Dopamine Prevents Ultraviolet B-induced Development and Progression of Premalignant Cutaneous Lesions through its D2 Receptors.

Although the role of dopamine (DA) in malignant tumors has been reported, its function in premalignant lesions is unknown. Herein we report that the stimulation of DA D2 receptors in endothelial cells in ultraviolet B (UVB)-induced cutaneous lesions in mice significantly reduced the tumor number, tumor burden, and malignant squamous cell carcinoma in these animals. DA D2 receptor agonist inhibited VEGFA-dependent proangiogenic genes in vitro and in vivo. However, the mice pretreated with selective DA D2 receptor antagonist inhibited the actions of the agonist, thereby suggesting that the action of DA was through its D2 receptors in the endothelial cells. To our knowledge, this study is the first to report DA-mediated regulation of pathogenesis and progression of UVB-induced premalignant skin lesions. PREVENTION RELEVANCE: This investigation demonstrates the role of dopamine and its D2 receptors in UVB induced premalignant squamous cell skin lesions and how DA through its D2 receptors inhibits the development and progression of these lesions and subsequently prevents squamous cell carcinoma of the skin.

Tomatoes protect against development of UV-induced keratinocyte carcinoma via metabolomic alterations.

Prolonged tomato consumption can mitigate ultraviolet (UV) light induced sunburn via unknown mechanisms. Dietary carotenoids distributed to skin are hypothesized to protect skin against UV-induced damage, although other phytochemicals may play a role. We hypothesize that tomato consumption would protect against skin cancer. SKH-1 hairless and immunocompetent mice (n = 180) were fed AIN-93G or AIN-93G + 10% tangerine or red tomato powder for 35 weeks. From weeks 11-20, mice (n = 120) were exposed to 2240 J/m2 UV-B light, 3x/week, and tumors were tracked weekly. Control mice were fed the same diets but not exposed to UV. Tumor number was significantly lower in male mice consuming red tomato diets (1.73 ± 0.50, P = 0.015) or pooled tomato diets (2.03 ± 0.45, P = 0.017) compared to controls (4.04 ± 0.65). Carotenoid levels in plasma and skin were quantitated, with total lycopene higher in skin of tangerine fed animals despite a lower dose. Metabolomic analyses elucidated compounds derived from tomato glycoalkaloids (including tomatidine and hydroxylated-tomatidine) as significantly different metabolites in skin after tomato exposure. Here, we describe that tomato consumption can modulate risk for keratinocyte carcinomas; however, the role of the newly identified specific phytochemicals possibly responsible for this action require further investigation.

25-Hydroxyvitamin D3 and its C-3 epimer are elevated in the skin and serum of Skh-1 mice supplemented with dietary vitamin D3.

SCOPE: UV exposure is a risk factor for keratinocyte carcinoma (KC) while critical for endogenous vitamin D production. We investigated dietary modulation of skin and serum 25-hydroxyvitamin D3 (25OHD3 ) and its C-3 epimer (C3epi) in a mouse model of KC. C3epi is an under-investigated metabolite of vitamin D with respect to its biological implications. METHODS AND RESULTS: Male and female Skh-1 mice were supplemented with 25, 150 or 1000 IU/kg diet vitamin D3 for 25 weeks, with some exposed to UV light. Skin and serum vitamin D metabolites were quantitated using HPLC-MS/MS (n = 3 per dose/sex/UV treatment). Serum and skin 25OHD3 and C3epi significantly increased with dose (P<0.0001), but with different response patterns. UV exposure significantly attenuated serum, but not skin, levels of both metabolites (P<0.001, P = 0.0287), while up-regulating expression of renal Cyp24a1 (P < 0.01). A dose by sex interaction trended toward significance with serum and skin levels of C3epi, wherein male mice attained higher levels of C3epi with higher dietary vitamin D3 . This reflected a similar, but non-significant pattern in average tumor size. CONCLUSION: The complex relationship between vitamin D and KC requires further investigation. This study provides insight into modulation of local and systemic vitamin D status with dietary supplementation.

Ultraviolet radiation accelerates NRas-mutant melanomagenesis: A cooperative effect blocked by sunscreen.

