Quantitative analysis of the level of p53 and p21WAF1 mRNA in human colon cancer HT-29 cells treated with inositol hexaphosphate

The aim of this study was to analyze the molecular mechanism of inositol hexaphosphate (InsP6) action through which it may inhibit proliferation of colon cancer cells and cell cycle progression. A kinetic study of p53 and p21WAF1 mRNA increase was performed on human colon cancer HT-29 cells after treatment with 1, 5 and 10 mM InsP6 for 6, 12, 24 and 48 h. Real-time-QPCR based on TaqMan methodology was applied to analyze quantitatively the transcript levels of these genes. The transcription of β-actin and GAPDH genes was assessed in parallel to select the control gene with least variability. The 2-ΔΔCt method was used to analyze the relative changes in gene transcription. InsP6 stimulated p53 and p21WAF1 expression at the mRNA level, with the highest increase in p21WAF1 mRNA occurring at 24 h, i.e., following the highest increase in p53 mRNA observed at 12 h. Based on these studies it may be concluded that the ability of InsP6 to arrest the cell cycle may be mediated by the transcriptional up-regulation of the p53-responsive p21WAF1 gene.