Beta-blockers disrupt mitochondrial bioenergetics and increase radiotherapy efficacy independently of beta-adrenergic receptors in medulloblastoma.

Our study showed that propranolol, carvedilol and nebivolol inhibited medulloblastoma cell proliferation and invasion by affecting energy metabolism pathways (OXPHOS and glycolysis) and by triggering a metabolic catastrophe that deprived tumor cells of their adaptive bioenergetics capacities. To better understand the importance of bioenergetics in response to treatment, we generated β-blocker-resistant ONS-76 cells by exposing them to increasing concentrations of propranolol, carvedilol or nebivolol for 16 weeks. The resulting cell lines i.e., ONS-76 RP, ONS-76 RC and ONS-76 RN, displayed a higher mitochondrial OCR and ATP production than the sensitive parental ONS-76 WT cells. By qRT-PCR, we showed that the expression of β-blockers canonical targets (β-ARs) was not altered in these resistant cells. Sequencing of total RNA from the four meduloblastoma cell models further indicated that cell resistance could not be explained by the down-regulation of key proteins of the β-AR downstream signaling, including the adenylate cyclase or their transcriptional targets. Our data also showed that the efficacy of propranolol, carvedilol and nebivolol was not impacted by β-AR silencing, further supporting the idea that β-blockers trigger an alternative signaling pathway in medulloblastoma cells. RNAseq from ONS-76 medulloblastoma parental cells and three derived cell lines resistant to beta-blockers.