Epigenetic switch reshapes epithelial progenitor cell signatures and drives inflammatory pathogenesis in hidradenitis suppurativa

Hidradenitis suppurativa (HS) is a complex inflammatory skin disease with undefined mechanistic underpinnings. Here, we investigated HS epithelial cells and demonstrated that HS basal progenitors modulate their lineage restriction and give rise to pathogenic keratinocyte clones, resulting in epidermal hyperproliferation and dysregulated inflammation in HS. When comparing to healthy epithelial stem/progenitor cells, in HS, we identified changes in gene signatures that revolve around the mitotic cell cycle, DNA damage response and repair, as well as cell-cell adhesion and chromatin remodeling. By reconstructing cell differentiation trajectory and CellChat modeling, we identified a keratinocyte population specific to HS. This population is marked by S100A7/8/9 and KRT6 family members, triggering IL1, IL10, and complement inflammatory cascades. These signals, along with HS-specific proinflammatory cytokines and chemokines, contribute to the recruitment of certain immune cells during the disease progression. Furthermore, we revealed a previously uncharacterized role of S100A8 in regulating the local chromatin environment of target loci in HS keratinocytes. Through the integration of genomic and epigenomic datasets, we identified genome-wide chromatin rewiring alongside the switch of transcription factors (TFs), which mediated HS transcriptional profiles. Importantly, we identified numerous clinically relevant inflammatory enhancers and their coordinated TFs in HS basal CD49fhigh cells. The disruption of the S100A enhancer using the CRISPR/Cas9-mediated approach or the pharmacological inhibition of the interferon regulatory transcription factor 3 (IRF3) efficiently reduced the production of HS-associated inflammatory regulators. Our study not only uncovers the plasticity of epidermal progenitor cells in HS but also elucidates the epigenetic mechanisms underlying HS pathogenesis.

NK and NKT cells in the pathogenesis of Hidradenitis suppurativa: Novel therapeutic strategy through targeting of CD2

Hidradenitis suppurativa (HS) is a chronic debilitating inflammatory skin disease with poorly understood pathogenesis. Single-cell RNAseq analysis of HS lesional and healthy individual skins revealed that NKT and NK cell populations were greatly expanded in HS, and they expressed elevated CD2, an activation receptor. Immunohistochemistry analyses confirmed significantly expanded numbers of CD2+ cells distributed throughout HS lesional tissue, and many co-expressed the NK marker, CD56. While CD4+ T cells were expanded in HS, CD8 T cells were rare. CD20+ B cells in HS were localized within tertiary follicle like structures. Immunofluorescence microscopy showed that NK cells (CD2 + CD56 dim ) expressing perforin, granzymes A and B were enriched within the hyperplastic follicular epidermis and tunnels of HS and juxtaposed with apoptotic cells. In contrast, NKT cells (CD2 + CD3 + CD56 bright ) primarily expressed granzyme A and were associated with α-SMA expressing fibroblasts within the fibrotic regions of the hypodermis. Keratinocytes and fibroblasts expressed high levels of CD58 (CD2 ligand) and they interacted with CD2 expressing NKT and NK cells. The NKT/NK maturation and activating cytokines, IL-12, IL-15 and IL-18, were significantly elevated in HS. Inhibition of cognate CD2-CD58 interaction with blocking anti-CD2 mAb in HS skin organotypic cultures resulted in a profound reduction of the inflammatory gene signature and secretion of inflammatory cytokines and chemokines in the culture supernate. In summary, we show that a cellular network of heterogenous NKT and NK cell populations drives inflammation, tunnel formation and fibrosis in the pathogenesis of HS. Furthermore, CD2 blockade is a viable immunotherapeutic approach for the management of HS.

Mechanism underlying follicular hyperproliferation and oncogenesis in hidradenitis suppurativa

Hidradenitis suppurativa (HS) is a skin disorder that causes chronic painful inflammation and hyperproliferation, often with the comorbidity of invasive keratoacanthoma (KA). Our research, employing high-resolution immunofluorescence and data science approaches together with confirmatory molecular analysis, has identified that the 5'-cap-dependent protein translation regulatory complex eIF4F is a key factor in the development of HS and is responsible for regulating follicular hyperproliferation. Specifically, eIF4F translational targets, Cyclin D1 and c-MYC, orchestrate the development of HS-associated KA. Although eIF4F and p-eIF4E are contiguous throughout HS lesions, Cyclin D1 and c-MYC have unique spatial localization and functions. The keratin-filled crater of KA is formed by nuclear c-MYC-induced differentiation of epithelial cells, whereas the co-localization of c-MYC and Cyclin D1 provides oncogenic transformation by activating RAS, PI3K, and ERK pathways. In sum, we have revealed a novel mechanism underlying HS pathogenesis of follicular hyperproliferation and the development of HS-associated invasive KA.

Quantitative analysis of restricted metals and metalloids in tattoo inks: A systematic review and meta-analysis

The various ingredients and impurities that can be detected within tattoo inks have been associated with a myriad of dermatologic complications. Legislation regarding these antigenic substances varies widely around the world, with Europe serving as both the research and regulatory center on these intradermal formulations. Although industry is said to be moving away from metallic and metalloid pigments in exchange for organic or organometallic dyes, surveys of commercially available inks continue to detect these elements at concentrations considered unsafe for application into the dermis. In order to better assess the formulation and safety of tattoo ink, we present a systematic review and meta-analysis of studies quantifying restricted metals and metalloids in commercially available tattoo ink products. Among the papers selected, inconsistencies were noted in the degree of specificity by which ink products were identified and the elements sampled for. In addition, the analytical targets' valency and/or solubility were not always considered in accordance with regulation criteria. Of note, chromium, by total content and that of its regulated +6 valency, exceeded its maximum allowed concentration in nearly every sample tested. Total copper content exceeded the limit for soluble copper in half of inks sampled. In descending order, concentrations of cadmium, barium, mercury, soluble copper, arsenic, zinc, antimony, and lead violated regulations in one-sixth or fewer of samples tested. Cobalt and tin levels never violated regulation. Overall, our findings indicate that unsafe levels of restricted elements continue to be detected across studies, warranting further investigation under a regulatory lens.

