| 摘要: | 綠茶中的表沒食子兒茶素沒食子酸酯 (EGCG) 和 檳榔中的檳榔鹼 (arecoline) 都曾被報導能影響大鼠血液中的睪固酮含量和前列腺的生長，然而在人類前列腺癌細胞中卻沒有文獻去釐清 EGCG 與 arecoline 之間的交互作用。藉由雄性素非依賴型的人類前列腺癌細胞株 PC-3 ，我們發現 EGCG 對於 arecoline 減少細胞存活率的效果有協同作用。在分析生長訊息分子的過程中發現EGCG 與 arecoline混合組相較於對照組與 arecoline 單獨處理組顯著降低 cdk1 、 cdk4 和 cdk6 的表現量，但對於 cdk2 沒有顯著影響。有趣的是在觀察 cyclin 蛋白時， EGCG 會拮抗 arecoline誘導 cyclin B1 蛋白增加的效果，且 cyclin D1 和 D3 相較於單獨處理 arecoline 組，在 EGCG 混合 arecoline 組中有較低的表現量。雖然細胞週期抑制蛋白中的 p18 不受 arecoline 或 EGCG 的藥效影響，但 EGCG 卻會增強 arecoline降低 p21 蛋白表現量的效果。除此之外， EGCG 也會促進 arecoline 在自噬蛋白 LC3β-II 和凋亡蛋白 PARP 之表現量的增加效果，但 EGCG 對於 LC3β-I 則沒有影響。有趣的是， EGCG 與另一種抗氧化物 NAC 都能阻止 arecoline 所產生的 ROS ，然而 NAC 雖然能回復單獨處理 arecoline 及 EGCG 混合 arecoline組所減少的細胞存活率，但不影響單獨處理 EGCG 組所減少的細胞存活率。從以上結果推測 EGCG 和 arecoline 共同作用在 PC-3 細胞生長上的機制可能是透過調控某些路徑，如 cdk 、 cyclin 和 CKI 的家族蛋白的變化、細胞自噬和細胞凋亡的過程以及細胞中的氧化系統。;Green tea epigallocatechin gallate (EGCG) and betel nut arecoline have been reported to regulate blood testosterone level and prostate gland growth in rats, respectively. However, a clear interaction between EGCG and arecoline on human prostate cancer cells was not reported. Using androgen-independent human PC-3 prostate cancer cells, we found that EGCG had a synergistic effect with arecoline to reduce the cell viability. When growth signaling molecules were examined, the combination of arecoline and EGCG treatment significantly reduced the level of cylin-dependent kinase (CDK) 1, CDK4 and CDK6, but not CDK2, relative to the arecoline group or the control. Interestingly, when the endogenous CDK activators cyclins were examined, EGCG antagonized the arecoline-induced increase in cyclin B1 protein, and EGCG in combination with arecoline significantly lowered the levels of cyclins D1 and D3 compared with the arecoline group. When the endogenous CDK inhibitors (CKIs) were examined, EGCG further reduced arecoline-suppressed p21 protein level but both EGCG and arecoline had no effect on the p18 protein expression. Moreover, EGCG enhanced the arecoline-increased PARP apoptotic protein level as well as the LC3β-II but not LC3β-I autophagic protein levels. Interestingly, EGCG and the antioxidant N-acetylcysteine (NAC) were found to prevent arecoline-induced reactive oxygen species (ROS) production. However, NAC enabled to reverse the suppressive effect of arecoline, and the combination of arecoline and EGCG on cell viability, while it did not alter EGCG-induced decrease in cell viability. These results suggest that the mechanisms for the combinatorial effect of EGCG with arecoline on PC-3 cell growth may be related to certain pathways, such as the modulations of particular CDK, cyclin, and CKI family members, processes of autophagy and apoptosis, and the redox status. |
