Mutant p53 reactivator SLMP53-2 hinders ultraviolet B radiation-induced skin carcinogenesis.

The growing incidence of skin cancer (SC) has prompted the search for additional preventive strategies to counteract this global health concern. Mutant p53 (mutp53), particularly with ultraviolet radiation (UVR) signature, has emerged as a promising target for SC prevention based on its key role in skin carcinogenesis. Herein, the preventive activity of our previously disclosed mutp53 reactivator SLMP53-2 against UVR-induced SC was investigated. The pre-treatment of keratinocyte HaCaT cells with SLMP53-2, before UVB exposure, depleted mutp53 protein levels with restoration of wild-type-like p53 DNA-binding ability and subsequent transcriptional activity. SLMP53-2 increased cell survival by promoting G1-phase cell cycle arrest, while reducing UVB-induced apoptosis through inhibition of c-Jun N-terminal kinase (JNK) activity. SLMP53-2 also protected cells from reactive oxygen species and oxidative damage induced by UVB. Moreover, it enhanced DNA repair through upregulation of nucleotide excision repair pathway and depletion of UVB-induced DNA damage, as evidenced by a reduction of DNA in comet tails, γH2AX staining and cyclobutane pyrimidine dimers (CPD) levels. SLMP53-2 further suppressed UVB-induced inflammation by inhibiting the nuclear translocation and DNA-binding ability of NF-κB, and promoted the expression of key players involved in keratinocytes differentiation. Consistently, the topical application of SLMP53-2 in mice skin, prior to UVB irradiation, reduced cell death and DNA damage. It also decreased the expression of inflammatory-related proteins and promoted cell differentiation, in UVB-exposed mice skin. Notably, SLMP53-2 did not show signs of skin toxicity for cumulative topical use. Overall, these results support a promising protective activity of SLMP53-2 against UVB-induced SC.

Comparison of skin cancer awareness and sun protection behaviours between renal transplant recipients and patients with glomerular disease treated with immunosuppressants.

BACKGROUND: There is no previous study that compare skin cancer awareness and photoprotective behaviours between renal transplant recipients (RTR) and patients with glomerular disease (GD). OBJECTIVES/METHODS: Sixty-one RTR and 51 patients with GD were given a self-reported questionnaire to evaluate skin cancer awareness and photoprotective behaviours in this cross-sectional study. The former group received a formal education on skin cancer and the latter an informal session prior to immunosuppressant use. RESULTS: Ninety-three percent (n = 57) of RTRs and 88% (n = 45) of patients with GD responded to the survey. Majority of participants from both groups were aware that ultraviolet radiation could play a role in the occurrence of skin cancers and the awareness increased in participants with higher education (odds ratio [OR] = 1.50, 95% confidence interval [CI] = 1.15-1.95, P = .003). Ninety-eight percent vs 71% were aware that immunosuppressants can increase the risk of developing cancer (P < .001) and higher awareness was noted in younger participants (OR = 0.92, 95% CI = 0.87-0.97, P = .003). Suboptimal photoprotective behaviours (sun avoidance, sunscreen usage and sun-protective clothing) were noted in both cohorts and slightly lower sun protection rates were reported in RTR when compared with patients having GD. The level of sun protective measures in RTR based on high, moderate and minimal use of photoprotective measures were 21%, 46% and 33%, respectively. In terms of patients with GD, the latter practices were 13%, 50% and 37%, respectively (P = .560). Higher educational status was significantly associated with better sunscreen usage in RTR (P = .017) whereas this finding was not observed in patients with GD. CONCLUSION: Patients with GD and RTR should have formal education on the risks of skin cancers before starting immunosuppressants. Follow-up education and surveillance is required to improve skin protective practices in these patients.

Loss of Setd4 delays radiation-induced thymic lymphoma in mice.