Next-generation retinoid X receptor agonists increase ATRA signaling in organotypic epithelium cultures and have distinct effects on receptor dynamics

Retinoid X receptors (RXRs) are nuclear transcription factors that partner with other nuclear receptors to regulate numerous physiological processes. Although RXR represents a valid therapeutic target, only a few RXR-specific ligands (rexinoids) have been identified, in part due to the lack of clarity on how rexinoids selectively modulate RXR response. Previously, we showed that rexinoid UAB30 potentiates all-trans-retinoic acid (ATRA) signaling in human keratinocytes, in part by stimulating ATRA biosynthesis. Here, we examined the mechanism of action of next-generation rexinoids UAB110 and UAB111 that are more potent in vitro than UAB30 and the FDA-approved Targretin. Both UAB110 and UAB111 enhanced ATRA signaling in human organotypic epithelium at a 50-fold lower concentration than UAB30. This was consistent with the 2- to 5- fold greater increase in ATRA in organotypic epidermis treated with UAB110/111 versus UAB30. Furthermore, at 0.2 μM, UAB110/111 increased the expression of ATRA genes up to 16-fold stronger than Targretin. The less toxic and more potent UAB110 also induced more changes in differential gene expression than Targretin. Additionally, our hydrogen deuterium exchange mass spectrometry analysis showed that both ligands reduced the dynamics of the ligand-binding pocket but also induced unique dynamic responses that were indicative of higher affinity binding relative to UAB30, especially for Helix 3. UAB110 binding also showed increased dynamics towards the dimer interface through the Helix 8 and Helix 9 regions. These data suggest that UAB110 and UAB111 are potent activators of RXR-RAR signaling pathways but accomplish activation through different molecular responses to ligand binding.

Conformationally Defined Rexinoids for the Prevention of Inflammation and Nonmelanoma Skin Cancers

Compound 1 is a potent rexinoid that is highly effective in cancer chemoprevention but elevates serum triglycerides. In an effort to separate the lipid toxicity from the anticancer activity of 1, we synthesized four new analogs of rexinoid 1, of which three rexinoids did not elevate serum triglycerides. Rexinoids 3 and 4 are twice as potent as rexinoid 1 in binding to Retinoid X receptor (RXR). All-trans retinoic acid (ATRA) plays a key role in maintaining skin homeostasis, and rexinoids 3-6 are highly effective in upregulating the genes responsible for the biosynthesis of ATRA. Inflammation plays a key role in skin cancer, and rexinoids 3 and 4 are highly effective in diminishing LPS-induced inflammation. Rexinoids 3 and 4 are highly effective in preventing UVB-induced nonmelanoma skin cancer (NMSC) without displaying any overt toxicities. Biophysical studies of rexinoids 3 and 5 bound to hRXRα-ligand binding domain (LBD) reveal important conformational and dynamical differences in the ligand binding domain.

Advances in molecular pathogenesis of hidradenitis suppurativa: Dysregulated keratins and ECM signaling

Hidradenitis suppurativa (HS) is characterized by deep-seated, highly inflamed, and painful lumps/abscesses, fistulae, and sinus tracts that grow extensively deep in the dermis and are highly immunogenic in nature. In about one-third of the HS patients there is strong evidence for the role of γ-secretase mutations along with dysregulated Notch signaling. However, the contribution of dysregulated Notch signaling in HS pathogenesis in relation to hair follicle alterations and hyper-activation of the immune system remains undefined. A genome-wide association study (GWAS), proteomic data and functional investigations of identified sequence variants in HS pathology are not fully revealing. The disease initiation or progression may involve bacterial infection besides intrinsic functional defects in keratinocytes, which may be key to further exacerbate immune cell infiltration and cytokine production in and around the lesional tissue. The absence of a suitable animal model that could fully recapitulate the pathogenesis of HS is a major impediment for proper understanding the underlying mechanisms and development of effective treatments. The presence of extracellular matrix (ECM) degradation products along with dysregulation in keratinocytes and, dermal fibroblasts ultimately affect immune regulation and are various components of HS pathogenesis. Bacterial infection further exacerbates the complexity of the disease progression. While anti-TNFα therapy shows partial efficacy, treatment to cure HS is absent. Multiple clinical trials targeting various cytokines, complement C5a and ECM products are in progress. This review provides state-of-the-art information on these aspects with a focus on dysregulated keratinocyte and immune cells; and role of ECM, and Keratin functions in this regard.

