Wogonin potentiates the antitumor effects of low dose 5-fluorouracil against gastric cancer through induction of apoptosis by down-regulation of NF-kappaB and regulation of its metabolism

Traditional Chinese medicines have been recognized as a new source of anticancer drugs or chemotherapy adjuvant to enhance the efficacy of chemotherapy and to ameliorate the side effects. Wogonin (WOG) has a potential for therapeutic use in the treatment of antitumor and chemoprophylaxis. 5-Fluorouracil (5-FU) is a key systemic chemotherapy drug and widely use in the treatment of solid tumors. In this study, we found that combination of WOG and 5-FU inhibited the viability of MGC-803 cells in a concentration-dependent manner and exhibited a synergistic anticancer effect (CI < 1) when 5-FU was used at relatively low concentrations. The pro-apoptotic activity of two-drug combination was much stronger than single. Furthermore, WOG could decrease the mRNA levels of dihydropyrimidine dehydrogenase (DPD), the metabolic enzymes of 5-FU. WOG could inhibit the NF-κB nuclear translocation and I-κB phosphorylation. Moreover, combined treatment caused significantly growth inhibition of human tumor xenografts. In addition, WOG markedly enhanced the antitumor activity of low dose 5-FU (i.p. 10 mg/kg/day), however there is no toxicity and influence on diet consumption in experimental animals. Taken together, our data's showed that WOG increased 5-FU retention for a prolonged catabolism by modulating 5-FU metabolic enzymes and sensitized the MGC-803 cells to 5-FU induced apoptosis by inhibiting the NF-κB nuclear translocation. The anti-gastric cancer effect of two-drug combination was much stronger than that of WOG or 5-FU alone. These results may be relevant to design new clinical therapeutic strategies against gastric cancer in future.