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 NRas^61R allele. By contrast, transient UV exposure does not alter tumor onset in mice lacking p16^INK4a or harboring an NRas^12D allele. To block the rapid onset of melanoma cooperatively caused by UV and NRas^61R , 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.

Abstract 900: In vivo modeling of NRAS-mutant melanoma reveals differential preventative efficacy amongst SPF30 sunscreens

Cutaneous melanoma claims the life of one American every hour, and while the etiology of this tumor type is not entirely understood, exposure to ultraviolet (UV) radiation (280-340nm) is a major risk factor. For this reason, the use of UV-blocking sunscreens is strongly advocated; however, few studies have tested the relative efficacy of these agents in preventing melanoma formation in vivo. Here, we employed a new genetically engineered mouse model (TpN61R) to examine the ability of 6 chemically distinct SPF30 sunscreens to prevent melanoma. In this TpN61R model, topical 4-hydroxytamoxifen (4OHT) treatment induces the melanocyte-specific expression of oncogenic NRas as well as inactivation of the p16INK4a tumor suppressor. These genetic lesions co-occur in ∼24% of all human melanomas, making the TpN61R model biologically relevant. Since NRAS mutations are an early and UV-independent event in human melanoma, TpN61R mice were first painted with 4OHT and then exposed to a single dose of 4.5 kJ/m2 UVB light one day later. Exposed skin from TpN61R mice showed transient cyclobutane pyrimidine dimer (CPD) formation, however no evidence of edema or inflammation was observed. Despite these mild effects, UVB exposure reduced the melanoma-free survival of TpN61R mice by 80% and increased tumor incidence rate from 1.2 to 3.4 tumors/mouse. Further experiments using a variety of UVB doses (0.25, 1.0, 2.3 and 9.0 kJ/m2) in the TpN61R model revealed a dose-dependent increase in early melanoma incidence. Together, these data establish the exquisite cooperation of UV light and oncogenic NRas mutations in driving melanoma. Taking advantage of this unique model, we tested the preventative efficacy of SPF30 sunscreens with differing chemical composition. Sunscreens components included UVA (avobenzene), UVB (homosalate, octisalate) and broad spectrum (oxybenzone, octocrylene, zinc oxide) blocking agents. Application of sunscreen prior to UVB exposure decreased DNA damage, delayed melanoma onset and reduced tumor incidence in a sunscreen-dependent manner. Thus, SPF30 sunscreens do not equally prevent UVB-induced, NRAS mutant melanoma. This work establishes the first in vivo system to test sunscreen efficacy in NRAS-driven melanoma and will help direct the development of improved melanoma preventatives.

Citation Format: Andrea M. Holderbaum, Rebecca C. Hennessey, James E. Gillahan, Anamaria Bonilla, Conor Delaney, Raleigh D. Kladney, Kathleen L. Tober, Tatiana M. Oberyszyn, Christin E. Burd. In vivo modeling of NRAS-mutant melanoma reveals differential preventative efficacy amongst SPF30 sunscreens. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 900.

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.

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

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.

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.

Abstract 4202: Sex disparities in the cutaneous response to acute ultraviolet light exposure

