Discovery of 5‑(3-Chlorophenylamino)benzo[<i>c</i>][2,6]naphthyridine Derivatives as Highly Selective CK2 Inhibitors with Potent Cancer Cell Stemness Inhibition

Multifunctional entities have recently been attractive for the development of anticancer chemotherapeutic drugs. However, such entities with concurrent CK2 along with cancer stem cell (CSC) inhibitory activities are rare in a single small molecule. Herein, a series of 5-(3-chlorophenylamino)­benzo­[c]­[2,6]­naphthyridine derivatives were synthesized using a known CK2 inhibitor, silmitasertib (CX-4945), as the lead compound. Among the resulting compounds, 1c exhibited stronger CK2 inhibitory activity with higher Clk2/CK2 selectivity than CX-4945. Significantly, 1c could modulate the Akt1­(ser129)-GSK-3β­(ser9)-Wnt/β-catenin signaling pathway and inhibit the expression of the stemness marker ALDH1A1, CSC surface antigens, and stem genes, showing potent CSC inhibitory activity. Moreover, 1c also displayed superior pharmacokinetics and antitumor activity compared with CX-4945 sodium salt, without obvious toxicity. The favorable antiproliferative and antitumor activity of 1c, its high inhibitory selectivity for CK2, and its potent inhibition of cancer cell stemness make this molecule a candidate for the treatment of cancer.多功能实体（multifunctional entities）近年来在抗癌化疗药物的研发领域备受关注。然而，能够同时兼具酪蛋白激酶2（CK2）与癌症干细胞（CSC）抑制活性的单一小分子实体却较为罕见。本研究以已知的CK2抑制剂丝米塞替尼（silmitasertib, CX-4945）作为先导化合物，合成了一系列5-(3-氯苯氨基)苯并[c][2,6]萘啶衍生物。在所获得的化合物中，化合物1c的CK2抑制活性更强，且CLK2/CK2选择性优于CX-4945。值得注意的是，化合物1c可调控Akt1（丝氨酸129位点）-糖原合成激酶3β（GSK-3β，丝氨酸9位点）-Wnt/β-连环蛋白信号通路，并抑制干细胞标志物乙醛脱氢酶1A1（ALDH1A1）、CSC表面抗原以及干细胞相关基因的表达，展现出强效的CSC抑制活性。此外，与CX-4945钠盐相比，化合物1c展现出更优异的药代动力学特性与抗肿瘤活性，且无明显毒性。化合物1c良好的抗增殖与抗肿瘤活性、对CK2的高抑制选择性，以及对癌细胞干性的强效抑制作用，使其成为癌症治疗的潜在候选化合物。