Evaluation of low-dose proton beam radiation efficiency in MIA PaCa-2 pancreatic cancer cell line vitality and H2AX formation

Background and objectiveThe aim of this study was to evaluate the efficiency of proton beam irradiation in pancreatic cancer cell line MIA PaCa-2 and its role in the cell cycle, apoptosis, and formation of histone γH2AX in different reparation times (72-h follow-up).Material and methodsThe MIA PaCa-2 pancreatic carcinoma cell line was irradiated with 1.6-Gy proton beam. After irradiation, cell viability was measured colorimetrically, and the cell cycle, apoptosis, and γH2AX expression were evaluated on a FACScan cytometer.ResultsLow-dose proton beam irradiation had an effect on the MIA PaCa-2 tumor cell line already 1 h after exposure, but maximal lethality was reached after 72 h postirradiation with a cell viability rate of 24%. The cell cycle went into partial G1/0 arrest, and was released after 72 h. The expression of γH2AX was strong and its levels were significantly elevated as late as 48 h post radiation. The apoptosis levels increased with post radiation incubation time to reach 79% after 72 h.ConclusionsOur data demonstrate that low-doses proton beam irradiation had an effect on MIA PaCa-2 pancreatic carcinoma cell line. Full extent of irradiation had an impact only 24 h postirradiation, triggering DNA arrested cell cycle in G1/0 phase. Formed DNA DSBs were found to be repaired via the NHEJ pathway mechanism within 72 h. Unsuccessful repaired DSBs induced apoptotic cell death. After 72 h reparation processes were completed, and cell cycle was released from arrest in G1/0 phase.