Fake Tan vs. Real Tan

Many sun worshipers have changed their ways, choosing Mystic Tan over wrinkles and skin cancer. But spray-on tans can leave a disconcerting orangecicle hue.

Researchers at the University of Kentucky are perfecting a better option: a skin cream that stimulates the body's own tan-generating cells, producing the same bronzed results as a natural tan without the sun exposure.

The commercial prospects of such a lotion are likely bright, at least among Jessica Simpson acolytes. But the scientists are not interested in your vanity, they said. They hope the lotion can prevent skin cancer.

"We didn't do this to be beauty scientists -- we're trying to prevent cancer," said lead researcher John D'Orazio, an assistant professor at Kentucky Children's Hospital. "Melanoma is the fastest-growing malignancy of the past three decades. If this drug stops people from going to tanning beds, I'll be happy."

The key to the ultimate fake bake, D'Orazio said, may be forskolin, a naturally occurring plant derivative that scientists have studied since the 1970s. Forskolin spurs production of cyclic adenosine monophosphate, or AMP, a molecule that among other things activates pigment-producing cells in the skin called melanocytes.

"Adaptive tanning is an important form of protection -- it lessens the dangers of being exposed to the sun," he said. "We wanted to see if this compound could have that effect."

To test forskolin's tan-generating properties, D'Orazio and David Fisher of the Dana Farber Cancer Institute coated pale-skinned mice with a forskolin-containing lotion for three weeks. Afterward, the treated mice were considerably tanner than controls. Also, following prolonged exposure to ultraviolet light, the treated mice suffered 20 times less sunburn and DNA damage, and developed fewer tumors. The study was published this month in Nature.

"From a UV standpoint, (forskolin) is like having sunscreen right in your skin," D'Orazio said, explaining that the cream would not need to be constantly reapplied, because it enhances the body's own sun-protective mechanism of churning out pigment. Forskolin could be particularly suited to redheads and others who have a hard time tanning, he added.

Magen BioSciences of Cambridge, Massachusetts, has already expressed interest in distributing a forskolin lotion, D'Orazio said, but human trials haven't yet begun. Some scientists are skeptical that the tanner will be safe.

"When you raise cyclic AMP levels, it's a challenge to keep the reaction limited to the skin," said Norman Levine, an Arizona dermatologist. "Lots of bad things can happen when those levels go up -- cardiac output and endocrine function might be affected."

D'Orazio said his mouse trials suggest side effects in humans won't be severe -- none of the animals stopped eating or showed any other signs of ill health during the study. Forskolin could, however, have unpredictable effects on human skin, because it's much thicker than mouse skin, D'Orazio said.

Human studies testing similar compounds in humans are promising. Robert Dorr, a pharmacologist at the Arizona Cancer Center in Tucson, has tested melanotan-1, which he describes as chemically similar to a natural melanocyte-stimulating hormone but "a thousandfold more potent in terms of biological activity."

A small group of human subjects received daily injections of the hormone. They tanned twice as fast as controls and had less sun-related damage to their skin. "We showed that you could tan in response to injections of the drug, and that this was vastly enhanced by small amounts of sunlight," he said. Large-scale trials, however, are still underway at Australian company Clinuvel, and it could be years before the drug is available in the United States.

Levine also experimented with a similar compound called melanotan-II, but soon found it had a completely unexpected side effect: giving male subjects erections. Other researchers have continued testing the drug with an eye to developing it as a Viagra alternative.