Radiation-induced lymphomagenesis results from a clonogenic lymphoid cell proliferation due to genetic alterations and immunological dysregulation. Mouse models had been successfully used to identify risk and protective factors for radiation-induced DNA damage and carcinogenesis. The mammalian SETD4 is a poorly understood putative methyl-transferase. Here, we report that conditional Setd4 deletion in adult mice significantly extended the survival of radiation-induced T-lymphoma. However, in Tp53 deficient mice, Setd4 deletion did not delay the radiation-induced lymphomagenesis although it accelerated the spontaneous T-lymphomagenesis in non-irradiated mice. The T-lymphomas were largely clonogenic in both Setd4flox/flox and Setd4Δ/Δ mice based on sequencing analysis of the T-cell antigen ß receptors. However, the Setd4Δ/Δ T-lymphomas were CD4+/CD8+ double positive, while the littermate Setd4flox/floxtumor were largely CD8+ single positive. A genomic sequencing analysis on chromosome deletion, inversion, duplication, and translocation, revealed a larger contribution of inversion but a less contribution of deletion to the overall chromosome rearrangements in the in Setd4Δ/Δ tumors than the Setd4flox/flox tumors. In addition, the Setd4flox/flox mice died more often from the large sizes of primary thymus lymphoma at earlier time, but there was a slight increase of lymphoma dissemination among peripheral organs in Setd4Δ/Δ at later times. These results suggest that Setd4 has a critical role in modulating lymphomagenesis and may be targeted to suppress radiation-induced carcinogenesis.

Aggressive Mammary Cancers Lacking Lymphocytic Infiltration Arise in Irradiated Mice and Can Be Prevented by Dietary Intervention.

Because the incidence of breast cancer increases decades after ionizing radiation exposure, aging has been implicated in the evolution of the tumor microenvironment and tumor progression. Here, we investigated radiation-induced carcinogenesis using a model in which the mammary glands of 10-month-old BALB/c mice were transplanted with Trp53-null mammary tissue 3 days after exposure to low doses of sparsely ionizing γ-radiation or densely ionizing particle radiation. Mammary transplants in aged, irradiated hosts gave rise to significantly more tumors that grew more rapidly than those in sham-irradiated mice, with the most pronounced effects seen in mice irradiated with densely ionizing particle radiation. Tumor transcriptomes identified a characteristic immune signature of these aggressive cancers. Consistent with this, fast-growing tumors exhibited an immunosuppressive tumor microenvironment with few infiltrating lymphocytes, abundant immunosuppressive myeloid cells, and high COX-2 and TGFß. Only irradiated hosts gave rise to tumors lacking cytotoxic CD8+ lymphocytes (defined here as immune desert), which also occurred in younger irradiated hosts. These data suggest that host irradiation may promote immunosuppression. To test this, young chimera mice were fed chow containing a honeybee-derived compound with anti-inflammatory and immunomodulatory properties, caffeic acid phenethyl ester (CAPE). CAPE prevented the detrimental effects of host irradiation on tumor growth rate, immune signature, and immunosuppression. These data indicated that low-dose radiation, particularly densely ionizing exposure of aged mice, promoted more aggressive cancers by suppressing antitumor immunity. Dietary intervention with a nontoxic immunomodulatory agent could prevent systemic effects of radiation that fuel carcinogenesis, supporting the potential of this strategy for cancer prevention.

RADIATION-INDUCED BYSTANDER EFFECT - MODELING, MANIFESTATION, MECHANISMS, PERSISTENCE, CANCER RISKS (literature review). / RADIATsIY̆NO-INDUKOVANYY̆ EFEKT SVIDKA ­ MODELIuVANNIa, PROIaVY, MEKhANIZMY ROZVYTKU, PERSYSTENTsIIa, ONKOLOGIChNI RYZYKY (ogliad literatury).

The review summarizes and analyzes the data of world scientific literature and the results of the own research con- cerning one of the main non-targeted effects of ionizing radiation - the radiation induced bystander effect (RIBE) - the ability of irradiated target cells to induce secondary biological changes in non-irradiated receptor cells. The his- tory of studies of this phenomenon is presented - it described under various names since 1905, began to study from the end of the twentieth century when named as RIBE and caused particular interest in the scientific community during recent decades. It is shown that the development of biological science and the improvement of research methods allowed to get new in-depth data on the development of RIBE not only at the level of the whole organism, but even at the genome level. The review highlights the key points of numerous RIBE investigations including mod- eling; methodological approaches to studying; classification; features of interaction between irradiated and intact cells; the role of the immune system, oxidative stress, cytogenetic disorders, changes in gene expression in the mechanism of development of RIBE; rescue effect, abscopal effect, persistence, modification, medical effects. It is emphasized that despite the considerable amount of research concerning the bystander response as the universal phenomenon and RIBE as one of its manifestations, there are still enough «white spots¼ in determining the mech- anisms of the RIBE formation and assessing the possible consequences of its development for human health.

