Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, New York.
Louis V. Gerstner, Jr. Graduate School of Biomedical Sciences, Memorial Sloan Kettering Cancer Center, New York, New York.
Mol Cancer Res. 2021 Apr;19(4):573-584. doi: 10.1158/1541-7786.MCR-20-0623. Epub 2020 Dec 10.
Mutational activation of the PI3K/AKT pathway is among the most common pro-oncogenic events in human cancers. The clinical utility of PI3K and AKT inhibitors has, however, been modest to date. Here, we used CRISPR-mediated gene editing to study the biological consequences of AKT1 E17K mutation by developing an AKT1 E17K-mutant isogenic system in a -null background. AKT1 E17K expression under the control of its endogenous promoter enhanced cell growth and colony formation, but had a paradoxical inhibitory effect on cell migration and invasion. The mechanistic basis by which activated AKT1 inhibited cell migration and invasion was increased E-cadherin expression mediated by suppression of transcription via altered β-catenin subcellular localization. This phenotypic effect was AKT1-specific, as AKT2 activation had the opposite effect, a reduction in E-cadherin expression. Consistent with the opposing effects of AKT1 and AKT2 activation on E-cadherin expression, a pro-migratory effect of AKT1 activation was not observed in breast cancer cells with PTEN loss or expression of an activating mutation, alterations which induce the activation of both AKT isoforms. The results suggest that the use of AKT inhibitors in patients with breast cancer could paradoxically accelerate metastatic progression in some genetic contexts and may explain the frequent coselection for mutations in -mutated breast tumors. IMPLICATIONS: AKT1 E17K mutation in breast cancer impairs migration/invasiveness via sequestration of β-catenin to the cell membrane leading to decreased transcription, resulting in increased E-cadherin expression and a reversal of epithelial-mesenchymal transition.
PI3K/AKT 通路的突变激活是人类癌症中最常见的致癌事件之一。然而，到目前为止，PI3K 和 AKT 抑制剂的临床应用效果一直不太理想。在这里，我们使用 CRISPR 介导的基因编辑技术，在 -null 背景下开发 AKT1 E17K 突变的同源基因系统，研究 AKT1 E17K 突变的生物学后果。在其内源启动子的控制下，AKT1 E17K 的表达增强了细胞的生长和集落形成，但对细胞迁移和侵袭有相反的抑制作用。激活的 AKT1 通过改变 β-连环蛋白的亚细胞定位抑制转录，从而增加 E-钙粘蛋白表达，从而产生这种表型效应的机制基础。这种表型效应是 AKT1 特异性的，因为 AKT2 的激活具有相反的效果，即 E-钙粘蛋白表达减少。与 AKT1 和 AKT2 激活对 E-钙粘蛋白表达的相反作用一致，在具有 PTEN 缺失或激活 突变表达的乳腺癌细胞中，AKT1 激活没有观察到促迁移作用，这些改变诱导两种 AKT 同工型的激活。结果表明，在某些遗传背景下，乳腺癌患者使用 AKT 抑制剂可能会产生矛盾的效果，加速转移进展，这可能解释了在 -突变的乳腺癌中经常选择 突变的原因。意义：乳腺癌中的 AKT1 E17K 突变通过将 β-连环蛋白隔离到细胞膜上，从而减少 转录，导致 E-钙粘蛋白表达增加，上皮-间充质转化逆转，从而损害迁移/侵袭能力。
