Mechanism Study of LncRNA LINC01137 Promoting the Progression of Non-small Cell Lung Cancer by Inducing CD8+T Cell Exhaustion / 现代检验医学杂志

ABSTRACT

Objective To investigate the biological function of long non-coding RNA(LncRNA)LINC01137 in immune escape of non-small cell lung cancer(NSCLC)cells and its potential regulatory mechanisms.Methods The blood samples of 24 healthy volunteers and 24 NSCLC patients were collected.The tumor tissues and paracancerous tissues of 24 NSCLC patients were collected,and the levels of LINC01137 were detected.The binding sites of LINC01137 and miR-22-3p were predicted by Starbase database and verified by the luciferase reporter gene analysis.A549 cells were transfected with exosomes derived from A549 cells and/or sh-LINC01137 interference sequence to detect cell proliferation and invasion.The supernatant of A549 cells were collected to culture CD8+T cells,and the levels of CD8+T cell exhaustion markers,including interfereron-γ(IFN-γ),tumor necrosis factor-α(TNF-α),granzyme B and interleukin-2(IL-2),and the percentage of PD-1+Tim3+CD8+T cells were detected.CD8+T cells were transfected with exosomes and/or miR-22-3p mimics to detect the protein level of PD-1.Results The expression of LINC01137 in tumor tissues of patients with NSCLC was increased compared with paracancerous tissues(3.357±0.548 vs 1.011±0.371),while the expression of LINC01137 in peripheral blood of patients with NSCLC was increased compared with healthy volunteers(3.216±0.342 vs 1.007±0.313),with statistically significant differences(t=-17.367,-17.147,all P<0.001).There was a positive correlation between the expression of LINC01137 in tumor tissue and peripheral blood(r=0.755,P<0.05).LINC01137 was significantly enriched in exosomes derived from A549 cells.Compared with Exo+sh-NC group,the cell viability(65.85%±4.71%vs 100.15%±11.93%)and cell invasion(21.46%±3.48%vs 43.12%±1.44%)in Exo+sh-LINC01137 group were decreased,and the differences were statistically significant(t=4.630,9.953,all P<0.01).The expression of LINC01137 in peripheral blood of NSCLC patients was negatively correlated with the percentage of CD8+T cells(r=-0.520,P<0.05).Compared with Exo+sh-NC group,the IFN-γ(3 865.31±543.85 pg/ml vs 1 786±105.98 pg/ml),TNF-α(4 631.93±510.71 pg/ml vs 1 973.24±379.62 pg/ml),Granzyme B(3 876.49±312.43 pg/ml vs 1 879.43±287.58 pg/ml),and IL-2 mRNA levels(3.286±0.437 vs 1.015±0.314)were increased,and the percentage of PD-1+Tim3+CD8+T cells(7.68%±2.18%vs 18.95%±3.21%)was decreased in Exo+sh-LINC01137 group,with statistical significances(t=-6.497,-7.237,-8.146,-7.310,5.021,all P<0.01).Our results showed that miR-22-3p was the target gene of LINC01137.Compared with Exo+NC mimic group,the level of PD-1 protein in Exo+miR-22-3p group(0.384±0.087 vs 1.003±0.147)was significantly decreased,and the difference was statistically significant(t=6.277,P<0.01).Conclusion The expression of LINC01137 was significantly up-regulated in tumor tissues and plasma of NSCLC patients.Exosomes LINC01137 derived NSCLC cell induces CD8+T cell exhaustion by targeting miR-22-3p and inhibiting its expression,and thus promoting NSCLC cell immune escape.