Regulation of the Proliferation of Glioma Stem Cell-Like Cells

In this dissertation, I report the identification of regulators of the proliferation of glioma stem cell-like cells at both the genetic and the epigenetic levels. Combining multiple sets of microarray data, we identified a group of highly connected glioma hub genes, including Aspm, Ect2, Racgap1, and Stk6, to be common regulators of the proliferation of both normal neural stem cells (NSCs) and glioma stem cell-like cells. Using the real-time PCR method for miRNA profiling, we identified a group of microRNAs (miRNAs) that are differentially expressed in GBM neurosphere cultures (NS) and serum cultures (SC) derived from the same patients. Candidate miRNAs enriched in NS (miR-210 and miR-378) enhanced while the ones enriched in SC (miR-27b and miR-145) suppressed neurosphere formation from glioma stem cell-like cells in vitro, suggesting that these miRNAs regulate the self-renewal/proliferation of glioma stem cell-like cells. We focused on miR-27b (a SC miRNA) and miR-210 (an NS miRNA) for in vivo and mechanistic studies. Human tumor xenograft assay suggests that miR-27b is a potential tumor suppressor and miR-210 an oncomiR in regulating the tumorigeneic capacity of glioma stem cell-like cells. Furthermore, miR-27b was found to directly target the oncogene BMI1. It also downregulates p-AKT, p-ERK1/2, and p-STAT3, while upregulating the level of p-16. MiR-210 directly targets EPHRIN-A3, and promotes the phosphorylation of AKT, ERK, p-STAT3, and p-SRC, and downregulates p-21. This work highlights the potential of targeted molecular therapy in glioma and of the application of miRNAs in the context of glioma stem cell-like cells.