Unchecked oxidative stress in skeletal muscle prevents outgrowth of disseminated tumour cells

Skeletal muscle has long been recognized as an inhospitable site for disseminated tumour cells (DTCs). Yet its antimetastatic nature has eluded a thorough mechanistic examination. Here, we show that DTCs traffic to and persist within skeletal muscle in mice and in humans, which raises the question of how this tissue suppresses colonization. Results from mouse and organotypic culture models along with metabolomic profiling suggested that skeletal muscle imposes a sustained oxidative stress on DTCs that impairs their proliferation. Functional studies demonstrated that disrupting reduction-oxidation homeostasis via chemogenetic induction of reactive oxygen species slowed proliferation in a more fertile organ: the lung. Conversely, enhancement of the antioxidant potential of tumour cells through ectopic expression of catalase in the tumour or host mitochondria allowed robust colonization of skeletal muscle. These findings reveal a profound metabolic bottleneck imposed on DTCs and sustained by skeletal muscle. A thorough understanding of this biology could reveal previously undocumented DTC vulnerabilities that can be exploited to prevent metastasis in other more susceptible tissues. Crist et al. show that tumour cells disseminate and accumulate in skeletal muscle but fail to proliferate and grow due to oxidative stress, thereby explaining why skeletal muscle is resistant to metastatic colonization and outgrowth.