Department of Pharmaceutical Microbiology, Faculty of Life Sciences, Kumamoto University, 5-1 Oe-honmachi, Chuo-ku, Kumamoto, 862-0973, Japan.
Department of Pharmaceutical Microbiology, School of Pharmacy, Kumamoto University, 5-1 Oe-honmachi, Chuo-ku, Kumamoto, 862-0973, Japan.
Pharm Res. 2019 Jan 11;36(3):39. doi: 10.1007/s11095-018-2565-4.
The 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.
SLC22A18-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.
SLC22A18-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.
Our 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.
本研究旨在探讨溶质载体家族 22 成员 18（SLC22A18）在脂代谢中的作用及其对 HepG2 细胞肿瘤表型的影响。
通过稳定转染 shRNA 建立 SLC22A18 敲低 HepG2 细胞。采用定量蛋白质组学和 Western blot 分析检测蛋白表达水平。通过细胞计数试剂盒检测细胞生长情况。用油红 O 染色法检测甘油三酯丰富的脂滴积累。通过 Transwell 测定法检测细胞迁移和侵袭。
SLC22A18 敲低 HepG2 细胞积累甘油三酯丰富的脂滴，并且溶酶体/自噬蛋白的表达水平降低，表明脂质降解受到抑制。SLC22A18 敲低可降低 HepG2 细胞的生长，但通过补充游离脂肪酸可恢复。此外，SLC22A18 敲低降低了胰岛素样生长因子结合蛋白 1（IGFBP-1）的表达，并增加了 HepG2 细胞的侵袭能力。外源性 IGFBP-1 阻断了 SLC22A18 敲低引起的侵袭活性增加。
我们的研究结果表明，SLC22A18 的抑制通过损害溶酶体/自噬降解途径减少了来自甘油三酯丰富的脂滴的细胞内游离脂肪酸供应，并通过降低 IGFBP-1 的表达降低了 HepG2 细胞的侵袭活性。