To mitigate melanoma risk, sunscreen use is widely advocated; yet, the ability of sunscreens to prevent melanoma remains controversial. Here, we test the tenet that sunscreens limit melanoma risk by blocking ultraviolet radiation (UV)-induced DNA damage using murine models that recapitulate the genetics and spontaneous evolution of human melanoma. We find that a single, non-erythematous dose of UV dramatically accelerates melanoma onset and increases tumor multiplicity in mice carrying an endogenous, melanocyte-specific NRas61R allele. By contrast, transient UV exposure does not alter tumor onset in mice lacking p16INK4a or harboring an NRas12D allele. To block the rapid onset of melanoma cooperatively caused by UV and NRas61R , we employed a variety of aerosol sunscreens. While all sunscreens delayed melanoma formation and blocked UV-induced DNA damage, differences in aerosol output (i.e., amount applied/cm2 ) caused variability in the cancer preventative efficacy of products with identical sunburn protection factor (SPF) ratings.

Cyclosporine A immunosuppression drives catastrophic squamous cell carcinoma through IL-22.

Immune-suppressed organ transplant recipients (OTRs) can develop catastrophic squamous cell carcinoma (SCC), characterized by multiple primary tumors, extensive body surface area involvement, or metastases. There are currently no curative systemic therapies available. We previously showed that IL-22 enhances SCC proliferation. Herein, we examined links between cyclosporine (CSA), IL-22, and SCC in patients, cell lines, and mice with UV light-induced SCC. Eighteen of 114 OTRs developed catastrophic SCC, which was strongly associated with CSA treatment. We found that CSA drives T cell polarization toward IL-22-producing T22 cells, and CSA treatment increased IL-22 receptor in SCC cells. SCC tissue from OTRs showed increased expression of IL-22RA1. CSA potentiated rescue by IL-22 of serum-starved SCC cells; treatment of SCC cells with IL-22 and CSA increased both their migratory and invasive capacity. In a UV-induced model of SCC in SKH-1 immunocompetent mice, treatment with anti-IL-22 antibody reduced tumor number and tumor burden. We found that catastrophic SCC in OTRs is associated with CSA use, which may be acting by favoring T22 polarization. Since anti-IL-22 antibody administration decreased tumor number and tumor burden in vivo, blockade of the IL-22 axis may be developed as a viable therapeutic option for catastrophic SCC.

Sex differences in skin carotenoid deposition and acute UVB-induced skin damage in SKH-1 hairless mice after consumption of tangerine tomatoes.

SCOPE: UVB exposure, a major factor in the development of skin cancer, has differential sex effects. Tomato product consumption reduces the intensity of UVB-induced erythema in humans, but the mechanisms are unknown. METHODS AND RESULTS: Four-week-old SKH-1 hairless mice (40 females, 40 males) were divided into two feeding groups (control or with 10% tangerine tomatoes naturally rich in UV-absorbing phytoene and phytofluene) and two UV exposure groups (with or without UV). After 10 weeks of feeding, the UV group was exposed to a single UV dose and sacrificed 48 h later. Blood and dorsal skin samples were taken for carotenoid analysis. Dorsal skin was harvested to assess sex and UV effects on carotenoid deposition, inflammation (skinfold thickness, myeloperoxidase levels), and DNA damage (cyclobutane pyrimidine dimers, p53). Females had significantly higher levels of both skin and blood carotenoids relative to males. UV exposure significantly reduced skin carotenoid levels in females but not males. Tomato consumption attenuated acute UV-induced increases in CPD in both sexes, and reduced myeloperoxidase activity and percent p53 positive epidermal cells in males. CONCLUSION: Tangerine tomatoes mediate acute UV-induced skin damage in SKH-1 mice via reduced DNA damage in both sexes, and through reduced inflammation in males.

Endogenous Retinoic Acid Required to Maintain the Epidermis Following Ultraviolet Light Exposure in SKH-1 Hairless Mice.

