Modulation of in vitro transformation and the early and late modes of DNA replication of uv-irradiation Syrian hamster cells by caffeine
The effect of caffeine on post-uv DNA replication was studied to determine its relevance to carcinogenesis. The level of uv-induced transformed colonies of Syrian hamster embryo cells (HEC) was increased up to fivefold when caffeine was added to cells between 0 and 6 h post-uv. The greatest increase was observed when the interval between uv irradiation and caffeine addition was 4 h. Two modes of DNA replication occurred after uv irradiation. During the early mode (0 to 3 h post-uv) the size of nascent strands, as measured by alkaline sucrose sedimentation, was smaller than those in nonirradiated cells, whereas during the late mode they recovered to normal size. Caffeine inhibited the rate of elongation of nascent strands during the early mode. When caffeine was added immediately after uv irradiation, the conversion of the early mode to the late mode was inhibited. Studies on the effects of caffeine have now been extended to the late mode. While caffeine has little effect with the fd elements beginning from the 10th day after irradiation is connected with their proliferation but not with the migration out from lymphoid organs.
- Research Organization:
- National Cancer Inst., Bethesda, MD
- OSTI ID:
- 6200315
- Journal Information:
- Radiat. Res.; (United States), Vol. 87:3
- Country of Publication:
- United States
- Language:
- English
Similar Records
Excision and postreplication DNA repair capacities, enhanced transformation, and survival of Syrian hamster embryo cells irradiated by ultraviolet light
Requirement of long progression time for the expression of neoplastic phenotypes following direct perturbation to specific region(s) of DNA of Syrian hamster embryo cells
Related Subjects
CAFFEINE
RADIOSENSITIVITY EFFECTS
CELL CULTURES
GENETIC RADIATION EFFECTS
DNA
BIOLOGICAL REPAIR
BIOLOGICAL PATHWAYS
CARCINOGENESIS
COMPARATIVE EVALUATIONS
DNA REPLICATION
HAMSTERS
IN VITRO
RADIATION DOSES
TIME DEPENDENCE
ULTRAVIOLET RADIATION
ANALEPTICS
ANIMALS
BIOLOGICAL EFFECTS
BIOLOGICAL RADIATION EFFECTS
BIOLOGICAL RECOVERY
CENTRAL NERVOUS SYSTEM AGENTS
DOSES
DRUGS
ELECTROMAGNETIC RADIATION
GENETIC EFFECTS
HETEROCYCLIC COMPOUNDS
MAMMALS
NUCLEIC ACID REPLICATION
NUCLEIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
PATHOGENESIS
PURINES
RADIATION EFFECTS
RADIATIONS
RECOVERY
REPAIR
RODENTS
VERTEBRATES
XANTHINES
560121* - Radiation Effects on Cells- External Source- (-1987)