Epidemiological evidence has identified a 3-fold increase in squamous cell skin cancer incidence in men compared to women. The historical explanation for this sex-bias is increased occupational exposure to ultraviolet (UV) light. Our studies demonstrated, however, that when chronically exposed to equivalent doses of UV light, male mice developed more skin tumors that were larger and more aggressive than those arising in female mice. Additionally, the skin of male mice acutely exposed to UV light had higher levels of oxidative DNA damage and decreased total antioxidant capacity compared to females (Thomas-Ahner, JM Cancer Research 2007). The hypothesis for the current study is that the topical application of anti-inflammatory and/or antioxidant compounds may differentially affect the acute UVB induced inflammatory response in the sexes. To test this hypothesis, female and male Skh-1 mice were exposed to 2240J/m2 UVB light followed immediately by topical application of either an anti-inflammatory compound (Solaraze), an antioxidant (Vitamin E), or a combination of the 2 compounds. Animals were sacrificed at 24 and 48 hrs following a single exposure and topical treatment. Skin was analyzed for myeloperoxidase (MPO) activity as a measure of neutrophil infiltration, catalase activity, and immunohistochemically for the presence of p53 protein in the epidermis. In response to UVB exposure, vehicle treated female mice had significantly increased MPO activity compared to male mice. Topical treatments with Solaraze, Vitamin E or the combination significantly reduced MPO levels in female mice but had no effects on the already low levels of UV-induced MPO in male skin. Catalase is a key enzyme used for detoxifying hydrogen peroxide in the skin. Baseline levels of catalase were lower in male skin compared to female skin and UVB exposure significantly reduced catalase in both sexes. Topical treatment with Solaraze significantly increased male catalase activity to levels similar to female unirradiated skin while vitamin E partially restored catalase activity in female mice but had no effect in male skin. The single exposure to UVB induced higher numbers of p53 positive epidermal cells in male skin, however at this time point topical treatment had no effect on UVB-induced p53 levels in either sex. Our data suggests that UVB differentially effects inflammation in the sexes and that topical application of anti-inflammatory or anti-oxidant compounds have differential effects on markers of an acute inflammatory response in the skin. Future studies will evaluate the effects of additional compounds and delivery vehicles following both acute and chronic UVB exposure.

This work was supported by NIH NCI CA133629.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4202.

Abstract 3378: E-cadherin suppresses breast cancer cell growth and interleukin-6 production

Carcinomas arise from epithelial tissues and represent the most common type of human cancer. E-cadherin is an epithelial-specific intercellular adhesion molecule, which localizes to epithelial cell adherens junctions and is a critical mediator of carcinoma cell invasion and metastasis. Although impaired E-cadherin expression can be clinically utilized to predict breast cancer cell invasiveness, metastasis, and patient survival, E-cadherin has received less attention for its role as a putative regulator of epithelial cell growth. We have previously shown that interleukin-6 (IL-6), a pleiotropic inflammatory cytokine associated with poor clinical outcome in breast cancer patients, is a potent growth factor and repressor of E-cadherin in human breast cancer cells. Consistent with clinical reports and our previous findings, we hypothesized that E-cadherin repression may be responsible for IL-6-induced breast cancer cell growth. The current study demonstrated that IL-6 enhanced the growth rates of estrogen receptor-alpha (ERα)-positive breast cancer cells in a three-dimensional (3D) tumor growth assay (TGA) in a dose-dependent manner. We showed that IL-6 also repressed E-cadherin protein levels in ERα-positive breast cancer cells in a 3D TGA in a dose-dependent manner. We have previously shown that IL-6 treatment does not affect E-cadherin-negative MDA-MB-231 cell growth, and the current study showed similar results in MCF-7 cells which express Twist and therefore lack E-cadherin. MDA-MB-231 cells lack E-cadherin and express IL-6, thus allowing us to express stable ectopic E-cadherin to evaluate its impact on cell growth and IL-6 production. Ectopic E-cadherin expression significantly suppressed MDA-MB-231 cell growth (P-value &lt; 0.005) and IL-6 production (P-value &lt; 0.00005) as measured by 3D TGA and ELISA, respectively. Our current findings reveal an association between enhanced breast cancer cell growth and E-cadherin repression following exposure to IL-6. Furthermore, we demonstrated that E-cadherin suppresses breast cancer cell growth and IL-6 production, which suggests a positive feedback loop in which IL-6 promotes E-cadherin repression, thereby inducing autocrine IL-6 production in breast cancer cells.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3378.

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.

