A Study on the Angiogenesis Function of Melanotan II

• Main Author: 黃博玲
• Other Authors: Huang, R.L.
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/72657172888623263230

碩士 === 美和科技大學 === 健康與生技產業研究所 === 100 === Angiogenesis refers to the physiological process for the growth of new blood vessels evolving from pre-existing vessels. Angiogenesis is a normal and vital process in growth and development, as well as in wound healing and granulation tissue. Moreover, it is also a fundamental step in the transition of tumors from dormant to malignant state. It has also been found that one of the critical events required for metastasis is the growth of a new network of blood vessels. Without angiogenesis, the tumor growth will simply cease. Thus, to develop angiogenesis inhibitor becomes a very important target for anti-neoplasia medicinal development. Pro-opiomelanocortin (POMC) is a prohormone of various neuropeptides, including α-, β-, and γ-melanocyte–stimulating hormone (α-, β-, and γ-MSH), lipotropins, and β-endorphin. POMC peptides possess pleiotropic functions, including pigmentation, adrenocortical function, metabolism of energy storage, regulation of the immune system. Recently, it has been reported that over expression of POMC gene transfer attenuates the migration of endothelin-1, and the ability of tube formation in cultured endothelial cells. Since Melanotan II (MT II) belongs to the synthetic analog of α-MSH, it is therefore interesting and clinically important to explore the roles of α-MSH in angiogenesis, and the possibility of anti-neoplasia effects and the angiogenic treatments in endothelial cells. A series of angiogenic experiments on in vitro proliferation of endothelial cells (EA. hy 926) were performed in this study. MTT assay showed that MT-II showed no cytotoxic effects at concentrations of 10-11 M, 10-10 M and 10-9 M, and it only marginally suppressed the proliferation of endothelial cells at a concentration of 10-8 M. By using Boyden chamber assay for angiogenic migration assay and Matrigel assay for angiogenic tube formation assay, our results showed that MT II inhibited the motility and tube formation of cultured endothelial cells at 10-11 M, and showed a strong dose-dependent inhibition with increasing concentration. Since ex vivo assay provides a direct proof of angiogenesis, we have also performed ex vivo aortic ring assay on rats and the results indeed showed reduced exogenous microvessel growth. Finally, as matrix metalloproteinases (MMPs) which are of degrading all kinds of extracellular matrix proteins and thus play a major role on angiogenesis, our gelatin zymography results showed that MT II indeed lightly inhibit MMP-2 at 10-8 M. In conclusion, our findings suggest that MT II have significant inhibition effects on angiogenesis in vitro and ex vivo, and thus could be beneficial for the prevention of cancer.