Therapeutic antagonists of microRNAs deplete leukemia-initiating cell activity
Chinavenmeni S. Velu, … , Brian Gebelein, H. Leighton Grimes
Chinavenmeni S. Velu, … , Brian Gebelein, H. Leighton Grimes
Published December 16, 2013
Citation Information: J Clin Invest. 2014;124(1):222-236. https://doi.org/10.1172/JCI66005.
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Research Article Oncology

Therapeutic antagonists of microRNAs deplete leukemia-initiating cell activity

Abstract

Acute myelogenous leukemia (AML) subtypes that result from oncogenic activation of homeobox (HOX) transcription factors are associated with poor prognosis. The HOXA9 transcription activator and growth factor independent 1 (GFI1) transcriptional repressor compete for occupancy at DNA-binding sites for the regulation of common target genes. We exploited this HOXA9 versus GFI1 antagonism to identify the genes encoding microRNA-21 and microRNA-196b as transcriptional targets of HOX-based leukemia oncoproteins. Therapeutic inhibition of microRNA-21 and microRNA-196b inhibited in vitro leukemic colony forming activity and depleted in vivo leukemia-initiating cell activity of HOX-based leukemias, which led to leukemia-free survival in a murine AML model and delayed disease onset in xenograft models. These data establish microRNA as functional effectors of endogenous HOXA9 and HOX-based leukemia oncoproteins, provide a concise in vivo platform to test RNA therapeutics, and suggest therapeutic value for microRNA antagonists in AML.

Authors

Chinavenmeni S. Velu, Aditya Chaubey, James D. Phelan, Shane R. Horman, Mark Wunderlich, Monica L. Guzman, Anil G. Jegga, Nancy J. Zeleznik-Le, Jianjun Chen, James C. Mulloy, Jose A. Cancelas, Craig T. Jordan, Bruce J. Aronow, Guido Marcucci, Balkrishen Bhat, Brian Gebelein, H. Leighton Grimes

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Figure 4

Inhibition of miR-21 and miR-196b specifically interferes with maintenance of MLL oncoprotein–initiated leukemia.

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Inhibition of miR-21 and miR-196b specifically interferes with maintenan...
(A and B) Enumeration of methylcellulose CFU assay (A) with serial replating of antagomir-treated MLL-AF9–initiated AML (n = 3, mean ± SD), (B) TaqMan analysis of miR-21 and miR-196b expression in CD45.1+CD45.2+ MLL-AF9 cells treated with either CA21+CA196b or A21+A196b for 72 hours (n = 3). (C) Scheme of experimental strategy showing transplant with MLL-AF9 CD45.1+CD45.2+ leukemic splenocytes and implantation of pumps with treatment groups (n = 6 per group) and flow analysis. (D) Kaplan-Meier survival curve of partially conditioned (500 cGy) C57BL/6 mice (CD45.2+) transplanted with 1 million CD45.1+CD45.2+ MLL-AF9 leukemic splenocytes. Four days later, 6-week osmotic pumps containing A21+A196b or CA21+CA196b (shaded area denotes time of pump activity) were implanted in the mice (n = 6). Treated mice were analyzed by flow cytometry for CD45.1 versus CD45.2 (inset) to identify leukemic cells at time of death (CA21+CA196b) or at the termination of the experiment at 165 days (A21+A196b). (E) Same as C, but with 1 million AML-ETO9a–initiated murine leukemic splenocytes. Antagomir (A21+A196b) or control (CA21+CA196b) *P < 0.05; **P < 0.01; ***P < 0.001.