Department of Endocrinology, Physiopathology, and Applied Biology, University of Milan, Via Balzaretti 9, 20133 Milan, Italy.
Endocrinology. 2010 Oct;151(10):4643-53. doi: 10.1210/en.2010-0163. Epub 2010 Aug 4.
We showed previously that GnRH receptors are expressed in melanoma cells; their activation reduces cell growth and metastatic behavior. Here, we investigated whether GnRH agonists might affect the expression of genes involved in melanoma progression. By genome-wide transcriptomic and real-time PCR analysis, we first observed that GnRH agonists decrease the expression of the pro-angiogenic factor vascular endothelial growth factor (VEGF) (all isoforms) in BLM melanoma cells. Then, we demonstrated that GnRH agonists specifically decrease the expression of the VEGF165 isoform as well as its secretion from BLM cells. These data suggested that activation of GnRH receptors might reduce the pro-angiogenic behavior of melanoma cells. To verify this hypothesis, we treated BLM cells with a GnRH agonist; the conditioned medium from these cells was tested to assess its capability to stimulate human umbilical vein endothelial cell (HUVEC) motility. The migration of HUVECs towards the conditioned medium of GnRH agonist-treated BLM cells was significantly lower than the migration of HUVECs toward the conditioned medium of untreated cells. Thus, GnRH agonists reduce the pro-angiogenic behavior of melanoma cells through a decreased production of bioactive VEGF. We then found that GnRH receptors are also expressed on HUVECs and that GnRH agonists reduce their ability to proliferate and to form capillary-like tubes when stimulated by VEGF. These findings suggest that GnRH agonists exert an anti-angiogenic activity indirectly by decreasing VEGF secretion from tumor cells and directly by counteracting the pro-angiogenic activity of the growth factor. These data might lead to the development of novel targeted approaches for melanoma.
我们之前已经证明 GnRH 受体在黑色素瘤细胞中表达；其激活可降低细胞生长和转移行为。在这里，我们研究了 GnRH 激动剂是否可能影响黑色素瘤进展相关基因的表达。通过全基因组转录组学和实时 PCR 分析，我们首先观察到 GnRH 激动剂可降低 BLM 黑色素瘤细胞中促血管生成因子血管内皮生长因子 (VEGF)（所有同工型）的表达。然后，我们证明 GnRH 激动剂特异性降低了 VEGF165 同工型及其从 BLM 细胞中的分泌。这些数据表明 GnRH 受体的激活可能降低黑色素瘤细胞的促血管生成行为。为了验证这一假设，我们用 GnRH 激动剂处理 BLM 细胞；检测这些细胞的条件培养基以评估其刺激人脐静脉内皮细胞 (HUVEC) 迁移的能力。HUVEC 向 GnRH 激动剂处理的 BLM 细胞条件培养基中迁移的速度明显低于向未处理细胞条件培养基中迁移的速度。因此， GnRH 激动剂通过降低生物活性 VEGF 的产生来降低黑色素瘤细胞的促血管生成行为。然后我们发现 GnRH 受体也在 HUVEC 上表达，并且 GnRH 激动剂在受到 VEGF 刺激时降低了它们的增殖能力和形成毛细血管样管的能力。这些发现表明 GnRH 激动剂通过减少肿瘤细胞分泌的 VEGF 间接发挥抗血管生成活性，并通过拮抗生长因子的促血管生成活性直接发挥抗血管生成活性。这些数据可能为黑色素瘤的发展提供新的靶向方法。