Type I Interferons Enhance the Repair of Ultraviolet Radiation-Induced DNA Damage and Regulate Cutaneous Immune Suppression

Type I interferons (IFNs) are important enhancers of immune responses which are downregulated in human cancers, including skin cancer. Solar ultraviolet (UV) B radiation is a proven environmental carcinogen, and its exposure contributes to the high prevalence of skin cancer. The carcinogenic effects of UV light can be attributed to the formation of cyclobutane pyrimidine dimers (CPD) and errors in the repair and replication of DNA. Treatment with a single dose of UVB (100 mJ/cm2) upregulated IFNα and IFNβ in the skin of C57BL/6 mice. IFNα and IFNβ were predominantly produced by CD11b+ cells. In mice lacking the type I IFN receptor 1 (IFNAR1), the repair of CPD following cutaneous exposure to a single dose of UVB (100 mJ/cm2) was decreased. UVB induced the expression of the DNA repair gene xeroderma pigmentosum A (XPA) in wild-type (WT) mice. In contrast, such treatment in IFNAR1 (IFNAR1-/-) mice downregulated XPA. A local UVB regimen consisting of UVB radiation (150 mJ/cm2) for 4 days followed by sensitization with hapten 2,4, dinitrofluorobenzene (DNFB) resulted in significant suppression of immune responses in both WT and IFNAR1-/- mice. However, there were significantly higher CD4+CD25+Foxp3+ regulatory T-cells in the draining lymph nodes of IFNAR1-/- mice in comparison to WT mice. Overall, our studies reveal a previously unknown action of type I IFNs in the repair of photodamage and the prevention of UVB-induced immune suppression.

The Challenge of Melanoma Chemoprevention

Melanoma is a treatment-resistant cancer of melanocytes. There is a serious unmet need for chemopreventive agents that can inhibit their evolution from preexisting dysplastic nevi. Low-dose aspirin and NSAIDs are potential chemopreventive candidates because they inhibit the enzyme COX-2 which has a number of procarcinogenic effects. Unfortunately, the clinical trial reported by Okwundu and colleagues in this issue of Cancer Prevention Research did not show an effect of aspirin on biomarkers associated with progression of premalignant dysplastic nevi to melanomas. Further clinical trials with other aspirin or NSAID biomarkers or clinical trials with other potential chemopreventive agents offer hope to those who are at increased risk for melanomas.See related article, p. 129.

Toll-Like Receptor-4 Antagonist Enhances the Repair of Ultraviolet Radiation-Induced DNA Damage and Augments Anti-Tumor Immune Responses in Mice

Simple Summary

Ultraviolet B (UVB) radiation is largely responsible for the development of skin cancer. When UVB-induced DNA damage in cells is not repaired, it can lead to the initiation of non-melanoma skin cancers. Xeroderma pigmentosum (XP) disease is caused by a defect in the repair of damaged DNA. Toll-like receptor-4 (TLR4) and NLR family pyrin domain containing 3 (NLRP3) belong to the family of innate immune receptors and are highly expressed in skin tumors. In this study, we determined the mechanism through which TLR4 inhibitor TAK-242 regulates inflammation and prevents skin cancer.

Abstract

Ultraviolet (UV) irradiation of the skin is related to the development of skin cancer. UVB also causes DNA damage in the form of cyclobutane pyrimidine dimers (CPDs), which can result in stable mutations. Toll-like receptor 4 (TLR4), a component of innate immunity, plays a key role in cancer. Previous studies from our laboratory have observed that TLR4 deficiency resulted in the repair of UVB-induced DNA damage, inhibition of UVB-induced immune suppression, and carcinogenesis. In this study, we determined the efficacy of TLR4 antagonist TAK-242 in regulation of UVB-induced DNA damage, inflammation, and tumor development. Our results indicate that TAK-242 treatment increased the expression of xeroderma pigmentosum group A (XPA) mRNA, resulting in the repair of UVB-induced CPDs in skin of SKH-1 mice. Treatment with TAK-242 also inhibited the activation of NLR family pyrin domain containing 3 (NLRP3) in UVB-exposed skin of SKH-1 mice. Cutaneous carcinogenesis was significantly reduced in mice treated with TAK-242 in comparison to vehicle-treated mice. The proinflammatory cytokines IL-1β, IL-6, and TNF-α were also found to be significantly greater in vehicle-treated mice than TAK-242-treated mice. Finally, treatment with TAK-242 augmented anti-tumor immune responses in mice. Our data provide further evidence that activation of the TLR4 pathway promotes the development of UV-induced non-melanoma skin cancer mediated at least in part on its negative effects on DNA damage. Moreover, treatment with the TLR4 inhibitor TAK-242 may be effective for prevention of skin cancer.

IL-23 and the Tumor Microenvironment

The tumor microenvironment (TME), which assists in the development, progression, and metastasis of malignant cells, is instrumental in virtually every step of tumor development. While a healthy TME can protect against malignancy, in an unhealthy state, it can result in aberrant cellular behavior and augment tumor progression. Cytokines are one component of the TME, therefore, understanding the composition of the cytokine milieu in the tumor microenvironment is critical to understand the biology of malignant transformation. One cytokine, interleukin (IL)-23, has received particular scrutiny in cancer research because of its ability to manipulate host immune responses, its role in modulating the cells in TME, and its capacity to directly affect a variety of premalignant and malignant tumors. IL-23 belongs to the IL-12 cytokine family, which is produced by activated dendritic cells (DC) and macrophages. IL-23 acts by binding to its receptor consisting of two distinct subunits, IL-12Rβ1 and IL-23R. This, in turn, leads to janus kinase (JAK) activation and signal transducer and activator of transcription (STAT) 3/4 phosphorylation. There have been contradictory reports of pro- and antitumor effects of IL-23, which likely depend on the genetic background, the type of tumor, the causative agent, and the critical balance of STAT3 signaling in both the tumor itself and the TME. Clinical trials of IL-12/23 inhibitors that are used to treat patients with psoriasis, have been scrutinized for reports of malignancy, the most common being nonmelanoma skin cancers (NMSCs). Continued investigation into the relationship of IL-23 and its downstream pathways holds promise in identifying novel targets for the management of cancer and other diseases.

