Fig. 4

LINC00022 promotes cell-cycle progression in ESCC cells. (A) Cell cycle phase distribution of KYSE150 and TE1 following siRNA-mediated knockdown of LINC00022 was detected by PI-staining flow cytometry (left panel). Ablation of LINC00022 led to a significant increase in the proportion of cells in G0/G1 phase, a slight decrease in the proportion of cells in S phase but with no significant difference, and an obvious decrease in the proportion of cells in G2/M phase (right panel), *p < 0.05; **p < 0.01; ns means no significance. (B) Cell-cycle change of KYSE70 cells after LINC00022 over-expression was evaluated by PI-labeling flow cytometry (upper panel). Up-regulation of LINC00022 resulted in a significant reduction in the proportion of cells in G0/G1 phase, a slight increase in the proportion of cells in S phase but with no significant difference, and a dramatic elevation in the proportion of cells in G2/M phase (nether panel), *p < 0.05; **p < 0.01; ns means no significance. (C-E) Western blot was used to detect the changes of cell cycle regulator protein levels in KYSE150 (C) and TE1 (D) cells following LINC00022 knockdown, and in KYSE70 (E) cells following LINC00022 over-expression. The positive cell-cycle regulators include CDK2, Cyclin E1, CDK4 and Cyclin D1, while the negative regulators include p16, p21 and p53. The numbers below each band represent the relative protein levels change