Knockdown of Orphan Transporter SLC22A18 Impairs Lipid Metabolism and Increases Invasiveness of HepG2 Cells
Knockdown of Orphan Transporter SLC22A18 Impairs Lipid Metabolism and Increases Invasiveness of HepG2 Cells
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DOI：
10.1007/s11095-018-2565-4
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发表时间：
2019-03-01
影响因子：
3.7
通讯作者：
Ohtsuki, Sumio
中科院分区：
文献类型：
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作者：
Ito, Shingo;Honda, Gentaro;Ohtsuki, Sumio
目的探讨溶质载体家族22成员18 （SLC22A18）在HepG2细胞脂质代谢和肿瘤表型建立中的作用。方法用shRNA稳定转染sslc22a18敲低的HepG2细胞。采用定量蛋白质组学和Western blot方法检测蛋白表达水平。细胞计数试剂盒检测细胞生长情况。油红O染色测定富甘油三酯脂滴的积累。Transwell法检测细胞迁移和侵袭。结果slc22a18敲除的HepG2细胞积累了富含甘油三酯的脂滴，溶酶体/自噬蛋白的表达水平下降，表明脂质降解受到抑制。SLC22A18基因敲除可抑制HepG2细胞的生长，但补充游离脂肪酸可恢复细胞的生长。SLC22A18敲低可降低胰岛素样生长因子结合蛋白1 （IGFBP-1）的表达，增强HepG2细胞的侵袭能力。外源性IGFBP-1阻断SLC22A18敲低诱导的侵袭活性增加。结论抑制SLC22A18可通过破坏溶酶体/自噬降解途径减少富甘油三酯脂滴的细胞内游离脂肪酸供应，并通过降低IGFBP-1的表达降低HepG2细胞的侵袭活性。
PurposeThe aim of this work is to investigate the roles of solute carrier family 22 member 18 (SLC22A18) in lipid metabolism and in establishing the tumor phenotype of HepG2 cells.MethodsSLC22A18-knockdown HepG2 cells were established by stable transfection with shRNA. Protein expression levels were measured by quantitative proteomics and Western blot analysis. Cell growth was examined by cell counting kit. Accumulation of triglyceride-rich lipid droplets was measured by Oil-Red O staining. Cell migration and invasion were examined by Transwell assays.ResultsSLC22A18-knockdown HepG2 cells accumulated triglyceride-rich lipid droplets and showed decreased expression levels of lysosomal/autophagic proteins, suggesting that lipid degradation is suppressed. Growth of HepG2 cells was decreased by SLC22A18 knockdown, but was restored by free fatty acid supplementation. In addition, SLC22A18 knockdown decreased the expression of insulin-like growth factor-binding protein 1 (IGFBP-1) and increased the invasion ability of HepG2 cells. Exogenous IGFBP-1 blocked the increase of invasion activity induced by SLC22A18 knockdown.ConclusionOur results suggest that suppression of SLC22A18 decreased the supply of intracellular free fatty acids from triglyceride-rich lipid droplets by impairing the lysosomal/autophagy degradation pathway and reduced the invasive activity of HepG2 cells by decreasing IGFBP-1 expression.