Toll-like receptor-4 deficiency inhibits ultraviolet radiation-induced tumor development by modulation of immune and inflammatory responses

Ultraviolet (UV) B irradiation of the skin induces acute inflammation, as characterized by erythema, edema, and immunosuppression, and is subsequently linked to the progression of skin cancer. Toll-like receptor 4 (TLR4), a component of innate immunity, has been shown to play an important role in cancer. To elucidate the role of TLR4 in UVB-induced tumor development, TLR4-proficient (C3H/HeN) and TLR4-deficient (C3H/HeJ) mice were exposed to multiple doses of UVB radiation (200 mJ/cm² ) for 40 weeks. Photocarcinogenesis was retarded in terms of tumor incidence, and tumor latency, in mice deficient in TLR4 compared with TLR4-proficient mice, whereas significantly greater numbers of tumors occurred in TLR4-proficient mice. There was significant upregulation of inflammatory markers like COX-2, PGE₂ , S100A8, and S100A9 in the skin of TLR4-proficient mice than the skin of TLR4-deficient mice. Furthermore, we found that TLR4-proficient mice had a significantly higher number of Gr1+CD11b+ myeloid cells CD4+CD25+ regulatory T-cells than TLR4-deficient mice. Furthermore, the levels of interferon (IFN)-γ cytokine was increased and the levels of interleukin (IL)-4, IL-10, and IL-17 cytokines were decreased in serum, skin, and tumor lysates of TLR4-deficient mice in comparison with samples from TLR4-proficient mice. Together, our data indicate that TLR4-mediated inflammation may cause suppression of antitumor responses and trigger the development of UVB-induced skin cancers. Thus, strategies to inhibit TLR4-mediated immune suppression may allow us to develop preventive and therapeutic approaches for the management of UVB-induced cutaneous tumors.

Regulatory T Cells Play an Important Role in the Prevention of Murine Melanocytic Nevi and Melanomas

Melanocytic nevi are benign proliferations of pigment cells that can occasionally develop into melanomas. There is a significant correlation between increased nevus numbers and melanoma development. Our previous reports revealed that 7,12-dimethylbenz(a)anthracene (DMBA) and 12-O-tetradecanoyl-phorbol-13-acetate (TPA) induced dysplastic nevi in C3H/HeN mice, with a potential to transform into melanomas. To understand the immune mechanisms behind this transformation, we applied increasing DMBA doses followed by TPA to the skin of C3H/HeN mice. We observed that increased doses of DMBA correlated well with increased numbers of nevi. The increased DMBA dose induced diminished immune responses and promoted the expansion of regulatory T cells (Treg) that resulted in increased IL10 and reduced IFNγ levels. Mice with increased nevus numbers had loss of p16 expression. These mice had increased migration of melanocytic cells to lymph nodes (LN) and a greater percent of LNs produced immortalized melanocytic cell lines. DMBA-induced immunosuppression was lost in CD4-knockout (KO) mice. Lymphocytes in the CD4KO mice produced less IL10 than CD8KO mice. Furthermore, CD4KO mice had significantly reduced nevus numbers and size compared with wild-type and CD8KO mice. These results suggest that Tregs play a vital role in the incidence of nevi and their progression to melanoma.Prevention Relevance: There has been little progress in developing novel strategies for preventing premalignant dysplastic nevi from becoming melanomas. In this study in mice, regulatory-T cells enhanced progression of benign nevi to malignant melanomas; and by inhibiting their activity, melanomas could be retarded. The findings identify new possibilities for melanoma prevention in high risk individuals.

Moving Immune Therapy Forward Targeting TME

The host immune system shapes the fate of tumor progression. Hence, manipulating patients' immune system to activate host immune responses against cancer pathogenesis is a promising strategy to develop effective therapeutic interventions for metastatic and drug-resistant cancers. Understanding the dynamic mechanisms within the tumor microenvironment (TME) that contribute to heterogeneity and metabolic plasticity is essential to enhance the patients' responsiveness to immune targeted therapies. Riera-Domingo et al. (Riera-Domingo C, Audige A, Granja S, Cheng WC, Ho PC, Baltazar F, Stockmann C, Mazzone, M. Physiol Rev 100: 1-102, 2020) describe the immune landscape within the TME and highlight the significance of metabolic and hypoxic signatures that impact immune function and response to immunotherapy strategies. Current literature in this field confirms that targeting tumor metabolism and the acidic microenvironment commonly associated with tumors may present viable strategies to modulate the host immune system in favor of response to immune targeted therapies. However, development of better tools to understand tumor-immune interactions and identify mechanisms driving nonresponders, more innovative clinical trial design, and new therapies will need to be identified to move the field forward. Personalized immune therapies incorporating metabolic and microbiome-based gene signatures to influence the therapeutic response and novel methods to generate immunologically "hot" tumors are at the forefront of immunotherapy currently. The combination of these approaches with clinically approved immunotherapies will be valuable moving forward.

Joint AAD-NPF Guidelines of care for the management and treatment of psoriasis with topical therapy and alternative medicine modalities for psoriasis severity measures

Psoriasis is a chronic, inflammatory, multisystem disease that affects up to 3.2% of the United States population. This guideline addresses important clinical questions that arise in psoriasis management and care and provides recommendations based on the available evidence. The treatment of psoriasis with topical agents and with alternative medicine will be reviewed, emphasizing treatment recommendations and the role of dermatologists in monitoring and educating patients regarding benefits as well as risks that may be associated. This guideline will also address the severity assessment methods of psoriasis in adults.

