Adenocarcinoma cell proliferation of lung was inhibited by miR-1247-3p. A: We identified the best mimic and inhibitor sequences. B: As compared to control groups, a lower expression of miR-1247-3p was observed in inhibitor group and higher in mimic group. C: Reduced expression of miR-1247-3p resulted in an increased cell proliferation and invasion. D: Suppression process can result in increment of cell number as shown. LV-mimics group was found to be decreased in cell number of A459 cell lines whereas it was higher in LV-mNC group. E-F: Cell number percent in A549 cell lines was raised by inhibitor group when comparing to LV-INC group. G-H: Cell apoptosis was measured. ***p<0.001 compared with group INC, mNC, LV-INC, or LV-mNC. Lentiviruses-inhibitor normal control (LV-INC), Lentiviruses-inhibitor (LV-inhibitor), Lentiviruses-mimics normal control (LV-mNC), Lentiviruses- mimics (LV-mimics). The experiments were repeated at least 3 independent times.