Chromosomal aberrations in UVB-induced tumors of immunosuppressed mice

In immunocompromised individuals, such as organ transplant recipients, the risk of cutaneous squamous cell carcinoma (SCC) is increased 60-250 fold, and there is an increased likelihood to develop aggressive, metastatic SCC. An understanding of the genes involved in SCC tumorigenesis is critical to prevent SCC-associated morbidity and mortality. Mouse models show that different immunosuppressive drugs lead to SCCs varying in size, number, and malignant potential. In this study, we used mouse models that mimic adult transplant recipients to study the effect of immunosuppressive drugs and UV light on SCC development. UV-induced tumors from six treatment groups, control, tacrolimus (Tac), rapamycin (Rap), cyclosporin (CsA), mycophenolate mofetil (MMF), and Rap plus CsA, were evaluated by array comparative genomic hybridization. Mouse SCCs appear to show similar genomic aberrations as those reported in human SCCs and offer the ability to identify genomic changes associated with specific and combinatorial effects of drugs. Fewer aberrations were seen in tumors of mice treated with MMF or Rap. Tumors from Tac-treated animals showed the highest number of changes. Calcineurin inhibitors (Tac and CsA) did not cluster together by their genomic aberrations, indicating their contribution to UV mediated carcinogenesis may be through different pathways. The combination treatment (Rap plus CsA) did not cluster with either treatment individually, suggesting it may influence SCC tumorigenesis via a different mechanism. Future studies will identify specific genes mapping to regions of aberration that are different between treatment groups to identify target pathways that may be affected by these drugs.

Clinically relevant immunosuppressants influence UVB-induced tumor size through effects on inflammation and angiogenesis

Immunosuppressive therapies allow long-term patient and transplant survival, but are associated with increased development of UV-induced skin cancers, particularly squamous cell carcinomas. The mechanisms by which CsA, MMF, tacrolimus (TAC) or sirolimus (SRL), alone or in dual combinations, influence tumor development and progression are not completely understood. In the current study, chronically UV-exposed mice treated with SRL alone or in combination with CsA or TAC developed more tumors than mice treated with vehicle or other immunosuppressants, but the tumors were significantly smaller and less advanced. Mice treated with CsA or TAC developed significantly larger tumors than vehicle-treated mice, and a larger percentage in the CsA group were malignant. The addition of MMF to CsA, but not to TAC, significantly reduced tumor size. Immunosuppressant effects on UVB-induced inflammation and tumor angiogenesis may explain these findings. CsA enhanced both UVB-induced inflammation and tumor blood vessel density, while MMF reduced inflammation. Addition of MMF to CsA reduced tumor size and vascularity. SRL did not affect inflammation, but significantly reduced tumor vascularity. Thus the choice of immunosuppressants has important implications for tumor number, size and progression, likely due to the influence of immunosuppressants on UVB-induced inflammation and angiogenesis.

Depletion of CD4+ Cells Exacerbates the Cutaneous Response to Acute and Chronic UVB Exposure

Solid organ transplant recipients have a 60-250-fold increased likelihood of developing sunlight-induced squamous cell carcinoma (SCC) compared with the general population. This increased risk is linked to the immunosuppressive drugs taken by these patients to modulate T cell function, thus preventing organ rejection. To determine the importance of T cells in the development of cutaneous SCC, we examined the effects of selectively depleting Skh-1 mice of systemic CD4+ or CD8+ T cells, using monoclonal antibodies, on ultraviolet B (UVB) radiation-induced inflammation and tumor development. Decreases in systemic CD4+ but not CD8+ T cells significantly increased and prolonged the acute UVB-induced cutaneous inflammatory response, as measured by neutrophil influx, myeloperoxidase activity, and prostaglandin E2 levels. Significantly more p53+ keratinocytes were observed in UVB-exposed CD4-depleted than in CD4-replete mice, and this difference was abrogated in mice depleted of neutrophils before UVB exposure. Increased acute inflammation was associated with significantly increased tumor numbers in CD4-depleted mice chronically exposed to UVB. Furthermore, topical treatment with the anti-inflammatory drug celecoxib significantly decreased tumor numbers in both CD4-replete and CD4-depleted mice. Our findings suggest that CD4+ T cells play an important role in modulating both the acute inflammatory and the chronic carcinogenic response of the skin to UVB.

