Scutellaria barbata D. Don extract synergizes the antitumor effects of low dose 5-fluorouracil through induction of apoptosis and 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. This study aimed to investigate the antitumor effects of combined Scutellaria barbata D. Don extract (SBE) and 5-FU treatment in vitro and in vivo and the potential mechanisms. SBE was prepared and analyzed by HPLC. Tumor growth inhibition both in vitro and in vivo, cell apoptosis, apoptosis related protein expressions (P53, bid, bax, bcl-2), caspase-3 activities and 5-FU related enzymes were assessed. SBE could significantly synergize the antitumor effects of low dose 5-FU both in vivo and in vitro. SBE could increase the apoptosis inducing effect of low dose 5-FU in both Bel-7402 and HCT-8 cells. Also, caspase-3 activities, P53 and bax expressions were significantly increased, while bid and bcl-2 expressions were significantly decreased in drug combination groups, compared with individual drug treatment groups. Furthermore, SBE could significantly decrease the mRNA levels of dihydropyrimidine dehydrogenase. These results showed that combined treatment with SBE and low dose 5-FU can significantly inhibit the tumor growth both in vitro and in vivo, which might be related with apoptosis and regulations of 5-FU metabolism.