Gene expression profiling can predict the fate of HeLa cells exposed to X-ray irradiation with or without protoporphyrin accumulation.
Protoporphyrin IX (PpIX) enhances the generation of reactive oxygen species in cells following physicochemical interactions with X-rays. To evaluate the use of porphyrins as radio-sensitizers in radiotherapy, the transcriptomic effects of PpIX and/or X-ray irradiation were investigated in HeLa cells. Microarray experiments were performed using Agilent-014,850 Whole Human Genome Microarray 4x44K G4112F (GEO#: GSE61805). We selected the condition corresponding to 1 μg/mL PpIX exposure prior to 3 Gy-irradiation of cells, and collected cells 24 h post irradiation. X-ray exposure at a dose of 3 Gy did not affect cell survival 24 h post irradiation, regardless of the concentration of PpIX. Approximately 50% cells exposed to X-ray irradiation alone (XT) and 70% cells exposed to PpIX treatment for 6 h before X-ray irradiation (PpIX-XT) lost clonogenic ability. Based on p-values (p < 0.01), we selected genes for functional analysis. The majority of the regulated genes in the XT and PpIX-XT groups were related to cell cycle arrest. Furthermore, transcriptome analysis of the cells collected 24 h post irradiation revealed the fate of the cells that lost clonogenic ability due to cell cycle arrest.
Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki, Japan.
Junko
J
Takahashi
Health Research Institute, National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki, Japan.
Masaki
M
Misawa
Faculty of Applied Biological Sciences, Gifu University, Gifu, Japan.
Hitoshi
H
Iwahashi
Cancer; Photodynamic therapy; Protoporphyrin IX (PpIX); Radiotherapy; Sensitizer; X-ray