Non 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. As 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. Addition 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. These 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.

中文翻译：

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DHA及其代谢物RvD1通过miR-138-5p / FOXC1途径抑制肺癌的生长和转移。

非小细胞肺癌（NSCLC）是世界上最常见的癌症之一。已知DHA能够抑制NSCLC细胞增殖和转移。但是，DHA发挥其抗肿瘤作用的机制尚不清楚。在这里，我们旨在确定DHA及其代谢产物对肺癌细胞生长和侵袭的影响及其机制。作为细胞增殖和侵袭能力的量度，在体外使用细胞活力和transwell测定法。将将ω-6PUFA转换为ω-3PUFA的转基因mfat-1小鼠用于检测内源性DHA对肿瘤移植的影响。LC-MS / MS分析确定了DHA的几种类花生酸代谢产物的升高。通过使用qPCR miRNA芯片，在线预测软件，荧光素酶报告基因分析和Western印迹分析，我们进一步阐明了机制。外源DHA的添加在体外抑制了NSCLC细胞的生长和侵袭。内源产生的DHA在转基因mfat-1小鼠中减弱了LLC衍生的肿瘤生长和转移。在DHA代谢产物的升高中，resolvin D1（RvD1）显着促进了细胞生长和侵袭的抑制。MiRNA微阵列显示，RvD1治疗后，miR-138-5p的水平显着增加。MiR-138-5p模拟细胞活力和侵袭性降低；而miR-138-5p抑制剂取消了RvD1介导的细胞活力和侵袭抑制。miR-138-5p的过表达会明显降低FOXC1的表达，而荧光素酶报告基因检测表明FOXC1是miR-138-5p的直接靶标。体内，mfat-1转基因产生的内源性DHA增强了miR-138-5p的表达并降低了FOXC1的表达。此外，FOXC1的过表达逆转了RvD1处理诱导的细胞活力和侵袭的抑制。这些数据确定了RvD1 / miR-138-5p / FOXC1途径是DHA及其代谢产物RvD1的新机制，并且靶向这种途径作为治疗NSCLC的治疗策略具有潜力。