3134 - PA2G4 as a Candidate Therapeutic Target in Pediatric Diffuse Gliomas
Presenter(s)
Z. Sirhan1, B. E. Sells2, J. L. Fleming1, H. Manring1, R. T. Graham3, J. Haque4, C. A. Showalter1, K. Singh1, N. S. Marchal5, J. McElroy6, D. R. Boue7, A. P. Becker5, J. L. Finlay8, and A. Chakravarti1; 1The Ohio State University Comprehensive Cancer Center, Columbus, OH, 2Department of Medicine Washington University in St. louis, St. Louis, MO, 3University of Cincinnati Department of Pediatrics, Cincinnati, OH, 4Department of Radiation Oncology, Arthur G. James Hospital/The Ohio State University Wexner Medical Center/Comprehensive Cancer Center, Columbus, OH, 5The Ohio State University, Columbus, OH, 6Department of Biomedical Informatics, College of Medicine The Ohio State University, Columbus, OH, 7Dept. of Laboratory Medicine and Pathology Nationwide Children's Hospital, Columbus, OH, 8Pediatrics and Radiation Oncology-The Ohio State University College of Medicine, Columbus, OH
Purpose/Objective(s):
Central nervous system (CNS) tumors are the most frequent solid tumors in children, accounting for 21% of cancer cases. The majority of CNS tumors are gliomas, a tumor type composed of heterogenous populations of glial cells. These tumors are classified pathologically as either being low grade (WHO grade 1 or 2) or high grade (WHO grade 3 or 4). Even with substantial improvements in the diagnosis and treatment of pediatric glioma, clinical outcomes remain poor. Our aim is to identify biological mechanisms and proteins that could serve as prognostic biomarkers and/or novel therapeutic targets for pediatric glioma. In this study, we identified proliferation-associated protein 2G4 (PA2G4) to be associated with worse clinical outcomes in pediatric patients with diffuse glioma and investigated its involvement in tumor progression.
Materials/Methods:
Proteomic data was captured on a cohort (n = 28) of primary diffuse gliomas (grades 2-4) from Nationwide Children’s Hospital (Columbus, OH) using liquid chromatography-tandem mass spectrometry. Pediatric glioblastoma cell lines SF188 and KNS42 were used and stable cell lines with shRNA-mediated knockdown of PA2G4 (PA2G4-KD) using lentiviral particles were generated by puromycin selection. Protein levels were detected by Western blot analysis. Cell viability and cell proliferation were assessed by MTS assays (Time points: 24-96 hours). Cells were treated with WS6, a selective PA2G4 inhibitor (Selleck Chemicals, Houston, TX) for 72 hours and cell proliferation was detected using MTS assay.
Results:
Proteomic profiling revealed that high PA2G4 expression was associated with significantly worse progression-free survival (PFS) [HR 9.5 (2.4-37.9); p=0.041] and overall survival (OS) [HR 18.0 (2.9-110.5); p=0.035]. Additionally, we found that PA2G4 was expressed 2-fold higher in high grade glioma patients compared to low grade glioma patients (p=0.015). We observed that shRNA-mediated knockdown of PA2G4 (~95% Knockdown) decreased cell proliferation in SF188 (p = 0.08) and KNS42 (p = 0.04) cell lines. WS6 was shown to significantly reduce cell proliferation in SF188 (IC50 = 1.25 mM) and KNS42 (IC50 = 4 mM) cell lines, suggesting its therapeutic potential in pediatric glioma.
Conclusion:
High PA2G4 expression was associated with worse PFS and OS in a pediatric diffuse glioma cohort. Inhibition of PA2G4 in pediatric GBM cells decreased cell proliferation, suggesting PA2G4 may serve as a potentially vulnerable therapeutic target in this disease. Further studies are underway to elucidate the role of PA2G4 in chemoradiotherapy resistance and in in vivo mouse models of pediatric GBM.