Ultraviolet light B (UVB) exposure induces cutaneous squamous cell carcinoma (cSCC), one of the most prevalent human cancers. Reoccurrence of cSCC in high-risk patients is prevented by oral retinoids. But oral retinoid treatment causes significant side effects; and patients develop retinoid resistance. Exactly how retinoids prevent UVB-induced cSCC is currently not well understood. Retinoid resistance blocks mechanistic studies in the leading mouse model of cSCC, the UVB-exposed SKH-1 hairless mouse. To begin to understand the role of retinoids in UVB-induced cSCC we first examined the localization pattern of key retinoid metabolism proteins by immunohistochemistry 48 h after UVB treatment of female SKH-1 mice. We next inhibited retinoic acid (RA) synthesis immediately after UVB exposure. Acute UVB increased RA synthesis, signaling and degradation proteins in the stratum granulosum. Some of these proteins changed their localization; while other proteins just increased in intensity. In contrast, acute UVB reduced the retinoid storage protein lectin:retinol acyltransferase (LRAT) in the epidermis. Inhibiting RA synthesis disrupted the epidermis and impaired differentiation. These data suggest that repair of the epidermis after acute UVB exposure requires endogenous RA synthesis.

Role of vitamin D3 in modulation of ΔNp63α expression during UVB induced tumor formation in SKH-1 mice.

ΔNp63α, a proto-oncogene, is up-regulated in non-melanoma skin cancers and directly regulates the expression of both Vitamin D receptor (VDR) and phosphatase and tensin homologue deleted on chromosome ten (PTEN). Since ΔNp63α has been shown to inhibit cell invasion via regulation of VDR, we wanted to determine whether dietary Vitamin D3 protected against UVB induced tumor formation in SKH-1 mice, a model for squamous cell carcinoma development. We examined whether there was a correlation between dietary Vitamin D3 and ΔNp63α, VDR or PTEN expression in vivo in SKH-1 mice chronically exposed to UVB radiation and fed chow containing increasing concentrations of dietary Vitamin D3. Although we observed differential effects of the Vitamin D3 diet on ΔNp63α and VDR expression in chronically irradiated normal mouse skin as well as UVB induced tumors, Vitamin D3 had little effect on PTEN expression in vivo. While low-grade papillomas in mice exposed to UV and fed normal chow displayed increased levels of ΔNp63α, expression of both ΔNp63α and VDR was reduced in invasive tumors. Interestingly, in mice fed high Vitamin D3 chow, elevated levels of ΔNp63α were observed in both local and invasive tumors but not in normal skin suggesting that oral supplementation with Vitamin D3 may increase the proliferative potential of skin tumors by increasing ΔNp63α levels.

Isothiocyanate metabolism, distribution, and interconversion in mice following consumption of thermally processed broccoli sprouts or purified sulforaphane.

SCOPE: Broccoli sprouts are a rich source of glucosinolates, a group of phytochemicals that when hydrolyzed, are associated with cancer prevention. Our objectives were to investigate the metabolism, distribution, and interconversion of isothiocyanates (ITCs) in mice fed thermally processed broccoli sprout powders (BSPs) or the purified ITC sulforaphane. METHODS AND RESULTS: For 1 wk, mice were fed a control diet (n = 20) or one of four treatment diets (n = 10 each) containing nonheated BSP, 60°C mildly heated BSP, 5-min steamed BSP, or 3 mmol purified sulforaphane. Sulforaphane and erucin metabolite concentrations in skin, liver, kidney, bladder, lung, and plasma were quantified using HPLC-MS/MS. Thermal intensity of BSP processing had disparate effects on ITC metabolite concentrations upon consumption. Mild heating generally resulted in the greatest ITC metabolite concentrations in vivo, followed by the nonheated and steamed BSP diets. We observed interconversion between sulforaphane and erucin species or metabolites, and report that erucin is the favored form in liver, kidney, and bladder, even when only sulforaphane is consumed. CONCLUSION: ITC metabolites were distributed to all tissues analyzed, suggesting the potential for systemic benefits. We report for the first time tissue-dependent ratio of sulforaphane and erucin, though further investigation is warranted to assess biological activity of individual forms.

MIF antagonist (CPSI-1306) protects against UVB-induced squamous cell carcinoma.

