miR-126 Regulates Distinct Self-Renewal Outcomes in Normal and Malignant Hematopoietic Stem Cells

Summary

To investigate miRNA function in human acute myeloid leukemia (AML) stem cells (LSC), we generated a prognostic LSC-associated miRNA signature derived from functionally validated subpopulations of AML samples. For one signature miRNA, miR-126, high bioactivity aggregated all in vivo patient sample LSC activity into a single sorted population, tightly coupling miR-126 expression to LSC function. Through functional studies, miR-126 was found to restrain cell cycle progression, prevent differentiation, and increase self-renewal of primary LSC in vivo. Compared with prior results showing miR-126 regulation of normal hematopoietic stem cell (HSC) cycling, these functional stem effects are opposite between LSC and HSC. Combined transcriptome and proteome analysis demonstrates that miR-126 targets the PI3K/AKT/MTOR signaling pathway, preserving LSC quiescence and promoting chemotherapy resistance.

Graphical Abstract

Highlights

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  Clinical outcome in AML correlates with LSC-associated miRNA expression

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  miR-126 targets multiple components of the PI3K/AKT/MTOR signaling pathway

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  miR-126 promotes chemotherapy resistance by preserving LSC in a quiescent state

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  miR-126 governs opposing self-renewal outcomes in normal and malignant stem cells

Abstract

Lechman et al. show that miR-126 targets the PI3K/AKT/MTOR signaling pathway to preserve quiescence, increase self-renewal, and promote chemotherapy resistance of acute myeloid leukemia stem cells (LSC). Reducing the miR-126 level impairs LSC maintenance in contrast to expanding normal hematopoietic stem cells.