Abstract 1950: Whole genome microRNA profiling in functionally validated invasive GBM cells identifies a novel set of microRNAs driving GBM invasion

Glioblastoma multiforme (GBM) is the most malignant brain tumor that occurs in both adults and children. One of the key features that makes GBM particularly difficult to treat is the diffuse invasion of tumor cells into surrounding normal brain tissue. We hypothesize that direct comparison of matched invasive (GBM INV ) and tumor core GBM cells (GBM TC ) would facilitate the discovery of drivers of GBM invasion. However, GBM INV cells that have migrated deep into normal brain tissues are extremely difficult to obtain from patients as resection of normal human brain tissue can result in debilitating morbidities. To overcome this barrier, we utilized a panel of 6 pediatric patient tumor-derived orthotopic xenograft (PDOX) mouse models to isolate matched pairs of GBM TC cells from the visible tumor mass and GBM INV cells from the “normal” mouse brains. Global profiling of 768 human microRNA using a real-time PCR-based Taqman system identified 23 microRNAs were upregulated in the GBM INV cells in at least 5 of the 6 GBM models as compared with the matching GBM TC cells. Functional validation was performed by lentivirus-mediated silencing of miR-126, miR-487b and miR-369-5p, the top three overexpressed microRNA in the GBM INV cells. Compared with the untreated parental cells and tumor cells transduced with non-target control lentiviruses, silencing of miR-126, miR-487b or miR-369-5p suppressed GBM INV cell (both as neurosphere and monolayer) migration in vitro without affecting tumor proliferation and significantly inhibited the in vivo invasive growth of GBM INV cells, which were pre-enriched through 3 rounds of in vivo selections, into normal mouse brains. The depth of the invasive fronts were remarkably decreased/eliminated, exhibiting sharp, well-demarcated margins between tumor and normal mouse brain. To identify target genes of the 3 microRNAs, whole genome gene expression profiling from the same pairs of GBM INV and GBM TC cells was performed and identified a subset of genes suppressed by miR-126 (n = 74), miR-487b (n = 46) and miR-369-5p (n = 2) that occurred in at least 4 of the 6 pairs. Among them, RDX was inhibited by all three microRNAs, MANEA by miR-126 and miR-369, and a 32 genes (including PDK1, CREBZF, PRKAA2, TMF1 and HSPA13) by miR-126 and miR-487b. In conclusion, our novel strategy of utilizing functionally validated pairs of GBM INV and GBM TC cells has identified a set of microRNAs that are selectively over-expressed in GBM INV cells and allowed functionally confirmation of miR-126, miR-487b and miR-369-5p as drivers of GBM invasion. Citation Format: Lin Qi, Yu-lun Huang, Hua Mao, Mari Kogiso, Xiumei Zhao, Yuchen Du, Holly Lindsay, Xiaojun Yuan, Patricia Baxter, Jack Su, Chris Man, Laszlo Perlaky, Zhong Wang, You-Xing Zhou, Xiao-Nan Li. Whole genome microRNA profiling in functionally validated invasive GBM cells identifies a novel set of microRNAs driving GBM invasion. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1950.