UNLABELLED: Macrophage migration inhibitory factor (MIF) is a homotrimeric proinflammatory cytokine implicated in chronic inflammatory diseases and malignancies, including cutaneous squamous cell carcinomas (SCC). To determine whether MIF inhibition could reduce UVB light-induced inflammation and squamous carcinogenesis, a small-molecule MIF inhibitor (CPSI-1306) was utilized that disrupts homotrimerization. To examine the effect of CPSI-1306 on acute UVB-induced skin changes, Skh-1 hairless mice were systemically treated with CPSI-1306 for 5 days before UVB exposure. In addition to decreasing skin thickness and myeloperoxidase (MPO) activity, CPSI-1306 pretreatment increased keratinocyte apoptosis and p53 expression, decreased proliferation and phosphohistone variant H2AX (γ-H2AX), and enhanced repair of cyclobutane pyrimidine dimers. To examine the effect of CPSI-1306 on squamous carcinogenesis, mice were exposed to UVB for 10 weeks, followed by CPSI-1306 treatment for 8 weeks. CPSI-1306 dramatically decreased the density of UVB-associated p53 foci in non-tumor-bearing skin while simultaneously decreasing the epidermal Ki67 proliferation index. In addition to slowing the rate of tumor development, CPSI-1306 decreased the average tumor burden per mouse. Although CPSI-1306-treated mice developed only papillomas, nearly a third of papillomas in vehicle-treated mice progressed to microinvasive SCC. Thus, MIF inhibition is a promising strategy for prevention of the deleterious cutaneous effects of acute and chronic UVB exposure. IMPLICATIONS: Macrophage migration inhibitory factor is a viable target for the prevention of UVB-induced cutaneous SSCs.

Extended UVB Exposures Alter Tumorigenesis and Treatment Efficacy in a Murine Model of Cutaneous Squamous Cell Carcinoma.

Epidemiological studies support a link between cumulative sun exposure and cutaneous squamous cell carcinoma (SCC) development. However, the presumed effects of extended ultraviolet light B (UVB) exposure on tumorigenesis in the sexes have not been formally investigated. We examined differences in ultimate tumorigenesis at 25 weeks in mice exposed to UVB for either 10 or 25 weeks. Additionally, we investigated the effect of continued UVB exposure on the efficacy of topical treatment with anti-inflammatory (diclofenac) or antioxidant (C E Ferulic or vitamin E) compounds on modulating tumorigenesis. Vehicle-treated mice in the 25-week UVB exposure model exhibited an increased tumor burden and a higher percentage of malignant tumors compared to mice in the 10-week exposure model, which correlated with increases in total and mutant p53-positive epidermal cells. Only topical diclofenac decreased tumor number and burden in both sexes regardless of UVB exposure length. These data support the commonly assumed but not previously demonstrated fact that increased cumulative UVB exposure increases the risk of UVB-induced SCC development and can also affect therapeutic efficacies. Our study suggests that cessation of UVB exposure by at-risk patients may decrease tumor development and that topical NSAIDs such as diclofenac may be chemopreventive.

Ultraviolet light exposure stimulates HMGB1 release by keratinocytes.

The primary cause of non-melanoma skin cancer is ultraviolet (UV) light from the sun. Many studies have demonstrated that cutaneous inflammation resulting from UV exposure is important for the development of skin cancer. In fact, anti-inflammatory drugs have been shown to be effective in preventing skin cancer in animal models and in clinical trials. One new class of inflammatory mediators that could regulate UV-induced inflammation and skin carcinogenesis is alarmins. Alarmins are endogenous molecules that act as potent pro-inflammatory mediators when they are released by cells or accumulate extracellularly. The purpose of the current studies was to examine the expression and release of the alarmin high mobility group box 1 (HMGB1) after acute and chronic UV irradiation. Acute UV exposure stimulated the release of HMGB1 in cultured human keratinocytes and epidermal keratinocytes in murine skin. HMGB1 release correlated with pro-inflammatory cytokine production in vitro and inflammatory cell infiltration in vivo. HMGB1 was also examined in tumors arising in chronically irradiated murine skin. HMGB1 protein expression in low grade, benign papillomas was similar to adjacent skin. However, HMGB1 staining was more widespread with a higher number of HMGB1-positive cells observed in high grade papillomas and malignant tumors. Overall, the data suggest that HMGB1 may be an important regulator of UV-induced cutaneous inflammation and tumor formation. Additional studies are needed to assess whether targeting HMGB1 would be a useful strategy to prevent tumors from developing in response to chronic UV exposure.

