Objective:To investigate the effects and mechanism of MIR155 HG on proliferation

cell cycle

migration and invasion of A549 human lung cancer cells. Methods:MTS assay

flow cytometry

migration assay and invasion assay were applied to study the changes of cell proliferation

cell cycle

migration and invasion after overexpression or knock down of MIR155 HG in A549 cells. The expression level of mi R-155-5p was detected after overexpression of MIR155 HG. Results:MTS results showed that the absorbance(A)value was higher in MIR155 HG overexpression group at 72 h(2.47±0.14)and 96 h(3.13±0.15)after transfection respectively

compared with vector control group at 72 h(2.09 ±0.12) and 96 h(2.50 ±0.13) after transfection(P =0.006

P =0.027;A value in MIR155 HG knockdown group at 48 h(1.69 ±0.15)

72 h(1.87 ±0.09) and 96 h(2.24 ±0.16) after transfection was lower than in negative control group at 48 h(2.04 ±0.06)

72 h(2.43 ±016) and 96 h(2.88 ±0.11) after transfection respectively(P =0.006

P =0.006

P =0.004);The percentage of G0/G1 phase increased from 54.32% in negative control group to 63.93% in MIR155 HG knockdown group. Transwell migration assay indicated that the number of migrated cells in MIR155 HG overexpression group(31.67±3.51)was more than in vector control group(12.67±2.51)(P=0.002);the number of migrated cells in MIR155 HG knockdown group(13.67 ±3.21) was less than in negative control group(36.00±4.58)(P=0.002). Transwell invasion assay showed that the number of invaded cells in MIR155 HG overexpression group(42.33 ±7.02) was more than in vector control group(15.67 ±3.51)(P =0.004);the number of invaded cells in MIR155 HG knockdown group(15.00 ±3.60) was less than in negative control group(39.00±4.36)(P=0.002). Real-time PCR analysis showed that the fold change of mi R-155-5P expression in MIR155 HG overexpression group was upregulated to 17.99 ±2.42 compared with vector control group(P =0.000). Conclusion:MIR155HG may promote A549 cells proliferation

migration and invasion possibly via mi R-155-5p.