臺灣蜂膠衍生物誘導人類肝癌細胞凋亡機制探討
Study of the molecular mechanisms of Taiwanese propolis
derivatives on the induction of apoptosis in human hepatoma cells
中文摘要
Activating transcription factor 3 (ATF3) 屬於 basic-region leucine zipper (bZIP) 家族中，ATF (Activating transcription factor)/CREB (cAMP response
elementbinding) 次家族的一員，可誘導 CCAAT/enhancer-binding protein (C/EBP) 和 AP-1 活化。 ATF 3 是易受不同生理壓力快速誘發的轉錄因子，並在許多研究 中證實其具有誘導癌細胞走向凋亡的能力。坊間常見的健康食品 - 蜂膠，在過去 文獻指出，其具有多種生物性功能，包括: 抗菌、抗氧化、抗發炎和抗腫瘤功效等 在本實驗室先前的研究中發現，台灣蜂膠衍生物NBM-TP-007 -GS-002 (GS-002) 和 PPG 在免疫不全裸鼠體內具有抑制神經膠質瘤生長的功效。本研究中探討 GS-002 和 PPG 在肝癌細胞 (Hep3B 和 HepG2) 中的抗腫瘤能力。首先，我們發 現，GS-002 和 PPG 隨著劑量增加，明顯抑制肝癌細胞生長並誘導
細胞走向凋亡途徑。GS-002 可經由活化細胞凋亡所需的 caspase-3、caspase-9 和 PARP cleavage 形式的蛋白質等，使 Hep3B 細胞凋亡。GS-002 和 PPG 皆可引起 ATF3 mRNA 和蛋白質的表現，使肝癌細胞走向細胞凋亡的途徑。此外，本實驗 也測試了誘導ATF3 的壓力訊息傳遞路徑-MAPK (mitogen-activated protein kinase) 訊息傳遞路徑中三個主要的路徑，分別為 p38，JNK (c-Jun N-terminal kinase)/SAPK(stress-activated protein kinase) 和 ERK (extracellular-signal-regulated kinase)) 訊息傳遞路徑，也發現 GS-002 可活化 MAPK 相關的蛋白質激酶。更進 一步利用暫時性基因轉殖使細胞內 ATF3 大量表現，發現在 ATF3 過表現並給
予GS-002 的情形下，其細胞存活率明顯較對照組低。由上述結果可知，蜂膠衍
生物 GS-002 可透過依賴 ATF3 的細胞死亡路徑使細胞凋亡，達到抗腫瘤的功效。
因此，蜂膠衍生物 GS-002 可能具有提供抗肝癌藥物研發及肝癌治療之價值。
英文摘要
Activating transcription factor 3 (ATF3) is a member of the ATF/CREB subfamily of the basic-region leucine zipper (bZIP) family, which includes members of
CCAAT/enhancer-binding protein (C/EBP) and AP-1. ATF3 is rapidly up-regulated under various stress conditions and plays an important role in induction of cancer cell apoptosis. NBM-TP-007-GS-002 (GS-002) and PPG are Taiwanese propolis
derivatives. Recent reporters indicated that propolis had various biological activities, including anti-microbial, antioxidative, anti-inflammatory and anti-tumoral activity.
Our previous examination have found that both GS-002 and PPG significantly inhibited tumor growth in nude mice (Balb/cAnN-Foxn1nu/CrlNarl) which bearing xenografts of C6 glioma cells. In this study, we have examined the anti-tumoral effect
of GS-002 and PPG in human hepatoma cells Hep3B and HepG2 in vitro. First we found that GS-002 and PPG significantly inhibited cell proliferation and induced cell apoptosis by a dose-dependent manner. Several main apoptotic indicators were found in GS-002- and PPG-treated cells, such as cleavage form of caspase-3、caspase-9 and PARP. Both GS-002 and PPG also dose-dependently induced the mRNA and protein expression of ATF3. The induction of ATF3 expression is mediated through mitogen-activated protein kinases (MAPKs) signalling pathways in GS-002-treated cells. Furthermore we found that GS-002 induced more cell apoptosis in ATF3 overexpression cells than control cells. These results suggest that the induction of apoptosis by propolis derivatives GS-002 is partially mediated through ATF3-
dependent pathway, and the GS-002 has a potential to develop as a anti-tumoral drug.
