茶多酚Epigallocatechin-3-gallate抑制口腔癌細胞的侵襲、上皮間質的轉化及腫瘤之生長

臺灣最近幾年口腔癌的發生率有逐年上升的趨勢，其中有超過90%的口腔癌被診斷為鱗狀上皮細胞癌。上皮間質的轉化（Epithelial- mesenchymal transition；EMT）是上皮細胞腫瘤癌化（tumorgenesis）時progression、侵襲（invasion）和轉移（metastasis）的關鍵。癌細胞的轉移往往是造成癌症病人病灶復發致死及最難根治的主要原因，其過程包括細胞的貼附、細胞外基質的降解及細胞轉移能力的改變。Epigallocatechin-3-gallate（EGCG）是一種天然的多酚類，廣泛存在綠茶之中，目前已有許多文獻指出其具有抗氧化活性、降低血脂肪、促使癌細胞凋亡及防止正常細胞癌化等作用。然而，EGCG對於口腔癌轉移的詳細作用機轉尚不清楚。因此，我們選用SCC-9這株高度惡化的口腔癌鱗狀上皮細胞，在體外實驗中，利用MTT assay、Transwell assay、傷口癒合試驗、gelatin zymography與casein zymography assay觀察EGCG對SCC-9細胞的存活率、侵襲、運動和移行能力及其分泌proteinases能力的影響。結果顯示EGCG不會影響癌細胞的存活率，EGCG可經由降低SCC-9細胞MMP-2（P＜0.001）和u-PA（P＜0.001）的活性，而幾乎完全抑制SCC-9細胞侵襲（P＜0.001），且EGCG亦能有效的抑制細胞的移行（migration）、運動（motility）、延展（spread）及附著（adhesion）。因此，我們進一步以immunoblotting分析其相關蛋白的表達，發現EGCG會抑制MMP-2、u-PA蛋白的表現，並且抑制FAK及Src的磷酸化、vimentin、snail-1和NF-κB在細胞核內的表現，且會抑制經PMA誘發的細胞侵襲及MMP-9的表現。最後在動物實驗中，於BALB/c nu/nu老鼠皮下異種移殖SCC-9細胞，其結果與控制組相比，發現在有處理EGCG的組別中，其腫瘤大小有明顯被抑制的效果。綜合以上結果，EGCG具有抑制腫瘤細胞生長與侵襲轉移之效果，或許可以應用在預防口腔癌的轉移或輔助口腔癌的治療上。

關鍵字

上皮間質轉化；茶多酚；口腔癌

並列摘要

In Taiwan, the incidence of oral cancer shows an increased tendency during the last decade. More than 90% oral cancers have been identified as squamous epithelium cell carcinoma. Epithelial-mesenchymal transition (EMT) are critical for the progression, invasion, and metastasis of epithelial tumorgenesis. Metastasis, the major cause of cancer death and various treatment strategies have targeted on preventing the occurrence of metastasis, is a multi-step process involving cell adhesion and proteolytic degradation of the extracellular matrix (ECM), essential to achieving cell motility. Epigallocatechin-3 gallate (EGCG), a large group of natrual polyphenols existing in a wide range of green tea, have been evidented to possess various prominent bio-activities. They are widely used for their antioxidant properties. Recent studies have also revealed pleiotropic anticancer and antiproliferative capabilities of EGCG. However, little is known about the precise molecular mechanisms of EGCG on metastasis of oral cancer.For this reason, we investigated that the inhibitory effect of EGCG in SCC-9 cells, a malignant oral squamous carcinoma cell line. We assayed the cell viability, cell invasion/motility, migration, matrix metalloproteinases (MMPs) activity, and urokinase- plasminogen activator (u-PA) activity of SCC-9 cells with EGCG treatment by MTT assays, invasion/motility assays, wound healing migration assay, gelatin zymography, and casein zymography. Here, We found that EGCG would not affect cell viability. We provided molecular evidence associated with the antimetastatic effect of green tea polyphenol epigallocatechin-3-gallate (EGCG) in an oral squamous cell culture system by showing a nearly complete inhibition on the invasion (P<0.001) of SCC-9 cells via a reduced expression of MMP-2 (P<0.001) and u-PA (P<0.001). EGCG exerted an inhibitory effect on cell migration, motility, spread and adhesion. We further used immunoblotting assay to evaluate the effect on the EGCG-inhibited SCC-9 cells metastasis. Fouthermore, we showed that EGCG downregulated the protein level of MMP-2 and u-PA, attenuated the phosphorylation of focal adhesion kinase (FAK) and Src, as well as suppressed the nuclear level of nuclear factor kappa B (NF-κB) and Snail-1. EGCG was also sufficient to inhibit PMA-induced cell invasion and MMP-9 expression, and evidenced by its inhibition on the tumor growth of SCC-9 cells in vivo via cancer cell xenografted nude mice mode. These results suggested that EGCG could reduce the invasion and cell growth of tumor cells and such characteristic may be of great value in developing a potential cancer therapy.

並列關鍵字

EMT ； EGCG ； OSCC

參考文獻

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茶多酚Epigallocatechin-3-gallate抑制口腔癌細胞的侵襲、上皮間質的轉化及腫瘤之生長

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