Department of Bioscience and Biotechnology, Sejong University, Seoul, Korea.
Clin Exp Metastasis. 2010 Dec;27(8):601-9. doi: 10.1007/s10585-010-9350-z. Epub 2010 Sep 7.
Angiogenesis is induced by soluble factors such as vascular endothelial growth factor (VEGF) released from tumor cells in hypoxia. It enhances solid tumor growth and provides an ability to establish metastasis at peripheral sites by tumor cell migration. Thymosin beta-4 (TB4) is an actin-sequestering protein to control cytoskeletal reorganization. Here, we investigated whether angiogenesis and tumor metastasis are dependent on hypoxia conditioning-induced TB4 expression in B16F10 melanoma cells. TB4 expression in B16F10 cells was increased by hypoxia conditioning in a time-dependent manner. In addition, we found an increase of angiogenesis and HIF-1α expression in TB4-transgenic (Tg) mice as compared to wildtype mice. When wound healing assay was used to assess in vitro tumor cell migration, hypoxia conditioning for 1 h enhanced B16F10 cell migration. When TB4 expression in B16F10 cells was inhibited by the infection with small hairpin (sh) RNA of TB4 cloned in lentiviral vector, tumor cell migration was retarded. In addition, hypoxia conditioning-induced tumor cell migration was reduced by the infection of lentiviral shRNA of TB4. HIF-1α stabilization and the expression of VEGF isoform 165 and 121 in hypoxia were also reduced by the infection of lentiviral shRNA of TB4 in B16F10 cells. We also found an increase of tumor growth and lung metastasis count in TB4-Tg mice as compared to wildtype mice. Collectively, hypoxia conditioning induced tumor cell migration by TB4 expression-dependent HIF-1α stabilization. It suggests that TB4 could be a hypoxia responsive regulator to control tumor cell migration in angiogenesis and tumor metastasis.
血管生成是由缺氧条件下肿瘤细胞释放的可溶性因子（如血管内皮生长因子 [VEGF]）诱导的。它增强了实体瘤的生长，并通过肿瘤细胞迁移提供了在周围部位建立转移的能力。胸腺肽β-4（TB4）是一种肌动蛋白结合蛋白，可控制细胞骨架的重组。在这里，我们研究了血管生成和肿瘤转移是否依赖于缺氧条件诱导的 B16F10 黑色素瘤细胞中 TB4 的表达。TB4 在 B16F10 细胞中的表达随缺氧条件而呈时间依赖性增加。此外，我们发现 TB4 转基因（Tg）小鼠的血管生成和 HIF-1α 表达增加，与野生型小鼠相比。当使用划痕愈合实验评估体外肿瘤细胞迁移时，1 小时的缺氧条件增强了 B16F10 细胞的迁移。当 B16F10 细胞中的 TB4 表达通过感染带有 TB4 的慢病毒载体克隆的短发夹（sh）RNA 而被抑制时，肿瘤细胞迁移被延迟。此外，TB4 的感染也降低了缺氧诱导的肿瘤细胞迁移。TB4 的感染还降低了缺氧条件下 HIF-1α 的稳定和 VEGF 同工型 165 和 121 的表达。我们还发现 TB4-Tg 小鼠的肿瘤生长和肺转移计数增加，与野生型小鼠相比。总之，缺氧条件通过 TB4 表达依赖性 HIF-1α 稳定诱导肿瘤细胞迁移。这表明 TB4 可能是一种缺氧反应调节剂，可控制血管生成和肿瘤转移中的肿瘤细胞迁移。
