Silencing superoxide dismutases (SOD1&SOD2) potentiates ROS-induced apoptosis in chordoma cells.

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Chordoma, characterized as a slow growing yet locally invasive and destructive bone tumor mainly emerging in the sacrum and clivus, presents a unique challenge due to its rarity, hampering the development of effective treatment strategies. Comprehensive understanding of tumor biology is crucial to suggest novel treatment modalities. Reactive oxygen species (ROS), a family of chemically reactive and unstable oxygen derivatives, are controlled by an intracellular antioxidant system to maintain homeostasis. Higher doses of ROS levels have been associated with the oxidative stress-induced tumor cell death, highlighting the potential of fine-tuning ROS regulation as a target for cancer therapies. The association of ROS mechanism and chordoma remains to be elucidated. In this study, we investigated the effect of targeting the ROS mechanism in chordoma, focusing on superoxide dismutase 1 and superoxide dismutase 2. Two different chordoma datasets were used to assess oxidative stress-related genes. ROS levels and mitochondrial membrane potential (mtMP) in chordoma cells were measured. The gene expression levels of SOD1 and SOD2 in chordoma patients were also evaluated. SOD2 and SOD1 targeted siRNAs were used to silence gene expression in chordoma cells, and quantitative real-time PCR (qRT-PCR) was used to compare gene expression levels. Apoptotic cell populations were determined using flow cytometry. The levels of ROS and mtMP were increased in chordoma cell lines compared to healthy nucleus pulposus cells. The chordoma omics data showed induced levels of SOD2. Chordoma tissues also showed high levels of the SOD2 gene. Silencing SOD2 and combined silencing of SOD2 and SOD1 expression increased ROS levels or mtMP, and both induced apoptosis in chordoma cells. ROS imbalance plays a role in chordoma pathogenesis. SOD2 and SOD1 might be key enzymes in chordoma to modulate ROS levels, and inhibiting the SOD2 and SOD1 activity might be a potential therapeutic target for chordoma treatment.