Hypoxia and Therapeutics Group, School of Pharmacy and Pharmaceutical Sciences, University of Manchester, Oxford Road, Manchester M13 9PT, United Kingdom.
J Clin Endocrinol Metab. 2011 Dec;96(12):E1934-43. doi: 10.1210/jc.2011-1426. Epub 2011 Oct 12.
Phosphoinositide 3-kinase (PI3K) regulates the transcription factor hypoxia-inducible factor-1 (HIF-1) in thyroid carcinoma cells. Both pathways are associated with aggressive phenotype in thyroid carcinomas.
Our objective was to assess the effects of the clinical PI3K inhibitor GDC-0941 and genetic inhibition of PI3K and HIF on metastatic behavior of thyroid carcinoma cells in vitro and in vivo.
Vascular endothelial growth factor ELISA, HIF activity assays, proliferation studies, and scratch-wound migration and cell spreading assays were performed under various O(2) tensions [normoxia, hypoxia (1 and 0.1% O(2)), and anoxia] with or without GDC-0941 in a panel of four thyroid carcinoma cell lines (BcPAP, WRO, FTC133, and 8505c). Genetic inhibition was achieved by overexpressing phosphatase and tensin homolog (PTEN) into PTEN-null cells and by using a dominant-negative variant of HIF-1α (dnHIF). In vivo, human enhanced green fluorescence protein-expressing follicular thyroid carcinomas (FTC) were treated with GDC-0941 (orally). Spontaneous lung metastasis was confirmed by viewing enhanced green fluorescence protein-positive colonies cultured from lung tissue.
GDC-0941 inhibited hypoxia/anoxia-induced HIF-1α and HIF-2α expression and HIF activity in thyroid carcinoma cells. Basal (three of four cell lines) and/or hypoxia-induced (four of four) secreted vascular endothelial growth factor was inhibited by GDC-0941, whereas selective HIF targeting predominantly affected hypoxia/anoxia-mediated secretion (P < 0.05-0.0001). Antiproliferative effects of GDC-0941 were more pronounced in PTEN mutant compared with PTEN-restored cells (P < 0.05). Hypoxia increased migration in papillary cells and cell spreading/migration in FTC cells (P < 0.01). GDC-0941 reduced spreading and migration in all O(2) conditions, whereas dnHIF had an impact only on hypoxia-induced migration (P < 0.001). In vivo, GDC-0941 reduced expression of HIF-1α, phospho-AKT, GLUT-1, and lactate dehydrogenase A in FTC xenografts. DnHIF expression and GDC-0941 reduced FTC tumor growth and metastatic lung colonization (P < 0.05).
PI3K plays a prominent role in the metastatic behavior of thyroid carcinoma cells irrespective of O(2) tension and appears upstream of HIF activation. GDC-0941 significantly inhibited the metastatic phenotype, supporting the clinical development of PI3K inhibition in thyroid carcinomas.
磷酸肌醇 3-激酶（PI3K）调节甲状腺癌细胞中的转录因子缺氧诱导因子-1（HIF-1）。这两种途径都与甲状腺癌的侵袭性表型有关。
我们的目的是评估临床 PI3K 抑制剂 GDC-0941 以及 PI3K 和 HIF 的基因抑制对甲状腺癌细胞在体外和体内转移行为的影响。
在各种氧张力[常氧、缺氧（1%和 0.1%O2）和缺氧]下，使用血管内皮生长因子 ELISA、HIF 活性测定、增殖研究、划痕迁移和细胞扩展测定，在一组四种甲状腺癌细胞系（BcPAP、WRO、FTC133 和 8505c）中进行了评估，同时使用 GDC-0941 进行或不进行 GDC-0941。通过过表达磷酸酶和张力蛋白同源物（PTEN）到 PTEN 缺失细胞中，以及使用 HIF-1α 的显性负变体（dnHIF）来实现基因抑制。在体内，用 GDC-0941（口服）处理人增强型绿色荧光蛋白表达滤泡性甲状腺癌（FTC）。通过观察从肺组织培养的增强型绿色荧光蛋白阳性集落来证实自发性肺转移。
GDC-0941 抑制了甲状腺癌细胞中缺氧/缺氧诱导的 HIF-1α 和 HIF-2α 表达和 HIF 活性。GDC-0941 抑制了基础（四种细胞系中的三种）和/或缺氧诱导的（四种细胞系中的四种）分泌的血管内皮生长因子，而选择性 HIF 靶向主要影响缺氧/缺氧介导的分泌（P < 0.05-0.0001）。与 PTEN 恢复细胞相比，GDC-0941 在 PTEN 突变细胞中更显著地抑制了增殖作用（P < 0.05）。缺氧增加了乳头状细胞的迁移和 FTC 细胞的细胞扩展/迁移（P < 0.01）。GDC-0941 减少了所有 O2 条件下的扩展和迁移，而 dnHIF 仅对缺氧诱导的迁移有影响（P < 0.001）。在体内，GDC-0941 降低了 FTC 异种移植物中 HIF-1α、磷酸化 AKT、GLUT-1 和乳酸脱氢酶 A 的表达。dnHIF 表达和 GDC-0941 减少了 FTC 肿瘤的生长和转移性肺定植（P < 0.05）。
PI3K 在甲状腺癌细胞的转移行为中起着突出的作用，而与 O2 张力无关，并且似乎在 HIF 激活的上游。GDC-0941 显著抑制了转移表型，支持甲状腺癌中 PI3K 抑制的临床发展。
