Figure 5. hsa_circ_0001869 binds directly to miR-638 to facilitate NSCLC progression. (A) Predicted binding sites of miR-638 in hsa_circ_0001869. Mutated (Mut) version of hsa_circ_0001869 is shown. (B) Relative luciferase activity was determined 48 h after transfection with miR-638 mimic/normal control (NC) or with hsa_circ_0001869 wild-type/Mut in HEK293T cells. n = 3. Data are expressed as mean ± SD. ***P < 0.001. (C) miR-638 expression was examined in NSCLC tissues and matched peritumor samples using qRT-PCR. Expression level of miR-638 was significantly lower in NSCLC tissues than in peritumor samples. Data are expressed as mean ± SD, n = 20. ***P < 0.001 vs. normal tissues. (D) Significant negative correlation was observed between hsa_circ_0001869 and miR-638 in NSCLC tissues: n = 20, P = 0.014. (E) qRT-PCR was used to investigate miR-638 levels in hsa_circ_0001869-silenced A549 and PC9 cells. Data are expressed as mean ± SD. ***P < 0.001 vs. NC. (F and G) Colony formation assay was used to determine the colony-forming ability of A549 and PC9 cells after knockdown of hsa_circ_0001869 with or without silencing miR-638. Data are expressed as mean ± SD. ***P < 0.001 vs. NC. (H–J) Cell migration and invasion were determined in A549 and PC9 cells using the Transwell® assay. n = 3. Data are expressed as mean ± SD. ***P < 0.001 vs. NC.