Sorafenib (BAY 43-9006) inhibits tumor growth and vascularization and induces tumor apoptosis and hypoxia in RCC xenograft models
Sorafenib (BAY 43-9006) inhibits tumor growth and vascularization and induces tumor apoptosis and hypoxia in RCC xenograft models
复制标题
DOI：
10.1007/s00280-006-0393-4
复制
发表时间：
2007-04-01
影响因子：
3
通讯作者：
Wilhelm, Scott
中科院分区：
文献类型：
--
作者：
Chang, Yong S.;Adnane, Jalila;Wilhelm, Scott
新的研究发现揭示了血管内皮生长因子（VEGF）在刺激肾透明细胞癌（RCC）血管生成中的关键作用，RCC是一种高度血管化和治疗抗性的肿瘤。索拉非尼（BAY 43-9006，Nexavar（（R）是一种多激酶抑制剂，其靶向参与肿瘤进展和肿瘤血管生成的受体酪氨酸和丝氨酸/苏氨酸激酶。索拉非尼口服给药于小鼠皮下（SC，异位）或肾包膜下（SRC，原位）肿瘤的小鼠（Renca）或人（786-O）RCC。通过测量肿瘤体积和肿瘤生长延迟来确定治疗功效。在作用机制研究中，使用786-O和Renca RCC肿瘤模型，在SC模型中给药3或5天后以及在SRC模型中给药21天后评估索拉非尼的作用。通过免疫组织化学（IHC）测量CD 31和α-平滑肌肌动蛋白（α SMA）染色水平来评估肿瘤血管生成的抑制。还通过分别测量磷酸化ERK、磷酸化组蛋白H3和Ki-67染色水平，通过IHC评估索拉非尼对MAPK信号传导、细胞周期进程和细胞增殖的影响。肿瘤细胞凋亡的程度通过末端脱氧核苷酸转移酶介导的缺口末端标记（TUNEL）测定。最后，在786- 0 SC模型中通过在肿瘤收集前1小时静脉内注射盐酸哌莫硝唑来评估索拉非尼对肿瘤缺氧的影响，并用FITC缀合的Hypoxyprobe抗体对肿瘤切片进行染色。索拉非尼产生显著的肿瘤生长抑制（TGI），并减少异位和原位Renca和786- 0肿瘤的肿瘤血管，每日给药时剂量低至15 mg/kg。早在治疗后3天就观察到肿瘤血管的抑制，并且这种血管生成的抑制与肿瘤细胞凋亡（TUNEL阳性）和中央坏死水平的增加相关。与这些结果一致，在786- 0 SC模型中治疗后3天也观察到肿瘤缺氧显著增加。然而，索拉非尼对磷酸化ERK，磷酸化组蛋白H3或Ki-67水平在任何RCC肿瘤模型中均无显著影响，我们的研究结果表明索拉非尼能够有效抑制异位和原位植入的Renca和786-O肿瘤的生长。观察到的肿瘤生长抑制和肿瘤停滞或稳定与肿瘤血管生成减少密切相关，这至少部分是由于VEGF和PDGF介导的内皮细胞和周细胞存活的抑制。最后，索拉非尼介导的肿瘤生长和血管生成抑制发生在与临床患者中达到的浓度相当的浓度。
New research findings have revealed a key role for vascular endothelial growth factor (VEGF) in the stimulation of angiogenesis in clear cell renal carcinoma (RCC) which is a highly vascularized and treatment-resistant tumor. Sorafenib (BAY 43-9006, Nexavar((R))) is a multi-kinase inhibitor which targets receptor tyrosine and serine/threonine kinases involved in tumor progression and tumor angiogenesis. The effect of sorafenib on tumor growth and tumor histology was assessed in both ectopic and orthotopic mouse models of RCC.Sorafenib was administered orally to mice bearing subcutaneous (SC, ectopic) or sub-renal capsule (SRC, orthotopic) tumors of murine (Renca) or human (786-O) RCC. Treatment efficacy was determined by measurements of tumor volume and tumor growth delay. In mechanism of action studies, using the 786-O and Renca RCC tumor models, the effect of sorafenib was assessed after dosing for 3 or 5 days in the SC models and 21 days in the SRC models. Inhibition of tumor angiogenesis was assessed by measuring level of CD31 and alpha-smooth muscle actin (alpha SMA) staining by immunohistochemistry (IHC). The effect of sorafenib on MAPK signaling, cell cycle progression and cell proliferation was also assessed by IHC by measuring levels of phospho-ERK, phospho-histone H3 and Ki-67 staining, respectively. The extent of tumor apoptosis was measured by terminal deoxynucleotidyl transferase-mediated nick-end labeling (TUNEL) assays. Finally, the effects of sorafenib on tumor hypoxia was assessed in 786-O SC model by injecting mice intravenously with pimonidazole hydrochloride 1 h before tumor collection and tumor sections were stained with a FITC-conjugated Hypoxyprobe antibody.Sorafenib produced significant tumor growth inhibition (TGI) and a reduction in tumor vasculature of both ectopic and orthotopic Renca and 786-O tumors, at a dose as low as 15 mg/kg when administered daily. Inhibition of tumor vasculature was observed as early as 3 days post-treatment, and this inhibition of angiogenesis correlated with increased level of tumor apoptosis (TUNEL-positive) and central necrosis. Consistent with these results, a significant increase in tumor hypoxia was also observed 3 days post-treatment in 786-O SC model. However, no significant effect of sorafenib on phospho-ERK, phospho-histone H3 or Ki-67 levels in either RCC tumor model was observed.Our results show the ability of sorafenib to potently inhibit the growth of both ectopically- and orthotopically-implanted Renca and 786-O tumors. The observed tumor growth inhibition and tumor stasis or stabilization correlated strongly with decreased tumor angiogenesis, which was due, at least in part, to inhibition of VEGF and PDGF-mediated endothelial cell and pericyte survival. Finally, sorafenib-mediated inhibition of tumor growth and angiogenesis occurred at concentrations equivalent to those achieved in patients in the clinic.