Genes involved in the destruction of leukaemic cells by induced photosensitivity

Gene expression changes were observed in the HEL and HL-60 cell lines after the stimulation of protoporphyrin IX synthesis by ALA administration and p hotodynamic process induction. Isolated ribonucleic acids were radiolabelle d by reverse transcription, and the cDNA obtained was hybridized to membran e macroarrays (Clontech 7742-1) containing 588 gene probes, Besides changes in the activity of genes supposed to be involved in the programmed cell de ath and DNA reparation processes, increased or diminished transcription act ivity was also observed in several other genes; the reason for this phenome non was not clear. The activation of programmed-cell-death genes appeared a fter the ALA load application, indicating the toxic effect of ALA, The gene expression changes observed in the two cell lines differed substantially, only a few of them were common for both cell lines.