Rersveratrol甲基衍生物3,5,3'',4'',5''–pentamethoxystilbene (MR-5)抑制人類乳癌細胞MCF-7生長及細胞週期G1停滯之分子研究

Resveratrol，是一種trihydroxy trans-stilbene，來自於葡萄及其他植物中，本身具有很強的抗氧化及抗腫瘤活性之天然化合物。3,5,3’,4’,5’–pentamethoxystilbene (MR-5)為一種以化學方式合成的resveratrol甲基衍生物，藉由官能基的修飾，是否和Resveratrol一樣，具有相同生物活性。因此，本研究之目的為探討白藜蘆醇及其甲基衍生物PTER, MR-3, MR-5，在人類乳癌細胞株MCF-7細胞中，對抑制細胞增生之效應及其可能之作用機轉作進一步探討。研究結果顯示，在比較resveratrol和其PTER, MR-3, MR-5甲基衍生物實驗中，MR-5最能有效抑制人類乳癌細胞株MCF-7之細胞生長，降低細胞癌化程度，且呈現劑量及處理時間依賴性的效果，並造成細胞週期停滯於G1期。由西方墨點分析之結果顯示MR-5的生長抑制作用可能是與減少細胞內cyclin D1、cyclin D3、cyclin E和Cdk2、Cdk4和Cdk6蛋白量的表現以及增加p15、p16、p21和p27的表現量有關。由於上述分子在蛋白質表現量上的變化使得 Cdk2 和 Cdk4 激酶活性降低並導致RB無法被磷酸化。除此之外，MR-5也會影響人類乳癌細胞MCF-7內AKT、mitogen-activated protein kinase (ERK1/2)、p38 mitogen-activated protein kinase (p38 MAPK)和focal adhesion kinase (FAK)之活性，顯示MR-5抑制MCF-7增生與癌化的機轉，和這些訊息傳遞分子有關。綜合上述， 本研究經由細胞模式結果顯示，MR-5活性具有抑制MCF-7乳癌增生之功效。本研究成果有助於了解resveratrol及其甲基衍生物對於抗乳癌活性上之保健功效，亦可提供未來開發結構相關新藥之重要參考。

3,5,3’,4’,5’-Pentamethoxystilbene (MR-5) is a synthetically met- hoxylated analogue of resveratrol and has been suggested to have antitumor activity because of structural similarity to resveratrol. Herein, we investigate the antiproliferative effect of MR-5 in human breast cancer MCF-7 cells and demonstrate that MR-5 had a more potent inhibition on cell growth compared with resveratrol and other methoxylated derivatives. Exploring the growth-inhibitory mechanisms of MR-5, we found that it is accompanied by G1 cell cycle arrest, which coincides with a marked inhibition of G1 cell cycle regulatory proteins, including decreased cyclins (D1/D3/E) and cyclin dependent kinases (CDK2/4/6) and increased CDK inhibitors (CKIs) such as p15, p16, p21, and p27. Furthermore, the increase in CKI levels by MR-5 resulted in a concomitant increase in their interactions of CDK4 and CDK2, along with a strong inhibition in CDK4 kinase activity and the accumulation of hypophosphorylated Rb. MR-5 also modulated some critical kinase activities related to cell cycle regulation, including Akt, mitogen activated protein kinase (ERK1/2), p38 mitogen-activated protein kinase (p38 MAPK), and focal adhesion kinase (FAK) in MCF-7 cells. In total, our results demonstrate that MR-5 affects multiple cellular targets that contribute to its antiproliferative activity in MCF-7 cells and provide novel information for synthetic chemists to design new antitumor agents with introduction of methoxylated group(s) in the basic compound.