Caffeine and exercise may help prevent skin cancer

First, allow me to please introduce the primary source of evidence, Proceedings of the National Academy of Sciences (PNAS):

Here is what appears to be accurate information as of July 30, 2007:

The Proceedings of the National Academy of Sciences of the United States of America, usually referred to as PNAS, is the official journal of the United States National Academy of Sciences. PNAS is an important scientific journal that printed its first issue in 1915 and continues to publish cutting-edge research reports, commentaries,[1] reviews,[2] perspectives,[3] colloquium papers,[4] and actions of the Academy.[5] Coverage in PNAS spans the biological, physical, and social sciences. Although most of the papers published in the journal are in the biomedical sciences, PNAS recruits papers and publishes special features in the physical and social sciences and in mathematics.[6] PNAS (abbreviated Proc Natl Acad Sci USA for referencing and indexing purposes) is published weekly in print, and daily online in PNAS Early Edition.[7]

Impact
PNAS is widely read by researchers, particularly those involved in basic sciences, around the world. The journal is notable for its policy of making research articles freely available online to everyone 6 months after publication (delayed open access), or immediately if authors have chosen the "open access" option (hybrid open access). Immediately free online access (without the 6-month delay) is provided for 144 developing countries and for some categories of papers such as colloquia. Abstracts, tables of contents, and online supporting information are free. Anyone can sign up to receive free tables of contents by email.[8]

Because PNAS is self-sustaining and receives no direct funding from the government or the National Academy of Sciences, the journal charges authors publication fees to help offset the cost of the editorial and publication process.

The journal's impact factor for 2004 was 10.452, for 2005 was 10.231, and 2006 was 9.643 (as measured by Thomson ISI). PNAS is the second most cited scientific journal with 1,338,191 citations from 1994-2004 (the Journal of Biological Chemistry is the most cited journal over this period with 1,740,902 citations in total).

I think it appears that PNAS is a scientific journal rather than a medical journal. I don't think that implies anything either way regarding the integrity of the information; and impact factor (a measurement of citation frequency) is considered a "punative marker of journal quality" (1).

Anyways, here's the abstract:

Published online before print July 30, 2007
Proc. Natl. Acad. Sci. USA, 10.1073/pnas.0705839104

Pharmacology
Voluntary exercise together with oral caffeine markedly stimulates UVB light-induced apoptosis and decreases tissue fat in SKH-1 mice

Yao-Ping Lu *, Bonnie Nolan , You-Rong Lou *, Qing-Yun Peng *, George C. Wagner , and Allan H. Conney *
*Susan Lehman Cullman Laboratory for Cancer Research, Department of Chemical Biology, Ernest Mario School of Pharmacy, Department of Neuroscience, and Department of Psychology, Rutgers, the State University of New Jersey, Piscataway, NJ 08854

Contributed by Allan H. Conney, June 21, 2007 (sent for review April 17, 2007)

Treatment of SKH-1 mice orally with caffeine (0.1 mg/ml in the drinking water), voluntary running wheel exercise, or a combination of caffeine and exercise for 2 weeks (i) decreased the weight of the parametrial fat pads by 35, 62, and 77%, respectively; (ii) decreased the thickness of the dermal fat layer by 38, 42, and 68%, respectively; (iii) stimulated the formation of UVB-induced apoptotic sunburn cells in the epidermis by 96, 120, and 376%, respectively; and (iv) stimulated the formation of UVB-induced caspase 3 (active form)-positive cells in the epidermis by 92, 120, and 389%, respectively (average of two experiments). Oral administration of caffeine (0.4 mg/ml in the drinking water) in combination with voluntary exercise was less effective than administration of the low dose of caffeine in combination with exercise in stimulating UVB-induced apoptosis. Although orally administrated caffeine (0.1 mg/ml in the drinking water) or voluntary exercise for 2 weeks caused only a small nonsignificant stimulation of UVB-induced increase in the percentage of phospho-p53 (Ser-15)-positive cells in the epidermis (27 or 18%, respectively), the combination of the two treatments enhanced the UVB-induced increase in phospho-p53 (Ser-15)-positive cells by 99%. The plasma concentration of caffeine in mice ingesting caffeine (0.1-0.4 mg/ml drinking water) is similar to that in the plasma of most coffee drinkers (one to four cups per day). Our studies indicate a greater than additive stimulatory effect of combined voluntary exercise and oral administration of a low dose of caffeine on UVB-induced apoptosis.