Photocarcinogenesis

Purpose of Review

Skin cancers account for more than 40% of all cancers in the USA and continue to rise in incidence. It is prudent to understand the current burden and pathogenesis of photocarcinogenesis and preventive measures.

Recent Findings

Insights into recently discovered mechanisms have paved way for potential targets for prevention and therapeutics. Nicotinamide has shown promising results as an oral chemopreventive agent. UVB affects the DHODH pathway of pyrimidine synthesis via STAT 3. DHODH inhibition by leflunomide may be a potential targeted chemoprevention strategy. A photolyase containing sunscreen, which repairs UV-damaged DNA, effectively reduced new precancerous lesions. Several antioxidants and anti-inflammatory agents including many phytochemicals ameliorate the process of photocarcinogenesis in preclinical and clinical studies, e.g., green tea polyphenols, Polypodium leucotomos extract, and Timosaponin A III. Diet can potentially affect skin cancer risk by its ability to modify oxidative stress and cell signaling pathways.

Summary

Photocarcinogenesis is a multi-step process. An in-depth understanding is instrumental in development of novel agents for prevention and treatment of skin cancers.

Murine Skin Carcinogenesis and the Role of Immune System Dysregulation in the Tumorigenicity of 2-Ethylhexyl Acrylate

Some chemicals act as human carcinogens in various organ systems including the skin. Mice have been an ideal model to study a wide variety of chemical carcinogens because the pathogenesis in that species often mirrors that in humans. However, different mouse strains vary in their susceptibility to these agents. Thus, reliance on a single strain may lead to inaccurate findings. 2-Ethylhexyl acrylate (2-EHA) is an acrylate used as a co-monomer in the production of polymer resins for adhesives, latex paints, cross-linking agents, finishes for textiles and leather, and paper coatings. Monomer exposure may occur in occupational settings where it is produced or used; the only exposure that may occur to consumers or construction personnel is trace amounts in the final polymer product. There are no reports of cancer in humans caused by exposure to 2-EHA. However, 2-EHA has been reported to cause cancer in one strain of mice. This is an important issue since recommendations about its safety in humans depend, in part, on information derived from animal studies. We reviewed the literature on the preclinical effects of acrylates on skin carcinogenesis in C3H/HeJ mice, which can be criticized because of peculiarities in the immunological composition of that strain, the lack of rigorous histopathologic characterization of tumors that developed, the high doses of 2-EHA that were used for evaluation, and the lack of reproducibility in a second strain of mice. The C3H/HeJ mouse model is not ideal as it has a mutation in Toll-like receptor 4 (TLR4) that impairs its innate and adaptive immune responses. Inconsistencies in the histological evaluation of tumors induced in C3H/HeJ mice provide further evidence that the tumorigenic effect of 2-EHA was strain specific, a result of chronic inflammation during the promotion stage and/or a skewed immune response caused by the TLR4 mutation. In conclusion, 2-EHA has not convincingly been demonstrated to have skin carcinogenic activity to date. More relevant mouse models that mimic human squamous cell carcinoma, basal cell carcinoma, and melanoma with amounts that do not exceed a maximum tolerated dose are needed to assess the carcinogenic effects of 2-EHA.

Joint American Academy of Dermatology-National Psoriasis Foundation guidelines of care for the management of psoriasis with systemic nonbiologic therapies

Psoriasis is a chronic inflammatory disease involving multiple organ systems and affecting approximately 2% of the world's population. In this guideline, we focus the discussion on systemic, nonbiologic medications for the treatment of this disease. We provide detailed discussion of efficacy and safety for the most commonly used medications, including methotrexate, cyclosporine, and acitretin, and provide recommendations to assist prescribers in initiating and managing patients on these treatments. Additionally, we discuss newer therapies, including tofacitinib and apremilast, and briefly touch on a number of other medications, including fumaric acid esters (used outside the United States) and therapies that are no longer widely used for the treatment of psoriasis (ie, hydroxyurea, leflunomide, mycophenolate mofetil, thioguanine, and tacrolimus).

The clinical course of actinic keratosis correlates with underlying molecular mechanisms

BACKGROUND

Actinic keratoses (AKs) are common premalignant skin lesions triggered by excessive ultraviolet exposure. The majority of AKs regress or persist, but some progress to squamous cell carcinomas. Biomarkers associated with their persistence, progression and regression have not been characterized.

OBJECTIVES

We performed skin biopsies in patients with extensive actinic damage to identify biomarkers that correlate with clinical progression and regression of AKs.

METHODS

This was an observational study of a cohort of patients with extensive actinic damage. AKs were mapped on a clear plastic template in 26 patients at months 3, 6, 9 and 11. Biopsies were taken from randomly selected, predetermined AKs and were evaluated for p53, E-cadherin, Snail, Slug and Twist. The study is registered at Clinicaltrials.gov: NCT00027976.

RESULTS

p53 exhibited greater expression in clinically apparent AKs (histological score 2·89 ± 1·45) than in regressed AKs (0·75 ± 0·96); P < 0·01. There was also significantly less membrane E-cadherin, the lack of which is a marker of epithelial-mesenchymal transition, in clinically apparent AKs (1·89 ± 1·81) than in sun-exposed skin (3·07 ± 1·75); P < 0·005. The E-cadherin transcription repressors Snail, Slug and Twist were increased in AKs compared with sun-exposed skin. A limitation of the study is that measurement of histological biomarkers was not a primary end point. In addition, patients were allowed to apply sunscreens.

