臺灣蜂膠衍生物誘導人類肝癌細胞凋亡機制探討
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 PA RP cleavage 形式的蛋白質等，使 Hep3B 細胞凋亡。 GS-002 和 PPG 皆可引起 AT F3 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 kinas e)) 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。
Study of the molecular mechanisms of Taiwanese propolis derivatives on the induction of apoptosis in human hepatoma cells
Activating transcription factor 3 (ATF3) is a member of the ATF/CREB subfamily of the basi c-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 p lays an important role in induction of cancer cell apoptosis. NBM-TP-007-GS-002 (GS-002) a nd PPG are Taiwanese propolis
derivatives. Recent reporters indicated that propolis had various biological activities, includin g 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 c ells. In this study, we have examined the anti-tumoral effect of GS-002 and PPG in human hep atoma cells Hep3B and HepG2 in vitro. First we found that GS-002 and PPG significantly inhi bited cell proliferation and induced cell apoptosis by a dose-dependent manner. Several main a poptotic indicators were found in GS-002- and PPG-treated cells, such as cleavage form of cas pase-3 、 caspase-9
and PARP. Both GS-002 and PPG also dose-dependently induced the mRNA and protein expr ession of ATF3. The induction of ATF3 expression is mediated through mitogen-activated pro tein 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 re sults suggest that the induction of
apoptosis by propolis derivatives GS-002 is partially mediated through ATF3-dependent path way, and the GS-002 has a potential to develop as a anti-tumoral drug.
