PF-4708671是一种哌嗪基嘧啶类似物,是第一个S6K1特异性抑制剂。PF-4708671不显著抑制紧密相关的S6K2亚型或一组其他AGC激酶 (Akt1, Akt2, PKA, PKCα, PKCϵ, PRK2, ROCK2, RSK1, RSK2 或SGK1)的活性。PF-4708671抑制S6K1介导的响应IGF-1(胰岛素样生长因子1)的S6蛋白的磷酸化,对PMA-诱导的底物磷酸化没有作用效果,底物与RSK (p90核糖体S6激酶)和MSK(丝分裂原和应激活化蛋白激酶)激酶高度相关。PF-4708671诱导S6K1的T型环和疏水性基序磷酸化,这种作用依赖于mTORC1 (mTOR复合体1)。PF-4708671不影响mTORC1的活性。
The tumor growth rate in mice treated with the combination of OSI-906+PF-4708671 is significantly slower than that of OSI-906 alone (P=0.0189) or PF4708671 alone (P=0.0165) treated mice. The average tumor volume in the OSI-906+PF-4708671-treated mice is approximately 50% of that in mice treated with OSI-906 (P=0.0056) or PF-4708671 alone (P<0.001) at the end of a 15-day treatment.