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. 2016 May 17;7(20):29400-11.
doi: 10.18632/oncotarget.8837.

Anti-miR delivery strategies to bypass the blood-brain barrier in glioblastoma therapy

Dong Geon Kim  1   2 , Kang Ho Kim  2 , Yun Jee Seo  2 , Heekyoung Yang  2   3 , Eric G Marcusson  4 , Eunju Son  2   5 , Kyoungmin Lee  1   2 , Jason K Sa  1   2 , Hye Won Lee  1   2   6 , Do-Hyun Nam  1   2   3
Affiliations

Anti-miR delivery strategies to bypass the blood-brain barrier in glioblastoma therapy

Dong Geon Kim et al. Oncotarget. .

Abstract

Small non-coding RNAs called miRNAs are key regulators in various biological processes, including tumor initiation, propagation, and metastasis in glioblastoma as well as other cancers. Recent studies have shown the potential for oncogenic miRNAs as therapeutic targets in glioblastoma. However, the application of antisense oligomers, or anti-miRs, to the brain is limited due to the blood-brain barrier (BBB), when administered in the traditional systemic manner. To induce a therapeutic effect in glioblastoma, anti-miR therapy requires a robust and effective delivery system to overcome this obstacle. To bypass the BBB, different delivery administration methods for anti-miRs were evaluated. Stereotaxic surgery was performed to administer anti-Let-7 through intratumoral (ITu), intrathecal (ITh), and intraventricular (ICV) routes, and each method's efficacy was determined by changes in the expression of anti-Let-7 target genes as well as by immunohistochemical analysis. ITu administration of anti-miRs led to a high rate of anti-miR delivery to tumors in the brain by both bolus and continuous administration. In addition, ICV administration, compared with ITu administration, showed a greater distribution of the miR across entire brain tissues. This study suggests that local administration methods are a promising strategy for anti-miR treatment and may overcome current limitations in the treatment of glioblastoma in preclinical animal models.

Keywords: anti-miR; delivery efficiency; glioblastoma; intratumoral injection; intraventricular injection.

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Conflict of interest statement

None.

