Singleton P A, Lingen M W, Fekete M J, Garcia J G N, Moss J
Department of Medicine, University of Chicago, Chicago, IL 60637, USA.
Microvasc Res. 2006 Jul-Sep;72(1-2):3-11. doi: 10.1016/j.mvr.2006.04.004. Epub 2006 Jul 3.
Angiogenesis or the formation of new blood vessels is important in the growth and metastatic potential of various cancers. Therefore, agents that inhibit angiogenesis have important therapeutic implications in numerous malignancies. We examined the effects of methylnaltrexone (MNTX), a peripheral mu opioid receptor antagonist, on agonist-induced human EC proliferation and migration, two key components in angiogenesis. Using human dermal microvascular EC, we observed that morphine sulfate (MS), the active metabolite, morphine-6-glucuronide (M6G), DAMGO ([d-Ala(2), N-Me-Phe(4), Gly(5)-ol]enkaphalin) and VEGF induced migration which were inhibited by pretreatment with MNTX at therapeutically relevant concentration (0.1 microM). The biologically inactive metabolite morphine-3-glucuronide (M3G) did not affect EC migration. We next examined the mechanism(s) by which MNTX inhibits opioid and VEGF-induced angiogenesis using human pulmonary microvascular EC. MS and DAMGO induced Src activation which was required for VEGF receptor transactivation and opioid-induced EC proliferation and migration. MNTX inhibited MS, DAMGO and VEGF induced tyrosine phosphorylation (transactivation) of VEGF receptors 1 and 2. Furthermore, MS, DAMGO and VEGF induced RhoA activation which was inhibited by MNTX or VEGF receptor tyrosine kinase inhibition. Finally, MNTX or silencing RhoA expression (siRNA) blocked MS, DAMGO and VEGF-induced EC proliferation and migration. Taken together, these results indicate that MNTX inhibits opioid-induced EC proliferation and migration via inhibition of VEGF receptor phosphorylation/transactivation with subsequent inhibition of RhoA activation. These results suggest that MNTX inhibition of angiogenesis can be a useful therapeutic intervention for cancer treatment.
血管生成或新血管的形成在各种癌症的生长和转移潜能中起着重要作用。因此，抑制血管生成的药物在众多恶性肿瘤中具有重要的治疗意义。我们研究了外周μ阿片受体拮抗剂甲基纳曲酮（MNTX）对激动剂诱导的人内皮细胞增殖和迁移的影响，这是血管生成中的两个关键组成部分。使用人真皮微血管内皮细胞，我们观察到硫酸吗啡（MS）、活性代谢物吗啡 - 6 - 葡萄糖醛酸苷（M6G）、DAMGO（[d - Ala(2)，N - Me - Phe(4)，Gly(5) - ol]脑啡肽）和血管内皮生长因子（VEGF）诱导的迁移在治疗相关浓度（0.1微摩尔）下被MNTX预处理所抑制。生物活性无的代谢物吗啡 - 3 - 葡萄糖醛酸苷（M3G）不影响内皮细胞迁移。接下来，我们使用人肺微血管内皮细胞研究了MNTX抑制阿片类药物和VEGF诱导的血管生成的机制。MS和DAMGO诱导Src激活，这是VEGF受体反式激活以及阿片类药物诱导的内皮细胞增殖和迁移所必需的。MNTX抑制MS、DAMGO和VEGF诱导的VEGF受体1和2的酪氨酸磷酸化（反式激活）。此外，MS、DAMGO和VEGF诱导RhoA激活，这被MNTX或VEGF受体酪氨酸激酶抑制所抑制。最后，MNTX或沉默RhoA表达（小干扰RNA）阻断了MS、DAMGO和VEGF诱导的内皮细胞增殖和迁移。综上所述，这些结果表明MNTX通过抑制VEGF受体磷酸化/反式激活并随后抑制RhoA激活来抑制阿片类药物诱导的内皮细胞增殖和迁移。这些结果表明MNTX对血管生成的抑制可能是癌症治疗的一种有用的治疗干预措施。
