HG-126: WHOLE GENOME microRNA PROFILING IN FUNCTIONALLY-VALIDATED INVASIVE GBM CELLS IDENTIFIES A NOVEL SET OF microRNAs DRIVING GBM INVASION

BACKGROUND/METHODS: Glioblastoma (GBM) cells diffusely invade into surrounding normal brain tissue. We hypothesized that direct comparison of matched invasive (GBMINV) and tumor core (GBMTC) GBM cells would facilitate discovery of drivers of invasion. GBMINV cells that have migrated deep into normal brain are difficult to obtain due to potential debilitating surgical morbidities. We utilized 6 pediatric patient tumor-derived orthotopic xenograft mouse models to isolate matched pairs of GBMTC cells from the visible tumor mass and GBMINV cells from “normal” surrounding mouse brains. RESULTS: Profiling of 768 human microRNAs identified 23 microRNAs upregulated in GBMINV cells in at least 5 of the 6 GBM models compared with matching GBMTC cells. Functional validation was performed by lentivirus-mediated silencing of miR-126, miR-487b, and miR-369-5p, the top three over-expressed microRNA in GBMINV cells. Compared with untreated parental cells and tumor cells transduced with non-target control lentiviruses, silencing of miR-126, miR-487b, or miR-369-5p suppressed GBMINV cell migration in vitro and inhibited in vivo invasive growth of GBMINV cells into normal mouse brains. Whole genome gene expression profiling of GBMINV/GBMTC pairs identified a subset of genes suppressed by miR-126 (n = 74), miR-487b (n = 46), and miR-369-5p (n = 2) in at least 4 of the 6 pairs. RDX was inhibited by all three microRNAs, MANEA by miR-126 and miR-369, and 32 genes by miR-126 and miR-487b. CONCLUSION: Our novel strategy of utilizing GBMINV/GBMTC cell pairs identified microRNAs that are selectively over-expressed in GBMINV cells and allowed functional confirmation of miR-126, miR-487b, and miR-369-5p as drivers of GBM invasion.