Differential effects of topical vitamin E and C E Ferulic® treatments on ultraviolet light B-induced cutaneous tumor development in Skh-1 mice.

Because of the ever-increasing incidence of ultraviolet light B (UVB)-induced skin cancer, considerable attention is being paid to prevention through the use of both sunscreens and after sun treatments, many of which contain antioxidants. Vitamin E is included as an antioxidant in many sunscreens and lotions currently on the market. Studies examining the efficacy of vitamin E as a topical preventative agent for UVB-induced skin cancer have yielded conflicting results. A likely contributor to differences in study outcome is the stability of vitamin E in the particular formulation being tested. In the current study we examined the effects of topical vitamin E alone as well as vitamin E combined with vitamin C and ferulic acid in a more stable topical formula (C E Ferulic®). Mice were exposed to UVB for 10 weeks in order to induce skin damage. Then, before the appearance of any cutaneous lesions, mice were treated for 15 weeks with a topical antioxidant, without any further UVB exposure. We found that topical C E Ferulic decreased tumor number and tumor burden and prevented the development of malignant skin tumors in female mice with chronically UVB-damaged skin. In contrast, female mice chronically exposed to UVB and treated topically with vitamin E alone showed a trend towards increased tumor growth rate and exhibited increased levels of overall DNA damage, cutaneous proliferation, and angiogenesis compared to vehicle-treated mice. Thus, we have demonstrated that topical 5% alpha tocopherol may actually promote carcinogenesis when applied on chronically UVB-damaged skin while treating with a more stable antioxidant compound may offer therapeutic benefits.

Preventative topical diclofenac treatment differentially decreases tumor burden in male and female Skh-1 mice in a model of UVB-induced cutaneous squamous cell carcinoma.

Ultraviolet B (UVB) light is the major environmental carcinogen contributing to non-melanoma skin cancer (NMSC) development. There are over 3.5 million NMSC diagnoses in two million patients annually, with men having a 3-fold greater incidence of squamous cell carcinoma (SCC) compared with women. Chronic inflammation has been linked to tumorigenesis, with a key role for the cyclooxygenase-2 (COX-2) enzyme. Diclofenac, a COX-2 inhibitor and non-steroidal anti-inflammatory drug, currently is prescribed to patients as a short-term therapeutic agent to induce SCC precursor lesion regression. However, its efficacy as a preventative agent in patients without evidence of precursor lesions but with significant UVB-induced cutaneous damage has not been explored. We previously demonstrated in a murine model of UVB-induced skin carcinogenesis that when exposed to equivalent UVB doses, male mice had lower levels of inflammation but developed increased tumor multiplicity, burden and grade compared with female mice. Because of the discrepancy in the degree of inflammation between male and female skin, we sought to determine if topical treatment of previously damaged skin with an anti-inflammatory COX-2 inhibitor would decrease tumor burden and if it would be equally effective in the sexes. Our results demonstrated that despite observed sex differences in the inflammatory response, prolonged topical diclofenac treatment of chronically UVB-damaged skin effectively reduced tumor multiplicity in both sexes. Unexpectedly, tumor burden was significantly decreased only in male mice. Our data suggest a new therapeutic use for currently available topical diclofenac as a preventative intervention for patients predisposed to cutaneous SCC development before lesions appear.

High-anxious individuals show increased chronic stress burden, decreased protective immunity, and increased cancer progression in a mouse model of squamous cell carcinoma.

