Division of Experimental Cancer Research, Department of Translational Medicine, Lund University, Clinical Research Centre, Malmö, Sweden.
Division of Basal Tumor Biology, Department of Molecular Biology, Umeå University, Umeå, Sweden.
Oncogene. 2019 Jan;38(3):375-389. doi: 10.1038/s41388-018-0438-2. Epub 2018 Aug 13.
Despite recent improvement in adjuvant therapies, triple-negative, and ER subtypes of breast cancer (BC) with metastatic potentials remain the leading cause of BC-related deaths. We investigated the role of phosphatidylinositol-4-phosphate 5-kinase alpha (PIP5Kα), a key upstream factor of PI3K/AKT, and the therapeutic effect of PIP5Kα inhibitor on subtypes of BC. The clinical importance of PIP5K1α and its association with survivals were analyzed using three BC cohorts from Nottingham (n = 913), KM plotter (n = 112) and TCGA (n = 817). Targeted overexpression or knockdown of PIP5K1α were introduced into BC cell lines. The effects of PIP5K1α and its inhibitor on growth and invasion of BC were confirmed by using in vitro assays including proliferation, migration, apoptosis and luciferase reporter assays and in vivo xenograft mouse models. All statistical tests were two-sided. PIP5K1α was associated with poor patient outcome in triple-negative BC (for PIP5K1α protein, p = 0.011 and for mRNA expression, p = 0.028, log-rank test). 29% of triple-negative BC had PIP5K1A gene amplification. Elevated level of PIP5K1α increased expression of pSer-473 AKT (p < 0.001) and invasiveness of triple-negative MDA-MB-231 cells (p < 0.001). Conversely, inhibition of PIP5K1α using its inhibitor ISA-2011B, or via knockdown suppressed growth and invasiveness of MDA-MB-231 xenografts (mean vehicle-treated controls = 2160 mm, and mean ISA-2011B-treated = 600 mm, p < 0.001). ISA-2011B-treatment reduced expression of pSer-473 AKT (p < 0.001) and its downstream effectors including cyclin D1, VEGF and its receptors, VEGFR1 and VEGFR2 (p < 0.001) in xenograft tumors. In ER cancer cells, PIP5K1α acted on pSer-473 AKT, and was in complexes with VEGFR2, serving as co-factor of ER-alpha to regulate activities of target genes including cyclin D1 and CDK1. Our study suggests that our developed PIP5K1α inhibitor has a great potential on refining targeted therapeutics for treatment of triple-negative and ER BC with abnormal PI3K/AKT pathways.
尽管辅助治疗最近有所改善，但具有转移潜力的三阴性和 ER 型乳腺癌（BC）仍然是导致 BC 相关死亡的主要原因。我们研究了磷脂酰肌醇-4-磷酸 5-激酶α（PIP5Kα）的作用，PIP5Kα 是 PI3K/AKT 的关键上游因子，以及 PIP5Kα 抑制剂对 BC 亚型的治疗效果。使用来自诺丁汉的三个 BC 队列（n=913）、KM plotter（n=112）和 TCGA（n=817）分析了 PIP5K1α 的临床重要性及其与存活率的关联。通过在体外测定（包括增殖、迁移、凋亡和荧光素酶报告基因测定）和体内异种移植小鼠模型中，将 PIP5K1α 的靶向过表达或敲低引入 BC 细胞系。使用 PIP5K1α 及其抑制剂对 BC 的生长和侵袭的影响进行了确认。所有统计检验均为双侧检验。在三阴性 BC 中，PIP5K1α 与患者预后不良相关（对于 PIP5K1α 蛋白，p=0.011，对于 mRNA 表达，p=0.028，对数秩检验）。29%的三阴性 BC 存在 PIP5K1A 基因扩增。PIP5K1α 水平升高会增加 pSer-473 AKT 的表达（p<0.001），并增加三阴性 MDA-MB-231 细胞的侵袭性（p<0.001）。相反，使用其抑制剂 ISA-2011B 或通过敲低抑制 PIP5K1α，可抑制 MDA-MB-231 异种移植物的生长和侵袭性（平均载体处理对照组为 2160mm，平均 ISA-2011B 处理组为 600mm，p<0.001）。ISA-2011B 治疗可降低异种移植肿瘤中 pSer-473 AKT 的表达（p<0.001）及其下游效应物，包括细胞周期蛋白 D1、VEGF 及其受体 VEGFR1 和 VEGFR2（p<0.001）。在 ER 癌细胞中，PIP5K1α 作用于 pSer-473 AKT，并与 VEGFR2 形成复合物，作为 ER-α 的辅助因子，调节包括细胞周期蛋白 D1 和 CDK1 在内的靶基因的活性。我们的研究表明，我们开发的 PIP5K1α 抑制剂在针对具有异常 PI3K/AKT 途径的三阴性和 ER BC 的靶向治疗方面具有巨大潜力。
