Abstract
Malignant pleural mesothelioma (MPM) is an aggressive tumor arising from serous surfaces. Eighty percent of patients will have a definite asbestos exposure history, often with 20- 40 year latency between asbestos exposure and development of malignancy. Due to asbestos was widely used in the world between the 1940s and 1979, it has been estimated that the number of men dying from MPM increase each year until a peak is reached in about 2020. MPM is resistant to radiotherapy, surgery or chemotherapy, and only slightly improve prognosis. So far, no effective therapeutics has been established for the disease-advanced case. We examined the radiosensitivity of MPM cell lines by X rays and carbon-ion beams last year and this year we investigated the relationship between cell-killing effect and the biological character, such as the modal chromosome number. Six kinds of MPM cell lines were used and irradiated with X rays or carbon-ion beams (13keV/μm and approximately 80keV/μm) at the Heavy Ion Medical Accelerator in Chiba (HIMAC). Cell-killing effect was detected using a colony-formation assay. The number of chromosomes was observed in a metaphase spread. The results indicated there was a good correlation in the D10 values of MPM cell lines between X rays and carbon-ion beams. Different MPM cell lines showed a great variation in numbers of chromosome, and the distribution of the number of chromosomes in the same cell line is also great different. The mean numbers of chromosomes of those cell lines are to be 48-95, and the D10 values are not clearly correlated to the chromosome number of each cell line except for the MESO-4. The results suggest that the radiosensitivity of MPM cell lines correlate to LET of radiation but did not clearly depend on the modal chromosome number.