Sunbed Use Increases Cutaneous Squamous Cell Carcinoma Risk in Women: A Large-scale, Prospective Study in Sweden.

The incidence of cutaneous squamous cell carcinoma has increased rapidly in Sweden in the past decades. Here, we present a prospective study of the Melanoma in Southern Sweden (MISS)-cohort, with 29,460 participating women in southern Sweden that investigates the risk factors for cutaneous squamous cell carcinoma. Data on the host and skin cancer risk factors were collected through questionnaires and then matched with the National Cancer Registry. Statistical analyses were based on uni- and multivariable Cox proportional hazards models, using age as the time-scale. We found that sunbed use (hazard ratio (HR) 1.2, 95% CI: 1.1-1.4), red and light blond hair (HR 1.6, 95% CI: 1.1-2.3), freckles (HR 1.4, 95% CI: 1.1-1.8) and immunosuppressive medications (HR 2.1, 95% CI: 1.3-4.5) were independent risk factors. Furthermore, we observed a dose-dependent relationship between sunbed use and the development of cutaneous squamous cell carcinoma. Our findings support the idea of integrating dermatological follow-up examinations for immunosuppressed patients and banning the use of sunbeds in order to prevent cutaneous squamous cell carcinoma.

RILA blood biomarker as a predictor of radiation-induced sarcoma in a matched cohort study.

PURPOSE: Radiation-induced sarcoma (RIS) is a rare but serious event. Its occurrence has been discussed during the implementation of new radiation techniques and justified appropriate radioprotection requirements. New approaches targeting intrinsic radio-sensitivity have been described, such as radiation-induced CD8 T-lymphocyte apoptosis (RILA) able to predict late radio-induced toxicities. We studied the role of RILA as a predisposing factor for RIS as a late adverse event following radiation therapy (RT). PATIENTS AND METHODS: In this prospective biological study, a total of 120 patients diagnosed with RIS were matched with 240 control patients with cancer other than sarcoma, for age, sex, primary tumor location and delay after radiation. RILA was prospectively assessed from blood samples using flow cytometry. RESULTS: Three hundred and forty-seven patients were analyzed (118 RIS patients and 229 matched control patients). A majority (74%) were initially treated by RT for breast cancer. The mean RT dose was comparable with a similar mean (± standard deviation) for RIS (53.7 ±â€¯16.0 Gy) and control patients (57.1 ±â€¯15.1 Gy) (p = .053). Median RILA values were significantly lower in RIS than in control patients with respectively 18.5% [5.5-55.7] and 22.3% [3.8-52.2] (p = .0008). Thus, patients with a RILA >21.3% are less likely to develop RIS (p < .0001, OR: 0.358, 95%CI [0.221-0.599]. CONCLUSION: RILA is a promising indicator to predict an individual risk of developing RIS. Our results should be followed up and compared with molecular and genomic testing in order to better identify patients at risk. A dedicated strategy could be developed to define and inform high-risk patients who require a specific approach for primary tumor treatment and long term follow-up.

The Aftermath of Surviving Acute Radiation Hematopoietic Syndrome and its Mitigation.

Intensive research is underway to find new agents that can successfully mitigate the acute effects of radiation exposure. This is primarily in response to potential counterthreats of radiological terrorism and nuclear accidents but there is some hope that they might also be of value for cancer patients treated with radiation therapy. Research into mitigation countermeasures typically employs classic animal models of acute radiation syndromes (ARS) that develop after whole-body irradiation (WBI). While agents are available that successfully mitigate ARS when given after radiation exposure, their success raises questions as to whether they simply delay lethality or unmask potentially lethal radiation pathologies that may appear later in time. Life shortening is a well-known consequence of WBI in humans and experimental animals, but it is not often examined in a mitigation setting and its causes, other than cancer, are not well-defined. This is in large part because delayed effects of acute radiation exposure (DEARE) do not follow the strict time-dose phenomena associated with ARS and present as a diverse range of symptoms and pathologies with low mortality rates that can be evaluated only with the use of large cohorts of subjects, as in this study. Here, we describe chronically increased mortality rates up to 660 days in large numbers of mice given LD70/30 doses of WBI. Systemic myeloid cell activation after WBI persists in some mice and is associated with late immunophenotypic changes and hematopoietic imbalance. Histopathological changes are largely of a chronic inflammatory nature and variable incidence, as are the clinical symptoms, including late diarrhea that correlates temporally with changes in the content of the microbiome. We also describe the acute and long-term consequences of mitigating hematopoietic ARS (H-ARS) lethality after LD70/30 doses of WBI in multiple cohorts of mice treated uniformly with radiation mitigators that have a common 4-nitro-phenylsulfonamide (NPS) pharmacophore. Effective NPS mitigators dramatically decrease ARS mortality. There is slightly increased subacute mortality, but the rate of late mortalities is slowed, allowing some mice to live a normal life span, which is not the case for WBI controls. The study has broad relevance to radiation late effects and their potential mitigation and epitomizes the complex interaction between radiation-damaged tissues and immune homeostasis.

