Effect of heavy ions on the activity of migration and invasion of malignant cells

Previously, we have reported that the migration and invasion of H1299 human lung cancer cells irradiated with carbon-ion beams at 40 and 100 keV/μm were suppressed in a dose-dependent manner, regardless of the p53 status: the regulation of p53 in cells by transfecting the cells with a wild-type p53 expression vector (H1299/wtp53), mutant vector (H1299/248mtp53), or p53 null vector. The present study aimed to determine the relationship between p53 gene expression and matrix metalloproteinase (MMP) secretion from H1299 cells after irradiation. The cells were irradiated with carbon-ions and X-rays (150 kVp). The secreted MMP proteins from cells were evaluated by the gelatin zymography of conditioned medium which was collected following incubation of cells from 24 h to 48 h after irradiation. ProMMP-9 was induced in three kinds of cell lines irradiated with X-rays, but no MMP-2 induction was observed regardless of irradiation. Carbon ion irradiation below 1 Gy did not secrete MMP-9 in both null- and mutant-type p53 cells. (author)