Glycerol uptake in HCT-15 human colon cancer cell line by Na+-dependent carrier-mediated transport
Glycerol uptake in HCT-15 human colon cancer cell line by Na+-dependent carrier-mediated transport
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DOI：
10.1248/bpb.29.150
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发表时间：
2006-01-01
影响因子：
2
通讯作者：
Yuasa, H
中科院分区：
文献类型：
--
作者：
Fujimoto, N;Inoue, K;Yuasa, H
最近有人提出，Na+依赖性载体介导的转运系统参与肠甘油吸收。这种转运系统作为药物递送的可能途径和药物开发的靶点而受到普遍关注。然而，在小肠或任何其他器官中，细胞甘油摄取的Na+依赖性机制尚未完全阐明。本研究的目的是检查HCT-15人结肠癌细胞系中的甘油摄取，发现该细胞系能够进行Na+依赖性甘油摄取，以确定转运特征并帮助鉴定此类甘油转运系统。HCT-15细胞中甘油的摄取是高度饱和的，米氏常数为15.0 μ m，最大摄取速率为11.9 pmol/min/mg蛋白质，伴随着最小的不饱和转运;它在无Na+条件下显著降低，表明Na+需求。甘油摄取也减少了2，4-二硝基苯酚，代谢抑制剂。这些结果表明，载体介导的甘油转运系统，这是Na+依赖性和次要活性，是存在于HCT-15细胞。该转运系统可能对甘油和一些具有羟基的类似化合物具有特异性，因为甘油摄取被一些与甘油相关的醇和化合物抑制，例如1，2-丙二醇和甘油3-磷酸酯。然而，它可能代表了一个高亲和力的转运系统，这是不同于小肠中的一个，因为米氏常数为15.0 μ m，比在大鼠小肠中观察到的米氏常数低约50倍。总之，这是第一项在已建立的细胞系中证明Na+依赖性载体介导的甘油转运的研究。这将有助于确定一组Na+依赖性甘油转运系统，并阐明其转运机制，尽管本研究中在HCT-15细胞中发现的甘油转运系统似乎与先前在大鼠小肠中发现的甘油转运系统不同。
It has recently been suggested that an Na+-dependent carrier-mediated transport system is involved in intestinal glycerol absorption. Such a transport system is of general interest as a possible pathway of drug delivery and a target of drug development. However, the Na+-dependent mechanism of cellular glycerol uptake has not been fully clarified in the small intestine or in any other organ. The purpose of the present study was to examine glycerol uptake in the HCT-15 human colon cancer cell line, which was found to be able to perform Na+-dependent glycerol uptake, to determine the transport characteristics and help identify such glycerol transport systems. The uptake of glycerol in HCT-15 cells was highly saturable with a Michaelis constant of 15.0 mu m and a maximum uptake rate of 11.9 pmol/min/mg protein, accompanied by minimal unsaturable transport; it was reduced markedly under Na+-free conditions, indicating Na+ requirement. Glycerol uptake was also reduced by 2,4-dinitrophenol, a metabolic inhibitor. These results suggest that a carrier-mediated glycerol transport system, which is Na+-dependent and secondarily active, is present in HCT-15 cells. The transport system could be specific for glycerol and some analogous compounds with hydroxyl groups, since glycerol uptake was inhibited by some alcohols and compounds related to glycerol, such as 1,2-propanediol and glycerol 3-phosphpate. However, it may represent a high affinity transport system, which is different from the one in the small intestine, because the Michaelis constant of 15.0 mu m is about 50-fold lower than that observed in the rat small intestine. In conclusion, this is the first study to demonstrate an Na+-dependent carrier-mediated glycerol transport in an established cell line. This will help in identifying a group of Na+-dependent glycerol transport systems and elucidating their transport mechanisms, although the one found in HCT-15 cells in this study seems to be different from one previously found in the rat small intestine.