Ultraviolet light and melanoma.

Melanoma is a clinically heterogeneous disease, and current strategies for treatment of the primary tumour are based on pathological criteria alone. In the recent past, several DNA-sequencing and RNA-sequencing studies of primary and advanced melanoma samples have identified unique relationships between somatic mutations, genomic aberrations, and the genetic fingerprint of ultraviolet radiation (UVR). The recurrent patterns of genomic alterations reveal different disease pathways, drug targets and mechanisms limiting drug response. Here, we examine the known associations between the molecular categories of melanoma and the multidimensional UVR damage. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Ultraviolet Radiations: Skin Defense-Damage Mechanism.

UV-radiations are the invisible part of light spectra having a wavelength between visible rays and X-rays. Based on wavelength, UV rays are subdivided into UV-A (320-400 nm), UV-B (280-320 nm) and UV-C (200-280 nm). Ultraviolet rays can have both harmful and beneficial effects. UV-C has the property of ionization thus acting as a strong mutagen, which can cause immune-mediated disease and cancer in adverse cases. Numbers of genetic factors have been identified in human involved in inducing skin cancer from UV-radiations. Certain heredity diseases have been found susceptible to UV-induced skin cancer. UV radiations activate the cutaneous immune system, which led to an inflammatory response by different mechanisms. The first line of defense mechanism against UV radiation is melanin (an epidermal pigment), and UV absorbing pigment of skin, which dissipate UV radiation as heat. Cell surface death receptor (e.g. Fas) of keratinocytes responds to UV-induced injury and elicits apoptosis to avoid malignant transformation. In addition to the formation of photo-dimers in the genome, UV also can induce mutation by generating ROS and nucleotides are highly susceptible to these free radical injuries. Melanocortin 1 receptor (MC1R) has been known to be implicated in different UV-induced damages such as pigmentation, adaptive tanning, and skin cancer. UV-B induces the formation of pre-vitamin D3 in the epidermal layer of skin. UV-induced tans act as a photoprotection by providing a sun protection factor (SPF) of 3-4 and epidermal hyperplasia. There is a need to prevent the harmful effects and harness the useful effects of UV radiations.

Radiation-induced inflammatory cascade and its reverberating crosstalks as potential cause of post-radiotherapy second malignancies.

The disease-free survival following radiotherapy is often limited by the development of second/secondary cancers. This significant impediment to effective cancer treatment implicated even in the modern-day radiotherapy needs to be countered effectively. Critical analysis reveals that besides achieving effective tumor control, radiotherapy elicits certain cellular and systemic inflammatory events in tumor infiltrate, which remain relatively stable and tend to facilitate "in-field" or "out of field" oncogenesis in due course of time. Acute pro-inflammatory cytokines generated as a result of radiation-induced oxidative insult and DNA damage induce genetic instability that contributes to tumor heterogeneity and plasticity. The reverberating crosstalks between radiation-targeted tumor and its microenvironment in turn initiate inflammatory loops that feedback the immune system to manifest as systemic consequences. An "inflammatory switchover" within the tumor microenvironment is thus induced by cumulative radiation exposure, initiating pro-tumor events that can severely limit the outcome of radiotherapy. Various pro-survival tumorigenic pathways activated as a result regulate radiation-induced hypoxia, ECM remodeling, angiogenesis/vasculogenesis, and immune suppression/evasion within the tumor microenvironment. NF-κB, HIF and STAT are identified as central regulating mediators among others that orchestrate inflammatory switchover from apoptosis-mediated tumor surveillance to radiation-induced carcinogenesis. Radiation-induced interleukins stimulate recruited macrophages and endothelial cells to promote intravasation, which is further aided by release of chemokines favoring extravasation and secondary site lesions. We hence propose that delineating the inflammatory signaling network emanating from irradiation of complex tumor tissue is critical for devising suitable therapeutic strategies to prevent post-radiotherapy second cancers or metastasis. Graphical Abstract ᅟ.

