[Studies on the significance of PLD repair for radioresistance in human uterine adenocarcinoma cells].

Relationships between radioresistance of uterine adenocarcinoma cells and potentially lethal damage repair (PLDR) was studied using four human uterine carcinoma cell lines (HeLa S3, HEC-59, SNG-M and SKG-3a). The magnitude of PLDR was estimated by colony formation assay using cell densed and nutrition deficient cultured cells and transplanted cells in nude mice. PLDR of cultured cells and HeLa S3 cells in nude mice almost finished by 6 hours after irradiation. The magnitude of PLDR of HeLa S3 cells in vitro was almost the same 4-fold ratio as in vivo after radiation exposure at a dose of 5 Gray. This suggests that PLDR in vitro is correlated to that in vivo. Dose-surviving relationships demonstrated that radioresistance of four cultured cells was chiefly expressed as Do and Dq values in hit-theory and the magnitude of their radioresistance was as follows: HEC-59 greater than SNG-M greater than HeLa S3 greater than SKG-3a. On the other hand, the magnitude of their PLDR was as follows: HEC-59 greater than SNG-M greater than HeLa S3 greater than SKG-3a. This proved that the magnitude of radioresistance is correlated to that of PLDR and the more radioresistant adenocarcinoma cells have greater PLDR than squamous cell carcinoma cell. In conclusion, PLD repair may be an important cause of radioresistance in human uterine adenocarcinoma cells.