circFOXP1 Targets miR-4429 to Regulate Proliferation, Migration and Invasion of Nasopharyngeal Carcinoma 6-10B Cells

Objective To determine whether circular RNA forkhead box protein P1 (circFOXP1) regulates the proliferation, migration and invasion of nasopharyngeal carcinoma 6-10B cells by targeting miR-4429.

Methods The correlations of circFOXP1 and miR-4429 with pathological characteristics of nasopharyngeal carcinoma patients were analyzed. Nasopharyngeal carcinoma 6-10B cells were transfected with si-NC, si-circFOXP1, pcDNA, pcDNA-circFOXP1, miR-NC, miR-4429 mimics, or co-transfected with si-circFOXP1 and anti-miR-NC, or si-circFOXP1 and anti-miR-4429. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to detect circFOXP1 and miR-4429 expression in nasopharyngeal carcinoma tissues. Cell viability, colony formation, migration and invasion abilities were assessed by Cell Counting Kit-8 (CCK-8), colony formation, wound healing and Transwell assays. Western blotting was used to detect E-cadherin and N-cadherin protein expression. A dual-luciferase reporter assay verified the targeting relationship between circFOXP1 and miR-4429.

Results The expression level of circFOXP1 in nasopharyngeal carcinoma tissues (4.61 ± 0.31) was significantly higher than that in adjacent tissues (1.00 ± 0.05) (P < 0.001), while the expression level of miR-4429 (0.37 ± 0.03) was significantly lower than that in adjacent tissues (1.00 ± 0.08) (P < 0.001). The expression of miR-4429 was correlated with tumor volume and TNM stage (P < 0.05), while the expression of circFOXP1 was correlated with TNM stage(P < 0.05) but not with tumor volume (P > 0.05). Inhibition of circFOXP1 expression or overexpression of miR-4429 reduced cell viability, colony formation number, wound healing rate, invasive cell number and N-cadherin protein expression, while increased E-cadherin protein expression in nasopharyngeal carcinoma 6-10B cells (P < 0.05). circFOXP1 targeted and negatively regulated miR-4429 expression. Interference with miR-4429 reversed the inhibitory effects of circFOXP1 silencing on proliferation, migration and invasion of nasopharyngeal carcinoma cells (P < 0.05).

Conclusion Inhibition of circFOXP1 expression can attenuate the proliferation, migration and invasion of nasopharyngeal carcinoma 6-10B cells by targeting miR-4429.