磯松素和血根鹼對人類乳癌細胞增生抑制作用和細胞程式死亡機制之探討

CNU IR > Pharmacy and Science > Dept. of Biotechnology (including master's program) > MOST Project > Item 310902800/2383

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Title:	磯松素和血根鹼對人類乳癌細胞增生抑制作用和細胞程式死亡機制之探討 Plumbagin induces G2/M arrest and autophagy by inhibiting the AKT/mTOR pathway in breast cancer cells
Authors:	郭柏麟;Po-Lin Kuo
Contributors:	生物科技系
Keywords:	磯松素細胞週期細胞自噬 AKT mTOR autophagy cell cycle plumbagin
Date:	2005
Issue Date:	2008-07-31 14:37:40 (UTC+8)
Publisher:	台南縣：嘉南藥理科技大學生物科技系
Abstract:	本研究主要探討磯松素(plumbagin)的抗乳癌活性和相關分子機轉。結果發現磯松素會造成細胞週期停滯(cell cycle arrest)以及細胞自噬(autophagy)。磯松素促使細胞週期停滯於G2/M 期主要透過增加p21 表現、Chk2 活化以及降低cyclin B1、 cyclin A、cdc2 和cdc25C 的表現。除此，磯松素還會透過增加p21 和Cdc2 的結合，以及增加Chk2 的活化促使Cdc2 和Cdc25C 的磷酸化而抑制Cdc2 的功能。在細胞死亡誘導方面，磯松素主要會誘導細胞進行細胞自噬，而非細胞凋亡。磯松素可藉由抑制AKT 的活化以及相關下游分子，包括mammalian target of rapamycin (mTOR)、forkhead transcription factors (FKHR)和glycogen synthase kinase-3beta (GSK)，有效的阻斷PI3K (phosphatidylinositol 3-kinase)/AKT 訊息傳遞。再者，mTOR 的數個下游分子，包括p70 ribosomal protein S6 kinase (p70S6 kinase)和4E-BP1 的磷酸化也都一併受到抑制。當細胞過度表現AKT 時會抑制磯松素所造成的細胞自噬作用。相對的，當AKT 表現受到抑制時會明顯增加磯松素所造成的細胞自噬作用，因此證明磯松素透過AKT 的抑制作用促使啟動細胞自噬。除此，磯松素在裸鼠(nude mice)的研究也證實了其在in vivo 的條件下仍然具有抑制乳癌細胞增生、啟動細胞自噬以及抑制AKT 活化的能力。綜合以上結果，本研究證實磯松素可藉由抑制PI3K/AKT/mTOR 路徑促使細胞停滯以及啟動細胞自噬。 This study is the first to investigate the anticancer effect of plumbagin in human breast cancer cells. Plumbagin exhibited cell proliferation inhibition by inducing cells to undergo G2/M arrest and autophagic cell death. Blockade of the cell cycle was associated with increased p21/WAF1 expression and Chk2 activation, and reduced amounts of cyclinB1, cyclinA, Cdc2 and Cdc25C. Plumbagin also reduced Cdc2 function by increasing the association of p21/WAF1/Cdc2 complex and the levels of inactivated phospho-Cdc2 and phospho-Cdc25C by Chk2 activation. Plumbagin triggered autophagic cell death, but not, predominantly, apoptosis. Pretreatment of cells with autophagy inhibitor bafilomycin suppressed plumbagin-mediated cell death. We also found that plumbagin inhibited survival signaling through the PI3K (phosphatidylinositol 3-kinase)/AKT signaling pathway by blocking the activation of AKT and downstream targets, including the mammalian target of rapamycin (mTOR), forkhead transcription factors (FKHR) and glycogen synthase kinase-3beta (GSK). Phosphorylation of both of mTOR’s downstream targets, p70 ribosomal protein S6 kinase (p70S6 kinase) and 4E-BP1, was also diminished. Overexpression of AKT by AKT cDNA transfection decreased plumbagin-mediated autophagic cell death, whereas reduction of AKT expression by siRNA potentiated plumbagin’s effect, supporting inhibition of AKT beneficial to autophagy. Furthermore, suppression of AKT by plumbagin enhanced the activation of Chk2, resulting in increased inactive phosphorylation of Cdc25C and Cdc2. Further investigation revealed that plumbagin’s inhibition of cell growth was also evident in a nude mice model. Taken together, these results imply a critical role for AKT inhibition in plumbagin-induced G2/M arrest and autophagy of human breast cancer cells.
Relation:	計畫編號：NSC94-2320-B-041-007
Appears in Collections:	[Dept. of Biotechnology (including master's program)] MOST Project

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