Indoleamine 2,3-dioxygenase (IDO1) is a heme-containing enzyme mainly responsible for the metabolism of tryptophan to kynurenine. To date, the IDO1 inhibitors have been developed intensively for the re-activation of the anticancer immune response. In this report, we designed, and synthesized novel 1,3-dimethyl-6-amino indazole derivatives as IDO1 inhibitors based on the structure of IDO1 active site. We further examined their anticancer activity on hypopharyngeal carcinoma cells (FaDu), squamous cell carcinoma of the oral tongue (YD-15), breast cancer cells (MCF7), and human dental pulp stem cells (HDPSC). Of them, compound N-(4-bromobenzyl)-1,3-dimethyl-1H-indazol-6-amine (7) remarkably suppressed IDO1 expression in a concentration - dependent manner. In addition, 7 was the most potential anticancer compound with inducing apoptosis activity as well as selectively activated extracellular signal-regulated kinases (ERK) in mitogen-activated protein kinase (MAPK) pathways on FaDu cells. Finally, compound 7 suppressed cell mobility in wound healing assay with the reduced expression of matrix metalloproteinase MMP9. Taken together, we believe that 7 is the most promising compound, which may be applied to treatment of hypopharyngeal carcinoma.

吲哚胺2,3-双加氧酶（IDO1）是一种含血红素的酶，主要负责色氨酸代谢为犬尿氨酸。迄今为止，IDO1抑制剂已被集中开发用于重新激活抗癌免疫反应。在本报告中，我们根据IDO1活性位点的结构，设计并合成了新型1,3-二甲基-6-氨基吲唑衍生物作为IDO1抑制剂。我们进一步检测了它们对下咽癌细胞（FaDu）、口腔鳞状细胞癌（YD-15）、乳腺癌细胞（MCF7）和人牙髓干细胞（HDPSC）的抗癌活性。其中，化合物N-( 4-溴苄基)-1,3-二甲基-1H-吲唑-6-胺( 7）以浓度依赖性方式显着抑制IDO1表达。此外，7是最有潜力的抗癌化合物，具有诱导细胞凋亡活性以及在FaDu细胞上丝裂原激活蛋白激酶（MAPK）途径中选择性激活细胞外信号调节激酶（ERK）的作用。最后，化合物7通过降低基质金属蛋白酶 MMP9 的表达来抑制伤口愈合试验中的细胞迁移性。综上所述，我们认为7是最有前途的化合物，可能应用于下咽癌的治疗。