Abstract 4300: Cell cycle pathway gene regulation in glioblastoma multiforme (GBM) and GBM derived stem cells: Implicating Pentraxin 3 upregulation

Abstract Introduction: Glioblastoma Multiforme (GBM) is the most aggressive type of brain cancer and progresses at a rapid rate. The major obstacle in the treatment of GBM is selective survival of a subpopulation of GBM derived stem cells (GSC) which are highly proliferative and resistant to drug induced apoptosis. The proteins involved in the regulation of the cell cycle impact survival potential of GBM and GSCs. Pentraxin 3 (PTX3), an angiogenic and survival factor plays a key role in cell proliferation, angiogenesis and invasion. However, little is known about the association of PTX3 and cell cycle regulation in GBM derived stem cells. Mehods: GBM patient tumor lines, and GSC derived from the same GBM lines were used. These cell lines were exposed to hypoxia and re-oxygenation. Cell cycle profiling and analysis were carried out using flow cytometry and FlowJo Single Cell Data Analysis Software. Xeno-transplanted mouse brain sections were used for PTX3 expression analysis by immunohistochemistry and immunofluorescence staining. Targeted proteomic approach was used to determine PTX3 levels in GBM and GSC. Alterations in the cell cycle regulatory gene expression in GSC and GBM tumor line in presence and absence of PTX3 was identified by transcriptome array analysis. Results: Our targeted proteomic approach using antibody array identified substantially higher levels of PTX3 in GSCs. GBM tumor lines showed higher percent of cells in G1 phase, where as GSCs showed increased number of cells in G2 and S-phase, both under normoxia and hypoxia. GSCs showed increased levels of GADD45A, known to protect GBM cells from apoptosis. Increased PTX3 expression correlated with increased cell cycle progression. Furthermore, exogenous PTX3 increased CyclinD1, a protein required for progression through the G1 phase of the cell cycle. Conclusion: GSC cells show cell cycle progression, presumably with an increased growth advantage. PTX3 expression is associated with GBM malignancy, and may contribute to GBM cell cycle progression and invasion. Overall, these results indicate that PTX3 and the cell cycle pathway are strongly associated with malignant GBM. Citation Format: Umadevi V. Wesley, Paul Clark, Jacob Jaeger, John Kuo, Robert Dempsey. Cell cycle pathway gene regulation in glioblastoma multiforme (GBM) and GBM derived stem cells: Implicating Pentraxin 3 upregulation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4300.