In spite of widespread anecdotal and scientific evidence much remains to be understood about the long-suspected connection between psychological factors and susceptibility to cancer. The skin is the most common site of cancer, accounting for nearly half of all cancers in the US, with approximately 2-3 million cases of non-melanoma cancers occurring each year worldwide. We hypothesized that a high-anxious, stress-prone behavioral phenotype would result in a higher chronic stress burden, lower protective-immunity, and increased progression of the immuno-responsive skin cancer, squamous cell carcinoma. SKH1 mice were phenotyped as high- or low-anxious at baseline, and subsequently exposed to ultraviolet-B light (1 minimal erythemal dose (MED), 3 times/week, 10-weeks). The significant strengths of this cancer model are that it uses a normal, immunocompetent, outbred strain, without surgery/injection of exogenous tumor cells/cell lines, and produces lesions that resemble human tumors. Tumors were counted weekly (primary outcome), and tissues collected during early and late phases of tumor development. Chemokine/cytokine gene-expression was quantified by PCR, tumor-infiltrating helper (Th), cytolytic (CTL), and regulatory (Treg) T cells by immunohistochemistry, lymph node T and B cells by flow cytometry, adrenal and plasma corticosterone and tissue vascular-endothelial-growth-factor (VEGF) by ELISA. High-anxious mice showed a higher tumor burden during all phases of tumor development. They also showed: higher corticosterone levels (indicating greater chronic stress burden), increased CCL22 expression and Treg infiltration (increased tumor-recruited immuno-suppression), lower CTACK/CCL27, IL-12, and IFN-γ gene-expression and lower numbers of tumor infiltrating Th and CTLs (suppressed protective immunity), and higher VEGF concentrations (increased tumor angiogenesis/invasion/metastasis). These results suggest that the deleterious effects of high trait anxiety could be: exacerbated by life-stressors, accentuated by the stress of cancer diagnosis/treatment, and mediate increased tumor progression and/or metastasis. Therefore, it may be beneficial to investigate the use of chemotherapy-compatible anxiolytic treatments immediately following cancer diagnosis, and during cancer treatment/survivorship.

UV light B-mediated inhibition of skin catalase activity promotes Gr-1+ CD11b+ myeloid cell expansion.

Skin cancer incidence and mortality are higher in men compared with women, but the causes of this sex discrepancy remain largely unknown. UV light exposure induces cutaneous inflammation and neutralizes cutaneous antioxidants. Gr-1(+)CD11b(+) myeloid cells are heterogeneous bone marrow-derived cells that promote inflammation-associated carcinogenesis. Reduced activity of catalase, an antioxidant present in the skin, has been associated with skin carcinogenesis. We used the outbred, immune-competent Skh-1 hairless mouse model of UVB-induced inflammation and non-melanoma skin cancer to further define sex discrepancies in UVB-induced inflammation. Our results demonstrated that male skin had relatively lower baseline catalase activity, which was inhibited following acute UVB exposure in both sexes. Further analysis revealed that skin catalase activity inversely correlated with splenic Gr-1(+)CD11b(+) myeloid cell percentage. Acute UVB exposure induced Gr-1(+)CD11b(+) myeloid cell skin infiltration, which was inhibited to a greater extent in male mice by topical catalase treatment. In chronic UVB studies, we demonstrated that the percentage of splenic Gr-1(+)CD11b(+) myeloid cells was 55% higher in male tumor-bearing mice compared with their female counterparts. Together, our findings indicate that lower skin catalase activity in male mice may at least in part contribute to increased UVB-induced generation of Gr-1(+)CD11b(+) myeloid cells and subsequent skin carcinogenesis.

Short-term stress enhances cellular immunity and increases early resistance to squamous cell carcinoma.

