Division of Anti-Tumor Pharmacology, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China.
Acta Pharmacol Sin. 2013 Sep;34(9):1201-7. doi: 10.1038/aps.2013.81. Epub 2013 Jul 29.
To identify the contribution of individual isoform (α, β, γ, δ) of class I PI3Ks to tumor cell growth for proper use of PI3K inhibitors in cancer therapy.
A panel of human rhabdomyosarcoma Rh30 cells stably expressing myristoylation (Myr)-tagged one of class I PI3K p110 subunits was established. PI3K activity was analyzed by measuring phosphorylated Akt with Western blotting, and isoform-specific PI3K activities were validated with PI3K isoform-selective inhibitors. The growth of prostate cancer PC-3 cells and B cell type leukemia Raji cells was determined using SRB assay and CCK-8 assay, respectively.
The phosphorylation of Akt in Rh30-Myr-p110α, β, γ, δ cells was preferentially inhibited by PI3K isoform-selective inhibitors A66 (PI3Kα), TGX221 (PI3Kβ), AS604850 (PI3Kγ) and CAL-101 (PI3Kδ), respectively. A newly obtained PI3K inhibitor WJD008 (10 μmol/L) completely abrogated Akt phosphorylation by all the isoforms of class I PI3Ks, thus acted as a pan-PI3K inhibitor. In prostate cancer PC-3 cells, the PI3K isoform-selective inhibitors were much less potent than WJD008 in suppression of the proliferation. In B cell type leukemia Raji cells, inhibition of PI3Kδ alone or all the isoforms of class I PI3Ks displayed similar potency against the cell proliferation, whereas selective inhibition of individual PI3Kα/β/γ isoforms resulted in negligible activity.
Rh30-Myr-p110α, β, γ, δ cells are a useful cell model to identify the selectivity of PI3K inhibitors. Pan-PI3K inhibitors are suitable for treating PC-3 cells, whereas selective PI3Kδ inhibitor is sufficient to block Raji cell growth. The biased dependency on PI3K isoforms for tumor cell growth rationalizes the use of PI3K inhibitors with different selectivity for cancer therapy.
为了正确地将 PI3K 抑制剂用于癌症治疗，确定 I 类 PI3K 的个体同工型（α、β、γ、δ）对肿瘤细胞生长的贡献。
建立了一组稳定表达豆蔻酰化（Myr）标记的 I 类 PI3K p110 亚基之一的人横纹肌肉瘤 Rh30 细胞系。通过 Western blot 测定磷酸化 Akt 来分析 PI3K 活性，并使用 PI3K 同工型选择性抑制剂验证同工型特异性 PI3K 活性。使用 SRB 测定法和 CCK-8 测定法分别测定前列腺癌细胞 PC-3 和 B 细胞白血病 Raji 细胞的生长。
Rh30-Myr-p110α、β、γ、δ细胞中 Akt 的磷酸化分别被 PI3K 同工型选择性抑制剂 A66（PI3Kα）、TGX221（PI3Kβ）、AS604850（PI3Kγ）和 CAL-101（PI3Kδ）优先抑制。一种新获得的 PI3K 抑制剂 WJD008（10 μmol/L）完全阻断了 I 类 PI3K 的所有同工型对 Akt 的磷酸化作用，因此它是一种泛 PI3K 抑制剂。在前列腺癌细胞 PC-3 中，PI3K 同工型选择性抑制剂在抑制增殖方面的效力远低于 WJD008。在 B 细胞白血病 Raji 细胞中，单独抑制 PI3Kδ 或 I 类 PI3K 的所有同工型对细胞增殖具有相似的效力，而选择性抑制单个 PI3Kα/β/γ 同工型则几乎没有活性。
Rh30-Myr-p110α、β、γ、δ 细胞是一种有用的细胞模型，可用于鉴定 PI3K 抑制剂的选择性。泛 PI3K 抑制剂适用于治疗 PC-3 细胞，而选择性 PI3Kδ 抑制剂足以阻断 Raji 细胞的生长。肿瘤细胞生长对 PI3K 同工型的依赖性表明，为癌症治疗选择具有不同选择性的 PI3K 抑制剂是合理的。