Gender Differences in UVB-Induced Skin Carcinogenesis, Inflammation, and DNA Damage

The American Cancer Society reports the incidence of squamous cell carcinoma in males to be thrice the incidence in females. This increased squamous cell carcinoma incidence has been attributed to men accumulating more sun exposure and using less sun protection than women. To date, there have been no controlled studies examining the effect of gender on skin tumor development following equal doses of UVB. Gender differences in UVB-induced skin carcinogenesis were examined using the Skh-1 mouse model. After chronic exposure to equal doses of UVB, male mice developed tumors earlier and had more tumors than female mice; tumors in male mice tended to be larger, and the total tumor burden was greater than in females. In addition, tumors in males were of more advanced histologic grade compared with those of female mice. To evaluate the contribution of differences in inflammation and DNA damage to differences in skin carcinogenesis, male and female Skh-1 mice were exposed once to 2,240 J/m(2) UVB and examined 48 h after exposure. Surprisingly, male mice developed less of an inflammatory response, as determined by skin fold thickness and myeloperoxidase activity, compared with females. Interestingly, male mice showed more cutaneous oxidative DNA damage than the females and lower antioxidant levels. These results show a gender bias in skin carcinogenesis and suggest that the gender difference in tumor development is more influenced by the extent of oxidative DNA damage and antioxidant capacities than by inflammatory response.

Possible cross-regulation of the E prostanoid receptors

Exposure to UVB induces an inflammatory response in the skin that results in high levels of cyclooxygenase-2 (COX-2) and its enzymatic product, prostaglandin E2 (PGE(2)). PGE(2) signals via one of four E prostanoid (EP) receptors, EP1-4, but the roles of each of these receptors in UVB-mediated inflammation and skin carcinogenesis have not been fully defined. Topical application of ONO-8713, an EP1 antagonist, reduced the acute inflammatory effects of UVB irradiation. This compound also reduced UVB-induced tumor formation by approximately 50%, suggesting that signaling of PGE(2) via the EP1 receptor may play a role in UVB-mediated inflammation and carcinogenesis. Our laboratory has demonstrated that the EP1 receptor localized to the suprabasal layers of the epidermis and the EP3 receptor was found in the basal keratinocytes of unirradiated murine skin. While UVB exposure induced no change in the localization of the EP1 receptor, the EP3 receptor was detected in all layers of the epidermis in response to UVB. In mice that were topically treated with ONO-8713, UVB-induced changes in EP3 localization were prevented. This alteration in EP3 receptor localization was not seen following topical application of the anti-inflammatory drug celecoxib, indicating that the effects of ONO-8713 were not because of its anti-inflammatory properties. These results suggest a previously undescribed interaction between the EP1 and EP3 receptors in the epidermis.

Effects of UVB on E prostanoid receptor expression in murine skin

Prostaglandin E2 (PGE2) upregulation in response to UV light exposure is a significant factor in the development of non-melanoma skin cancer. It is known that PGE2 signals via the E prostanoid receptors, EP1-4, but the role that each receptor plays in skin carcinogenesis is unclear. Immunohistochemical analysis of EP receptor staining in unirradiated and UVB-exposed SKH-1 mouse skin demonstrated the localization of EP1 and EP2 to the plasma membrane of differentiated epidermal keratinocytes. In contrast, the EP3 receptor localized to the basal layer of the epidermis in unirradiated skin and throughout the epidermis in UVB-exposed skin. In unirradiated skin, cytoplasmic EP4 staining was seen throughout the epidermis, in dermal leukocytes, and in vascular endothelium. However, UVB exposure resulted in relocalization of the EP4 receptor to the plasma membrane of keratinocytes, with no change in the dermal staining pattern. In tumors isolated from UVB-exposed mice, EP1 and EP2 staining was detected in the more differentiated cells surrounding keratin pearls, whereas EP3 and EP4 were detectable throughout the tumors. Differential expression of the EP receptors suggests that each receptor may play a distinct role in skin tumor development.

