Withanolide類化合物引發乳癌細胞MDA-MB-231凋亡之機轉探討

Withanolides induce apoptosis in the human breast cancer cell line MDA-MB-231

陳勇先(Yung-Hsien Chen)

指導教授 ： 吳志中

共同指導教授 ： 吳永昌(Yang-Chang Wu)

高雄醫學大學/藥學院/天然藥物研究所碩士班/碩士(2007年)

摘要

4b-Hydroxywithanolide E (4HE) ，withaferin A (WA)和 peruvianolide H (PAH) 萃取自茄科植物，屬於withanolide類化合物。在本研究中，4HE與WA對於人類乳癌細胞MDA-MB-231有抑制其生長的作用，IC50分別為0.70 , 0.75 ?嵱。相較之下，PAH的作用則較弱。4HE與WA抑制細胞生長，使細胞停止於G2/M期 ; 亦使細胞走向細胞凋亡，增加subG1細胞比例，活化caspase-3, -8, -9，以及使poly(ADP-ribose)polymerase斷裂。使用pan-caspase抑制劑能有效抑制4HE與WA所引起的細胞凋亡。另一方面，4HE與WA亦會減少anti-apoptotic proteins : Bcl-2和Bcl-XL的表現。
MDA-MB-231乳癌細胞於4HE與WA處理過後，會造成ROS的增加，並引起Hsp 70的大量表現。此外，4HE與WA會造成Hsp 90 client proteins (Raf, Cdk4, cyclin D, 與AKT)的分解。使用N-acetylcysteine(一種抗氧化劑及thiol還原劑)可抑制4HE與WA引發的Hsp 70表現，防止Hsp 90 client proteins (Raf, Cdk4, cyclin D, 與AKT)分解，並抑制細胞凋亡。綜上所述，4HE與WA可造成乳癌細胞MDA-MB-231細胞週期停滯並引發細胞凋亡；此外，蛋白質thiol氧化和抑制Hsp 90的功能可能與4HE與WA的抗癌活性有關。

關鍵字

抗癌

並列摘要

4??-Hydroxywithanolide E (4HE), withaferin A (WA), and peruvianolide H (PAH) are withanolides from Solanaceae plants. In the present study, both 4HE and WA potently inhibited the growth of MDA-MB-231, a human breast cancer cell line, with IC50 values of 0.70 and 0.75 ?嵱, respectively. In contrast, PAH showed only weak antitumor activity. 4HE- and WA-induced growth inhibition was associated with G2/M cell cycle arrest. MDA-MB-231 cells treated with 4HE or WA showed induction of apoptosis, as indicated by morphological changes, increased subG1 cell population, caspase-3, -8, -9 activation, and the cleavage of poly(ADP-ribose)polymerase. Pretreatment of a pan-caspase inhibitor z-VAD-fmk significantly prevented either 4HE or WA-induced apoptosis. The levels of anti-apoptotic proteins, Bcl-2 and Bcl-XL, were decreased after 4HE or WA treatment.
4HE and WA also caused an increase in ROS generation and induced the expression of heat shock protein (Hsp)70. In addition, several Hsp90 client proteins (Raf, Cdk4, Cyclin D, and AKT) were degraded in 4HE- or WA-treated cells. All of these effects caused by 4HE and WA were prevented by N-acetylcysteine, an antioxidant and thiol-reducing agent . Taken together, our results suggest that the withanolides 4HE and WA induced cell cycle arrest and caspase-dependent apoptosis in human breast cancer MDA-MB-231 cells. Protein thiol oxidation and Hsp90 inhibition might be involved in the mechanism of 4HE- and WA-induced antitumor effect.

並列關鍵字

apoptosis

參考文獻

參考文獻

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