Proliferation capacity and p53 expression of HTB140 cells after proton irradiation

Human HTB140 melanoma cells were used to investigate different responses to single irradiation with protons, regarding cell proliferation, induction of apoptosis and expression of p53. Exponentially growing cells were irradiated close to the Bragg peak maximum of the unmodulated 62 MeV proton beam. Doses applied ranged from 8 to 24 Gy at the dose rate of 15 Gy/min. Cell proliferation, measured 6 and 48 h postirradiation, has shown highly significant dose and time dependent decrease. Protons induced apoptosis, 6 and 48 h after irradiation, decreasing with the increase of postirradiation incubation time. The largest number of apoptotic cells was at 6 h after irradiation with 16 Gy protons. High level of p53 expression was detected in all irradiated samples, as well as in controls and was independent of dose applied and postirradiation incubation time. (author)