| 摘要: | 天然食品及其衍生物已被用在作為新型治療劑的主要來源，在近期研究中發現綠茶對癌症的預防作用歸功於其抗氧化活性，兒茶素具有清除自由基、抗氧化、抗癌、抗突變以及改善心血管疾病症狀和調節免疫系統的作用，表兒茶素沒食子酸酯(epicatechin-3-gallate, ECG)也具有相同潛在有益作用，包括抗發炎、抗癌、抗氧化和抗過敏。癌症的轉移是導致病患癌症復發及預後不良的主要因素，癌細胞轉移必須經過上皮-間質細胞轉換(epithelial-mesenchymal transition, EMT)過程，才能變形與穿透血管組織。我們以MTT方法檢測ECG對由TGF-β1(transforming growth factor-β1)處理的A549細胞存活率，發現ECG不具細胞毒性。透過不同濃度ECG (0、10、30 和 50 μM)利用Western blotting、invasion assay、gelatin zymography和luciferase assay system去分析、觀察ECG對TGF-β1誘導A549肺腺癌細胞對於A549的轉移及蛋白表現影響。結果發現ECG可有效降低由TGF-β1所誘導A549的細胞移動及侵襲能力，並有效抑制MMP-2 的轉錄活性及分泌表現量，並在對細胞無毒性的條件下，能有效抑制A549的黏附能力。進一步發現， ECG可將由TGF-β1所誘導的EMT回復成為上皮細胞的特性，使E-cadherin表現量增加，fibronectin間質蛋白表現量下降。ECG也可使磷酸化的FAK (focal adhesion kinase)表現量下降，ECG可經由阻斷FAK的訊號傳導來抑制TGF-β1所誘導的A549細胞侵襲能力。總結來說，ECG能有效抑制A549的移動及侵襲能力，並使具有高轉移特性的間質型態的肺癌細胞回復成較為上皮的特性，表現E-cadherin，並降低fibronectin及磷酸化的FAK。綜合以上結果，ECG可逆轉肺癌細胞EMT，進一步抑制肺癌轉移的可能模型。Natural foods and their derivatives have been used as a major source of new therapeutic agents. In recent studies, evidence has shown that the chemical prophylaxis of green tea against cancer is due to its antioxidant activity. Catechins and epicatechin-3-gallate (ECG) has the similar potential beneficial effects, including anti-inflammatory, anti-cancer, anti-oxidation and anti-allergy, as well as anti-mutation and improvement of cardiovascular disease symptoms and regulation of the immune system. The metastasis of cancer is one of the leading cause of recurrence of cancer and poor prognosis. Cancer cell metastasis must undergo epithelial-mesenchymal transition (EMT) process to deform and penetrate vascular tissue. We investigated the activity of ECG on TGF-β1 (transforming growth factor-β1)-induced A549 cells by MTT assay, and found that ECG was not cytotoxic. The influence of ECG on TGF-β1-induced A549 cells invasion and protein expression was evaluated by Western blotting, invasion assay, gelatin zymography and luciferase assay system at different concentrations (0, 10, 30 and 50μM). The results showed that ECG could effectively reduce the TGF-β1-induced A549 cell movement and invasion ability, and effectively inhibit the activity and transcription activity of MMP-2 and inhibit the adhesion of A549 lung adenocarcinoma cells under the non-toxic conditions. Further study shows, ECG can transform the mesenchymal type induced by TGF-β1 into a more epithelial cell, so that the restutution of E-cadherin epithelium marker, fibronectin protein decreased. ECG can also reduce the phosphorylated FAK (focal adhesion kinase) protein expressions, and block the FAK signal transmission using FAK inhibitor PF573228 and then inhibit TGF-β1-induced A549 cell invasion ability. In summary, ECG can effectively inhibit the movement and invasion of A549 human lung adenocarcinoma cells, the high metastatic characteristics of mesenchymal type lung cancer cells and regain more epithelial characteristics, the performance of E-cadherin epithelial cell marker, and reduce TGF-β1-induced fibronectin mesenchymal cell marker and phosphorylated FAK. Combining all the results and discussion, ECG is a potential model for reversing lung cancer cell EMT and further inhibiting the metastasis of lung cancer. |
