Conclusions
Low-dose proton beam radiation had an obvious effect on the
MIA PaCa-2 cell line, a laboratory model for pancreatic
carcinoma. Viability data are in line with the data on apoptosis
and showed gradually increasing cell death in the irradiated
cultures up to 72 h after exposure. Recruitment of repair
proteins began immediately after radiation as demonstrated
by gH2AX mobilization; however, cell cycle arrest and,
therefore, the majority of repair processes started only at
24 h after irradiation. Low-dose proton beam irradiation
triggered DNA DSBs and arrested cell cycle. DSBs were repaired
via the NHEJ pathway within 72 h. After 72 h, DSB repair
processes stopped with released cell cycle and gH2AX levels
comparable to the control.