Exosomal miR-1228-5p down-regulates DUSP22 to promotes cell proliferation and migration in small cell lung cancer

Exosomes play a crucial role in promoting tumor progression, dissemination, and resistance to treatment. These extracellular vesicles hold promise as valuable indicators for cancer detection. Our investigation focuses on exploring the significance and clinical relevance of exosomal miRNAs in small cell lung cancer (SCLC). Serum exosomes were isolated from both SCLC patients and healthy controls, and subjected to exosomal miRNA sequencing analysis. Mimics and inhibitors were employed to investigate the function of exosomal miR-1128-5p in cell migration and proliferation, both in vitro and in vivo. Western blot and luciferase assay were utilized to identify the interaction between miR-1228-5p and dual specificity phosphatase 22 (DUSP22). Exosomal miRNA sequencing analysis revealed enrichment of specific miRNAs in SCLC compared to healthy controls. Circulating miR-1228-5p was upregulated in SCLC patients, associated with advanced stages, suggesting its potential oncogenic role. In vitro, miR-1228-5p expression was significantly higher in SCLC cells than in normal cells. SCLC cell-derived exosomes contained elevated levels of miR-1228-5p, facilitating its entry into co-cultured cells. Notably, migration and proliferation induced by SCLC exosomes were mainly mediated by miR-1228-5p. In vivo experiments confirmed these findings. Western blot analysis demonstrated miR-1228-5p's regulation of DUSP22 expression, and luciferase reporter assay validated DUSP22 as a direct target gene. Overexpressing DUSP22 counteracted miR-1228-5p's promotion of SCLC cell proliferation and migration. Collectively, our results suggest that exosomes play a role in facilitating cancer growth and metastasis by delivering miR-1228-5p. Moreover, circulating exosomal miR-1228-5p may serve as a potential marker for SCLC diagnosis and prognosis.