Importance of the EP(1) receptor in cutaneous UVB-induced inflammation and tumor development

Chronic exposure to UV light, the primary cause of skin cancer, results in the induction of high levels of cyclooxygenase-2 (COX-2) expression in the skin. The involvement of COX-2 in the carcinogenesis process is mediated by its enzymatic product, prostaglandin E(2) (PGE(2)). PGE(2) has been shown to have a variety of activities that can contribute to tumor development and growth. The effects of PGE(2) on different cell types are mediated by four E prostanoid (EP) receptors, EP(1)-EP(4). While recent studies have demonstrated the importance of EP(1) in the development of colon and breast cancer, the extent of EP(1) involvement in the cutaneous photocarcinogenesis process is unknown. This study found that topical treatment with celecoxib or the specific EP(1) antagonist ONO-8713 decreased acute UVB-induced inflammation in the skin and significantly reduced the number of tumors per mouse following 25 weeks of UVB exposure and topical treatment. This study suggests that drugs designed to block EP(1) may have the potential to be used as anti-inflammatory and/or chemopreventive agents that reduce the risk of skin cancer development.

The impact of cyclooxygenase-2 mediated inflammation on scarless fetal wound healing

Cyclooxygenase-2 (COX-2) and the prostaglandin products generated as a result of COX-2 activity mediate a variety of biological and pathological processes. Scarless healing occurs in fetal skin in the first and second trimesters of development. This scarless healing process is known to proceed without a significant inflammatory response, which appears to be important for the lack of scarring. Because the COX-2 pathway is an integral component of inflammation, we investigated its role in the fetal repair process using a mouse model of scarless fetal wound healing. COX-2 expression in scarless and fibrotic fetal wounds was examined. In addition, the ability of exogenous prostaglandin E(2) to alter scarless fetal healing was evaluated. The results suggest that the COX-2 pathway is involved in scar production in fetal skin and that targeting COX-2 may be useful for limiting scar formation in adult skin.

Treatment with 5-Fluorouracil and Celecoxib Displays Synergistic Regression of Ultraviolet Light B-Induced Skin Tumors

Standard chemotherapeutic agents used for the treatment of pre-cancerous skin lesions and non-melanoma skin cancers are not completely effective. Several studies have suggested that repeated inflammatory sunburn reactions, which include the induction of cyclooxygenase-2 (COX-2) and the subsequent production of prostaglandins, play a role in skin cancer development. COX-2 inhibition has been demonstrated to be a potent means of preventing skin cancer development in mice; however, COX-2 inhibitors alone are not effective as chemotherapeutic agents. Data in a variety of cancer types suggest greater efficacy in treating tumors with combination chemotherapies. Therefore, we hypothesized that a combination of the chemotherapeutic agent 5-fluorouracil (5-FU) and the COX-2 inhibitor and anti-inflammatory drug celecoxib would act synergistically to regress tumors in a murine model of ultraviolet light B- (UVB-) induced carcinogenesis. We found that topical treatment with 5-FU and celecoxib together was up to 70% more effective in reducing the number of UVB-induced skin tumors than 5-FU treatment alone. Our data suggest that more effective chemotherapy regimens can be developed to treat the millions of pre-cancerous and cancerous skin lesions that arise every year, which could ultimately lead to a significant reduction in costs and cosmetic defects (scarring) associated with surgical interventions.

Inhibition of ultraviolet light B-induced cutaneous inflammation by a specific cyclooxygenase-2 inhibitor

Ultraviolet B (UVB) radiation is responsible for the majority of cutaneous damage following both acute and long-term exposure, and is believed to be the most important etiologic agent in human skin cancer. UVB carcinogenesis initially induces an inflammatory response characterized by edema, dermal infiltration of leukocytes, as well as the production and release of prostaglandins, which may be critical to the observed damaging effects of UVB light on skin. Recently, a specific cyclooxygenase-2 (COX-2) inhibitor, Celecoxib, was developed, which inhibits COX-2-induced inflammation without inhibiting the cytoprotective function of cyclooxygenase-1 (COX-1). Studies have demonstrated that oral administration of Celecoxib decreased the incidence of skin and colon tumors. Recently, the process of inflammation has been linked to tumor formation. The present study examined the effects of a topical application of Celecoxib on the acute UVB-induced cutaneous inflammatory response. We show that topical Celecoxib treatment effectively reduced many parameters of UVB-mediated inflammation, including edema, dermal myeloperoxidase activity, neutrophil infiltration, and prostaglandin E2 (PGE2) levels. By inhibiting this inflammatory response, topical Celecoxib treatment could ultimately be effective in preventing tumor development and progression in the skin, which is known to result from long-term UV exposure.

