Sunscreen lotions prevent ultraviolet radiation-induced suppression of antitumor immune responses

Abstract

Exposure to subcarcinogenic doses of ultraviolet (UV) radiation suppresses tumor immunity, thus permitting the emergence and growth of highly immunogenic skin cancers in mice. Sunscreens prevent UV carcinogenesis; however, there are conflicting reports regarding their ability to block UVinduced tumor immune suppression. In this study we critically evaluated the effects of UV spectrum and dose on the tumor immune protective capacity of 4 marketed sunscreen lotions with labeled sun protection factors (SPF) 8-45. Effective tumor immune suppression doses (TISD), i.e., the lowest dose tested to induce outgrowth of transplanted nonmelanoma skin tumors in 100% of UV-exposed C3H mice, were established for 3 different UV sources. TISD were significantly lower for unfiltered (FS) and Kodacel-filtered (KFS) UVB-type FS20 sunlamps compared with a filtered xenon arc lamp solar simulator. Sunscreen tumor immune protection levels matched those predicted by their labeled SPF when sunscreen-protected mice were exposed to a fixed TISD of solar simulator UV radiation. SPF 30 and 45 sunscreens also blocked activation of tumor antigen-specific suppressor Tlymphocytes in mice exposed to solar simulator UV radiation. In comparison, sunscreens with SPF H15 provided partial to complete protection, as measured by tumor incidence, for mice exposed to UV radiation from KFS. All sunscreens tested reduced tumor growth rates in KFS UVexposed mice. None of the sunscreens tested provided measurable tumor immune protection for mice exposed to FS UV radiation. Thus, sunscreen lotions provide an extent of tumor immune protection consistent with their labeled SPF when appropriate testing conditions are employed. Int.

High Ultraviolet A Protection Affords Greater Immune Protection Confirming that Ultraviolet A Contributes to Photoimmunosuppression in Humans

“…Skin cancer is the most common type of malignancy a¡ecting white populations worldwide, and its incidence continues to increase in alarming proportions (Diepgen and Mahler, 2002). Because of the crucial role of immune suppression in the process of cutaneous carcinogenesis (Ullrich, 2002), protection against UV-induced immunosuppression has been the object of numerous research studies performed both in animal and human models (Bestak et al, 1995;Whitmore and Morrison, 1995;Damian et al, 1997;Moyal et al, 1997;Roberts and Beasley, 1997a;1997b;Serre et al, 1997). Indeed, methods to prevent photoimmune suppression must be considered of high priority in the global campaign on skin cancer prevention.Whereas the immunosuppressive and carcinogenic potential of the more erythemogenic UVB spectrum is well established, less is known about UVA, even though UVA comprises 90%^95% of terrestrial UV radiation and is more penetrating (e.g., through glass windows) than UVB.…”

High-SPF sunscreens (SPF ≥ 70) may provide ultraviolet protection above minimal recommended levels by adequately compensating for lower sunscreen user application amounts

“…8 Many studies have shown that sunscreens can protect from UV-induced damage and skin cancer. [9][10][11][12] The determination of their SPF value is regulated by the Food and Drug Administration (FDA) and other internationally recognized testing standards, which all dictate that sunscreens be tested at an application density of 2 mg/ cm 2 . 13,14 However, several investigations have shown that consumers typically apply less than 2 mg/cm 2 , 15-20 thus reducing the actual protection of the sunscreen.…”

Integrative approach in prevention and therapy of basal cellular carcinoma by association of three actives loaded into lipid nanocarriers

“…The solar ultraviolet (UV) radiation is the main causative factor in most skin cancers [2,3], being considered a complete carcinogen because it can both initiate and promote the growth of skin cancer cells [4]. In addition to the direct carcinogenic effect, the UV radiation suppresses immune reaction playing an active role in the development of skin cancer [5].…”