Cancer incidence vs. FM radio transmitter density.

BACKGROUND: In 2002, a strong association was highlighted between local melanoma incidence and the number of locally covering main Frequency Modulation (FM) transmitters in Sweden. This study investigated whether an association also exists between melanoma incidence and the average density of main FM transmitters in different European countries. METHODS: Twenty-three different European countries were asked to disclose the number of main transmitters used for the FM broadcasting band (87·5-108 MHz) in the respective country. Incidences of melanoma, breast cancer and all cancers together per country were correlated with their respective average density of transmitters per 10,000 km(2). FINDINGS: Both melanoma and breast cancer, as well as all cancers together, appear to be significantly associated with the density of main FM broadcasting transmitters in the European countries examined. INTERPRETATION: The findings present strong support to the earlier presented hypothesis that body-resonant broadcasting radiation emitted by horizontally polarized main FM transmitters has an immune-disturbing effect. FUNDING: This study was financed by internal funds within Hallberg Independent Research only.

Infiltration of F98 glioma cells in Fischer rat brain is temporary stimulated by radiation.

PURPOSE: Irradiation of brain stimulates the expression of inflammatory mediators, some of which can modify the ability of cancer cells to infiltrate the brain. In the present study, the time window during which this stimulation occurs was determined. MATERIALS AND METHODS: Brain of Fischer rat was irradiated (15 Gy) and expression of pro-inflammatory mediators IL-1ß, IL-6 and TNF-α was measured from 4 h to 20 days post-irradiation. Level of the matrix metalloproteinase 2 (MMP-2) and prostaglandin E2 (PGE2) which can favor cancer cell infiltration were also measured. The F98 glioma cells were implanted either during (4 h post-irradiation) or after (10 days post-irradiation) the pro-inflammatory phase. Infiltration distance of F98 cells in brain parenchyma and the median survival time of the animals were determined. RESULTS: Expression of IL-1ß, IL-6 and TNF-α was significantly increased in the irradiated brains with a peak at 4 h post-irradiation. Implantation of F98 glioma cells 4 h post-irradiation reduced the median survival time of Fischer rats to 18 days, compared to 25 days when the F98 were implanted in non-irradiated brain. Irradiation of the brain increased the distance of infiltration of F98 cells and was associated with increased levels of MMP-2 and PGE2. Conversely, F98 cells implanted 10 days post-irradiation have infiltrated the brain over a shorter distance and the median survival time of rats was increased to 35 days. CONCLUSIONS: Cancer recurrence is frequently observed in GBM patients. A better understanding of the inflammatory response observed in irradiated brain could contribute to develop new therapeutic modalities to further increase the efficiency of radiotherapy.

Sunlight Effects on Immune System: Is There Something Else in addition to UV-Induced Immunosuppression?

Sunlight, composed of different types of radiation, including ultraviolet wavelengths, is an essential source of light and warmth for life on earth but has strong negative effects on human health, such as promoting the malignant transformation of skin cells and suppressing the ability of the human immune system to efficiently detect and attack malignant cells. UV-induced immunosuppression has been extensively studied since it was first described by Dr. Kripke and Dr. Fisher in the late 1970s. However, skin exposure to sunlight has not only this and other unfavorable effects, for example, mutagenesis and carcinogenesis, but also a positive one: the induction of Vitamin D synthesis, which performs several roles within the immune system in addition to favoring bone homeostasis. The impact of low levels of UV exposure on the immune system has not been fully reported yet, but it bears interesting differences with the suppressive effect of high levels of UV radiation, as shown by some recent studies. The aim of this article is to put some ideas in perspective and pose some questions within the field of photoimmunology based on established and new information, which may lead to new experimental approaches and, eventually, to a better understanding of the effects of sunlight on the human immune system.