Dopaminergic therapy with carbidopa L-dopa for left neglect after stroke: a case series

OBJECTIVE

To evaluate the efficacy of carbidopa L-dopa (Sinemet) in reducing left spatial neglect after stroke.

DESIGN

Case series.

SETTING

Inpatient neurorehabilitation unit in a regional rehabilitation center.

PARTICIPANTS

A convenience sample of 4 women with right brain strokes and left neglect.

INTERVENTION

A trial of carbidopa L-dopa to treat left neglect, if indicated by selected subtests of the Behavioral Inattention Test (BIT).

MAIN OUTCOME MEASURES

Baseline and posttreatment evaluation with the modified BIT and the FIM instrument.

RESULTS

Three of 4 subjects had significant improvements in their modified BIT scores (8%, 12%, 27%, respectively) and their functional status on the FIM.

CONCLUSION

With further study, carbidopa L-dopa may be shown to reduce unilateral spatial neglect and thereby improve rehabilitation outcomes.

Inhibition of Cutaneous UV Light–induced Tumor Necrosis Factor-α Protein Production by Allotrap 1258, a Novel Immunomodulatory Peptide¶

Peptides derived from the heavy chain of the HLA Class-I molecules have been shown to modulate immune responses both in vivo and in vitro. Using a computer-aided rational drug design approach, novel immunomodulatory peptides were designed based on peptide 2702.75-85, derived from HLA-B2702. Several peptides were identified which had increased immunomodulatory activity, including peptides RDP1258 and its D-isomer the peptide Allotrap 1258. The present study using Skh/hr hairless mouse skin model evaluated the in vivo effects of Allotrap 1258 on acute UVB-induced skin inflammation. Here we demonstrate that intraperitoneal administration of Allotrap 1258 1 h prior to UV exposure resulted in significantly diminished levels of UV-induced tumor necrosis factor (TNF)-alpha protein production in the epidermis but had no effect on other parameters of the acute UV-induced inflammatory response. By virtue of its ability to suppress TNF-alpha protein production, Allotrap 1258 could prove to be an effective modulator of inflammatory responses.

Comparative expression of novel vascular endothelial growth factor/vascular permeability factor transcripts in skin, papillomas, and carcinomas of v-Ha-ras Tg.AC transgenic mice and FVB/N mice

One of the most frequently detected changes in human solid tumors is the mutation of the ras oncogene, which has been associated with production of angiogenic growth factors such as vascular endothelial growth factor/vascular permeability factor (VEGF/VPF). Using the v-Ha-ras Tg-AC transgenic mice and the background FVB/N strain of inbred mice, the pattern of expression of specific VEGF/VPF transcripts was characterized in major organs and in skin, papillomas, and carcinomas during multi-stage skin carcinogenesis. Three VEGF/VPF transcripts were found to be constitutively expressed in skin as well as the major organs in both mouse strains, which corresponded in size and sequence to previously reported murine VEGF120 with a bp size of 331, VEGF164 with a bp size of 333, and VEGF188 with a bp size of 407. A previously unreported fourth murine transcript was also detected in skin and major tissues from both mouse strains which corresponded to rat VEGF144, with a bp size of 404. In addition, a unique 425 bp VEGF transcript which corresponded to human VEGF205 was present in highly vascularized tissues including heart, lung, liver, kidney, brain, as well in papillomas and carcinomas isolated from v-Ha-ras Tg.AC mice. In contrast, VEGF205 was present only in carcinomas derived from FVB/N mice. An antibody generated from a peptide sequence designed to detect each of the five VEGF/VPF peptides defined by RT-PCR analysis confirmed the existence of these five peptides and confirmed that the murine VEGF205 peptide was selectively expressed in papillomas and carcinomas derived from v-Ha-ras Tg.AC mice. These results demonstrate that there is significant alternative splicing of the murine VEGF/VPF gene during multi-stage carcinogenesis, which results in four commonly expressed VEGF transcripts. In addition, these studies identified a fifth VEGF transcript and peptide at the later stages of tumor promotion and in progression which appears to be linked to the presence of v-Ha-ras.

