Targeted delivery of microRNA-29b by transferrin-conjugated anionic lipopolyplex nanoparticles: a novel therapeutic strategy in acute myeloid leukemia.

Huang X, Schwind S, Yu B, Santhanam R, Wang H, Hoellerbauer P, Mims A, Klisovic R, Walker AR, Chan KK, Blum W, Perrotti D, Byrd JC, Bloomfield CD, Caligiuri MA, Lee RJ, Garzon R, Muthusamy N, Lee LJ, Marcucci G
Clin Cancer Res 19 2355-67 05/01/2013

Abstract

PURPOSE: miR-29b directly or indirectly targets genes involved in acute myeloid leukemia (AML), namely, DNMTs, CDK6, SP1, KIT, and FLT3. Higher miR-29b pretreatment expression is associated with improved response to decitabine and better outcome in AML. Thus, designing a strategy to increase miR-29b levels in AML blasts may be of therapeutic value. However, free synthetic miRs are easily degraded in bio-fluids and have limited cellular uptake. To overcome these limitations, we developed a novel transferrin-conjugated nanoparticle delivery system for synthetic miR-29b (Tf-NP-miR-29b).

EXPERIMENTAL DESIGN: Delivery efficiency was investigated by flow cytometry, confocal microscopy, and quantitative PCR. The expression of miR-29b targets was measured by immunoblotting. The antileukemic activity of Tf-NP-miR-29b was evaluated by measuring cell proliferation and colony formation ability and in a leukemia mouse model.

RESULTS: Tf-NP-miR-29b treatment resulted in more than 200-fold increase of mature miR-29b compared with free miR-29b and was approximately twice as efficient as treatment with non-transferrin-conjugated NP-miR-29b. Tf-NP-miR-29b treatment significantly downregulated DNMTs, CDK6, SP1, KIT, and FLT3 and decreased AML cell growth by 30% to 50% and impaired colony formation by approximately 50%. Mice engrafted with AML cells and then treated with Tf-NP-miR-29b had significantly longer survival compared with Tf-NP-scramble (P = 0.015) or free miR-29b (P = 0.003). Furthermore, priming AML cell with Tf-NP-miR-29b before treatment with decitabine resulted in marked decrease in cell viability in vitro and showed improved antileukemic activity compared with decitabine alone (P = 0.001) in vivo.

CONCLUSIONS: Tf-NP effectively delivered functional miR-29b, resulting in target downregulation and antileukemic activity and warrants further investigation as a novel therapeutic approach in AML.

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