Anticarcinogenic effect of phytic acid (IP6): Apoptosis as a possible mechanism of action

Several in vivo and in vitro studies provide convincing evidence for the anticarcinogenic properties of phytic acid (PA) (Inositol hexaphosphate, IP6). The objectives of this investigation were to elucidate the effects of PA on suppression of colonic aberrant crypt foci (ACF) and to study the inhibitory effect of IP6 on human colon carcinoma, CaCo-2 cell line. Fisher 344 male, weanling rats were divided into 3 groups of 15 each and were fed control diet (AIN 93 G-C) and C+(1 or 2 g/100 g PA in water) for 13 weeks. Rats received 2 s.c. injections of azoxymethane (AOM) in saline at 16 mg/kg body weight at 7 and 8 weeks of age. There was a 36% and 42% reduction in ACF in 1 and 2 g/100 g PA groups compared to control group (P<0.001)(P<0.001). Cytotoxic effect of IP6 was evaluated on Caco-2 cell line at concentrations of 0.25–4 g mol/l using lactate dehydrogenase (LDH) assay (LDH released from the cytosol of damaged cells into the supernatant), histone-associated DNA fragmentation assay using a cell death detection ELISA® kit and microscopic analysis. The cells were treated with 0.25, 0.5, 1.0, 2.0, 4 g mol/l of IP6 and incubated for 24 and 48 h. After 24 h of incubation, LDH release ranged from 13.55% to 44.70%. Histone-associated DNA fragmentation (an assay based on the quantitative sandwich-enzyme-immunoassay- principle directed against DNA and histones which allows the specific determination of mono- and oligonucleosomes in the cytoplasmic fraction of cell lysates) was also dose dependent. CaCo-2 cells grown on slide flaskets in the presence of 0.25 g mol/l IP6 showed membrane blebbing (zeiosis) characteristic of apoptitic activity. Results of this study indicate that IP6 might exert anticarcinogenic activity through induction of apoptosis.