Yoshida Takayuki, Kakegawa Junya, Yamaguchi Takayuki, Hantani Yoshiji, Okajima Nobuyuki, Sakai Toshiyuki, Watanabe Yoshihiro, Nakamura Motonao
Pharmaceutical Frontier Research Laboratories, Central Pharmaceutical Institute, Japan Tobacco, Kanazawa-ku, Yokohama, Kanagawa, Japan.
Oncotarget. 2012 Dec;3(12):1533-45. doi: 10.18632/oncotarget.747.
A small molecule compound, JTP-74057/GSK1120212/trametinib, had been discovered as a very potent antiproliferative agent able to induce the accumulation of CDK inhibitor p15INK4b. To conduct its drug development rationally as an anticancer agent, molecular targets of this compound were identified as MEK1/2 using compound-affinity chromatography. It was shown that JTP-74057 directly bound to MEK1 and MEK2 and allosterically inhibited their kinase activities, and that its inhibitory characteristics were similar to those of the known and different chemotype of MEK inhibitors PD0325901 and U0126. It was further shown that JTP-74057 induced rapid and sustained dephosphorylation of phosphorylated MEK in HT-29 colon and other cancer cell lines, while this decrease in phosphorylated MEK was not observed in PD0325901-treated cancer cells. Physicochemical analyses revealed that JTP-74057 preferentially binds to unphosphorylated MEK (u-MEK) in unique characteristics of both high affinity based on extremely low dissociation rates and ability stabilizing u-MEK with high thermal shift, which were markedly different from PD0325901. These findings indicate that JTP-74057 is a novel MEK inhibitor able to sustain MEK to be an unphosphorylated form resulting in pronounced suppression of the downstream signaling pathways involved in cellular proliferation.
一种小分子化合物JTP-74057/GSK1120212/曲美替尼，已被发现是一种非常有效的抗增殖剂，能够诱导细胞周期蛋白依赖性激酶抑制剂p15INK4b的积累。为了作为抗癌药物合理地进行其药物开发，使用化合物亲和色谱法将该化合物的分子靶点鉴定为MEK1/2。结果表明，JTP-74057直接与MEK1和MEK2结合，并变构抑制它们的激酶活性，并且其抑制特性与已知的不同化学类型的MEK抑制剂PD0325901和U0126相似。进一步表明，JTP-74057在HT-29结肠癌细胞系和其他癌细胞系中诱导磷酸化MEK的快速和持续去磷酸化，而在PD0325901处理的癌细胞中未观察到磷酸化MEK的这种减少。物理化学分析表明，JTP-74057以基于极低解离速率的高亲和力和以高热位移稳定未磷酸化MEK（u-MEK）的能力等独特特性优先结合未磷酸化的MEK，这与PD0325901明显不同。这些发现表明，JTP-74057是一种新型MEK抑制剂，能够使MEK维持在未磷酸化形式，从而显著抑制参与细胞增殖的下游信号通路。
