Evaluation of the expression of transcriptional factor NF-kappaB induced by phytic acid in colon cancer cells

Over the last years phytic acid, a hexaphosphorylated inositol (IP6) has attracted particular attention due to its anti-cancer activity, however, the molecular mechanisms of its action have not been elucidated, as yet. The aim of this study was to evaluate the influence of phytic acid on the expression of genes encoding p65 and p50 subunits of NF-kappaB and of its inhibitor IkappaBalpha in human colorectal cancer cell line Caco-2. A kinetic study of p65 and p50 subunits and IkappaBalpha mRNAs expression was performed on Caco-2 cells after treatment with 1, 2.5 and 5 mM IP6 for 1, 6, 12 and 24 h. Quantification of the genes expression was carried out using real time QRT-PCR technique. Treatment of cells with 5 mM IP6 resulted in a strong increase in IkappaBalpha expression at 6 h, 12 h and 24 h. The level of p65 transcript after 1 h was lower in the cells exposed to 1, 2.5, and 5 mM IP6 than in the control cells. The increase in transcriptional activity of p65 gene in response to 5 mM IP6 after 6 h and 12 h was observed. Cells treated for 24 h with 2.5 mM and 5 mM IP6 showed a significant decrease in expression of p65 gene. There were no quantitative changes in the p50 gene expression in the cells treated with IP6 compared to the control cells. High positive correlation between the expression of IkappaBalpha and p65 was detected. The results of this study suggest that IP6 primarily influences p65 and IkappaBalpha genes expression in colon cancer cells. Changes in transcriptional activities of IkappaBalpha and p65 depend on IP6 concentration and time of its action.