CONCLUSIONS

At the molecular level, loss of E-cadherin and an increase in p53 are linked to the dynamic interplay between the persistence, progression and regression of AKs. What's already known about this topic? Actinic keratoses (AKs) are common dysplastic epidermal lesions that result from chronic and excessive ultraviolet exposure. Biomarkers associated with progression and regression of AK have not been characterized. What does this study add? Decreased E-cadherin and increased p53, Snail, Slug and Twist (E-cadherin transcription factors) were associated with progression from AK to nonmelanoma skin cancer. What is the translational message? Strategies targeting these molecules may be effective in reversing rising skin cancer rates. E-cadherin, p53, Snail, Slug and Twist are potential biomarkers that may be used to assess the efficacy of existing chemopreventive agents.

CD5 on dendritic cells regulates CD4+ and CD8+ T cell activation and induction of immune responses

The role of CD5 as a regulator of T cell signaling and tolerance is well recognized. Recent data show expression of CD5 on different subtypes of human dendritic cells, however its functional relevance in modulating DC mediated responses remains poorly understood. In this study, we show CD5 is expressed on CD11c+ DC from murine thymus, lymph node, spleen, skin and lung. Although the development of DC subpopulations in CD5-/- mice was normal, CD5-deficient DC produced significantly higher levels of IL-12 than wild type DC in response to LPS. CD5-/- DC, in comparison to CD5+/+ DC, enhanced the activation of CD4+ and CD8+ T cells in vitro and in vivo and induced significantly higher production of IL-2 and IFN-gamma by T cells. Consequently, CD5-/- DC were significantly more potent than wild type DC in the induction of anti-tumor immunity and contact hypersensitivity responses in mice. Restoration of CD5 expression in CD5-/- DC reduced IL-12 production and inhibited their capacity to stimulate T cells. Collectively, these data demonstrate that the specific expression of CD5 on DC inhibits the production of inflammatory cytokines and has a regulatory effect on their activity to stimulate T cells and induce immune responses. This study reveals a previously unrecognized regulatory role for CD5 on DC and provides novel insights into mechanisms for DC biology in immune responses.

Joint American Academy of Dermatology-National Psoriasis Foundation guidelines of care for the management and treatment of psoriasis with phototherapy

Psoriasis is a chronic inflammatory disease involving multiple organ systems and affecting approximately 3.2% of the world's population. In this section of the guidelines of care for psoriasis, we will focus the discussion on ultraviolet (UV) light-based therapies, which include narrowband and broadband UVB, UVA in conjunction with photosensitizing agents, targeted UVB treatments such as with an excimer laser, and several other modalities and variations of these core phototherapies, including newer applications of pulsed dye lasers, intense pulse light, and light-emitting electrodes. We will provide an in-depth, evidence-based discussion of efficacy and safety for each treatment modality and provide recommendations and guidance for the use of these therapies alone or in conjunction with other topical and/or systemic psoriasis treatments.

Abstract LB-247: 9cis-retinoic UAB30 inhibits UVB-induced pro-inflammatory cytokines/chemokines signaling via targeting Bromodomain-4

BET bromodomain-containing protein 4 (BRD4), an epigenome reader works as an oncogene for several cancer types including those that develop in the skin. BRD4 inhibitors have been shown to have antitumor efficacy in multiple cancer models. Additional studies demonstrate the involvement of BRD4 in onsetting inflammation which is a key component of the pathogenesis of cancers including in the development of tumor growth conducive microenvironment. Here we show that a recently developed non-hyperlipidemic retinoid X receptors (RXR) agonist 9cUAB30 besides its anticancer properties also reduces UVB-induced inflammation in a murine model. The molecular mechanism underlying anti-inflammatory effect of 9cUAB30 is complex that involves epigenetic modulation of histones. Orally administered 9cUAB30 reduces BRD4 expression and its downstream signaling. 9cUAB30 mediated inhibition of BRD4 is also evidenced by the downregulation of acetylated histones such as H3K27ac, H3K18ac, H3K9ac, H4K8ac and H4K5ac. This is further confirmed by RNAseq data that show UVB-mediated alterations in multiple BRD4 target genes are attenuated by 9cUAB30 treatment. Furthermore, the BRD4 regulated cytokines such as IL6, IL12a, IL19, IL23, IL27, and IL33 which are induced by UVB, are attenuated by 9cUAB30 treatment. However, UVB induced additional multiple cytokines/chemokines. 9cUAB30 treatment was also successful in diminishing their levels significantly. These data support the notion that 9cUAB30 acts by targeting additional inflammation regulating pathways besides those regulated by BRD4 dependent epigenetic modulation. These initial effects in the tumor adjacent skin could be seen even in the SCCs and BCCs which progress from these early benign lesions suggesting that BRD4 mediated signaling is important during the entire pathogenesis of highly malignant cutaneous lesions. This is further confirmed by in vitroinvestigation employing Squamous cell carcinoma A431 and SCC13 cells in culture. Further evidence that 9cUAB30 acts via dampening BRD4 regulated pathways comes from genetic studies employing the knockdown and forced expression approaches. Our data also demonstrate that 9cUAB30 dependent majority of anti-inflammation and EMT blocking effects are mediated by targeting BRD4- NFkB /BRD4-Twist axis. In summary 9cUAB30 elaborates anti-inflammatory effects by targeting BRD4 regulated chromatin remodeling.

Citation Format: Mohammad Waseem, Mahendra P. Kashyap, Changzhao Li, Sandeep C. Chaudhary, Darshan S. Chandrashekar, Venkatram R. Atigadda, Sooryanarayana Varambally, Craig A. Elmets, Mohammad Athar. 9cis-retinoic UAB30 inhibits UVB-induced pro-inflammatory cytokines/chemokines signaling via targeting Bromodomain-4 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr LB-247.

