Survival-related DNA repair phenomena in cultured rat-kangaroo cells.
Cultured cells (line PtK-2) from the marsupial mammal rat-kangaroo, or potoroo (Potorous tridactylis), which photoreactivate (PR) both UV-induced dimers and lethality, excise few dimers, and are only slightly sensitized by post-UV exposure to caffeine, were subjected to caffeine and hydroxyurea (HU) treatments during the 30-min PR period. It was found that neither caffeine nor HU inhibited PR of lethality as measured by colony-forming ability. Further, the cells exhibited no photoprotective properties and 3 mM caffeine potentiated the same slight survival decrease in both photoreactivated and unphotoreactivated cells. It is evident that caffeine does not inhibit PR or the survival-related dark repair systems to any great extent, and hence the caffeine-sensitive post-UV dark repair found in this (and possibly other) mammalian cell lines may not be related directly to survival-dependent pyrimidine dimer removal, but instead to lesions or repair processes other than, but not excluding, pyrimidine dimers.
Department of Biochemistry and Biophysics, Pennsylvania State University, University Park, PA 16802, USA.
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D000818:Animals; D002110:Caffeine / Q000494:pharmacology*; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects / Q000235:genetics* / Q000528:radiation effects; D004260:DNA Repair / Q000187:drug effects / Q000235:genetics* / Q000528:radiation effects; D004173:Dipodomys; D004305:Dose-Response Relationship, Drug; D004307:Dose-Response Relationship, Radiation; D014466:Ultraviolet Rays
D002110:Caffeine