Inhibitory effects of pentoxifylline on ultraviolet B light-induced cutaneous inflammation

It is now recognized that ultraviolet (UV) radiation is a potent environmental insult capable of interfering with immunity to skin cancers and modifying certain immunologic reactions within both locally irradiated skin and distant, unexposed sites. Exposure to UVB light (290-320 nm) induces a potent cutaneous inflammatory response that involves the infiltration of leukocytes into the dermis as well as the production of proinflammatory cytokines by both resident epidermal keratinocytes and dermal cells. Tumor necrosis factor-alpha (TNF-alpha) is a proinflammatory cytokine that has been shown to be a major mediator of UVB light effects on cutaneous immunity. Recent studies have demonstrated that pentoxifylline (PTX), a xanthine-derived phosphodiesterase inhibitor, has the ability to inhibit synthesis of TNF-alpha. To examine the effects of PTX on UVB-mediated cutaneous inflammation, Skh/hr hairless mice were injected intraperitoneally with either phosphate-buffered saline or 50 microg/g PTX 1 h before exposure to 2240 J/m2 UVB. Reverse transcription-polymerase chain reaction and immunohistochemical techniques were used to demonstrate that 24 h to 1 wk after UVB-light irradiation, PTX inhibited UVB-induced TNF-alpha gene expression, inhibited the increase in epidermal TNF-alpha protein synthesis, blocked the increase in epidermal proliferation observed after exposure to UVB light, and decreased production of myeloperoxidase by neutrophils infiltrating into the dermis. These studies demonstrated that PTX modifies epidermal responses after acute UVB light exposure and suggest that PTX treatment may be used clinically to modulate the deleterious effects of long-term UVB-light irradiation.

Beta2 integrin/ICAM-1 adhesion molecule interactions in cutaneous inflammation and tumor promotion

The beta2 integrin (CD 18/CD 11 a, b, c) family of proteins mediate adherence of leukocytes to vascular endothelium and the associated ligand, intercellular adhesion molecule-1 (ICAM-1; CD 54), interacts with beta2 integrin proteins to allow transendothelial migration of leukocytes into sites of inflammation. The present study examines the function of these proteins in a murine model of acute cutaneous inflammation induced following topical application of 12-O-tetradecanoylphorbol-13-acetate (TPA) to the dorsal epidermis of SENCAR mice and in a model of skin multistage carcinogenesis. At 24 h following topical application of TPA to the dorsal epidermis of mice, dermal leukocytes expressed higher levels of beta2 integrin protein compared with the lower levels of beta2 integrin protein expression by peripheral blood leukocytes. ICAM-1 protein was localized to epidermal keratinocytes and vascular endothelium in TPA-treated skin and to proliferating papilloma cells. Intravenous (i.v.) injection of either 50 microg anti-beta2 integrin antibody alone or in combination with anti-ICAM-1 antibody significantly inhibited both TPA-stimulated neutrophil infiltration into the dermis (P < 0.001) and myeloperoxidase (MPO) activity (P < 0.03 anti-beta2 integrin antibody; P < 0.01 anti-beta2 integrin + ICAM-1 adhesion molecule antibodies), but had no effect on TPA-induced epidermal hyperplasia. In addition, injection of either anti-ICAM-1 adhesion molecule antibody alone (P < 0.004) or in combination with anti-beta2 integrin antibody (P < 0.001) significantly inhibited TPA-induced production of 7,8-dihydroxy-2'-deoxyguanosine (8-OHdG) immunoreactive proteins by epidermal keratinocytes. Beta2 integrin/ICAM-1 adhesion molecules work in concert to regulate migration, retention and functional activation of leukocytes within the dermis during TPA-induced skin inflammation and within stromal tissue of papillomas that form during multi-stage carcinogenesis. Agents that inhibit these receptor/ligand interactions may be useful in defining the roles of specific cell populations in cutaneous inflammation and multistage carcinogenesis and may also have potential as anti-promoting and anti-progression agents.

