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ROSALIND protects the mitochondrial translational machinery from oxidative damage

ABSTRACT: Cancer therapy resistance, whether it is pre-existing, emerges after acquiring de novo mutations, or occurs through non-genetic adaptationwhether pre-existing or arising following the acquisition of de novo mutations and via non-genetic adaptation , is stillremains a clinical challenge. Multiple anticancer drugs are thought to cause cell death via increasing mitochondrial ROS which are a bioproduct of oxidative phosphorylation. However, when properly titrated, ROS can also promote cancer cell adaptation. In keeping line with this, upregulation of mitochondrial respiration coupled to high ROS-scavenging capacity is a characteristic shared by drug-tolerant cells in several cancers. Translational fidelity in the mitochondria and in the cytosol is essential for cell fitness and thus oxidative damage to the ribosomes should be prevented at all costs. While mechanisms for recognizing and repairing such damage exist in the cytoplasm, the status within mitochondria remains unclear. By performing ascorbate peroxidase (APEX)-proximity ligation assay directed to the mitochondrial matrix followed by isolation and sequencing of RNA associated to mitochondrial proteins, we identified the nuclear encoded lncRNA ROSALIND as a interacting partner of ribosomes. ROSALIND is upregulated in recurrent tumours and its expression can discriminate between responders and non-responders to immune checkpoint blockade in a melanoma cohort of patients. Featuring an unusually high G content, ROSALIND serves as a substrate for oxidation. Consequently, inhibiting ROSALIND leads to an increase in ROS and protein oxidation, resulting in severe mitochondrial respiration defects. This, in turn, impairs melanoma cell viability and immunogenicity both in vitro and ex vivo in preclinical humanized cancer models. These findings underscore the role of ROSALIND as a novel ROS buffering system, safeguarding mitochondrial translation from oxidative stress, and shed light on potential therapeutic strategies for overcoming cancer therapy resistance.

ORGANISM(S): Homo sapiens

PROVIDER: GSE249588 | GEO | 2024/09/19

REPOSITORIES: GEO

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Project description:Mitochondria are subcellular organelles that are more than just the powerhouse of cells, they also dictate if a cell dies or survives. The mitochondrial outer-membrane voltage-dependent anion channel 1 (VDAC1) has been shown to play a crucial role in metabolism and apoptosis, however its involvement in ischemic pathologies and cancer is not clear. Transcriptome analysis of Vdac1-/- mouse embryonic fibroblasts (MEF) highlighted cancer and inflammation as top diesases but also activation of the HIF-1 signaling pathway in normoxia. HIF-1α protein was stable due to ROS accumulation that decreased respiration and glycolysis and maintained basal apoptosis. However, in hypoxia increased activation of ERK in combination with maintenance of respiration and increased glycolysis counterbalanced the deleterious effects of ROS, thereby allowing Vdac1-/- MEF to proliferate better than wild-type MEF. Xenografts of RAS-transformed Vdac1-/- MEF in mice showed stabilization of both HIF-1α and HIF-2α which led to blood vessel destabilization and a strong inflammatory response. Moreover, expression of Cdkn2a, a HIF-1-target and tumor suppressor gene, was strongly decreased. Consequently RAS-transformed Vdac1-/- MEF tumors grew faster than wild-type MEF tumors. These findings provide new perspectives into the understanding of VDAC1 in the function of mitochondria not only in cancer but also in inflammatory diseases. Profiling of VDAC1-/- and wild-type (Wt) Mouse Embryonic Fibroblasts (MEFs) was performed using whole genome mouse microarrays. in normoxic or hypoxic conditions. MEF (Wt and Vdac1-/-) were incubated in normoxia (Nx, ie: 20% O2) or hypoxia (Hx, ie: 1% O2) for 72h and then lysed prior to RNA isolation, labelling and hybridization on microarrays. One color experiment with 2 biological replicates (marked 1 or 2) of the 4 experimental conditions. One condition (MEF WT Nx2) has been removed from the statistical analysis after microarray quality check due to high background. Total of 7 samples.

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