In contrast to chronic/long-term stress that suppresses/dysregulates immune function, an acute/short-term fight-or-flight stress response experienced during immune activation can enhance innate and adaptive immunity. Moderate ultraviolet-B (UV) exposure provides a non-invasive system for studying the naturalistic emergence, progression and regression of squamous cell carcinoma (SCC). Because SCC is an immunoresponsive cancer, we hypothesized that short-term stress experienced before UV exposure would enhance protective immunity and increase resistance to SCC. Control and short-term stress groups were treated identically except that the short-term stress group was restrained (2.5h) before each of nine UV-exposure sessions (minimum erythemal dose, 3-times/week) during weeks 4-6 of the 10-week UV exposure protocol. Tumors were measured weekly, and tissue collected at weeks 7, 20, and 32. Chemokine and cytokine gene expression was quantified by real-time PCR, and CD4+ and CD8+ T cells by flow cytometry and immunohistochemistry. Compared to controls, the short-term stress group showed greater cutaneous T-cell attracting chemokine (CTACK)/CCL27, RANTES, IL-12, and IFN-gamma gene expression at weeks 7, 20, and 32, higher skin infiltrating T cell numbers (weeks 7 and 20), lower tumor incidence (weeks 11-20) and fewer tumors (weeks 11-26). These results suggest that activation of short-term stress physiology increased chemokine expression and T cell trafficking and/or function during/following UV exposure, and enhanced Type 1 cytokine-driven cell-mediated immunity that is crucial for resistance to SCC. Therefore, the physiological fight-or-flight stress response and its adjuvant-like immuno-enhancing effects, may provide a novel and important mechanism for enhancing immune system mediated tumor-detection/elimination that merits further investigation.

Celecoxib reduces the effects of acute and chronic UVB exposure in mice treated with therapeutically relevant immunosuppressive drugs.

Solid organ transplant recipients have a greatly increased risk for the development of non-melanoma skin cancers. We have previously shown in our mouse model that sirolimus given in combination with cyclosporine A resulted in fewer and smaller tumors than cyclosporine A alone. In the current study, we tested the hypothesis that an anti-inflammatory agent celecoxib applied topically after UVB exposure would further reduce UVB induced skin cancer in mice treated with cyclosporine A and sirolimus. The effect of celecoxib treatment on acute inflammation, initiation/promotion and tumor development was examined through a set of four experiments. Delayed tumor onset was observed in both tumor development experiments. Reduced tumor size and number compared to vehicle was observed when CX was administered concurrently with UVB and when CX was administered after cessation of UVB treatments, respectively. Prostaglandin E2 was confirmed to be significantly reduced in the dorsal skin of mice concurrently treated with immunosuppressants, CX and UVB for 13 weeks, suggesting a reduction in the inflammatory response could be the mechanism by which CX reduced tumorigenesis. Furthermore, topical celecoxib treatment following acute UVB exposure reduced dermal neutrophil number and activity compared to vehicle. In all of these experiments, unirradiated and vehicle treated mice were utilized as controls. In conclusion, these data suggest that even in the presence of cyclosporine A and sirolimus, topical celecoxib treatment can result in reduced inflammation, tumor number and size; properties which may be beneficial in the therapeutic reduction of skin cancer development in solid organ transplant recipients.

Topical treatment with black raspberry extract reduces cutaneous UVB-induced carcinogenesis and inflammation.

Light in the UVB spectrum (280-320 nm) induces a number of changes in the epidermis and dermis of mice and humans, resulting in a robust inflammatory response. A standardized black raspberry extract (BRE) has been effective in reducing signaling pathways commonly initiated by inflammatory stimuli. In this study, we determined whether this extract could reduce cutaneous UVB-induced inflammation and carcinogenesis. In our carcinogenesis model, female SKH-1 hairless mice were exposed to one minimal erythemal dose of UVB thrice weekly on nonconsecutive days for 25 weeks. Immediately after each exposure, the mice were treated topically with either BRE dissolved in vehicle or with vehicle only. Beginning on week 19, mice treated with BRE had a significant reduction in tumor number and in average tumor size. This reduction correlated with a significant reduction in tumor-infiltrating CD3(+)foxp3(+) regulatory T-cells. In the acute model, mice were exposed to a single minimal erythemal dose of UVB and treated topically with BRE or with vehicle. At 48 hours post-UVB exposure, topical BRE treatment significantly reduced edema, p53 protein levels, oxidative DNA damage, and neutrophil activation. The ability of topical BRE to reduce acute UVB-induced inflammation and to decrease tumor development in a long-term model provides compelling evidence to explore the clinical efficacy of BRE in the prevention of human skin cancers.