The colonic epithelium is never exposed to a single factor, therefore studies on the effect of combinations of factors naturally and persistently present in the intestines are of special importance for understanding the phenomena occurring at this place. The aim of the study was to investigate the combined effect of 1 mM phytate and 1 mM butyrate (PA1B1) on cell lines derived from cancer (HCT116 and HT-29) and healthy (NCM460D) human colonic epithelium. Colorimetric and flow cytometry methods were used to determine the proliferation rate, cell cycle, and apoptosis. Selected markers of proliferation, inflammatory, and survival pathways were investigated at the mRNA and/or protein level. The combination of phytate and butyrate disturbed the cell cycle and triggered apoptosis and/or death in both studied cancer colonocytes to a higher extent compared to healthy colonocytes. Moreover, in healthy colonocytes, phytate activated the survival pathway without stimulation of inflammatory response. This may indicate that the response of healthy colonocytes to phytate protects colonic epithelium from the loss of integrity and tightness that would occur if inflammation developed. Based on the obtained results we postulate that studies on both cancer and/or healthy colonocytes should be carried out in the presence of butyrate as the permanent component of colonic contents. This should be of special importance when anti-proliferative/pro-apoptotic activity or inflammatory status of colonocytes is to be investigated.
Keywords: apoptosis; butyrate; cancer colonocytes; cell cycle; cell survival; diet; healthy colonocytes; phytate.