Transfer of aminolevulinic acid-induced protoporphyrin IX from tumor cells into the blood

Abstract

This work evaluates the δ -aminolevulic acid (ALA)-induced Protoporphyrin IX (PpIX) synthesis and the PPIX transference from the tumor cells to the whole blood cells. Human prostate tumor cells (DU145 cells) received ALA at different periods and doses to analyze the PPIX synthesis. Thereafter, blood of healthy animals was added to the cultured tumorigenic cells to monitor the transference of the PPIX synthesized from them to the blood cells. Our results demonstrated that the intracellular production and accumulation of PPIX into prostate human tumor cells depends on the ALA doses and the time of exposition. Besides, PPIX molecules synthesized by tumor cells were transferred to the blood cells, but they were not transferred to the DMEM medium solution, showing that it is not a simple diffusion process of PPIX migration, but probably a complex efflux mechanism that cells have developed to transport it through the blood cells to regulate PPIX concentration inside them, since an excess of PPIX is highly toxic. These findings can be useful to understand the accumulation of PPIX to the blood of tumor-bearing animals and cancer patients, and it can be useful to design treatment and diagnosis protocols.