While many people are fond of being under the sun, they are still aware of the deleterious sun rays that are known to damage the skin. Exposure to ultraviolet (UV) radiation can ultimately lead to cell death by directly damaging DNA, inducing the production of cell hampering molecules known as reactive oxygen species, initiating local inflammation, and exhausting cellular energy. A form of vitamin B3 that humans consume in their everyday diet is nicotinamide, which is the precursor to the highly important coenzyme known as nicotinamide adenine dinucleotide (NAD+), which is known to be a key player in the production of cellular energy, cellular health maintenance, and DNA damage repair. However, we have yet to determine the possible reparative and preventative effects of nicotinamide on cancerous human skin cells that result from exposure to UV radiation.
At the 29th European Academy of Dermatology and Venereology (EADV) Congress, EADV Virtual, researchers from Novara, Italy, shared their research and demonstrated how the damaging effects of UV radiation on skin cells could be combatted through consumption of nicotinamide. Lara Camillo, a research student from the Dermatological Unit of AOU Maggiore dell Carità, Novara, Italy, said in a press release, “Our study indicates that increasing the consumption of vitamin B3, which is readily available in the daily diet, will protect skin from some of the effects of UV exposure, potentially reducing the incidence of non-melanoma skin cancers. However, the protective effect of vitamin B3 is short-acting, so it should be consumed no later than 24 to 48 hours before sun exposure.”
Skin cancer can be broken down into two main subgroups: Melanoma skin cancer and non-melanoma skin cancer. Non-melanoma skin cancer is comprised of various rare skin cancers in addition to some more common ones such as basal cell skin cancer and squamous cell skin cancer, which are often found on parts of the body that routinely experience sun exposure (arms, head, and neck). However, other parts of the body that aren’t as exposed to the sun can still develop these types of cancer. In 2018 alone, doctors diagnosed over 1 million patients with non-melanoma skin cancer, which is currently the 5th most prevalent cancer among men and women. While safe and effective therapeutics are available to combat non-melanoma skin cancer, doctors are racing to develop preventative measures for this disease as the incidence rate continues to increase worldwide, with malignancy cases being most widespread among Caucasians.
Damaging DNA in skin cells through UV light radiation leads to most known skin cancers. Sunlight is the primary source of UV light. There are three types of UV light that come from sunlight: ultraviolet A (UVA), ultraviolet B (UVB), and ultraviolet C (UVC). UVC is the only source of UV light filtered out by the Earth’s atmosphere, thus leaving humans susceptible to skin damage by UVA and UVB. Exposure to UVA and UVB increases the chances of developing skin cancer, and melanoma skin cancer has been primarily linked to UVB exposure. Furthermore, one’s risk of developing skin cancer can be exacerbated by artificial sources of UV light, such as tanning beds and sunlamps. Whether someone is directly exposed to sunlight or artificial sources of UV light, recurrent sunburns will lead to skin being more at risk of developing non-melanoma skin cancer.
Camillo and colleagues sought out to potentially minimize the frequency of non-melanoma skin cancers by testing nicotinamide’s ability to combat the effects of UV exposure to the skin. The patients in this study all had melanoma skin cancer and were between the ages of 50-80 years old, and all patients were treated at the Dermatological Unit of AOU Maggiore della Carità, Novara, Italy. Each patient presented cancerous lesions, and investigators isolated human skin cells surrounding those lesions to test the effects of nicotinamide on those isolated skin cells. Various concentrations of nicotinamide were used to treat the obtained skin cells for 18, 24, and 48 hours prior to UVB exposure. The researchers then proceeded with determining if nicotinamide could assist cells in enduring several kinds of stress and inflammation generated by UVB exposure, in addition to observing whether treatment stimulated cell survival.
Results showed that neither nicotinamide nor UVB treatment in all conditions improved skin cell survival. Researches also concluded that UVB exposure significantly increased DNA damage, which led to the increased accumulation of DNA repair enzymes. However, investigators indicated that DNA damage within these skin cells could be prevented upon pretreatment with nicotinamide, which also leads to lower levels of DNA repair enzymes.
At high cellular levels, reactive oxygen species (ROS) can induce damaging effects on DNA and cells. Investigators showed that cellular levels of ROS were reduced in UVB exposed skin cells after pretreatment with nicotinamide at all concentrations. In addition, cells that were pretreated with nicotinamide also exhibited decreased levels in the enzyme responsible for producing nitric oxide, a compound whose concentration increases upon UVB exposure and plays a critical role in human skin inflammation. Similarly, the concentration of pro-inflammatory compounds barely increased upon UVB exposure, and local inflammation seemed to be halted upon pretreatment with nicotinamide.
The collected data illustrates how pretreatment of human skin cells with nicotinamide significantly reduces the deleterious effects of UVB exposure by strengthening DNA repair, minimizing nitric oxide release, reducing the production of ROS, and blocking local inflammation. Furthermore, investigators concluded that nicotinamide pretreatment one day before UVB exposure displayed the most beneficial effects within skin cells.
Camillo and colleagues show that skin protection against UV rays can be improved by consuming the right foods. This study shows that humans can dimmish their chances of developing skin cancer after UV exposure by vitamin B3 supplementation.