Oh Seung Hyun, Woo Jong Kyu, Yazici Yasemin Dakak, Myers Jeffrey N, Kim Woo-Young, Jin Quanri, Hong Soon Sun, Park Hyun-Ju, Suh Young-Ger, Kim Kyu-Won, Hong Waun Ki, Lee Ho-Young
Department of Thoracic/Head and Neck Medical Oncology, The University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Blvd, Houston, TX 77030, USA.
J Natl Cancer Inst. 2007 Jun 20;99(12):949-61. doi: 10.1093/jnci/djm007. Epub 2007 Jun 12.
The molecular chaperone heat shock protein 90 (Hsp90) participates in preserving the expression and activity of various oncoproteins, including hypoxia-inducible factor 1alpha (HIF-1alpha) and Akt. Deguelin is a rotenoid with antitumor activities. We investigated whether the antitumor activities of deguelin involve the functional inhibition of Hsp90.
Human xenograft tumors were generated in mice from H1299 (n = 6 per group) and A549 (n = 4 per group) non-small-cell lung cancer cells, UMSCC38 (n = 5 per group) head and neck cancer cells, MKN45 (n = 5 per group) stomach cancer cells, and PC-3 (n = 3 per group) prostate cancer cells. Tumor-bearing mice were treated with deguelin at 4 or 8 mg/kg or with vehicle (as a control) twice a day by oral gavage for 15-28 days. Protein expression was assessed by western blot analysis. Akt and Hsp90 were assessed by use of adenoviral vectors expressing constitutively active Akt or Hsp90. Binding of deguelin to Hsp90 was examined by docking analysis and by competition binding experiments with ATP-Sepharose beads. The proteasome inhibitor MG132 was used to investigate deguelin's effect on the induction of ubiquitin-mediated proteasomal degradation of HIF-1alpha. All statistical tests were two-sided.
Deguelin bound to the ATP-binding pocket of Hsp90 and disrupted Hsp90 function, leading to ubiquitin-mediated degradation of HIF-1alpha. Administration of deguelin to xenograft-bearing mice statistically significantly decreased tumor growth by inducing apoptosis and decreasing the expression of Hsp90 client proteins, without detectable toxic effects. For example, at 15 days after the start of deguelin treatment, the volume of untreated control H1299 xenograft tumors was 798 mm3 and that of xenograft tumors treated with deguelin at 4 mg/kg was 115.9 mm3 (difference = 682.1 mm3, 95% confidence interval = 480.4 to 883.9 mm3; P<.001).
The antitumor activities of deguelin appear to involve its binding to the ATP-binding pocket of Hsp90, which suppresses Hsp90 function.
分子伴侣热休克蛋白90（Hsp90）参与维持多种癌蛋白的表达和活性，包括缺氧诱导因子1α（HIF-1α）和Akt。鱼藤素是一种具有抗肿瘤活性的鱼藤酮类化合物。我们研究了鱼藤素的抗肿瘤活性是否涉及对Hsp90功能的抑制。
将人H1299（每组6只）和A549（每组4只）非小细胞肺癌细胞、UMSCC38（每组5只）头颈癌细胞、MKN45（每组5只）胃癌细胞和PC-3（每组3只）前列腺癌细胞接种到小鼠体内生成人异种移植瘤。荷瘤小鼠每天经口灌胃给予4或8mg/kg鱼藤素或溶剂（作为对照），共15 - 28天。通过蛋白质印迹分析评估蛋白质表达。使用表达组成型活性Akt或Hsp90的腺病毒载体评估Akt和Hsp90。通过对接分析和与ATP-琼脂糖珠的竞争结合实验检测鱼藤素与Hsp90的结合。使用蛋白酶体抑制剂MG132研究鱼藤素对HIF-1α泛素介导的蛋白酶体降解诱导作用的影响。所有统计检验均为双侧检验。
鱼藤素与Hsp90的ATP结合口袋结合并破坏Hsp90功能，导致HIF-1α的泛素介导降解。给荷异种移植瘤小鼠施用鱼藤素通过诱导凋亡和降低Hsp90客户蛋白的表达，在统计学上显著降低肿瘤生长，且未检测到毒性作用。例如，在鱼藤素治疗开始后15天，未治疗的对照H1299异种移植瘤体积为798mm³，而用4mg/kg鱼藤素治疗的异种移植瘤体积为115.9mm³（差异 = 682.1mm³，95%置信区间 = 480.4至883.9mm³；P <.001）。
鱼藤素的抗肿瘤活性似乎涉及其与Hsp90的ATP结合口袋结合，从而抑制Hsp90功能。
