Abstract 136: Suppression of the uPA/uPAR system causes the overexpression of miR124 and suppresses stemness in glioma stem cells

Abstract

Abstract The invasiveness and destructiveness of malignant neoplasms in the central nervous system are of great clinical importance. Higher-grade tumors, such as glioblastomas, are associated with poor prognosis, and patients’ average survival is only 8 to 12 months after chemotherapy and/or radiotherapy. This poor prognosis reflects the resistance of tumor cells to radiation and cytotoxic agents as well as the difficulty in achieving total tumor resection. Highly infiltrative gliomas are known to overexpress both uPA and uPAR. MicroRNAs (miRNAs) are essential post-transcriptional regulators known to determine cell identity and fate and are also known to be involved not only in development and differentiation but also in glioma progression. Acquisition of EMT has also recently been linked to stem cell phenotypes which is mediated by microRNAs. However, the molecular mechanism underlying EMT regulation still remains elusive. In the present study, we used glioma initiating cells (GICs), which show stem cell-like character, and determined whether their stemness can be suppressed by targeting the uPA/uPAR system. We raised glioma GICs from U87MG and 4910 glioma xenograft cells and observed that GICs expressed 2- to 3-fold increased levels of uPA and uPAR when compared to non-GIC. Further, the simultaneous downregulation of both uPA and uPAR suppressed GIC from establishing intracranial tumors in nude mice. Further, to understand whether this suppression of GIC involved microRNAs, we profiled miR expression in U87 cells and observed that miR124 and miR200a were significantly overexpressed. Using miRanda analysis, we determined that miR124 targets the regulation of Lhx-2 and Lhx-2 is over expressed (3- to 4-fold) in GIC when compared to non-GIC. To determine whether this suppression of Lhx-2 by downregulation of uPA and uPAR is mediated via miR124, we overexpressed miR124 in U87MG and 4910 glioma xenograft GICs and observed that miR124-overexpressed cells failed to establish intracranial tumors in nude mice. Our results demonstrate that the uPA/uPAR system may be involved in GIC maintenance via suppression of miR124. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 136. doi:1538-7445.AM2012-136