Blackberry extract inhibits UVB-induced oxidative damage and inflammation through MAP kinases and NF-κB signaling pathways in SKH-1 mice skin.

Extensive exposure of solar ultraviolet-B (UVB) radiation to skin induces oxidative stress and inflammation that play a crucial role in the induction of skin cancer. Photochemoprevention with natural products represents a simple but very effective strategy for the management of cutaneous neoplasia. In this study, we investigated whether blackberry extract (BBE) reduces chronic inflammatory responses induced by UVB irradiation in SKH-1 hairless mice skin. Mice were exposed to UVB radiation (100 mJ/cm(2)) on alternate days for 10 weeks, and BBE (10% and 20%) was applied topically a day before UVB exposure. Our results show that BBE suppressed UVB-induced hyperplasia and reduced infiltration of inflammatory cells in the SKH-1 hairless mice skin. BBE treatment reduced glutathione (GSH) depletion, lipid peroxidation (LPO), and myeloperoxidase (MPO) in mouse skin by chronic UVB exposure. BBE significantly decreased the level of pro-inflammatory cytokines IL-6 and TNF-α in UVB-exposed skin. Likewise, UVB-induced inflammatory responses were diminished by BBE as observed by a remarkable reduction in the levels of phosphorylated MAP Kinases, Erk1/2, p38, JNK1/2 and MKK4. Furthermore, BBE also reduced inflammatory mediators such as cyclooxygenase-2 (COX-2), prostaglandin E2 (PGE2), and inducible nitric oxide synthase (iNOS) levels in UVB-exposed skin. Treatment with BBE inhibited UVB-induced nuclear translocation of NF-κB and degradation of IκBα in mouse skin. Immunohistochemistry analysis revealed that topical application of BBE inhibited the expression of 8-oxo-7, 8-dihydro-2'-deoxyguanosine (8-oxodG), cyclobutane pyrimidine dimers (CPD), proliferating cell nuclear antigen (PCNA), and cyclin D1 in UVB-exposed skin. Collectively, these data indicate that BBE protects from UVB-induced oxidative damage and inflammation by modulating MAP kinase and NF-κB signaling pathways.

Photodamage: all signs lead to actinic keratosis and early squamous cell carcinoma.

Ultraviolet (UV) radiation is likely to drive the initiation and progression of skin cancer from actinic keratosis to squamous cell carcinoma. Signs of photodamage occur at multiple steps. UV radiation damages many cellular constituents, including lipids, proteins and DNA, all of which are likely to contribute to UV-induced skin cancer. Two biological events culminating from photodamage are mutations in the genes critical to the control of cell division, differentiation and invasion and immunosuppression. DNA photodamage, if unrepaired prior to cell division, can result in the incorporation of an incorrect nucleotide into newly synthesised DNA. Mutations in critical genes contribute to carcinogenesis. Photodamage to proteins such as those involved in DNA repair or proteins or lipids involved in cellular signalling can interfere with this repair process and contribute to mutagenesis. Mutations in key genes, including TP53, BRM, PTCH1, and HRAS, contribute to skin carcinogenesis. UV also damages immunity. Photodamage to DNA and signalling lipids as well as other molecular changes are detrimental to the key cells that regulate immunity. Photodamaged dendritic cells and altered responses by mast cells lead to the activation of T and B regulatory cells that suppress immunity to the protein products of UV-mutated genes. This stops the immune response from its protective function of destroying mutated cells, enabling the transformed cells to progress to skin cancer. UV appears to play a pivotal role at each of these steps, and therefore, signs of photodamage point to the development of skin cancer.

Sunscreens in the United States: current status and future outlook.

Incidence rates of nonmelanoma skin cancer and melanoma has been on the rise in the United States for the past 20 years. UV radiation (UVR) exposure remains the most preventable environmental risk factor for these cancers. Aside from sun avoidance, sunscreens remain our best protection. UVR directly damages DNA and cause indirect cellular damage through the creation of reactive oxygen species, the sum of which leads to cutaneous immunosuppression and a tumorigenic milieu. The current generation of sunscreens protect from UVR through two main mechanisms: absorption and deflection. In the US, new Food and Drug Association rules require sunscreen manufacturers to evaluate their products not only on sun protection factor but also on broad spectrum UVA protection by the end of 2013. New labeling requirements will also be instituted. The American Academy of Dermatology and the American Academy of Pediatrics have provided specific recommendations for proper sun protection and sunscreen usage. Plant polyphenols such as those isolated from green tea, pomegranate, and grape seed remain an interesting avenue of research as additives to sunscreens or stand-alone products that appear to modulate the immunosuppressive effects of UVR on the skin. Additionally, although UVR induces endogenous cutaneous production of vitamin D, its damaging effects overshadow this positive benefit, especially in light of the ease of achieving recommended amounts of vitamin D through diet and supplementation.