Abstract LB-245: 9cis-retinoid UAB30 by inhibiting aberrant fatty acid metabolism protects against UVB-induced skin inflammation and carcinogenesis

Tumor cells are characterized by aberrant energy metabolism such as an accelerated glycolytic flux and enhanced de novo fatty acid (FA) synthesis which underlie the pathogenesis of aggressive cancer growth. Increased FA synthesis that commensurates with high metabolic demand of cancer cells could be targeted for the prevention or therapeutic intervention of cancer pathogenesis. Retinoids, are well known to inhibit cell proliferation and induce cellular differentiation/apoptosis in various tumor cell types. However, their use is often limited due to severe adverse effects including hyperlipidemia. We have developed 9cUAB30, a selective retinoid X receptors (RXR) agonist with potential anti-carcinogenic effects. Interestingly, it does not manifest hyperlipidemia both in experimental animals and in humans. Here, we demonstrate that chronic administration of 9cUAB30 to Ptch+/-/SKH1 mice diminishes expression of enzymes involved in de novo fatty acid synthesis as well as in UVB-induced inflammatory response. The metabolic analysis of tumor adjacent skin revealed that 9cUAB30 decreases levels of cutaneous saturated fatty acids as well as medium and long chain acetyl carnitines. Additionally, 9cUAB30 inhibits de novo lipid synthesis by inhibiting transcription factor, sterol regulatory element-binding protein 1 (SREBP-1). UVB-induced cutaneous inflammatory response was characterized by an increase in skin bi-fold thickness and edema as well as by augmented levels of pro-inflammatory cytokines/chemokines. 9cUAB30 administered soon after UVB irradiation, significantly diminished these inflammatory responses. Our data confirm that 9cUAB30 decreased the SREBP1-mediated transcription regulation of inflammasome components and its downstream pro-inflammatory cytokines/chemokines such as IL-1β and IL18. 9cUAB30 mediated alterations of UVB-induced pro-inflammatory signaling were identical to those mediated by fatostatin, a potent inhibitor of SREBP1 activation and these data further confirm the role of SREBP1 in UVB-induced inflammation. The molecular mechanism associated with anti-inflammatory response of 9cUAB30 was confirmed in skin tumor cells which are known to secrete pro-inflammatory cytokines to develop a tumor growth condusive micro-environment. Treatment of human squamous cell carcinoma A431 and SCC13 cells with 9cUAB30 (10, 20 and 30 μM) resulted in the downregulation of multiple proteins involved in de novo FA synthesis. The expression of Acetyl-CoA carboxylase 1 (ACC1), ATP citrate lyase (ACLY) and fatty acid synthase (FASN) was significantly reduced in these SCC cells, but not in normal keratinocyte (KerCT). 9cUAB30 reduced the expression of Sirt1 and Sirt2, deacetylases required for the activation of acetyl-CoA synthetase (AceCS1) and Acetyl-CoA production. The expression of CPT1B and CPT2, but not CPT1A (a critical enzyme required for FA β-oxidation) were also decreased. Additionally, 9cUAB30 was instrumental in decreasing the levels of ACADL, ACADM, HADHA and Sirtulin-3. These changes in FA driven energy metabolism underlie the reduced pathogenesis of xenograft tumors in nude mice. In summary, these data demonstrate a novel mechanism by which 9cUAB30 targets lipid metabolism-driven pro-inflammatory and pro-cancer signaling pathways to block the pathogenesis of skin cancer.

Citation Format: Mahendra P. Kashyap, Mohammad Waseem, Changzhao Li, Mohd Shameel Iqbal, Venkatram R. Atigadda, Craig A. Elmets, Mohammad Athar. 9cis-retinoid UAB30 by inhibiting aberrant fatty acid metabolism protects against UVB-induced skin inflammation and carcinogenesis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr LB-245.

Joint AAD-NPF guidelines of care for the management and treatment of psoriasis with biologics

Psoriasis is a chronic, inflammatory multisystem disease that affects up to 3.2% of the US population. This guideline addresses important clinical questions that arise in psoriasis management and care, providing recommendations based on the available evidence. The treatment of psoriasis with biologic agents will be reviewed, emphasizing treatment recommendations and the role of the dermatologist in monitoring and educating patients regarding benefits as well as associated risks.

Joint AAD-NPF guidelines of care for the management and treatment of psoriasis with awareness and attention to comorbidities

Psoriasis is a chronic, inflammatory, multisystem disease that affects up to 3.2% of the US population. This guideline addresses important clinical questions that arise in psoriasis management and care, providing recommendations on the basis of available evidence.

Ultraviolet radiation, both UVA and UVB, influences the composition of the skin microbiome

BACKGROUND

Studies have begun to investigate the complex relationship between host and microorganisms in non-infectious pathologies such as acne, atopic dermatitis and psoriasis. Though the skin is exposed to environmental stressors such as ultraviolet radiation (UVR), no studies exist examining the effects of both UVA and UVB on the skin microbiome.

OBJECTIVE

To test the effect of UVA and UVB on human skin microbiome.

METHODS

To test whether UV will alter the cutaneous microbiome, participants were exposed to doses of UVA (22-47 J/cm² ) or UVB (100-350 mJ/cm² ) and samples were collected. DNA was isolated and sequenced to identify the microbial composition of each sample.

