覆盆子乙酸乙酯萃取物在人類肺腺癌細胞中透過調降snail-1進而提高E-cadherin表現量並抑制腫瘤在活體內之生長能力

肺癌目前在台灣及全球，高居所有癌症死因的第一位，且至少有8成以上是屬於非小細胞肺癌。非小細胞肺癌在組織學上又可細分為腺癌、鱗狀細胞癌及大細胞癌等，並以腺癌最為常見。腫瘤轉移是肺癌的致死主因，癌細胞會經由上皮-間質型態的相互轉換，得以侵襲、擴散而造成患者預後不佳。覆盆子是一種薔薇科懸鉤子屬的木本植物，富含多酚（polyphenol）物質，已被證實具有抗氧化、抗菌及抗發炎等生物活性，且有助於癌症的預防及治療，但其抗癌的詳細作用機轉仍不明瞭。因此本篇研究是以人類肺腺癌細胞株A549為實驗對象，探討覆盆子乙酸乙酯萃取物（RIEE）抑制A549細胞侵襲的作用機制，並進行裸鼠異種移植的體內試驗來檢測RIEE的抗腫瘤效果。先前我們實驗室已知RIEE會抑制PI3K/Akt訊號路徑、蛋白酶活性、snail-1及細胞骨架蛋白表現。本篇進一步利用PI3K抑制劑LY294002、snail-1 siRNA與RIEE處理A549細胞，依序進行invasion assay、gelatin zymography、casein zymography、western blot analysis及immunofluorescence staining等實驗，結果證實RIEE能夠抑制A549細胞的侵襲能力，也許可經由兩種作用機制：（1）抑制PI3K/Akt訊號路徑，減少NF-κB的蛋白表現，而降低MMP-2及u-PA的活性。（2）抑制PI3K/Akt訊號路徑，減少NF-κB的蛋白表現，而抑制snail-1並增加E-cadherin的表現。另外在A549細胞移植裸鼠的體內實驗，也證實RIEE可抑制腫瘤的生長。綜上所述，覆盆子乙酸乙酯的萃取物可能具有開發成為抗腫瘤轉移及治療肺癌藥物的潛力。

Lung cancer is the leading cause of cancer mortality in Taiwan and worldwide. At least 80% of lung cancer is non-small cell lung cancer (NSCLC) which is further divided histologically into adenocarcinoma, squamous cell carcinoma, and large cell carcinoma. Adenocarcinoma is the most common type of lung cancer. Metastases are the main cause of death from lung cancer. Carcinoma cells undergo epithelial-mesenchymal transition (EMT) to invade and disseminate from the primary tumor, leading to poor prognosis in lung cancer patients. Rubus idaeus L. is a woody plant belonging to the Rosaceae family, genus Rubus. The plant is rich in polyphenols with reported biological activities such as antioxidant, antimicrobial, and anti-inflammatory properties, which are beneficial in cancer prevention and treatment, but the detailed mechanisms underlying the anticancer effects of Rubus idaeus remain unclear. In this study, human lung adenocarcinoma epithelial cell line, A549 was used not only to investigate the mechanisms of action of ethyl acetate extract from Rubus idaeus (RIEE) on the invasion of A549 cells, but to explore the anti-tumor effects in a nude mice xenograft model. Our previous study showed that RIEE could inhibit the PI3K/Akt signaling pathway, the activities of proteases, and the expression of snail and cytoskeletal proteins. Here, we further performed a series of assays for cell invasion, gelatin zymography, casein zymography, western blot and immunofluorescence, using A549 cells treated with the PI3K/Akt inhibitor LY294002, snail-1 siRNA and RIEE. Our data demonstrates that RIEE may inhibit A549 cells invasion through two mechanisms: (1) inhibition of the PI3K/Akt pathway and NF-κB expression to suppress the activities of MMP-2 and uPA, and (2) inhibition of the PI3K/Akt pathway and NF-κB expression to up-regulation E-cadherin via inhibition of snail-1. In addition, we show that RIEE could inhibit tumor cell growth in an A549 xenograft model. Collectively, RIEE may have a potential to develope as anti-metastatic and cancer therapeutic drug for lung cancer.