Differential effects of ultraviolet irradiation in neonatal versus adult mice are not explained by defective macrophage or neutrophil infiltration.

Epidemiological studies suggest that ultraviolet B exposure (UVR) during childhood is the most important environmental risk factor for melanoma. In accordance, neonatal, but not adult, UVR exacerbates melanoma incidence in mouse models. The inability of neonates, as opposed to adults, to mount a proper neutrophil inflammatory response in the skin upon UVR exposure has been one of the driving hypotheses explaining this observation for the past decade. However, this aspect remains controversial. Here, we evaluated the UVR-induced inflammatory response in neonatal versus adult mice. In neonates, a significant neutrophil infiltration could be identified and quantified using three different antibodies by flow cytometry or immunohistochemistry. On day 1 after UVR, neutrophils were increased by 84-fold and on day 4 macrophages increased by 37-fold compared with nonexposed age-matched skin. When compared with adults, neonatal skin harbored a higher proportion of neutrophils in the myeloid compartment without significant differences in absolute counts. This response was reproduced with different kinetics in C57Bl/6 and FVB mice with a more rapid attenuation of neutrophil counts in the latter. Overall, our results suggest that the greatly increased sensitivity to melanomagenesis in neonates does not result from their incompetence in terms of myeloid inflammatory response to UVR.

Pharmacologically antagonizing the CXCR4-CXCL12 chemokine pathway with AMD3100 inhibits sunlight-induced skin cancer.

One way sunlight causes skin cancer is by suppressing anti-tumor immunity. A major mechanism involves altering mast cell migration via the C-X-C motif chemokine receptor 4-C-X-C motif chemokine ligand 12 (CXCR4-CXCL12) chemokine pathway. We have discovered that pharmacologically blocking this pathway with the CXCR4 antagonist AMD3100 prevents both UV radiation-induced immune suppression and skin cancer. The majority of control mice receiving UV-only developed histopathologically confirmed squamous cell carcinomas. In contrast, skin tumor incidence and burden was significantly lower in AMD3100-treated mice. Perhaps most striking was that AMD3100 completely prevented the outgrowth of latent tumors that occurred once UV irradiation ceased. AMD3100 protection from UV immunosuppression and skin cancer was associated with reduced mast cell infiltration into the skin, draining lymph nodes, and the tumor itself. Thus a major target of CXCR4 antagonism was the mast cell. Our results indicate that interfering with UV-induced CXCL12 by antagonizing CXCR4 significantly inhibits skin tumor development by blocking UV-induced effects on mast cells. Hence, the CXCR4-CXCL12 chemokine pathway is a novel therapeutic target in the prevention of UV-induced skin cancer.

Nutritional abrogation of photoimmunosuppression: in vivo investigations.

Skin cancer is a major public health concern, and the primary aetiological factor in the majority of skin cancers is ultraviolet radiation (UVR) exposure. UVR not only induces potentially mutagenic DNA damage but also suppresses cell-mediated immunity (CMI), allowing cancerous cells to escape destruction and progress to tumours. A considerable proportion of an individual's annual sun exposure is obtained outside the vacation period when topical and physical measures for photoprotection are irregularly used. Certain nutrients could provide an adjunctive protective role, and evidence is accruing from experimental studies to support their use in abrogation of photoimmunosuppression. Moreover, developments in clinical research methods to evaluate impact of solar-simulated radiation on cutaneous CMI allow the immune protective potential of nutritional agents to be examined in humans in vivo. This article summarises the mediation of CMI and its suppression by UVR, evaluates the methodology for quantitative assessment in vivo, reviews the human studies reported on nutritional abrogation of photoimmunosuppression including recent randomized controlled trials and discusses the mechanisms of photoprotection by the nutrients. This includes, in addition to antioxidants, novel studies of omega-3 polyunsaturated fatty acids and nicotinamide.