Identification of context of vulnerability for MLN4924, a neddylation inhibitor in glioblastoma
Glioblastoma (GBM) is the most malignant brain cancer with an average prognosis of 15 months. Current combinational treatment consists of surgical resection, radiation therapy, and chemotherapy, but an effective, targeted therapeutic has yet to be discovered. After screening genomic profiles of patient-derived xenografts (PDX) from individuals with GBM against a library of tool compounds and targeted drugs, we identified MLN4924 (Pevonedistat) as a potential therapeutic given its differential vulnerability between GBM cell lines. MLN4924 inhibits neddylation, shown to be overactive in GBM, which selectively degrades proteins, including apoptosis and cell cycle regulators. To assess the preferential sensitivity of the cell lines to the drug, we performed a 10-point drug dose response (DDR) assay on four long-term established GBM cell lines. The relative cell viability was determined with CellTiter-Glo at 72 hours after drug addition. Using Prism software, MLN4924 IC50 was calculated validating GB1 and LN18 as sensitive and M059K and SNU1105 as nonsensitive cell lines. To further investigate the mechanism of vulnerability in response to MLN4924 treatment in each cell line, we probed for cleaved caspase 3 (CC3) and λH2AX respectively, as representative markers of cell death and double-stranded DNA breaks. We applied a network-based analysis tool, EDDY (Evaluation of Differential DependencY), to RNAseq data in the Cancer Cell Line Encyclopedia (CCLE) and to MLN4924 response data in The Cancer Therapeutics Response Portal (CTRP); this identified candidate differential networks and mediators of cellular mechanisms underlying drug response. One network identified, “NFκB is activated and signals survival,” showed significant differential rewiring between non-sensitive and sensitive cell lines. To uncover the role of this pathway as a ‘context of vulnerability’ in MLN4924 treatment in GBM, we will be performing siRNA mediated short-term knockout of key essentiality mediators identified from EDDY (UBA52, NGFR) and their nearest neighbors (RELA, TRAF6). Then, we will repeat the DDRs to monitor changes in IC50- values indicative of an increase or decrease in sensitivity. Verification and implementation of this network analysis tool could result in predicting patient-specific vulnerability to MLN4924.