Relationship between growth fraction and clonogenic survival after ionizing irradiation in pancreatic MiaPaCa2 cells

Background. The prediction of cell radiosensitivity still remains a matter of great interest in the field of radiation biology and oncology. The aim of the present study was to examine the relationship between the value of growth fraction (GF) prior to irradiation and the clonogenic survival of the pancreatic cancer cell line MiaPaCa2. Materials and methods. Growth fraction prior to irradiation was determined by a novel method using bromodeoxyuridine-flow cytometry data from a single sample. The cells were irradiated with 2 and 8 Gy using a 60Co source. Cell survival after ionizing radiation was measured using a clonogenic assay. Pearson' product-moment correlation coefficient was used to estimate the correlation of GF and clonogenic survival fraction values. Results. A positive correlation between GF values and cell survival fraction was obtained after irradiation with 8 Gy (r = 0.67, P = 0.0002). We observed a trend of a higher GF and better clonogenic survival of cells after irradiation with 2 Gy. Conclusions. A higher growth fraction prior to irradiation is related to a better clonogenic survival of the pancreatic cell line MiaPaCa2. Whether or not this finding is applicable to other cell types remains to be established.