探討薯蓣皂素抑制乳癌細胞增生和惡化的功能

Diosgenin induces cell apoptosis and inhibits tumor invasion in human breast cancer cells.

林靜宜(Ching-Yi Lin)

指導教授 ： 鄭鈞文

中山醫學大學/醫學院/生化暨生物科技研究所/碩士(2006年)

摘要

Diosgenin是類固醇皂元(Steroidal sapogenin)的一種，存在於山藥或其他植物裡。文獻指出，它會抑制發炎反應、腫瘤細胞的增生，並且促使腫瘤細胞進行細胞凋亡。本研究對乳癌細胞株MCF-7和Hs578細胞處理diosgenin，並探討其抗癌之作用機轉。結果發現Diosgenin會終止細胞週期的演進，使細胞週期停滯於G2/M時期，並誘發細胞進行程序化凋亡作用，而有效的抑制MCF-7和Hs578細胞的生長。在細胞週期調控方面，diosgenin會誘導p53的表現，以調控降低cyclin A, cyclin B和cdc25c的表現。另外，在細胞凋亡方面， diosgenin會造成粒線體膜電位下降，發生DNA 斷裂成階梯狀片段，並降低Bcl-2的表現，促使cytochrome c 由粒線體釋放至細胞質，進而活化caspase 9和caspase 3。再者，diosgenin也會影響Fas的表現量，所以其凋亡路徑可能也與細胞膜上的死亡受體路徑有關。以彗星試驗偵測細胞的DNA 損傷程度，發現在高濃度diosgenin處理後，細胞拖尾的比例呈現明顯的劑量關聯。進一步檢測參與細胞週期調控蛋白的表現，隨著diosgenin的濃度增加， Chk2的表現量明顯地下降，我們推論Chk2表現量下降可能與DNA損傷後Chk2被磷酸化，進而影響到cdc25c磷酸化，促使cdc2-cyclin B complex功能失活，使細胞停滯在G2/M時期。隨之，啟動粒線體凋亡路徑，造成細胞的凋亡。本研究結果，針對diosgenin對乳癌細胞生長有明顯的抑制作用，將來能作為抗癌藥物研發的標的。

關鍵字

薯蓣皂素 ； 乳癌細胞 ； 細胞凋亡 ； 細胞週期

並列摘要

Diosgenin, a steroidal saponin present in fenugreek (Trigonella foenum graecum) and other plants, has been shown to suppress inflammation, inhibit proliferation, and induce apoptosis in a variety of tumor cells. However, understanding of the molecular mechanism of diosgenin effects on human breast cancer cells is not yet fully clarified. Therefore, the aim of the present study was to investigate the anticancer effect of diosgenin on human breast cancer cell lines, MCF-7 and Hs578. We found that diosgenin effectively induced cell cycle arrest at G2/M stage, associating with reduced expression of cyclin B, cyclinA, Cdc25c in a p53-dependent manner. In addition, diosgenin triggers cell apoptosis through a increase in the protein expression levels of cytohrome c, caspase 9 and caspase 3, whereas is inversely related to Bcl-2 protein expression. Moreover, Fas protein expression was significantly increased according to treatment of diosgenin. As a result, evidences of the mitochondrial membrane potential change and DNA fragmentation assay provide that diosgenin induced apoptosis on breast cancer cell lines. Worthnotingly, Chk2 protein was significantly reduced after diosgenin treatment, which effect might correlate with cdc25c phosphorylation. Cell thus arrest at G2/M stage through inactivation of the complex of cdc2-cyclin B due to the phosphorylated cdc25c. In conclusion, our results may shed light on the certainty that diosgenin is available in the induction of apoptosis on breast cancer cells, providing the development of new anticancer strategy for future therapeutic approaches.

並列關鍵字

diosgenin ； human breast cancer cell ； apoptosis ； cell cycle

參考文獻

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