Circle RNA FOXP1 promotes cell proliferation in lung cancer by regulating miR-185-5p/Wnt1 signaling pathway.

Objective: It is reported that circular RNA plays an important role in various cancers in recent years. However, there is less investigation reported in lung adenocarcinoma (LUAD) about circRNA. This study aims to explore the role and molecular mechanism of circle RNA FOXP1 in LUAD procession.
Patients and Methods: The levels of circFOXP1 and miR-185-5p in LUAD cell lines and LUAD cancer samples were examined by RT-PCR. The functions of circFOXP1 and miR-185-5p at LUAD cells were detected by cell transfection of the overexpression or repression. The A549 and H1299 cell proliferation were detected by MTT assay and colony formation assay. And the cell apoptosis was detected by TUNEL assay. The expression levels WNT1 were measured by Western blot in A549 and H1299 cells. Furthermore, the luciferase assay detected the direct interaction between circFOXP1 and miR-185-5p or miR-185-5p and WNT1.
Results: The circFOXP1 expression was increased in LUAD patients and LUAD cell lines. The downregulation of circFOXP1 significantly repressed LUAD cell proliferation and promoted cell apoptosis. Moreover, the luciferase assay results confirmed that circFOXP1 directly interacted with miR-185-5p. Overexpression of miR-185-5p could reverse the effect of circFOXP1 in LUAD cell. Besides, the luciferase results showed that miR-185-5p directly interacted with WNT1. miR-185-5p overexpression inhibited the WNT1 expression, while circFOXP1 repression decreased the WNT1 level in LUAD cell lines. The downregulating WNT1 could reverse the effects of miR-185-5p inhibition in LUAD cell lines. Furthermore, WNT1 was significantly upregulated in LUAD cancer tissues. In addition, circFOXP1 level was negatively correlated with miR-185-5p expression and positively correlated with WNT1 expression in LUAD cancer tissues.
Conclusions: These data suggested that circFOXP1 promoted cell proliferation and repressed cell apoptosis in LUAD by regulating miR-185-5p/WNT1 signaling pathway. It provides a novel potential therapeutic agent for the treatment of LUAD.