Ding Yangping, Chen Bingcan, Gao Zili, Suo Huayi, Xiao Hang
College of Food Science, Southwest University, Chongqing, China.
Department of Food Science, University of Massachusetts, Amherst, MA, USA.
Food Nutr Res. 2017 Nov 15;61(1):1400340. doi: 10.1080/16546628.2017.1400340. eCollection 2017.
The pro-apoptotic and inhibitory effects of the aflavin-3,3'-digallate (TFDG), which is the typical pigment in black tea, have been demonstrated in many cancer cell lines. However, TFDG is not stable in general culture conditions. So, to what extent TFDG or which degradation products of TFDG play an antitumor role is still unclear. In this study, we evaluated the effect of different treatments of TFDG on HCT116 cells. Compared with the control, both TFDG and O-TFDG (the TFDG that was pre-incubated in an incubator at 37°C for 3 hbefore adding into 96-well plates) significantly inhibited HCT116 cell growth. However, pre-treated TFDG was far better than TFDG. The IC50 values of TFDG and O-TFDG-3 were 17.26 μM and 8.98 μM, respectively (the cells were treated by O-TFDG for only 3 h, after which the media were replaced by fresh media for another 69 h incubation). Cell-cycle analysis revealed that 20 μM of O-TFDG and O-TFDG-3 caused cell-cycle arrest at G2 phase in HCT116 cells. Western blot analysis also demonstrated that the anti-inflammatory effect of O-TFDG-3 is stronger than that of TFDG by decreasing COX-2 and iNOS. On the other hand, O-TFDG induced HCT116 cells apoptosis mainly by increasing the expression of p53, p21, and cleaved caspase-3. The current study demonstrated that O-TFDG had a higher inhibitory effect on HCT116 cells than TFDG, and sowe may inferfromthis that the degradation products of TFDG play a key role against tumors.
茶黄素 -3,3'- 双没食子酸酯（TFDG）是红茶中的典型色素，其促凋亡和抑制作用已在多种癌细胞系中得到证实。然而，TFDG在一般培养条件下不稳定。因此，TFDG或其哪些降解产物在多大程度上发挥抗肿瘤作用仍不清楚。在本研究中，我们评估了TFDG的不同处理方式对HCT116细胞的影响。与对照组相比，TFDG和O - TFDG（在37°C培养箱中预孵育3小时后再加入96孔板的TFDG）均显著抑制HCT116细胞生长。然而，预处理的TFDG比TFDG效果好得多。TFDG和O - TFDG - 3的IC50值分别为17.26 μM和8.98 μM（细胞用O - TFDG处理仅3小时，之后更换为新鲜培养基再孵育69小时）。细胞周期分析显示，20 μM的O - TFDG和O - TFDG - 3导致HCT116细胞在G2期发生细胞周期阻滞。蛋白质免疫印迹分析还表明，O - TFDG - 3通过降低COX - 2和iNOS的表达，其抗炎作用比TFDG更强。另一方面，O - TFDG主要通过增加p53、p21和裂解的caspase - 3的表达诱导HCT116细胞凋亡。当前研究表明，O - TFDG对HCT116细胞的抑制作用比TFDG更高，因此我们可以由此推断TFDG的降解产物在抗肿瘤中起关键作用。
