Standard in vitro analyses determining the activity of different compounds included in the chemotherapy of colon cancer are currently insufficient. New ideas, such as photodynamic therapy (PDT), may bring tangible benefits. The aim of this study was to show that the biological activity of selected free-base and manganese (III) metallated porphyrins differs in the limitation of colon cancer cell growth in vitro. White light irradiation was also hypothesized to initiate a photodynamic effect on tested porphyrins. Manganese porphyrin (>1 μM) significantly decreased the viability of the colon tumor and normal colon epithelial cells, both in light/lack of light conditions, while decreasing a free-base porphyrin after only 3 min of white light irradiation. Both porphyrins interacted with cytostatics in an antagonistic manner. The manganese porphyrin mainly induced apoptosis and necrosis in the tumor, and apoptosis in the normal cells, regardless of light exposure conditions. The free-base porphyrin conducted mainly apoptosis and autophagy. Normal and tumor cells released low levels of IL-1β and IL-10. Tumor cells released a low level of IL-6. Light conditions and porphyrins were influenced at the cytokine level. Tested manganese (III) metallated and free-base porphyrins differ in their activity against human colon cancer cells. The first showed no photodynamic, but a toxic activity, whereas the second expressed high photodynamic action. White light use may induce a photodynamic effect associated with porphyrins.
Keywords: PDT; cell death; cytokines; human colon tumor and normal cell lines; porphyrin.