CAFFEIC ACID PHENETHYL ESTER INHIBITS AKTNF-ΚB SIGNALING PATHWAY AND PROMOTES APOPTOSIS OF HUMAN COLON CANCER CELLS

Xujie Wang¹, Fengyan Wang², Huimin Yu³, Yingming Li⁴, Xiugang Pan^{5, *}

¹Department of Gastrointestinal Surgery, Weihai Central Hospital, Weihai, PR China - ²Department of Gastroenterology, Weihai Central Hospital, Weihai, PR China - ³Department of Oncology, Weihai Central Hospital, Weihai, PR China - ⁴Department of Pathology, Weihai Central Hospital, Weihai, PR China - ⁵Department of Endoscopy Center, Weihai Central Hospital, Weihai, PR China

Objective: The mechanism of caffeic acid phenethyl ester (CAPE) inhibition of the NF-κB and Akt signalling pathway leading to the promotion of apoptosis of human colon cancer cells was explored. 

Methods: The human colon cancer cell line HT-29 was cultured and treated with CAPE at different concentrations: 0 μg/ml (blank control group) and 2.5 μg/ml, 5 μg/ml, 7.5 μg/ml, and 10 μg/ ml (CAPE groups). The effect of CAPE on the morphology of apoptotic cells was observed, and the groups were compared for the effects of different concentrations of CAPE on apoptosis and Akt, NF-κB, caspase-3 and caspase-9 protein expression. 

Results: In the 10 μg/ml CAPE group, green fluorescence and cell volume were reduced; nuclear chromatin had green plaques, and the membrane showed bubble expansion. Nuclear chromatin in the late stage showed an orange-red appearance or pyknosis. In the control group, the cells were stained fluorescent green, and had a round or oval shape with bright green chromatin. The rate of apoptosis of each CAPE group was significantly higher compared to that of the control group (p<0.05), and was concentration dependent. The expression of NF-κB and p-Akt in each CAPE group was significantly lower compared to that in the control (p<0.05), and was also concentration dependent. However, there was no significant difference in Akt protein expression between each CAPE group and the control (p>0.05). The BAX/Bcl-2 ratio of each CAPE group was significantly lower compared to that of the control (p<0.05); it was also concentration dependent. The expression of caspase-3 and caspase-9 proteins in each CAPE group was significantly higher compared to that in the control group (p<0.05), and was concentration dependent. 

Conclusion: The apoptotic effect of CAPE on human colon cancer cells may be achieved by inhibiting the Akt/NF-κB signalling pathway, reducing BAX/Bcl-2 ratio, and activating caspase-3 and caspase-9.