Gene expression and cellular sources of inducible nitric oxide synthase during tumor promotion

The present studies examined the temporal sequence of inducible nitric oxide synthase (iNOS) gene expression and the cellular sources of iNOS protein and of 3-nitrotyrosine, as a marker of production of nitric oxide-derived reactive nitrogen intermediates during murine multi-stage carcinogenesis. Levels of iNOS mRNA in dorsal skin isolated from acetone-treated female Sencar mice were 2.5-fold higher than iNOS gene expression detected in cutaneous tissue isolated from Sencar mice at 1, 3, 6, 10, 16 and 22 weeks after exposure to a single topical application of 25 nmol 7,12-dimethylbenz[a]anthracene (DMBA) followed by repetitive applications of 2 microgram 17-O-tetradecanoylphorbol-13-acetate (TPA). Papillomas isolated at 16 and 22 weeks of a tumor promotion protocol also had low levels of iNOS mRNA. The diminished levels of iNOS mRNA inversely correlated with the extent of TPA-induced epidermal hyperplasia. In acetone-treated mouse skin, iNOS immunospecific antibody binding was localized to the stratum corneum and suprabasal keratinocytes. In contrast, iNOS protein was present in lower amounts and was localized to the upper-most suprabasal keratinocytes in cutaneous tissue isolated at 22 weeks following a single exposure to either 25 nmol DMBA or acetone and repetitive applications of 2 microgram TPA. At all time points examined over the 22 week time period of papilloma growth, infiltrating neutrophils within the dermis bound significant levels of anti-iNOS antibodies. The production of iNOS by neutrophils within the dermis correlated with the formation of protein nitrotyrosination within the dermal tissue, as detected by 3-nitrotyrosine-specific antibodies. The present studies indicate that NOS and reactive nitrogen intermediates, including peroxynitrite, are produced specifically by dermal neutrophils during the tumor promotion process at time points that correspond to simultaneous production of reactive oxygen intermediates. Conversely, iNOS is simultaneously down-regulated in hyperplastic epidermis and in papillomas.

Inhibition of pro-inflammatory cytokine gene expression and papilloma growth during murine multistage carcinogenesis by pentoxifylline

Topical application of 12-O-tetradecanoylphorbol-13-acetate (TPA) to the dorsal epidermis of Sencar mice induces synthesis of pro-inflammatory cytokines, including interleukin-1 alpha (IL-1 alpha) and tumor necrosis factor-alpha (TNF-alpha). These proteins differentially regulate proliferation of epidermal keratinocytes, as well as stimulate chemotaxis, migration and production of reactive oxygen and nitrogen intermediates by leukocytes. Studies over the past several years have demonstrated that pentoxifylline ([1-(5-oxohexyl)-3,7-dimethyl-xanthine], oxpentifylline), which is a methylxanthine derivative used clinically for treatment of vascular insufficiency, has the unique ability to inhibit synthesis of pro-inflammatory cytokines. The present studies were performed to examine the effects of acute and chronic administration of pentoxifylline on TPA-induced cutaneous inflammation in female Sencar mice treated once with 10 micrograms TPA and also to determine the ability of pentoxifylline to inhibit the tumor promotion process in mice treated with a single application of 25 nmol 7,12-dimethylbenz[a]anthracene (DMBA) followed for 8 weeks by twice weekly topical application of TPA. Intraperitoneal injection of 50 micrograms/g pentoxifylline at 30 min prior to topical application of 10 micrograms TPA to the dorsal epidermis of Sencar mice inhibited TPA-induced IL-1 alpha and TNF-alpha gene expression 24 h after TPA treatment. Administration of pentoxifylline also significantly inhibited all parameters of acute TPA-induced inflammatory response examined 24 h later, including skin thickening (P < 0.005), infiltration of neutrophils into the dermis (P < 0.001), the corresponding dermal myeloperoxidase activity (P < 0.01) and epidermal hyperplasia (P < 0.001). Injection of 50 micrograms/g pentoxifylline over an 8 week time period significantly inhibited DMBA/TPA-induced papilloma growth (P < 0.05). These results indicate that administration of pentoxifylline is an effective means of inhibiting acute TPA-induced cutaneous inflammation and pro-inflammatory cytokine gene expression, as well as is effective as an antipromoter that inhibits papilloma growth.