biogenesis and other RNAi-related processes. By specific ablation of Dicer in aNSCs in vivo and in vitro, we demonstrate that miRNAs are required for the generation of new neurons, but not astrocytes, in the adult murine hippocampus. Moreover, we identify 11 miRNAs, of which 9 have not been previously characterized in neurogenesis, that determine neurogenic lineage fate choice of aNSCs at the expense of astrogliogenesis. Finally, we propose that the 11 miRNAs sustain adult hippocampal neurogenesis through synergistic modulation of 26 putative targets from different pathways.
This pilot study provides the proof-of-principle for the clinical application of biodegradable IM-loaded PMC as feasible, safe and effective ex vivo purging agents to target CML stem cells, in order to improve transplant outcome of resistant/relapsed patients or reduce IM dose escalation.
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