Author contributions: Y-P.L., G.C.W., and A.H.C. designed research; Y-P.L., B.N., Y-R.L., and Q-Y.P. performed research; Y-P.L., G.C.W., and A.H.C. analyzed data; and Y-P.L. and A.H.C. wrote the paper.

The authors declare no conflict of interest.

To whom correspondence should be addressed at: 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.

Allan H. Conney, E-mail: aconney@rci.rutgers.edu

www.pnas.org/cgi/doi/10.1073/pnas.0705839104

Click here for a definition of apoptosis.

For a "mainstream" take on this story, click here to read: "CBC News: Caffeine and exercise may help prevent skin cancer." That's where I got the title from.

Thoughts or comments?

Take care.

Great justification for my morning coffee and running/biking..... ;-)

Click HERE to rent this advertising spot for SUPPLEMENTS (in thread) to support LongeCity (this will replace the google ad above).

Exercise Plus Coffee May Ward Off Skin Cancer
07.30.07, 12:00 AM ET

MONDAY, July 30 (HealthDay News) -- A coffee habit, coupled with regular exercise, may help prevent skin cancers better than either factor alone, new research suggests.
The study was done only with animals, however, and it's not a reason to abandon standard sun-protection habits.

"You should not give up the sunblock," said Dr. Allan H. Conney, senior author of the study, published in this week's Proceedings of the National Academy of Sciences.

The findings aren't entirely new. "In earlier studies, we found caffeine and exercise -- either one by themselves -- inhibited ultraviolet light-induced skin cancer in mice," said Conney, the director of the Laboratory for Cancer Research at the School of Pharmacy at Rutgers, the State University of New Jersey.

But the new research shows that "the combination [of the two] works better," he said, providing a dramatically better anti-cancer result.

Both caffeine and exercise seem to help kill the UVB-damaged cells before malignancy sets in. "We really don't know how that happens," Conney said.

In the study, his team looked at four groups of hairless mice. The rodents' exposed skin is very vulnerable to the sun.

One group was given caffeinated water to drink each day, the equivalent of a person drinking a couple of cups of coffee a day, Conney said. Another group ran voluntarily on a running wheel, the equivalent of a person running two or two and a half miles every day, he said. (These mice will happily go on an exercise wheel if one is available, Conney said.) A third group had both the caffeine and the exercise, while a fourth group had neither and served as the control group.

The mice in all four groups were exposed to lamps that generated UVB radiation that damaged the skin cells' DNA.

While some degree of healthy, programmed skin cell death ("apoptosis") was seen in all four groups of mice, the caffeine drinkers and exercisers were best at killing off the damaged cells, the researchers found.

To find out how different the four groups were in terms of killing off damaged skin cells, the researchers looked at physical changes in those cells. They also looked at chemical markers, such as enzymes, involved in killing damaged cells.

The differences were dramatic. The caffeine drinkers showed a 96 percent increase in damaged cell death compared to the control group and the exercisers showed a 120 percent increase. Even more significant, the mice that drank caffeine and ran on the training wheel had a nearly 400 percent increase in cell death of damaged cells.

Whether this combination would work in people is not known, Conney said, although some research has found that caffeine and exercise does reduce certain cancer risks. He said he would like to do a clinical study in humans next.

More than a million non-melanoma skin cancers are diagnosed in the United States annually, according to the American Cancer Society. About 62,190 cases of melanoma, the most deadly skin cancer type, will be diagnosed this year.

A spokesman for the Skin Cancer Foundation urged caution in interpreting the study findings, however. "It will take years of extensive testing to determine whether this will be a worthwhile concept before you can say anything specific about it," said Dr. Michael Gold, founder of the Gold Skin Care Center in Nashville, Tenn.

"Mice and humans are very different. That said, we do know that caffeine applied topically has been popular as a 'cosmeceutical' anti-aging ingredient and might be useful in helping prevent non-melanoma skin cancers," Gold said. "The concept of systemic caffeine needs to be addressed further. We also know that moderate exercise is an immune moderator and can help ward off cancers and other diseases."

He echoed standard advice to wear sunscreen when out in the sun. "If you are exercising outside you must wear sunscreen no matter what," Gold said. "If you don't protect yourself from the sun while exercising outdoors you are increasing your risk of getting non-melanoma skin cancers and melanoma. Protecting yourself from the sun is currently the only proven way to prevent skin cancer."

More information

To learn more about skin cancer, visit the American Cancer Society.

Edited by bixbyte, 31 July 2007 - 02:13 PM.