Phytic acid, a hexaphosphorylated inositol (IP6) is a major fiber-associated component of wheat bran and legumes. A number of recent studies revealed strong anti-cancer activity of IP6, and hence, the molecular mechanisms of its action are still under investigation. IP6 is hypothesized to target cancer through multiple pathways, i.e., modulation of cell signal transduction, inhibition of cell proliferation, and cell cycle progression, and activation of apoptosis, and induction of cell differentiation. IP6 may also be involved in many nuclear processes, including DNA repair, transcriptional regulation and mRNA transport.

Nuclear factor kB (NF-kB), a member of transcriptional factors, plays an important role in regulation of the expression of genes employed in these processes. It has been shown that NF-kB is constitutively activated in several types of tumors including colorectal cancer.

The aim of this study was to evaluate the influence of IP6 on the expression of genes encoding p65 and p50 subunits of NF-kB and of its inhibitor IkBα in human colorectal cancer cell line Caco-2.

The cells cultured in RPMI 1640 medium supplemented with 10% fetal bovine serum, 100 U/ml penicilline and 100 μg/ml streptomycin. They were grown at 37°C as monolayers in a humidified atmosphere containing 5% CO₂. Cells were treated with 1, 2.5, 5 mM IP6 for 1, 6, 12 and 24 h. Total RNA was extracted from control and IP6 treated cells with the use of TRIZOL^® reagent according to the producer’s protocol. Quantification of the genes expression was performed by real time QRT-PCR with a SYBR Green I chemistry (SYBR Green Quantitect RT-PCR Kit, Qiagen) using an Opticon™ DNA Engine Sequence Detector (MJ Research, USA). The results were recalculated per mg of total RNA. Statistical analysis was performed with the use of Statistica 6.0 software.

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 incubation, compared to the expression of this gene in the control cells (p=0,7353; ANOVA). Treatment of cells with 5 mM of IP6 resulted in strong increase in IκBa expression observed at 6h (p=0,0009; Tukey test), 12h (p=0,0002) and 24h (p=0,0011). 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 (p<0,05; Tukey test). There was no statistically significant difference between p65 mRNA quantities in the cells exposed to increasing concentrations of IP6 for 1 h. However, the increase in transcriptional activity of p65 gene in response to 5 mM IP6 after 6h (p=0,0009) and 12 h (p=0,048) was observed. Cells treated for 24h with 2.5 mM (p=0,0026) and 5 mM IP6 (p=0,0112) 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 (p>0,05; ANOVA). High correlation between the expression of IκBα and p65 (R=0,72, p=0,000; Spearman’s rank correlation test) was observed. There were any correlations between IκBα and p50 (R=0,37, p=0,1465) as well as between p50 and p65 transcript levels (R=0,39, p=0,1220).

In summary, the findings of this study show that IP6 alters p65 and IkBα genes expression in colon cancer cells. Changes in transcriptional activities of IkBα and p65 depend on IP6 concentration and time of interaction. These results suggest that the ability of 5 mM phytic acid to inhibit colon cancer cells proliferation may be mediated through the stimulation of IκBα expression at the mRNA level.

• Legal notice:
  

  Copyright (c) Pielaszek Research, all rights reserved.
  The above materials, including auxiliary resources, are subject to Publisher's copyright and the Author(s) intellectual rights. Without limiting Author(s) rights under respective Copyright Transfer Agreement, no part of the above documents may be reproduced without the express written permission of Pielaszek Research, the Publisher. Express permission from the Author(s) is required to use the above materials for academic purposes, such as lectures or scientific presentations.
  In every case, proper references including Author(s) name(s) and URL of this webpage: https://science24.com/paper/14659 must be provided.

1. Detection of the poor metabolizer-associated CYP2D6 gene by long- and tetra-primer PCR technology
2. Role of gene polymorphism in the optimalisation of the treatment with vitamin K antagonist. 
3. The effect of sulphasalazine and 5-aminosalicylic acid on the human colon myofibroblasts
4. The antiproliferative effect of pterostilbene on colon cancer cells in vitro
5. Antiproliferative activity of inositol hexaphosphate against human skin melanoma cells
6. The effect of inositol hexaphosphate on the transcriptional activity of genes encoding cyclin D1 and histone H3 in human intestinal cells stimulated with interleukin 1β
7. Inhibition of inducible nitric oxide synthase expression by inositol hexaphosphate in cultured human colon cancer cells exposed to proinflammatory agents
8. Effect of phytic acid on the expression of IL-6, IL-8 and NFkB in human colonic epithelial cells treated with IL-1β  
9. The influence of TNF-α (tumor necrosis factor - alpha) on concentration of soluble adhesion molecules in cultures of HT-29 cells exposed to inositol hexaphosphate (IP6)
10. Phytic acid down-regulates IL-8 secretion from IL-1β stimulated colonic epithelial cells by influencing mitogen-activated protein kinase signaling pathway.
11. Impact of celecoxib on soluble intercellular adhesion molecule-1 (sICAM-1) and soluble E-cadherin (sE-cadherin) concentrations in human colon cancer cell line cultures exposed to phytic acid (IP6) and TNF-α (tumor necrosis factor-alpha)
12. The effect of inositol hexaphosphate on the transcriptional activity of genes encoding metalloproteinases and their tissue inhibitors in colon cancer cellsstimulated with phorbol-12-myristate 13-acetate
13. Modulation of the expression of genes encoding TGF-β isoforms and their receptors by inositol hexaphosphate in human colon cancer cells
14. Influence of troglitazone, sodium butyrate and 5-aminosalicylic acid on the chemokine ENA-78/CXCL5 secretion in the intestinal subepithelial myofibroblasts
15. The chelation ability of chosen metal ions by protective ointments containing Na₂H₂EDTA  and aminoacid
16. Microsatellite markers analysis in the treatment and diagnosis of familial hypertrophic cardiomyopathy
17. The influence of inositol hexaphosphate on the expression of genes encoding matrix metalloproteinases 2 and 9 and their tissue inhibitors in human colon cancer cells
18. Evaluation of transcriptional activity of genes encoding IL-6 and its receptor in colon cancer cells treated with phytic acid
19. Transcriptional activity of interferon γ and two subunits of its receptor as molecular markers of myocarditis
20. Expression of matrix metalloproteinase 2 and matrix metalloproteinase 9 in laryngeal squamous cell carcinoma
21. Expression of genes of tumor necrosis factor -α and its receptors in colon cancer Caco-2 cells treated with inositol hexaphosphate
22. The influence of phytic acid on NFκB expression in human colon cancer cells
23. The degree of substitution of Desulfovibrio desulfuricans lipopolysaccharides and their lipid A component by phosphates
24. The comparison of free and melanin-bound lipofuscin isolated from pig iris
25. GROWTH OF HUMAN CHONDROCYTES ON BIODEGRADABLE SYNTHETIC POLYMERS
26. INFLUENCE OF SODIUM BUTYRATE ON ANTIOXIDATIVE ENZYMES ACTIVITY IN CACO-2 CELL LINES.
27. ANTI-PROLIFERATIVE EFFECTS OF INOSITOL HEXAPHOSPHATE AND VERAPAMIL ON HUMAN COLON CANCER CACO-2 AND HT-29 CELLS