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The influence of phytic acid on NFκB expression in human colon cancer cells

Ludmiła Węglarz ,  Beata Parfiniewicz ,  Małgorzata Kapral ,  Agnieszka Zachacz 

Department of Biochemistry, Medical University of Silesia, Narcyzów 1, Sosnowiec 41-200, Poland


Nuclear factor kB (NF-kB), a member of transcriptional factor family plays a central role in coordinating the expression of a wide variety of genes. It is involved in promoting cancer cell proliferation, preventing apoptosis, and increasing a tumor’s angiogenic and metastatic potential. It has been shown that NF-kB is constitutively activated in several types of tumors including colorectal cancer. Several studies in recent years have revealed both preventive and interventive efficacy of phytic acid (IP6) in different animal tumor models, however, the mechanisms of its action have not been elucidated as yet.

The aim of this study was to analyze the influence of phytic acid on the expression of p65 and p50 subunits of NF-kB and that of its inhibitor IkBa in colorectal cancer cell line Caco-2. A kinetic study of p65 and p50 subunits and IkBa mRNAs was performed on Caco-2 cells after treatment with 1; 2.5; 5 mM IP6 for 1, 6, 12 and 24 hours. Real time QRT-PCR based on SYBR Green methodology was applied to analyze quantitatively the transcript levels of these genes.

Statistical analysis of the experimental data revealed time dependent changes in transcriptional activities of IκBα and p65 occurring in both control cells and in cells incubated with IP6. The expression of IκBα inhibitor did not show any significant changes in response to 1.0, 2.5, and 5 mM IP6 at 1 h of incubation, compared to the expression of this gene in the control cells. Treatment of cells with 5 mM of IP6 resulted in strong increase in IκBa expression observed at 6, 12 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. There were no statistically significant differences between p65 mRNA quantities in the cells exposed to IP6 at its increasing concentrations for 1 h. However, the increase in transcriptional activity of p65 gene in response to 5 mM IP6 after 6 and 12 h was observed. Cells treated with 2.5 and 5 mM IP6 showed a significant decrease in the expression of p65 gene occurring at 24h. There were no quantitative changes in the p50 gene expression in the cells treated with IP6 compared to the control cells. High correlation between the expression of IκBα and p65, and also statistical correlations between IκBα and p50 as well as between p50 and p65 transcript levels were observed. The overall results of this study suggest that the ability of 5 mM phytic acid to inhibit colon cancer cells proliferation may be mediated by the stimulation of IκBα expression at the mRNA level.


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Presentation: Poster at Zjazd Polskiego Towarzystwa Biochemicznego, Sympozjum E, by Ludmiła Węglarz
See On-line Journal of Zjazd Polskiego Towarzystwa Biochemicznego

Submitted: 2007-04-27 13:16
Revised:   2009-06-07 00:44