We previously reported that
gallic acid (3,4,5-trihydroxybenzoic acid), a naturally occurring plant
phenol, can induce apoptosis in four kinds of human
lung cancer cell lines in vitro. The present study further investigated the in vivo anti-
tumor effects of orally administered
gallic acid.
Gallic acid reduced cell viability of LL-2 mouse
lung cancer cells in vitro dose dependently, with a 50% inhibitory concentration (IC50) value of around 200 microM. C57Black mice were transplanted with LL-2 cells, and administered
gallic acid (1 mg/ml in
drinking water, ad libitum) and/or
cisplatin (4 mg/kg i.p. injection, once a week). The average weight of the transplanted
tumors, obtained at 29 days after
transplantation, in the mice of control,
gallic acid-treated
cisplatin-treated and
cisplatin plus
gallic acid-treated groups was 4.02, 3.65, 3.19 and 1.72 g, respectively. The average
tumor weight of the mice treated with
cisplatin combined with
gallic acid was significantly smaller than that of the control group (p<0.05). The amount of apoptotic cells in the
tumor tissues of mice treated with
gallic acid and/or
cisplatin was significantly higher than those of the control mice. Combination of
gallic acid and
cisplatin increased the
tumor cell apoptosis compared with the treatment with
cisplatin alone. The present findings suggest that the combination of
gallic acid with an anti-
cancer drug, including
cisplatin, may be an effective protocol for
lung cancer therapy.