Abstract A50: Plantago major inhibits azoxymethane-induced aberrant crypt foci in C57BL/6 mice and modulates apoptosis in mice and human colon cancer cells

Abstract

Plantago major (PM), commonly known as common plantain, is a temperate perennial herb. Traditionally, its seeds and leaves have been ingested or applied externally to treat inflammation and infection. Studies showed PM possesses inhibitory effects towards a variety of tumors and cancer cell lines, including mice Ehrlich ascites carcinoma and breast adenocarcinoma, gastric, leukaemia, ovary, melanoma, and renal human cell lines. While PM has been shown to exhibit selective cytotoxic activity against cancer cells, its quantitative potential as a chemopreventive agent on colon cancer has yet to be elucidated. In this study, C57BL/6 mice (N = 30) of 9 wk old were randomized into three groups (N = 10). Positive and experimental mice groups were injected with Azoxymethane (AOM; 5 mg/kg body weight) at the onset and second wk of the 8-wk duration of the in vivo study while the negative group received no injection. The mice in the experimental group were given daily oral feedings of 20 mg/ml of PM from the onset of the study while the negative and positive control groups were given a sterilized water placebo. All groups were sacrificed after 8 wks and 25 mm cuts of the proximal colon were analyzed for aberrant crypt foci (ACF). PM feeding significantly reduced the number of AOM-induced ACF in the proximal colon compared to the water-fed positive control AOM-induced group (7.02 ± 2.61 < 32.1 ± 9.86; P < 0.0003). The negative control, water placebo group had minimal ACF (2.0 ± 1.56) compared to the experimental and positive control groups. The potency index of the herb was calculated as 4.57. Percent inhibition of AOM-induced ACF formation of 78.1% was obtained with the PM treatment. On average, all three groups gained weight (calculated as % increase) through the course of the experiment (experimental, 6.93 < negative control 15.6 < positive control 39.4). Histological (H&E) slides of the proximal colon displayed a significantly higher apoptotic index than the positive control (AOM only) (2.0 > 0.6) and a lower mitotic index (MI) than control (1.5 < 2.8). Caspase 3 induction was identified in human colon cancer cells (COLO-205) treated with PM (5mg/ml) in chamber slides, using a specific carboxyfluorecein (FAM) labeled peptide fluoromethyl ketone (FMK) caspase inhibitor (FAM-Peptide-FMK). Caspase 3 activation was also observed in immunofluorescent slides of PM treated proximal colon tissues. Through inhibition of AOM-induced ACF via apoptosis, our data suggests PM to be a prospective chemopreventive and potential therapeutic agent for colon cancer. Citation Information: Cancer Prev Res 2010;3(12 Suppl):A50.