Contribution of equilibrative nucleoside transporter(s) to intestinal basolateral and apical transports of anticancer trifluridine
Contribution of equilibrative nucleoside transporter(s) to intestinal basolateral and apical transports of anticancer trifluridine
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平衡核苷转运蛋白对抗癌三氟尿苷肠道基底外侧和顶端转运的贡献
DOI：
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发表时间：
2018
影响因子：
2.1
通讯作者：
I. Tamai
中科院分区：
文献类型：
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作者：
Koichi Takahashi;K. Yoshisue;M. Chiba;T. Nakanishi;I. Tamai
尽管曲氟尿苷 (FTD) 具有亲水性，但口服后仍表现出抗癌活性。此前有报道称，浓缩核苷转运蛋白（CNT）1介导人小肠上皮细胞（HIEC）顶端摄取FTD。在本研究中，FTD 还被确定为转运蛋白基因转染细胞中平衡核苷转运蛋白 (ENT) 1 和 ENT2 的底物。免疫细胞化学分析显示 ENT1 在 HIEC 的基底外侧膜和顶膜上表达。在耳鼻喉科选择性抑制剂 S-(4-硝基苯甲基)-6-硫肌苷 (NBMPR) 存在下，细胞积累增加。 NBMPR 增加了 HIEC 单层在低 FTD 浓度下的细胞毒性，这可能是由于 NBMPR 抑制了 ENT 介导的 FTD 基底外侧转运。这些结果表明，ENTs 通过促进 FTD 的基底外侧流出来降低 FTD 的肠道细胞毒性。另一方面，NBMPR 在较高浓度的 FTD 下降低了 HIEC 中 FTD 的细胞内积累和细胞毒性，这可能是由于 NBMPR 抑制了 FTD 的顶端摄取，而这被认为是由 CNT 和 ENT 介导的。总之，ENTs通过介导FTD被CNT1从顶端侧摄取后的基底外侧流出来负责肠道跨上皮渗透，从而减少其在人体的细胞内积累和肠道毒性。平衡核苷转运蛋白也可能部分促进 FTD 与高亲和力 CNT1 一起穿过顶膜的低亲和力摄取。
Trifluridine (FTD) exhibits anticancer activities after its oral administration despite its hydrophilic nature. It was previously reported that concentrative nucleoside transporter (CNT) 1 mediates the apical uptake of FTD in human small intestinal epithelial cells (HIECs). In the present study, FTD was also identified as a substrate for equilibrative nucleoside transporter (ENT) 1 and ENT2 in transporter gene‐transfected cells. An immunocytochemical analysis revealed that ENT1 was expressed at the basolateral and apical membranes of HIECs. Cellular accumulation increased in the presence of S‐(4‐nitrobenzyl)‐6‐thioinosine (NBMPR), an ENT selective inhibitor. Cytotoxicity in HIEC monolayers at low FTD concentrations was increased by NBMPR, and this may have been due to inhibition of the ENT‐mediated basolateral transport of FTD by NBMPR. These results suggest that ENTs reduce the intestinal cytotoxicity of FTD by facilitating its basolateral efflux. On the other hand, the intracellular accumulation and cytotoxicity of FTD in HIECs were decreased at higher concentrations of FTD by NBMPR, and this may have been due to the NBMPR inhibition of the apical uptake of FTD, which has been suggested to be mediated by CNTs and ENTs. In conclusion, ENTs were responsible for intestinal transepithelial permeation by mediating the basolateral efflux of FTD after its uptake by CNT1 from the apical side, resulting in decreases in its intracellular accumulation and intestinal toxicity in humans. Equilibrative nucleoside transporters may also partially contribute to the low‐affinity uptake of FTD across the apical membrane along with high‐affinity CNT1.