Radiosensitivity and mechanism of lethal effect in mesothelioma by heavy ions

Officially distributed 6 kinds of Malignant pleural mesothelioma (MPM) cell lines were used and irradiated with X rays or carbon-ion beams (13.3 keV/μm and approximately 80 keV/μm). Cell-killing effect was detected using a colony-formation assay. D₁₀, which is one of the parameters for cellular radio-sensitivity, of 6 kinds of cell lines ranges from 2.74 Gy to 5.42 Gy for X rays, 2.17 Gy to 4.21 Gy for 13 keV/μm- and 1.08 Gy to 2.38 Gy for 80 keV/μ-carbon ions. The relative biological effectiveness (RBE) values calculated by the D₁₀ relative to X rays, range from 1.24 to 1.42 for 13 keV/μm- and from 2.31 to 3.09 for approximate 80 keV/μm-carbon ions on each cell line. The results suggest that the irradiation of high linear energy transfer (LET) carbon ions are also significantly more effective in cell killing for the 6 kinds of MPM cell lines than that of low LET ion beams or X rays. The potential lethal damage repair (PLDR) of some kinds of plateau phase MPM cell lines irradiated by heavy ions were also assessed by comparing the radio-sensitivities of immediately plating with delayed plating (DP), and found in the PLDR for high LET radiation maybe less than in low LET radiation like other cells. (author)