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低剂量格尔德霉素可抑制肝细胞生长因子及缺氧刺激的癌细胞侵袭。

Low dose geldanamycin inhibits hepatocyte growth factor and hypoxia-stimulated invasion of cancer cells.

作者信息

Koga Fumitaka, Tsutsumi Shinji, Neckers Leonard M

机构信息

Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland 20892-1107, USA.

出版信息

Cell Cycle. 2007 Jun 1;6(11):1393-402. doi: 10.4161/cc.6.11.4296. Epub 2007 Jun 13.

Abstract

Hepatocyte growth factor (HGF) receptor Met and hypoxia-inducible factor-1 (HIF-1) signaling pathways are commonly activated in aggressive tumors and promote progression. Since both Met and HIF-1alpha proteins are heat shock protein (Hsp) 90 clients, Hsp90 inhibitors might be expected to positively impact tumor progression. Here, we systematically evaluated the inhibitory effects of the prototypical Hsp90 inhibitor geldanamycin (GA) on cellular processes involved in invasion and angiogenesis in T24 bladder cancer cells stimulated with HGF and chemical hypoxia. First, we demonstrated the positive feedback loop between Met and HIF-1 pathways, which serves to sustain and amplifies their signaling in T24 cells. GA downregulated Met by inhibiting new protein maturation, thereby dampening HGF signaling. HGF and chemical hypoxia with CoCl2 cooperatively promoted in vitro invasion and vascular endothelial growth factor (VEGF) secretion, while CoCl2 but not HGF activated urokinase-type plasminogen activator and matrix metalloproteinase 2, both of which promote invasion and angiogenesis. Low dose GA (100 nmol/L) inhibited these processes by suppressing both HGF and HIF-1 pathways. Notably, brief GA pretreatment inhibited in vitro invasion and VEGF secretion induced by HGF as effectively as did continuous treatment. Moreover, we found that GA inhibited activation of focal adhesion kinase, focal adhesion assembly, and actin reorganization induced by HGF and integrin engagement by extracellular matrix. Thus, GA widely suppresses extrinsic stimuli-induced signaling that contribute to tumor invasion and angiogenesis in this bladder carcinoma model, suggesting the utility of Hsp90 inhibitors in preventing tumor progression and metastasis.

摘要

肝细胞生长因子(HGF)受体Met和缺氧诱导因子-1(HIF-1)信号通路在侵袭性肿瘤中通常被激活,并促进肿瘤进展。由于Met和HIF-1α蛋白均为热休克蛋白(Hsp)90的作用底物,因此Hsp90抑制剂可能有望对肿瘤进展产生积极影响。在此,我们系统评估了典型的Hsp90抑制剂格尔德霉素(GA)对HGF刺激和化学性缺氧条件下T24膀胱癌细胞侵袭及血管生成相关细胞过程的抑制作用。首先,我们证实了Met和HIF-1通路之间存在正反馈回路,该回路可维持并放大其在T24细胞中的信号传导。GA通过抑制新蛋白成熟来下调Met,从而减弱HGF信号传导。HGF和用CoCl2诱导的化学性缺氧协同促进体外侵袭和血管内皮生长因子(VEGF)分泌,而CoCl2而非HGF激活尿激酶型纤溶酶原激活剂和基质金属蛋白酶2,这两者均促进侵袭和血管生成。低剂量GA(100 nmol/L)通过抑制HGF和HIF-1通路来抑制这些过程。值得注意的是,短暂的GA预处理对HGF诱导的体外侵袭和VEGF分泌的抑制效果与持续处理一样有效。此外,我们发现GA抑制了HGF和细胞外基质整合素结合诱导的粘着斑激酶激活、粘着斑组装及肌动蛋白重排。因此,在该膀胱癌模型中,GA广泛抑制了有助于肿瘤侵袭和血管生成的外源性刺激诱导的信号传导,这表明Hsp90抑制剂在预防肿瘤进展和转移方面具有应用价值。

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