Queen Mary University of London, Barts and The London School of Medicine and Dentistry, Blizard Institute of Cell and Molecular Science, Centre for Diabetes, Inositide Signalling Group, 4 Newark Street, London E1 2AT, UK.
Br J Cancer. 2010 Jan 5;102(1):104-14. doi: 10.1038/sj.bjc.6605408.
Owing to its role in cancer, the phosphoinositide 3-kinase (PI3K)/Akt pathway is an attractive target for therapeutic intervention. We previously reported that the inhibition of Akt by inositol 1,3,4,5,6-pentakisphosphate (InsP(5)) results in anti-tumour properties. To further develop this compound we modified its structure to obtain more potent inhibitors of the PI3K/Akt pathway.
Cell proliferation/survival was determined by cell counting, sulphorhodamine or acridine orange/ethidium bromide assay; Akt activation was determined by western blot analysis. In vivo effect of compounds was tested on PC3 xenografts, whereas in vitro activity on kinases was determined by SelectScreen Kinase Profiling Service.
The derivative 2-O-benzyl-myo-inositol 1,3,4,5,6-pentakisphosphate (2-O-Bn-InsP(5)) is active towards cancer types resistant to InsP(5) in vitro and in vivo. 2-O-Bn-InsP(5) possesses higher pro-apoptotic activity than InsP(5) in sensitive cells and enhances the effect of anti-cancer compounds. 2-O-Bn-InsP(5) specifically inhibits 3-phosphoinositide-dependent protein kinase 1 (PDK1) in vitro (IC(50) in the low nanomolar range) and the PDK1-dependent phosphorylation of Akt in cell lines and excised tumours. It is interesting to note that 2-O-Bn-InsP(5) also inhibits the mammalian target of rapamycin (mTOR) in vitro.
InsP(5) and 2-O-Bn-InsP(5) may represent lead compounds to develop novel inhibitors of the PI3K/Akt pathway (including potential dual PDK1/mTOR inhibitors) and novel potential anti-cancer drugs.
磷酸肌醇 3-激酶（PI3K）/Akt 途径在癌症中发挥作用，是治疗干预的一个有吸引力的靶点。我们之前报道过，肌醇 1,3,4,5,6-五磷酸（InsP（5））抑制 Akt 可产生抗肿瘤特性。为了进一步开发这种化合物，我们修改了它的结构，以获得更有效的 PI3K/Akt 途径抑制剂。
通过细胞计数、硫酸罗丹明或吖啶橙/溴化乙锭测定法测定细胞增殖/存活；通过 Western blot 分析测定 Akt 激活。在 PC3 异种移植中测试化合物的体内作用，而在体外通过 SelectScreen Kinase Profiling Service 测定激酶活性。
衍生物 2-O-苄基肌醇 1,3,4,5,6-五磷酸（2-O-Bn-InsP（5））对体外和体内对 InsP（5）耐药的癌症类型具有活性。2-O-Bn-InsP（5）在敏感细胞中比 InsP（5）具有更高的促凋亡活性，并增强抗癌化合物的作用。2-O-Bn-InsP（5）在体外特异性抑制 3-磷酸肌醇依赖性蛋白激酶 1（PDK1）（IC（50）在低纳摩尔范围内）和细胞系和切除的肿瘤中 PDK1 依赖性 Akt 磷酸化。有趣的是，2-O-Bn-InsP（5）也在体外抑制哺乳动物雷帕霉素靶蛋白（mTOR）。
InsP（5）和 2-O-Bn-InsP（5）可能代表开发新型 PI3K/Akt 途径抑制剂（包括潜在的双重 PDK1/mTOR 抑制剂）和新型潜在抗癌药物的先导化合物。
