CircAFF4 inhibits lung cancer progression via destabilizing GPX4 and triggering ferroptosis

Lung cancer has been the most common diagnosed cancer and the leading cause of cancer-related death. Growing evidence has demonstrated that circular RNAs (circRNAs) are closely associated with the occurrence and progression of tumors. Ferroptosis is an iron-dependent form of cell death triggered by the accumulation of lipid peroxides, and it has been considered as a potential target for cancer therapy. However, the specific mechanism by which circRNAs modulate ferroptosis in lung cancer remains largely unknown. Through retrieval from The Cancer Genome Atlas (TCGA) database, the differential expression of AFF4 mRNA in lung cancer was identified. Further screening and validation revealed that circAFF4, a circular RNA derived from AFF4 host gene, also exhibited a similar trend in lung cancer. Subsequently, quantitative reverse transcription-PCR (qRT-PCR) and fluorescent in situ hybridization (FISH) were used to detect its expression pattern and distribution. Functional studies were conducted both in vitro and in vivo to determine the biological functions of circAFF4. Furthermore, the interaction between circAFF4 and ubiquitin-specific peptidase 10 (USP10) as well as the relationship between USP10 and Glutathione peroxidase 4 (GPX4), were investigated by biotin-labeled RNA pull-down, mass spectrometry, RNA immunoprecipitation (RIP), FISH and co-immunoprecipitation (Co-IP) assays. Here we demonstrated that circAFF4 was significantly downregulated in lung cancer tissues and lung cancer cells. In vitro and in vivo experiments suggested that circAFF4 inhibited the proliferation of lung cancer cells and promoted ferroptosis. Mechanistically, circAFF4 bound to the deubiquitinating enzyme USP10, which in turn suppressed USP10-mediated deubiquitination of GPX4, and enhanced the ubiquitin-dependent proteasome degradation of GPX4, thereby facilitating ferroptosis in lung cancer cells. Our findings reveal a novel mechanism by which circAFF4 interacts with USP10, impairing USP10-mediated stabilization of GPX4, promoting ferroptosis in lung cancer cells, and ultimately suppressing lung cancer progression. The circAFF4/USP10/GPX4 axis provides a new direction and may be a potential target for lung cancer treatment.