Inhibitory effects of voluntary running wheel exercise on UVB-induced skin carcinogenesis in SKH-1 mice.
Earlier studies showed that oral administration of green tea or caffeine to SKH-1 mice inhibited ultraviolet B light (UVB)-induced skin carcinogenesis, decreased dermal fat thickness and increased locomotor activity. In the present study, the effects of voluntary running wheel exercise on thickness of dermal fat as well as on UVB-induced tumorigenesis in SKH-1 mice were studied in UVB-initiated high-risk and UVB-induced complete carcinogenesis models. In the high-risk model, animals were exposed to UVB (30 mJ/cm(2)) 3 times/week for 16 weeks. For 14 weeks subsequent to UVB exposure, half of the animals had access to running wheels in their cages whereas the other half did not. In the complete carcinogenesis model, animals were exposed to UVB (30 mJ/cm(2)) 2 times/week for 33 weeks. From the beginning, half of the animals had access to running wheels whereas the other half did not. At the conclusion of each study, body weights were not different between groups, although animals with running wheels consumed significantly more food and water than animals without running wheels. In addition, animals with running wheels had decreases in parametrial fat pad weight and thickness of the dermal fat layer. In both UVB-initiated high-risk and complete carcinogenesis models, voluntary running wheel exercise delayed the appearance of tumors, decreased the number of tumors per mouse and decreased tumor volume per mouse. Histopathology studies revealed that running wheel exercise decreased the number of non-malignant tumors (primarily keratoacanthomas) by 34% and total tumors per mouse by 32% in both models, and running wheel exercise decreased the formation of squamous cell carcinomas in the UVB-induced complete carcinogenesis model by 27%. In addition, the size of keratoacanthomas and squamous cell carcinomas were decreased substantially in both models. The effects described here indicate that voluntary running wheel exercise inhibits UVB-induced skin tumorigenesis and may also inhibit tumor growth.
Michna
Laura
L
Joint Graduate Program in Toxicology, The State University of New Jersey, Piscataway, NJ 08854, USA.
Wagner
George C
GC
Lou
You-Rong
YR
Xie
Jian-Guo
JG
Peng
Qing-Yun
QY
Lin
Yong
Y
Carlson
Kirsten
K
Shih
Weichung Joe
WJ
Conney
Allan H
AH
Lu
Yao-Ping
YP
D000273:Adipose Tissue / Q000473:pathology; D000818:Animals; D001823:Body Composition; D001835:Body Weight; D005260:Female; D051379:Mice; D008812:Mice, Hairless; D009381:Neoplasms, Radiation-Induced / Q000517:prevention & control*; D010805:Physical Conditioning, Animal; D012420:Running; D012878:Skin Neoplasms / Q000517:prevention & control*; D014466:Ultraviolet Rays