Abstract

We have recently shown that cancer cells devoid of mitochondrial (mt) DNA (rho0 cells) form syngeneic tumours with a delay, and that malignant cells in the resulting tumours contain host mtDNA.1 We now studied what happens during the lag phase between grafting rho0 cells and the onset of tumour initiation. We show that several days after grafting, tumour cells start to acquire mtDNA from host cells, and its level increases until the tumour starts to grow. mtDNA acquisition triggers retrograde signalling to the nucleus, and is accompanied by mtDNA replication and transcription, with ensuing assembly of mitochondrial complexes and recovery of respiration. We also document that recovery of respiration is important for ‘unlocking’ tumour cells from their auxotrophic state. We propose that recovery of respiration is important for metabolic remodelling of tumour cells. In conclusion, cancer cells devoid of mtDNA ought to recover respiration to a threshold level, which is a prerequisite for the cells to initiate tumour formation and growth. 1Tan A et al (2015) Mitochondrial genome acquisition restores respiratory function and tumorigenic potential in cancer cells without mitochondrial DNA . Cell Metab 21, 81-94.