Priya Karmali

Therapeutic potential of targeting microRNA‐10b in established intracranial glioblastoma: first steps toward the clinic

MicroRNA‐10b (miR‐10b) is a unique oncogenic miRNA that is highly expressed in all GBM subtypes, while absent in normal neuroglial cells of the brain. miR‐10b inhibition strongly impairs proliferation and survival of cultured glioma cells, including glioma‐initiating stem‐like cells (GSC). Although several miR‐10b targets have been identified previously, the common mechanism conferring the miR‐10b‐sustained viability of GSC is unknown. Here, we demonstrate that in heterogeneous GSC, miR‐10b regulates cell cycle and alternative splicing, often through the non‐canonical targeting via 5′UTRs of its target genes, including MBNL1‐3, SART3, and RSRC1. We have further assessed the inhibition of miR‐10b in intracranial human GSC‐derived xenograft and murine GL261 allograft models in athymic and immunocompetent mice. Three delivery routes for the miR‐10b antisense oligonucleotide inhibitors (ASO), direct intratumoral injections, continuous osmotic delivery, and systemic intravenous injections, have been explored. In all cases, the treatment with miR‐10b ASO led to targets’ derepression, and attenuated growth and progression of established intracranial GBM. No significant systemic toxicity was observed upon ASO administration by local or systemic routes. Our results indicate that miR‐10b is a promising candidate for the development of targeted therapies against all GBM subtypes.

Anti-miR-17 therapy delays tumorigenesis in MYC-driven hepatocellular carcinoma (HCC)

Hepatocellular carcinoma (HCC) remains a significant clinical challenge with few therapeutic options. Genomic amplification and/or overexpression of the MYC oncogene is a common molecular event in HCC, thus making it an attractive target for drug therapy. Unfortunately, currently there are no direct drug therapies against MYC. As an alternative strategy, microRNAs regulated by MYC may be downstream targets for therapeutic blockade. MiR-17 family is a microRNA family transcriptionally regulated by MYC and it is commonly overexpressed in human HCCs. In this study, we performed systemic delivery of a novel lipid nanoparticle (LNP) encapsulating an anti-miR-17 oligonucleotide in a conditional transgenic mouse model of MYC driven HCC. Treatment with anti-miR-17 in vivo, but not with a control anti-miRNA, resulted in significant de-repression of direct targets of miR-17, robust apoptosis, decreased proliferation and led to delayed tumorigenesis in MYC-driven HCCs. Global gene expression profiling revealed engagement of miR-17 target genes and inhibition of key transcriptional programs of MYC, including cell cycle progression and proliferation. Hence, anti-miR-17 is an effective therapy for MYC-driven HCC.

Lipid Nanoparticle–Mediated Delivery of Anti-miR-17 Family Oligonucleotide Suppresses Hepatocellular Carcinoma Growth

Hepatocellular carcinoma (HCC) is one of the most common human malignancies with poor prognosis and urgent unmet medical need. Aberrant expression of multiple members of the miR-17 family are frequently observed in HCC, and their overexpression promotes tumorigenic properties of HCC cells. However, whether pharmacologic inhibition of the miR-17 family inhibits HCC growth remains unknown. In this study, we validated that the miR-17 family was upregulated in a subset of HCC tumors and cell lines and its inhibition by a tough decoy inhibitor suppressed the growth of Hep3B and HepG2 cells, which overexpress the miR-17 family. Furthermore, inhibition of the miR-17 family led to a global derepression of direct targets of the family in all three HCC cell lines tested. Pathway analysis of the deregulated genes indicated that the genes associated with TGFβ signaling pathway were highly enriched in Hep3B and HepG2 cells. A miR-17 family target gene signature was established and used to identify RL01-17(5), a lipid nanoparticle encapsulating a potent anti-miR-17 family oligonucleotide. To address whether pharmacologic modulation of the miR-17 family can inhibit HCC growth, RL01-17(5) was systemically administrated to orthotopic Hep3B xenografts. Suppression of Hep3B tumor growth in vivo was observed and tumor growth inhibition correlated with induction of miR-17 family target genes. Together, this study provides proof-of-concept for targeting the miR-17 family in HCC therapy. Mol Cancer Ther; 16(5); 905–13. ©2017 AACR.