ABSTRACT
Objective To investigate the effects of natural killer (NK)-cell-derived miR-30e-3p-containing exosomes (Exo) on esophageal squamous cell carcinoma (ESCC) cell proliferation, apoptosis and invasion. Methods NK cells were isolated and amplified from the peripheral blood of healthy donors, and NK cell-derived Exo was isolated and identified, which were further co-cultured with NEC cells and were randomly grouped into Exo1 and Exo2 groups. Transmission electron microscopy (TEM) was used to observe the morphology and size of exosomes. Western blot analysis was used to detect the expression levels of exosome markers apoptosis related gene 2- interacting protein X(ALIX), tumor susceptibility gene 101(TSG101), CD81 and calnexin. The NC plasmids, mimics and inhibitors of miR030e-3p were respectively delivered into the NK cells, and the corresponding NK cells-derived Exo were co-cultured with NEC cells, which were divided into NC, Exo, mimic and inhibitor groups. CCK-8 assay was used to evaluate cell proliferation, flow cytometry was conducted to determine cell cycle, annexin V-FITC/PI double staining was employed to detect cell apoptosis, and TranswellTM assay was performed to detect cell invasion abilities. Real-time quantitative PCR was used to detect the expression of miR-23b, miR-422a, miR-133b, miR-124, miR-30e-3p and miR-99a in NCE cells and exosomes. Results The percentages of CD56+CD3+ cells and CD56+CD16+ cells in NK cells were (0.071±0.008)% and (90.6±10.6)%, respectively. Exosome isolated from NK cells ranged from 30 nm to 150 nm, and was positive for ALIX, TSG101 and CD81, while negative for calnexin. NK cell-derived Exos inhibited the proliferation, reduced the proportion of S-phase cells and the number of invaded cells of NEC cells, and promoted the apoptosis and the proportion of G1 phase cells. Overexpression of miR-30E-3p in NK cell-derived exosome inhibited the proliferation and invasion of NEC cells, and blocked cell cycle and promoted apoptosis, while knockdown miR-30e-3p in NK cell-derived exosomes did the opposite. Conclusion miR-30e-3p in NK cell-derived exosomes can inhibit the proliferation and invasion of ESCC cells, block their cell cycle and induce their apoptosis.