Figures

Figure 1
Figure 1. Schematic illustration of the local administration methods
Three different routes were employed for the evaluation of anti-miR delivery efficacy: (A) Intratumoral injection (ITu). (B) Intraventricular injection (ICV). (C) Intrathecal injection (ITh). (D) Stereotaxic surgery was performed to administer anti-miR into the mouse brain. A brain cannula was implanted with anti-miR-filled osmotic pumps for continuous administration.
Figure 2
Figure 2. Local delivery of an anti-Let-7 bolus or continuous administration to the brain in a non-tumor-bearing mouse model
(A) Detailed experimental schedules using non-tumor-bearing mice (BALB/c-nu, 7 weeks) are illustrated (upper). Anti-Let-7 was administered twice (250 μg/5 μL each time, n = 10) in the parenchymal (stereotaxic coordinate site of ITu administration, n = 10) and lateral cerebroventricular space (stereotaxic coordinate site of ICV administration, n = 10) of the mouse brain, and all mice were sacrificed 2 days after the last treatment. qRT-PCR analysis of target gene expression (miRNA-Let-7 targeting mRNAs in mouse tissue: mIgfbp2, mNras, and mTgfbr1) in the mouse brain after applying the different routes of administration (bottom). (B) Detailed experimental schedules of osmotic pump surgery in the non-tumor-bearing mice (BALB/c-nu, 7 weeks, n = 10 each group) are illustrated (upper). An osmotic pump was used to continuously administer anti-Let-7 (35 μg/day for 7 days). Immunohistochemical analysis using an anti-miR specific antibody in the mouse brain after continuous administration (35 μg/day for 7 days) of anti-Let-7 by osmotic pump (bottom). (C) qRT-PCR analysis of Let-7-targeting genes in mouse tissue (mIgf2bp2, mNras, and mTgfbr1) at the injection site (I) for anti-Let-7 (35 μg/day for 7 days) using an osmotic pump. Data are presented as means ± S.E.M. *p < 0.05, **p < 0.01, and *** p < 0.001 compared with the control.
Figure 3
Figure 3. Anti-Let-7 mediates differential expression of its target genes in glioblastoma cell lines and glioblastoma patient-derived cells
Quantitative RT-PCR (qRT-PCR) was used to determine the expression of target genes. qRT-PCR analysis of (A) hHMGA2, (B) hIGF2BP2, and (C) hLIN28B mRNA expression in glioblastoma cell lines after anti-Let-7 (20 or 50 nM for 48 h) administration. Data are presented as means ± S.E.M. *p < 0.05, **p < 0.01, and ***p < 0.001 compared with the control.
Figure 4
Figure 4. Expression levels of target genes were analyzed to evaluate the efficiency of intratumoral, intraventricular, and intrathecal administration of anti-Let-7 in the U87MG xenograft model
(A) U87MG cells (2 × 105 Cells/5 μL HBSS, n = 10 each group) were injected intracranially using a stereotaxic apparatus in the mouse brain. Twenty days after cell injection, anti-Let-7 was administered twice (250 μg/5 μL each time) via the three different routes of administration. The stereotaxic apparatus was used for the ITu and ICV methods of administration. (B) Tissues were isolated from different sites in the mouse brain: tumor core (c), tumor periphery (p) and the opposite hemisphere. (C) qRT-PCR analysis of target gene expression (Let-7-targeting mRNAs in human tissue: hHMGA2, hLIN28B, and hIGF2BP2) in the tumor core (c) and periphery (p). (D) qRT-PCR analysis of target gene expression (Let-7-targeting mRNAs in mouse tissue: mIgfbp2, mNras, and mTgfbr1) in the opposite hemisphere. C: tumor core, P: tumor periphery, OH: opposite hemisphere. Data are presented as means ± S.E.M. *p < 0.05, **p < 0.01, and ***p < 0.001 compared with the control.
Figure 5
Figure 5. Anti-Let-7 is delivered directly into the brain tumor by intratumoral administration via osmotic pump in U87MG orthotopic and glioblastoma patient-derived xenograft models
U87MG cells (2 × 105/5 μL HBSS, n = 10 for each group) were implanted into mouse brains using the stereotaxic apparatus. The brain cannula was implanted 20 days after U87MG cell implantation using anti-miR-filled osmotic pumps. (A) The osmotic pump was inserted into the mouse subcutaneously, and the cannula was located at the coordinate site of intratumoral administration in the mouse. Anti-Let-7 was released (35 μg/day) into the brain tumor for 7 days via the brain cannula and osmotic pump. (B) qRT-PCR analysis of target gene expression (miRNA-Let7-targeting mRNAs in mouse tissue: mIgfbp2, mNras, and mTgfbr1) in brain tumors from U87MG orthotopic models after anti-Let-7 administration. (C, D) qRT-PCR analysis of Let-7 target gene expression in mouse tissue (mIgfbp2, mNras, and mTgfbr1) in nearby tumor and opposite hemisphere tissue from U87MG orthotopic models after anti-Let-7 administration. T: tumor, NT: normal tissue nearby tumor, OH: opposite hemisphere. Data are presented as means ± S.E.M. *p < 0.05, **p < 0.01, and ***p < 0.001 compared with the control.
Figure 6
Figure 6. Anti-Let-7 is delivered directly into the cerebrospinal fluid by intraventricular administration via osmotic pump in U87MG orthotopic xenograft models
U87MG cells (2 × 105 Cells/5 μL HBSS, n = 10 each group) were implanted using the stereotaxic coordinate site in the mouse brain. (A) Anti-Let-7 was released (35 μg/day) into the brain for 7 days using an osmotic pump and brain infusion cannula located at the site of intraventricular administration. (B) qRT-PCR analysis of target gene expression in the tumor of the U87MG orthotopic model after administration of anti-Let-7. (C, D) qRT-PCR analysis of target gene expression in normal nearby tumor tissue and the opposite hemisphere of the U87MG orthotopic model after administration of anti-Let-7. T: tumor, NT: normal tissue nearby tumor, OH: opposite hemisphere. Data are presented as means ± S.E.M. *p < 0.05, **p < 0.01, and ***p < 0.001 compared with the control.
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References

    1. Jhanwar-Uniyal M, Labagnara M, Friedman M, Kwasnicki A, Murali R. Glioblastoma: molecular pathways, stem cells and therapeutic targets. Cancers. 2015;7:538–555. - PMC - PubMed
    1. Stupp R, Mason WP, van den Bent MJ, Weller M, Fisher B, Taphoorn MJ, Belanger K, Brandes AA, Marosi C, Bogdahn U, Curschmann J, Janzer RC, Ludwin SK, et al. Radiotherapy plus concomitant and adjuvant temozolomide for glioblastoma. N Engl J Med. 2005;352:987–996. - PubMed
    1. van den Bent MJ, Gao Y, Kerkhof M, Kros JM, Gorlia T, van Zwieten K, Prince J, van Duinen S, Sillevis Smitt PA, Taphoorn M, French PJ. Changes in the EGFR amplification and EGFRvIII expression between paired primary and recurrent glioblastomas. Neuro Oncol. 2015;17:935–941. - PMC - PubMed
    1. van Tellingen O, Yetkin-Arik B, de Gooijer MC, Wesseling P, Wurdinger T, de Vries HE. Overcoming the blood-brain tumor barrier for effective glioblastoma treatment. Drug Resist Updat. 2015;19:1–12. - PubMed
    1. Macfarlane LA, Murphy PR. MicroRNA: Biogenesis, Function and Role in Cancer. Curr Genomics. 2010;11:537–561. - PMC - PubMed