Non-lethal ALA-based PDT stimulates expression of neutrophil activation pathways in tumor cells.

Gene set enrichment analysis (GSEA) revealed activation of a set of genes 24 h after non-lethal PDT of all 4 prostate and glioblastoma cell lines (data are shown for PC-3) which is also found to be characteristic for neutrophil activation during wound healing [55]. Upregulation is illustrated by the concentration of the vertical black lines (that represent gene set member positions within the ranked gene list) at the left side of the gene list (“zero cross”; see “waterfall plot” at the bottom of the graph). This distribution leads to a high and significant enrichment score (maximum deviation of the green line from zero; P<0.001 and false discovery rate (FDR) <0.001).