Sphingosine-1-phosphate receptor 2 (S1PR2) has been identified as a brand-new GPCR target for designing antagonists to reverse 5-FU resistance. We herein report the structural optimization and structure-activity relationship of JTE-013 derivatives as S1PR2 antagonists. Compound 9d was the most potent S1PR2 antagonist (K_D = 34.8 nM) among developed compounds. Here, compound 9d could significantly inhibit the expression of dihydropyrimidine dehydrogenase (DPD) to reverse 5-FU-resistance in HCT116^DPD and SW620/5-FU cells. Further mechanism studies demonstrated that compound 9d not only inhibited S1PR2 but also affected the transcription of S1PR2. In addition, compound 9d also showed acceptable selectivity to normal cells (NCM460). Importantly, compound 9d with suitable pharmacokinetic properties could significantly reverse 5-FU-resistance in the HCT116^DPD and SW620/5-FU xenograft models without obvious toxicity, in which the inhibition rates of 5-FU were increased from 23.97% to 65.29% and 27.23% to 60.81%, respectively. Further immunohistochemistry and western blotting analysis also demonstrated that compound 9d significantly decreases the expression of DPD in tumor and liver tissues. These results indicated that compound 9d is a promising lead compound to reverse 5-FU-resistance for colorectal cancer therapy.

1-磷酸鞘氨醇受体 2 (S1PR2) 已被确定为一种全新的 GPCR 靶标，用于设计逆转 5-FU 抗性的拮抗剂。我们在此报告了 JTE-013 衍生物作为 S1PR2 拮抗剂的结构优化和构效关系。化合物9d是已开发化合物中最有效的 S1PR2 拮抗剂 (K _D  = 34.8 nM)。在这里，化合物9d可以显着抑制二氢嘧啶脱氢酶 (DPD) 的表达，从而逆转 HCT116 ^DPD和 SW620/5-FU 细胞中的 5-FU 抗性。进一步的机制研究表明，化合物9d不仅抑制 S1PR2，而且影响 S1PR2 的转录。此外，化合物9d对正常细胞（NCM460）也显示出可接受的选择性。重要的是，具有合适药代动力学特性的化合物9d可以显着逆转 HCT116 ^DPD和 SW620/5-FU 异种移植模型中的 5-FU 耐药性，且无明显毒性，其中 5-FU 的抑制率从 23.97% 提高到 65.29%，并且分别为 27.23% 至 60.81%。进一步的免疫组织化学和蛋白质印迹分析还表明，化合物9d显着降低了 DPD 在肿瘤和肝组织中的表达。这些结果表明，化合物9d是一种很有前途的先导化合物，可逆转结直肠癌治疗中的 5-FU 耐药性。