Sublethal and potentially lethal damage repair on thermal neutron capture therapy.
Tonicity shock or caffeine postirradiation treatment makes evident fast-type potentially lethal damage (PLD). Caffeine expresses fast-type PLD more efficiently than tonicity shock in X-irradiated B-16 mouse melanoma cells, compared with V79 Chinese hamster cells. The survival curves of thermal neutrons for either V79 or B-16 cells exhibit no shoulder. Neither V79 nor B-16 cells show the sublethal damage (SLD) repair of thermal neutrons. Caffeine-sensitive fast-type PLD repairs exist in X-irradiated B-16 cells, as well as V79 cells. The fast-type PLD repair of B-16 cells exposed to thermal neutrons alone is rather less than that of X-irradiated cells. Furthermore, an extremely low level of fast-type PLD repair of B-16 cells with 10B1-paraboronophenylalanine (BPA) preincubation (20 hours) followed by thermal neutron irradiation indicated that 10B(n,alpha)7Li reaction effectively eradicates actively growing melanoma cells. The plateau-phase B-16 cells are well able to repair the slow-type PLD of X-rays. However, cells can not repair the slow-type PLD induced by thermal neutron irradiation with or without 10B1-BPA preincubation. These results suggest that thermal neutron capture therapy can effectively kill radioresistant melanoma cells in both proliferating and quiescent phases.
Utsumi
H
H
Radiation Biology Center, Kyoto University, Japan.
Ichihashi
M
M
Kobayashi
T
T
Elkind
M M
MM
D000818:Animals; D001896:Boron Compounds / Q000378:metabolism / Q000494:pharmacology*; D002470:Cell Survival / Q000528:radiation effects; D006224:Cricetinae; D003412:Cricetulus; D007554:Isotopes; D008546:Melanoma, Experimental / Q000378:metabolism / Q000473:pathology* / Q000532:radiotherapy; D051379:Mice; D009502:Neutrons; D010649:Phenylalanine / Q000378:metabolism / Q000494:pharmacology / Q000031:analogs & derivatives; D011833:Radiation Injuries, Experimental / Q000473:pathology*; D012878:Skin Neoplasms / Q000378:metabolism / Q000473:pathology* / Q000532:radiotherapy; D014407:Tumor Cells, Cultured / Q000378:metabolism / Q000473:pathology / Q000528:radiation effects
D001896:Boron Compounds; D007554:Isotopes; D010649:Phenylalanine; C033685:4-boronophenylalanine