ABSTRACT
PURPOSE: Mutations of the isocitrate dehydrogenase (IDH) gene are common genetic mutations in human malignancies. Increasing evidence indicates that IDH mutations play critical roles in malignant transformation and progression. However, the therapeutic options for IDH-mutated cancers remain limited. In this study, the investigation of patient cohorts revealed that the PI3K/protein kinase B (AKT) signaling pathways were enhanced in IDH-mutated cancer cells. EXPERIMENTAL DESIGN: In this study, we investigated the gene expression profile in IDH-mutated cells using RNA sequencing after the depletion of AKT. Gene set enrichment analysis (GSEA) and pathway enrichment analysis were used to discover altered molecular pathways due to AKT depletion. We further investigated the therapeutic effect of the AKT inhibitor, ipatasertib (Ipa), combined with temozolomide (TMZ) in cell lines and preclinical animal models. RESULTS: GSEA and pathway enrichment analysis indicated that the PI3K/AKT pathway significantly correlated with Nrf2-guided gene expression and ferroptosis-related pathways. Mechanistically, AKT suppresses the activity of GSK3ß and stabilizes Nrf2. Moreover, inhibition of AKT activity with Ipa synergizes with the genotoxic agent TMZ, leading to overwhelming ferroptotic cell death in IDH-mutated cancer cells. The preclinical animal model confirmed that combining Ipa and TMZ treatment prolonged survival. CONCLUSIONS: Our findings highlighted AKT/Nrf2 pathways as a potential synthetic lethality target for IDH-mutated cancers.
Subject(s)
Brain Neoplasms , Ferroptosis , Glioma , Animals , Humans , Proto-Oncogene Proteins c-akt/metabolism , Isocitrate Dehydrogenase/genetics , NF-E2-Related Factor 2/genetics , Phosphatidylinositol 3-Kinases/genetics , Phosphatidylinositol 3-Kinases/metabolism , Ferroptosis/genetics , Cell Line, Tumor , Glioma/drug therapy , Glioma/genetics , Glioma/pathology , Temozolomide/pharmacology , Temozolomide/therapeutic use , Mutation , Brain Neoplasms/drug therapy , Brain Neoplasms/genetics , Brain Neoplasms/metabolismABSTRACT
The progressive loss of midbrain (MB) dopaminergic (DA) neurons defines the motor features of Parkinson disease (PD), and modulation of risk by common variants in PD has been well established through genome-wide association studies (GWASs). We acquired open chromatin signatures of purified embryonic mouse MB DA neurons because we anticipated that a fraction of PD-associated genetic variation might mediate the variants' effects within this neuronal population. Correlation with >2,300 putative enhancers assayed in mice revealed enrichment for MB cis-regulatory elements (CREs), and these data were reinforced by transgenic analyses of six additional sequences in zebrafish and mice. One CRE, within intron 4 of the familial PD gene SNCA, directed reporter expression in catecholaminergic neurons from transgenic mice and zebrafish. Sequencing of this CRE in 986 individuals with PD and 992 controls revealed two common variants associated with elevated PD risk. To assess potential mechanisms of action, we screened >16,000 proteins for DNA binding capacity and identified a subset whose binding is impacted by these enhancer variants. Additional genotyping across the SNCA locus identified a single PD-associated haplotype, containing the minor alleles of both of the aforementioned PD-risk variants. Our work posits a model for how common variation at SNCA might modulate PD risk and highlights the value of cell-context-dependent guided searches for functional non-coding variation.
