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 mm³, and mean ISA-2011B-treated = 600 mm³, 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.

中文翻译：

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PIP5K1α/ pAKT的作用和使用PIP5K1α抑制剂靶向抑制乳腺癌亚型的生长。

尽管最近辅助治疗，三阴性和ER ⁺有所改善具有转移潜能的乳腺癌（BC）亚型仍然是与BC相关的死亡的主要原因。我们研究了磷脂酰肌醇-4-磷酸5-激酶α（PIP5Kα）（PI3K / AKT的关键上游因子）的作用，以及PIP5Kα抑制剂对BC亚型的治疗作用。使用来自诺丁汉（n = 913），KM绘图仪（n = 112）和TCGA（n = 817）的三个BC队列分析了PIP5K1α的临床重要性及其与生存的关系。将靶向过表达或敲低的PIP5K1α导入BC细胞系。通过使用体外试验（包括增殖，迁移，凋亡和荧光素酶报告基因试验）以及体内异种移植小鼠模型，证实了PIP5K1α及其抑制剂对BC生长和侵袭的影响。所有统计检验都是两面的。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具有PIP5K1A基因扩增。PIP5K1α水平升高会增加pSer-473 AKT的表达（p <0.001）和三阴性MDA-MB-231细胞的侵袭性（p <0.001）。相反，使用抑制剂ISA-2011B或通过敲低抑制PIP5K1α抑制了MDA-MB-231异种移植物的生长和侵袭（平均媒介物处理对照组= 2160 mm³，平均ISA-2011B处理= 600 mm ³，p <0.001）。ISA-2011B处理可降低异种移植肿瘤中pSer-473 AKT及其下游效应物（包括细胞周期蛋白D1，VEGF及其受体，VEGFR1和VEGFR2）的表达（p <0.001）（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的辅因子来调节靶基因（包括细胞周期蛋白D1和CDK1）的活性。我们的研究表明，我们开发的PIP5K1α抑制剂在精制靶向疗法方面具有巨大潜力，可用于治疗PI3K / AKT途径异常的三阴性和ER ⁺ BC。