The importance of ERK5 kinase signaling in tumorigenicity, metastasis, and drug resistance of cancer stem cells (CSCs) has been recognized recently, and we report a unique dual inhibitor that blocks binding of the ERK5 activator and ERK5 autophosphorylation simultaneously. The conventional ATP-binding site inhibitors have not yet yielded expected level of anti-cancer effects, due to complexities in converting ERK5 activation into CSC biological effects. We designed the first ERK5-targeted anti-CSC dual active hetero-bivalent inhibitor that blocks the regulatory peptide interaction involved in ERK5 kinase activation and that simultaneously inhibits the conventional ATP-binding pocket as well. We utilized two assay systems to independently prove disruption of these two ERK5 activities via a single compound. We also showed that this compound inhibited CSC activities, such as colony formation, cell proliferation, and migration.

ERK5激酶信号传导在肿瘤干细胞（CSCs）的致瘤性，转移和耐药性中的重要性已得到公认，并且我们报道了一种独特的双重抑制剂，可同时阻断ERK5激活剂和ERK5自磷酸化的结合。由于将ERK5激活转化为CSC生物学效应的复杂性，传统的ATP结合位点抑制剂尚未产生预期水平的抗癌作用。我们设计了首个靶向ERK5的抗CSC双活性异二价抑制剂，该抑制剂可阻断参与ERK5激酶激活的调节肽相互作用，同时也可抑制常规的ATP结合口袋。我们利用了两种测定系统，以通过单一化合物独立证明这两种ERK5活性的破坏。