LAUSR

Glioblastoma multiforme (GBM) are the most malignant primary central nervous system tumors. The standard of care for newly diagnosed GBM patients includes surgery followed by combined radiation therapy (RT) and adjuvant temozolomide (TMZ) therapy. However, one of the therapeutic challenges is the inevitable resistance and recurrence after radiotherapy. Glioblastoma stem cells (GSC) are tumor initiating cells for GBM and plays key roles in radio resistance. Thus, we performed a genome-wide CRISPR screen using a radiation resistant GSC to identify potential RT sensitizing targets. We identified 139 potential RT sensitizing targets with a filter for only those genes associated with a greater than 2-fold reduction in representation with a p<0.05. There were 22 genes with a direct function in key DNA double-strand break repair pathways including 5 genes central to non-homologous end-joining (NHEJ1, XLF, PRKDC, DCLRE1C, XRCC4, LIG4), 6 genes involved in homologous recombination (RAD51D, CYREN, ATM, TONSL, BRCA2, RFWD3), and 7 genes central to initial DNA damage sensing (RNF8, RNF168, TP53BP1, RAD17, FOXM1, RAD9A, RAD1). These results are consistent with the crucial role of DNA repair following radiation exposure and demonstrate the success of the screening. Besides that, one of the top hits is NANP (N-acylneuraminate-9-phosphatase), which is involved in sialic acid synthetic pathway. Knocking down of NANP causes more G2/M arrest followed by apoptosis after radiation. γH2A.X staining and comet assay shows more DNA damage in NANP knock down cells after radiation. Transcriptome analysis reveals NANP inhibition restrain mesenchymal status and NF-κB pathway activation. Furthermore, activation of NF-κB pathway could rescue the RT-induced G2/M arrest of NANP knock down cells. TCGA and CGGA dataset shows NANP is highly expressed in GBM patients and patients with NANP high expression have poorer survival. In conclusion, our study identified NANP as a novel radio-sensitizing target for glioblastoma by regulating NF-κB pathway and mesenchymal status of GSCs. Citation Format: Yingwen Ding, Ze-Yan Zhang, Ravesanker Ezhilarasan, Aram S. Modrek, Jerome Karp, Erik P. Sulman. Genome-wide CRISPR screen identifies NANP as a radio-sensitizing target of GBM by regulating NF-κB pathway [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2819.