Abstract
Acute leukemia is a rapidly progressing blood cancer with low survival rates. Unfavorable prognosis is attributed to insufficiently characterized subpopulations of leukemia stem cells (LSC) that drive chemoresistance and leukemia relapse. Here we utilized a genetic reporter that assesses stemness to enrich and functionally characterize LSCs. We observed heterogeneous activity of the ERG+85 enhancer-based fluorescent reporter in human leukemias. Cells with high reporter activity (tagBFPHigh) exhibited elevated expression of stemness and chemoresistance genes and demonstrated increased clonogenicity and resistance to chemo- and radiotherapy as compared with their tagBFPNeg counterparts. The tagBFPHigh fraction was capable of regenerating the original cellular heterogeneity and demonstrated increased invasive ability. Moreover, the tagBFPHigh fraction was enriched for leukemia-initiating cells in a xenograft assay. We identified the ubiquitin hydrolase USP9X as a novel ERG transcriptional target that sustains ERG+85-positive cells by controlling ERG ubiquitination. Therapeutic targeting of USP9X led to preferential inhibition of the ERG-dependent leukemias. Collectively, these results characterize human leukemia cell functional heterogeneity and suggest that targeting ERG via USP9X inhibition may be a potential treatment strategy in patients with leukemia. SIGNIFICANCE: This study couples a novel experimental tool with state-of-the-art approaches to delineate molecular mechanisms underlying stem cell-related characteristics in leukemia cells.
Highlights
Acute leukemia is a highly aggressive group of blood malignancies that originate from hematopoietic stem cells (HSC)
On the basis of our findings that ERGþ85 enhancer is active in human HSPCs and a subset of Acute myeloid lymphoma (AML), we recently developed a lentiviral fluorescent reporter in which ERGþ85 enhancer regulates tagBFP expression, while a constitutively active EF1/SV40 promoter drives EGFP cassette
As ERGþ85 enhancer can bind numerous high variance transcription factor (TF) implicated in regulation of stem cells in both T- and myeloid leukemogenesis, we hypothesized that this reporter can be a tool to track, characterize, and link transcriptional and functional heterogeneity of leukemia cells
Summary
Acute leukemia is a highly aggressive group of blood malignancies that originate from hematopoietic stem cells (HSC). Accumulation of blast cells in the bone marrow due to deregulation of molecular pathways controlling self-renewal and differentiation of immature blood cells is the main feature of leukemia [1, 2]. Well-recognized and prognostic genetic heterogeneity, Note: Supplementary data for this article are available at Cancer Research Online (http://cancerres.aacrjournals.org/).
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
