綠茶(Camellia sinensis)最主要的多酚類成分Epigallocatechingallate (EGCG)表沒食子兒茶素沒食子酸酯在許多癌細胞研究中證實會抑制基質金屬蛋白水解酶-2 (matrix metalloproteinase-2, MMP-2)活性，但是在葡萄膜黑色素瘤細胞（uveal melanoma cells）的相關性仍不清楚。本研究發現葡萄膜黑色素瘤細胞株（M17）細胞存活率分析顯示在100 μM的EGCG處理下仍不具有細胞毒性。而在傷口癒合分析中顯示EGCG抑制細胞移行的能力與劑量相關。明膠水解分析顯示MMP-2的活性受到EGCG的抑制，但蛋白和mRNA的表現則不受影響。此外在EGCG處理下MMP-2的內源性抑制劑TIMP2及RECK表現量明顯增加。利用西方墨點法檢測EGCG對MAPK路徑的影響，顯示EGCG可有效抑制細胞外訊息調節激酶1/2 (extracellular signal-regulated kinase 1/2; ERK1/2) 的磷酸化，但不影響p38及JNK路徑。利用ERK1/2的抑制劑也可M17細胞的爬行能力及MMP-2的活性 。 綜合以上結果，EGCG在對M17細胞不具毒性的濃度下可抑制ERK1/2磷酸化進而降低MMP-2的活性使得其移行能力降低。因此，EGCG或許可開發應用在抑制葡萄膜黑色素瘤細胞轉移的藥劑研究上。 Epigallocatechingallate (EGCG), the major polyphenol in green tea, has been shown to downregulate matrix metalloproteinase-2 (MMP-2) in many cancer cell types. However, the effect of EGCG on the migration and expression of MMP-2 of uveal melanoma cells has not been reported. We studied this effect and relevant signaling pathways in a human uveal melanoma cell line M17. MTT study revealed that EGCG did not affect the cell viability of M17 cells up to 100 μM. Wound-healing assay showed that EGCG significantly reduced the migration ability of cells in a dose-dependent manner from 20 to 100 μM. Gelatin zymography showed that secreted MMP-2 activity was inhibited dose-dependently by EGCG, whereas the MMP-2 expression at protein and mRNA levels were not affected as determined by Western blot and RT-PCR. EGCG significantly increased the expressions of MMP-2 endogenous inhibitors (TIMP-2 and RECK) in M17 cells. Western blot analysis of MAPK signal pathways showed that EGCG significantly decreased phosphorylated ERK1/2 levels, but not p38 and JNK levels, in melanoma cells. ERK1/2 inhibitors also reduced the migration and activity of MMP-2 in M17 cells. The present study suggested EGCG at nontoxic levels could inhibit migration of melanoma cells via downregulation of activities of secreted MMP-2 through the inhibition of the ERK1/2 phosphorylation. Therefore, EGCG may be a promising agent to be explored for the prevention of metastasis of uveal melanoma.
