Inhibition of miR-9-3p facilitates ferroptosis by activating SAT1/p53 pathway in lung adenocarcinoma.

Background: Lung adenocarcinoma (LUAD) is the most common subtype of non-small cell lung cancer (NSCLC) and accounts for about 40% of all lung cancer cases. This research aims to investigate the effects of miR-9-3p on ferroptosis in LUAD cells and to elucidate its regulatory mechanisms. Studies have shown that LUAD is related to ferroptosis, and specific microRNAs (miRNA) are also related to ferroptosis. However, further research is needed to elucidate the mechanisms by which miR-9-3p induces ferroptosis in LUAD. Methods: Our study comprehensively analyzed multiple databases to investigate miR-9-3p expression in LUAD tissues. Quantitative polymerase chain reaction (qPCR) was utilized to detect miR-9-3p levels in LUAD cells and tissues, examining its prognostic significance. Reactive oxygen species (ROS) and superoxide dismutase (SOD) assays assessed the impact of miR-9-3p on lipid peroxidation in LUAD cells. Dual-luciferase reporter assays were conducted to evaluate the binding affinity between miR-9-3p and target genes, while Western blotting and immunofluorescence were used to examine the regulation of miR-9-3p on downstream signaling pathways. Results: We observed that miR-9-3p was upregulated in LUAD cells by qPCR, and the ferroptosis of LUAD cells increased upon treatment with erastin following the transfection of miR-9-3p inhibitor. Cell Counting Kit-8 (CCK-8), ROS, and SOD activity assays confirmed that inhibiting miR-9-3p enhanced lipid peroxidation in LUAD cells, contributing to higher rates of ferroptosis. Subsequent dual-luciferase reporter assays validated spermidine/spermine N1-acetyltransferase 1 (SAT1) as a target gene of miR-9-3p. Further Western blot confirmed that miR-9-3p regulated the expression of SAT1 and p53 proteins in p53 wild-type (WT) LUAD cells. Rescue experiments demonstrated that SAT1 was necessary for miR-9-3p to promote cell proliferation and suppress ferroptosis in p53 WT LUAD cells. Additionally, the effect of miR-9-3p on ferroptosis in LUAD cells was regulated by p53 signaling pathway. Conclusions: Overall, these findings demonstrate that miR-9-3p negatively regulates ferroptosis in LUAD cells through SAT1 and p53 signaling pathway, suggesting that miR-9-3p plays a crucial role in LUAD pathogenesis and targeting this miRNA with an inhibitor exhibits promising potential for the treatment of LUAD.