The expression of LncRNA MEG3, miR-543, and IDO (IDO1, IDO2, and TDO proteins) in the lung tissue of rats using IDO inhibitor was also evidently elevated, while miR-543 was declined compared with that of lung carcinoma model rats, suggesting that IDO inhibitor can obviously reduce the activity of carcinoma cells. This evidence concerns the gene IDO2 and carcinoma.