中草藥抑制乳癌細胞中FASN與HER2/neu之研究

Identification of Chinese herbal medicines that inhibit FASN and HER2/neu in breast cancer cells

許丹斐(Tan-Fei Hsu)

指導教授 ： 呂紹俊

國立臺灣大學/醫學院/生物化學暨分子生物學研究所/碩士(2007年)

https://doi.org/10.6342/NTU.2007.10257

摘要

乳癌為全世界女性最常見的癌症，在癌症死因中排名第二順位 (次於肺癌)。此外，根據衛生署的統計，乳癌已成為國內女性發生率第一的惡性腫瘤，死亡率為第四位。因此，乳癌治療的研究與發展是相當重要的。
fatty acid synthase (FASN) 在人類大部分組織中的表現量很低，但在乳癌組織及ㄧ些carcinomas中表現增加，這樣過量表現的情形和預後較差有所關聯。若在乳癌細胞中加入FASN的inhibitor，會導致細胞生長停滯與細胞凋亡。所以，FASN被認為在腫瘤的發育過程中扮演重要角色，可用來當作癌症治療的標靶。另外，HER2/neu過量表現的乳癌病患，大部分預後較差且存活率較低。之前的研究指出，FASN與HER2/neu過量表現的情形，存在正相關的關係；且抑制FASN後，可進ㄧ步經由轉錄層次抑制HER2蛋白的表現。本研究的目的就是篩選出可抑制FASN與HER2/neu的中草藥。
由於本實驗室的賴昱昇同學由60種中草藥篩選可以降低HepG2細胞三酸甘酯含量的藥材，並進一步利用Western blot方法篩選，發現其中的18種中草藥可使HepG2細胞中的FASN降低。因此，我們探討這18種中草藥在人類乳癌細胞中，是否也具有抑制FASN的作用。首先，利用Western blot發現其中9種中草藥可使MCF-7細胞中的FASN減少，這9種中的A23與A24兩種中草藥單方對Au565細胞中的FASN與HER2/neu具有抑制作用，免疫螢光分析法的結果也顯示A23與A24可降低Au565細胞膜上HER2/neu蛋白的表現量。接著，利用RT-PCR發現這2種中草藥可降低人類乳癌細胞中FASN與HER2/neu的mRNA表現量，且這樣的抑制情形具dose-dependent的效果。
利用MTT assay偵測經過A23與A24萃取液處理後乳癌細胞的存活情形，發現細胞存活率降低，且呈現time-dependent與dose-dependent趨勢，IC30也會隨著中草藥處理時間增加而降低。除此之外，利用TUNEL assay分析細胞凋亡的情形，在螢光顯微鏡下觀察的結果，發現在經過較高濃度的A23與A24處理後，Au565細胞出現細胞凋亡的現象，且隨著萃取液劑量增加，細胞凋亡的情形變得更加明顯。另外，我們利用Migration assay與Invasion assay探討A23與A24對於人類乳癌細胞能動性與侵略性的影響，發現此兩種中草藥單方可降低Au565與SKBR3細胞的移行與侵襲能力。
接下來我們使用MTT assay與TUNEL assay探討A23與A24對於正常人類乳房上皮細胞H184B5F5/M10 (簡稱M10) 在細胞生長情形以及細胞凋亡的影響，實驗結果得知，相同濃度的A23與A24萃取液對於M10細胞存活率的影響，和對人類乳癌細胞相比，顯得較為輕微，也不會導致M10細胞凋亡。
綜合以上，A23與A24這2種中草藥單方可降低人類乳癌細胞中FASN與HER2/neu的表現量、抑制細胞生長、導致細胞存活率減少與細胞凋亡、並影響細胞的移行與侵襲能力等作用，而且對於正常人類乳房上皮細胞的生長情形影響不大。接下來需進一步分析2種中草藥之有效成分，並探討其詳細抗癌機制。

關鍵字

乳癌 ； FASN ； HER2/neu ； 中草藥

並列摘要

Breast cancer is the most common cancer among women, and the second leading cause of cancer death for women worldwide. According to the statistical data from Department of Health, breast cancer is the most common cancer, and the fourth leading cause of death for Taiwanese. Therefore, it makes developing of therapy for treatment of breast cancer more important.
fatty acid synthase (FASN) is expressed at low level in most normal human tissues. However, increased expression of FASN has emerged as a common phenotype in breast cancer and some carcinomas, particularly those with a poor prognosis. Treatment of tumor cells with inhibitors of FASN leads to cell growth arrest and apoptosis of breast tumor cells. Therefore, FASN plays an important role in tumorigenesis. In addition, tumors with HER-2/neu overexpression are associated with a poor prognosis and a more aggressive phenotype. Consequently, FASN and HER2/neu could be a therapeutic target for anti-tumor therapy. Moreover, previous studies showed that FASN expression are positively correlated to HER2/neu expression, and inhibition of FASN activity repressed HER2 protein expression by affecting the transcriptional level.
Our lab screened 60 Chinese herbal medicines (CHMs) for that decreased triglyceride in HepG2; and found 18 CHMs could inhibited FASN in HepG2. Therefore, we tried to investigate whether these 18 CHMs could inhibit FASN in breast cancer cells. Western blot showed that nine of these CHMs inhibited FASN in MCF-7 cells, and two of them (A23 and A24) inhibited FASN and HER2/neu in Au565 cells. Immunofluorescence assay also showed that A23 and A24 downregulated of HER2/neu on cell membrane of Au565. Besides, RT-PCR showed that A23 and A24 inhibited FASN and HER2/neu mRNA expression in a dose-dependent manner in Au565 cells.
Additionally, MTT assay showed that A23 and A24 inhibited the proliferation of breast cancer cells in a dose- and time-dependent manner. We also used TUNEL assay to assess cell apoptosis in Au565 cells, and the results showed that A23 and A24 induced apoptotic cell death in a dose-dependent manner. Furthermore, migration assay and invasion assay showed that cellular migration and invasion of Au565 were inhibited by A23 and A24.
MTT assay showed that A23 and A24 inhibited the proliferation of human mammary epithelial cells H184B5F5/M10 (M10) to a small extent compared with breast cancer cells treated with the same concentration of A23 and A24. Moreover, TUNEL assay showed that A23 and A24 did not induce apoptosis in M10 cells.
Taken together, A23 and A24 have potential in lowering FASN and HER2/neu, suppressing migration and invasion, inhibiting cell growth and inducing apoptosis in breast cancer cells. Further studies are needed to clarify the anti-tumor roles of A23 and A24 in vivo; and to find out the active components in these CHMs.

並列關鍵字

breast cancer cell ； FASN ； HER2/neu ； Chinese herbal medicines

參考文獻

張憲昌, 溫彩玉, 林哲輝 (2006) 市售莪朮、薑黃與鬱金類藥材之鑑別。藥物食品檢驗局調查研究年報。

江滄炫 (2007) 新藥研發生技公司之亞洲經營模式。國立台灣大學管理學院碩士在職專班高階公共管理組碩士論文。

陳明和, 吳劭彥, 吳蓉茹 (2008) 中醫藥配合放射線治療乳癌的病例報告。台灣中醫臨床醫學雜誌。

Ambrosini, G., Adida, C.,and Altieri, D.C. (1997). A novel antiapoptosis gene, survivin, expressed in cancer and lymphoma. Nat Med 3, 917–921.

Arteaga, C.L., Moulder, S.L.,and Yakes, F.M. (2002). HER (erbB) tyrosine kinase inhibitors in the treatment of breast cancer. Semin Oncol 3, 4–10.