Loss of function of CDK7 is Synthetically Lethal with Fatty Acid Oxidation Inhibition in Glioblastoma
CDK7 has been identified as a potential drug target for glioblastoma (GBM), a highly lethal primary brain tumor. However, resistance to therapy develops quickly, which may be facilitated by drug-induced reprogramming of metabolism. By combination of a transcriptome and metabolite screening analyses followed by carbon tracing (U-13C-Glucose, U-13C-Glutamine and U-13C-Palmitic acid) and extracellular flux analysis, we demonstrated that both genetic and pharmacological (YKL-5-124 and THZ1) CDK7 inhibition elicited substantial metabolic reprogramming. Specifically, CDK7 inhibition elicited an increase of oxygen consumption rate fueled by enhanced fatty acid oxidation (FAO) manifested by enhanced labeling of citric acid cycle intermediates from palmitic acid. Consistently, the combination treatment of CDK7 inhibitors with blockers of FAO (etomoxir) exerted substantial synergistic growth inhibition in patient derived xenograft as well as neurosphere GBM cultures, which was mainly driven by a collapse of oxidative energy metabolism. In turn, exogenous administration of adenosine triphosphate partially rescued from the cell death induced by the combination treatment. Finally, the combined administration of YKL-5-124 and etomoxir extended overall in an orthotopic patient-derived xenograft model of GBM. In summary, these data support that simultaneous targeting of CDK7 and FAO might be a potential novel therapy against GBM. Overall design: GBM43 cells were treated with DMSO, THZ1, Etomoxir or combination of both for 24h. Cells were collected and were extracted for total RNA by using miRNAeasy Mini Kit from QIAGEN. RNA samples were sequences and analyzed for gene set enrichment.