Enhancement of radiation effects by Plantago major in MCF-7 human breast cancer: an animal study.

PURPOSE

We aimed to evaluate the potential effects of Plantago major (PM) to enhance the radiosensitivity of human breast adenocarcinoma cell line (MCF-7) in an animal model.

MATERIALS AND METHODS

Seventy-two female Balb/c mice were divided into nine groups (8 mice per group) as follows: MCF-7 breast cancer control group, MCF-7+low dose of PM (1000 mg/kg), MCF-7+high dose of PM (1500 mg/kg), MCF-7+3 Gy superficial X-ray, MCF-7+5 Gy superficial X-ray, MCF-7+1000&1500 mg/kg of PM with 3 and 5 Gy irradiations. For each treatment group, micronuclei in 500 binucleate MCF-7 cells from a minimum of three experiments were counted. The alkaline comet assay was used to calculate % DNA in the tail and % of apoptotic comets. The tumor size in the treated groups (3 mice per group) was assessed at 4- and 8-weeks post-treatment.

RESULTS

The number of total micronuclei and binucleated micronuclei in the PM and/or irradiation treated groups was significantly higher than in the control group (P < 0.05). Irradiation+PM resulted in a significant increase treatment effect compared to the irradiation-only groups (P < 0.01). In addition, the higher PM concentration had a significantly higher number of micronucleated binucleate cells when combined with 5 Gy irradiation (P = 0.022). Irradiation alone or in combination with PM resulted in significant increases in percentages of DNA in tail and apoptotic comet values compared to the PM-only treatment groups (P < 0.02). Combining 5 Gy of irradiation with 1000 mg/kg of PM led to a 26% reduction in tumor size (0.28±0.04 vs. 0.38 ± 0.03) after 4 weeks, and combining 5 Gy of irradiation with 1500 mg/kg of PM resulted in a 40% decrease in tumor volume after 4 weeks (0.21±0.04 vs. 0.35±0.03).

CONCLUSION

PM extract at both doses demonstrated an antitumor effect on induced MCF-7 breast cancer tumors, with this effect being enhanced when combined with irradiation.