Abstract
BACKGROUND: Radiation resistance limits radiotherapy efficacy in esophageal squamous cell carcinoma (ESCC). The tumor microenvironment, particularly adipocytes, plays a role in promoting cancer progression. Extracellular vesicles and microRNAs (miRNAs) regulate gene expression and hold prognostic potential for esophageal carcinoma. Elucidating radioresistance mechanisms and identifying radiosensitization targets can help enhance radiotherapy efficacy for esophageal cancer. AIM: To investigate the potential role of miRNAs derived from adipocyte exosomes as prognostic markers for radiotherapy efficacy in ESCC. METHODS: Free adipocytes were isolated from human thoracic adipose tissue. A co-culture model of adipocytes and ESCC cells was established to observe colony formation and cell survival post-irradiation. ESCC cell apoptosis was assessed by flow cytometry. Western Blot and immunofluorescence assays were performed to evaluate DNA damage in ESCC cells post-irradiation. Adipocyte-derived exosomes were isolated by ultracentrifugation and identified by electron microscopy. A similar set of experiments was performed on ESCC cells to analyze cell survival, apoptosis, and DNA damage post-radiation exposure. Exosomes from adipose tissue and serum exosomes from ESCC patients pre- and post-radiotherapy were subjected to high-throughput miRNA-sequencing and validated using real-time quantitative polymerase chain reaction. The correlation between potential target miRNAs and the short-term prognosis of radiotherapy in ESCC was evaluated by receiver operating characteristic curve analysis. RESULTS: Co-culturing adipocytes with ESCC cells enhanced radioresistance, as evidenced by increased colony formation. Adipocyte co-culture reduced ESCC cell apoptosis and DNA damage post-radiation. Adipocyte-derived exosomes similarly conferred radioresistance in ESCC cells, decreasing apoptosis and DNA damage post-irradiation. High-throughput miRNA-sequencing identified miR-660-5p in serum and adipose tissue exosomes. Patients with high expression of serum exosome miR-660-5p showed poor prognosis after radiotherapy. CONCLUSION: Adipocyte-derived exosomal miR-660-5p is a potential biomarker for evaluating radiotherapy efficacy in ESCC.