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.
Schroy
C B
CB
Department of Biochemistry and Biophysics, Pennsylvania State University, University Park, PA 16802, USA.
Todd
P
P
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