Isolation and establishment of radiotolerant hepatoma cell subline

Objective To induce and isolate the monoclonal cell subline, in order to establish the experimental model for further investigating biologic characteristics in radiotolerant hepatoma cells. Methods HepG2 cells were irradiated by γ-rays at the dose of 2 Gy each time with the total absorbed dose of 60 Gy. After monoclonal cell being selected and extensively cultured, the cell subline was named as HepG2/R60. Furthermore, HepG2/R60 cells were identified by observing the changes of morphology, ultrastructure, growth characteristics and radiosensitivity. The levels of radioresistant correlative gene mRNA in HepG2/R60 cells after exposure to 2 Gy irradiation, were also detected by RT-PCR, and then compared with parental HepG2 cells. Results HepG2/R60 cell subline was successfully established by fractionated irradiation at 2 Gy. HepG2/R60 cells displayed higher irregularity, the clearer appearance and dissociation of cell junctions compared with parental HepG2 cells. Ultrastnictural investigations through transmission electron microscopy (TEM) showed that there was an increase of microvillus on the surfaces of HepG2/R60 cells with plenty of rough endo-plasmic reticulum, abundance of mitochondria and viable Golgi complex. Further observation found that the growth of HepG2/R60 cells was slower and its population doubling time (PDT) prolonged arrived at 34.9 h. Moreover, the radiosensitivity of HepG2/R60 cells was lower than that of parental HepG2 cells. Additionally, the levels of radioresistance correlative genes were increased in HepG2/R60 cells by 2 Gy irradiaiton Conclusions Radiotolerant cell subline - HepG2/R60 was successfully isolated and established by fractionated irradiation. Key words: Radiation; Hepatoma cells;  Clone;  Radiation tolerance