Inhibition of lung cancer growth and metastasis by DHA and its metabolite, RvD1, through miR-138-5p/FOXC1 pathway

Xiaoming Bai,Zhenggang Zhao,Allan Z Zhao,Jiaofang Shao,Fanghong Li,Sujin Zhou,Rong Xiang,Jinshun Pan

doi:10.1186/s13046-019-1478-3

Abstract

BackgroundNon small cell lung cancer (NSCLC) is one of the most common cancers in the world. DHA is known to be capable of suppressing NSCLC cell proliferation and metastasis. However, the mechanisms by which DHA exhibits its antitumor effects are unknown. Here we aimed to identify the effects and mechanisms of DHA and its metabolites on lung cancer cell growth and invasion.MethodsAs measures of cell proliferation and invasion ability, the cell viability and transwell assays were used in vitro. Transgenic mfat-1 mice, which convert ω-6 PUFAs to ω-3 PUFAs, were used to detect the effect of endogenous DHA on tumor transplantation. An LC − MS/MS analysis identified the elevation of several eicosanoid metabolites of DHA. By using qPCR miRNA microarray, online prediction software, luciferase reporter assays and Western blot analysis, we further elucidated the mechanisms.ResultsAddition of exogenous DHA inhibited the growth and invasion in NSCLC cells in vitro. Endogenously produced DHA attenuated LLC-derived tumor growth and metastasis in the transgenic mfat-1 mice. Among the elevation of DHA metabolites, resolvin D1 (RvD1) significantly contributed to the inhibition in cell growth and invasion. MiRNA microarray revealed that the level of miR-138-5p was significantly increased after RvD1 treatment. MiR-138-5p mimics decreased cell viability and invasion; while miR-138-5p inhibitor abolished RvD1-mediated suppression of cell viability and invasion. The expression of FOXC1 was significantly reduced upon overexpression of miR-138-5p while luciferase reporter assay showed that FOXC1 was a direct target of miR-138-5p. In vivo, endogenous DHA by the mfat-1 transgene enhanced miR-138-5p expression and decreased FOXC1 expression. Furthermore, overexpression of FOXC1 reversed the inhibition in cell viability and invasion induced by RvD1 treatment.ConclusionsThese data identified the RvD1/miR-138-5p/FOXC1 pathway as a novel mechanism by DHA and its metabolite, RvD1, and the potential of targeting such pathway as a therapeutic strategy in treating NSCLC.

Highlights

Non small cell lung cancer (NSCLC) is one of the most common cancers in the world
We found that endogenous Docosahexaenoic acid (DHA) produced by mfat-1 gene significantly inhibited cell viability and metastasis, and increased resolvin D1 (RvD1) production in lung cancer cells
The following were commercially obtained antibodies: the anti-Protein kinase B (Akt) (#9272), anti-phospho-Akt (Ser473, #4060), the anti-Erk1/2 (#4696), and anti-phospho-Erk1/2 (Thr202/Tyr204, #8544) antibodies were obtained from Cell Signaling Technology (Danvers, MA, USA); the anti-Forkhead Box C1 (FOXC1) antibody (#115201) was obtained from Abcam plc (Cambridge, UK); the anti-GAPDH antibody was obtained from Bioworld Technology (Atlanta, Georgia30,305, USA)

Summary

Introduction

DHA is known to be capable of suppressing NSCLC cell proliferation and metastasis. The mechanisms by which DHA exhibits its antitumor effects are unknown. We aimed to identify the effects and mechanisms of DHA and its metabolites on lung cancer cell growth and invasion. In NSCLC, DHA inhibits cancer cell proliferation and migration [9], and suppresses angiogenesis [10]. Resolvin D1 (RvD1), one of DHA metabolites, has been reported to suppress tumor growth in several murine cancer cell lines at the doses 10,000 times lower than DHA [11]. The potential effects and underlying mechanisms of RvD1 on NSCLC cell growth and invasion, are completely unknown, apart from inhibiting TGF-β1-induced epithelial mesenchymal transition in lung cancer [12, 13]

Objectives

Methods

Results

Conclusion