Metabolic plasticity drives mechanisms of PARP inhibitor persistence in ovarian cancer

PARP inhibitors (PARPi) are the standard maintenance therapy for ovarian cancer, but the frequent emergence of resistance remains a major clinical challenge. Emerging evidence suggests that tumor cell plasticity is an important mechanism enabling this adaptive resistance. In this study, we combined both experimental and computational techniques to model this evolutionary process by long term treatment of the OVCAR3 ovarian cancer cell line with Olaparib (a PARPi). We then performed single-cell RNA sequencing (scRNAseq) on both naive and persistent cells to capture cancer cells heterogenous response. scRNAseq profiling suggested an adaptive metabolic reprogramming in response to long term Olaparib treatment. We then scored single cells for metabolic function, and persister cells were found to have reprogrammed their glutamine metabolism. To test these findings, both persister and naive cells were cultured in glutamine-deprived media and persister cells were found to have higher viability than the naive cells particularly when exposed to Olaparib. To test the cells capacity to switch their metabolic state toward glycolysis, we performed Seahorse mitochondrial and glycolytic stress tests. These analyses revealed that persister cells were less dependent on glutamine metabolism and instead exhibited increased glycolytic capacity compared to naive cells. This metabolic shift resulted in an acquired dependency on glucose, representing a potential therapeutic vulnerability. Together, these results indicate that prolonged Olaparib exposure promotes metabolic plasticity in ovarian cancer cells. To explore how this plasticity might be exploited therapeutically, we developed a proof-of-concept mathematical model that leverages metabolic state transitions to optimize treatment scheduling. ONE SENTENCE SUMMARYOvarian cancer cells exploit metabolic plasticity to increase their evolvability to persist PARP inhibitor treatment.