Objective  This study aimed to determine whether apigenin can enhance the inhibitory effect of aspirin on colorectal cancer cell lines and to investigate the underlying mechanism in vitro.

  Methods  The colorectal cancer cell lines HT-29, HCA-7, Moser, and DLD-1 were selected for this study.All cell lines were divided into four groups: control group, group treated with 10 μmol/L apigenin, group treated with aspirin at 2.5, 5, and 10 mmol/L, and group treated with apigenin and aspirin at varying concentrations.Apigenin was applied 2 h prior to aspirin addition.Cell viability was detected by MTT assay at 24, 48, and 72 h post-treatment.Western blot and reverse-transcription polymerase chain reaction analysis were performed to determine the effect of different treatments on the expression of COX-2 in Moser cells 48 h after treatment.Protection of IκBα degradation by TNF-α treatment was detected by Western blot analysis to validate the effect of apigenin and aspirin against NF-κB activation.

  Results  Apigenin enhanced the inhibitory effect of aspirin on colorectal cancer cells in a dose-and time-dependent manner.The effect was correlated with the suppression of COX-2 expression.COX-2 expression was markedly inhibited in the combined treatment group.In addition, combined treatment resulted in a remarkable inhibition of the TNF-α-induced degradation of IκBα.

  Conclusion  Apigenin can potentiate the inhibitory effect of aspirin on colorectal cancer cells by inhibiting COX-2 expression.