Stimulatory effect of oral administration of tea, coffee or caffeine on UVB-induced apoptosis in the epidermis of SKH-1 mice.
Oral administration of green tea or a caffeine solution, but not decaffeinated green tea, inhibits UVB-induced complete carcinogenesis in SKH-1 mice. Oral administration of green tea, coffee or a caffeine solution for 2 weeks enhanced UVB-induced increases in apoptosis in the epidermis, but these treatments had no effect in non-UVB treated normal epidermis. Our results suggest that administration of green tea, coffee and caffeine may inhibit UVB-induced carcinogenesis--at least in part--by enhancing UVB-induced apoptosis. Plasma levels of caffeine observed after its oral administration at cancer-preventive dose levels were within the range observed in moderate coffee drinkers. Topical applications of caffeine to mice previously treated with UVB for 20 weeks (high risk mice without tumors) inhibited the formation of tumors and stimulated apoptosis in the tumors but not in areas of the epidermis away from tumors. The selective effects of caffeine administration to stimulate UVB-induced apoptosis or apoptosis in tumors but not in normal epidermis or in areas of the epidermis away from tumors is of considerable interest, but the reasons for the selective effects of caffeine on apoptosis in DNA damaged tissues are unknown. Further studies are needed to determine mechanisms of these effects of caffeine and to determine the effects of caffeine administration on sunlight-induced actinic keratoses and squamous cell carcinomas in humans.
Conney
Allan H
AH
Susan Lehman Cullman Laboratory for Cancer Research, Department of Chemical Biology, Ernest Mario School of Pharmacy, Rutgers, The State University of New Jersey, 164 Frelinghuysen Road, Piscataway, NJ 08854-8020, USA. aconney@rci.rutgers.edu
Zhou
Sherry
S
Lee
Mao-Jung
MJ
Xie
Jian Guo
JG
Yang
Chung S
CS
Lou
You Rong
YR
Lu
YaoPing
Y
D000284:Administration, Oral; D000818:Animals; D017209:Apoptosis / Q000187:drug effects* / Q000528:radiation effects; D002110:Caffeine / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D003069:Coffee / Q000737:chemistry*; D004817:Epidermis / Q000187:drug effects* / Q000473:pathology / Q000528:radiation effects; D051379:Mice; D009374:Neoplasms, Experimental / Q000209:etiology / Q000517:prevention & control; D013662:Tea / Q000737:chemistry*; D014466:Ultraviolet Rays / Q000009:adverse effects*
D003069:Coffee; D013662:Tea; D002110:Caffeine