RESULTS

There was vast intra- and inter-subject variation at all time points, and phylum and species-level differences were identified. These included an increase in the phylum Cyanobacteria and a decrease in the family Lactobacillaceae and Pseudomonadaceae. The sensitivity of microbes to UVR and their re-colonization potential following exposure differed in UVA vs UVB samples.

LIMITATIONS

The sample size was small, and the study was limited to males.

CONCLUSION

The results demonstrate that UVR has profound qualitative and quantitative influences on the composition of the skin microbiome, possibly effecting skin pathology in which UVR is a factor.

Abstract LB-170: 9cis-retinoid UAB30 manifests potent chemopreventive effects in a murine model of UVB-induced basal cell and squamous cell carcinoma

Vitamin A derivatives such as retinoids are known to inhibit cell proliferation and induce cellular differentiation/apoptosis in various tumor cells. Although many retinoids have been limited due to their severe adverse effects, but 9cUAB30, a highly selective novel retinoid X receptors (RXR)-agonist has been shown an effective anti-carcinogenic activity. Here, we demonstrated the chemopreventive and chemotherapeutic efficacy of 9cUAB30 in UVB-induced photocarcinogenesis in Ptch+/-/SKH-1 murine model, which develops both basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). Both topical and systemic application to 9cUAB30 significantly reduced UVB-induced skin photocarcinogenesis in terms of tumor number and tumor volume. 9cUAB30 reduced UVB-induced skin hyperplasia, proliferation, and enhanced differentiation of suprabasal epidermal keratinocytes. Induction of apoptosis was also noted in these neoplastic lesions treated with this retinoid. 9cUAB30 was almost equally potent in the inhibition of either UVB-induced skin BCCs or SCCs in Ptch+/-/SKH-1 mice. 9cUAB30-treated residual tumors were manifesting reduced epithelial-mesenchymal transition (EMT) progression with a less aggressive tumor phenotype, which was associated with the enhanced expression of E-cadherin and reduced expression of N-cadherin, Fibronectin, Snail and Twist. 9cUAB30-mediated therapeutic intervention against these tumors was also involved induction of extensive DNA double strand breaks (DSBs) characterized by the enhanced phosphorylation of H2AX. This DNA damage response was unique to 9cUAB30 compare to other known RXR inhibitors such as Bexarotene. It was also independent of reactive oxygen species (ROS) production as ROS scavenger namely, N-acetyl cysteine did not effectively block it. However, 9cUAB30 provoked DNA damage response signaling was associated with the enhanced phosphorylation and activation of ATM, Rad50, ATR, Chk1, and Chk2. In summary, these data demonstrate that 9cUAB30 is a novel cancer chemopreventive agent for UVB-induced skin neoplasm and acts by invoking extensive DDSBs similar to those caused by chemotherapeutic drug like cisplatin.

Citation Format: Sandeep C. Chaudhary, Mahendra P. Kashyap, Gloria Nguyen, Craig A. Elmets, Mohammad Athar. 9cis-retinoid UAB30 manifests potent chemopreventive effects in a murine model of UVB-induced basal cell and squamous cell carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr LB-170.

Tea polyphenols for the prevention of UVB-induced skin cancer

Skin cancer is the most common type of cancer with increasing incidence rate and public health burden. Solar ultraviolet (UV) radiation causes an array of damaging cellular and molecular events that eventually lead to the development of skin cancer. Despite increased awareness about sun protection, the exposure rate remains high with less than 15% of men and 30% of women using sunscreen on a regular basis. Therefore, there is an imperative need for the development of novel preventive approaches. Skin cancer chemoprevention using phytochemicals either as dietary supplements or by topical applications has gained considerable attention due to their low toxicity, availability, and anticarcinogenic properties. Tea, the second most commonly consumed beverage in the world, is a rich source of promising phytochemicals known as polyphenols. In this review, we discuss the findings of various in vitro, in vivo and human studies signifying the chemopreventive effects of tea polyphenols against UVB-induced skin cancer. This is accomplished by exploring the role of tea polyphenols in DNA repair, inflammation, oxidative stress, signaling pathways, and epigenetics. Finally, this review discusses a variety of innovative delivery methods that enhance the photochemopreventive effects of tea polyphenols against skin cancer.

Association of Vitamin D Receptor Polymorphisms With the Risk of Nonmelanoma Skin Cancer in Adults

Importance

Protective effects of UV-B radiation against nonmelanoma skin cancer (NMSC) are exerted via signaling mechanisms involving the vitamin D receptor (VDR). Recent studies have examined single-nucleotide polymorphisms (SNPs) in the VDR, resulting in contradictory findings as to whether these polymorphisms increase a person's risk for NMSC.

Objective

To examine whether the polymorphisms in the VDR gene are associated with the development of NMSC and the demographic characteristics of the participants.

Design, Setting, and Participants

This case-control study recruited 100 individuals who received a diagnosis of and were being treated for basal cell carcinoma or squamous cell carcinoma (cases) and 100 individuals who were receiving treatment of a condition other than skin cancer (controls) at the dermatology clinics at the Kirklin Clinic of the University of Alabama at Birmingham Hospital between January 1, 2012, and December 31, 2014. All participants completed a questionnaire that solicited information on skin, hair, and eye color; skin cancer family history; and sun exposure history, such as tanning ability and number of severe sunburns experienced throughout life. Blood samples for DNA genotyping were collected from all participants.

Main Outcomes and Measures

Polymorphisms in the VDR gene (ApaI, BsmI, and TaqI) were assessed to determine the association of polymorphisms with NMSC development and demographic characteristics. χ2 Analysis was used to determine whether genotype frequencies deviated significantly from Hardy-Weinberg equilibrium. Logistic regression was used to calculate odds ratios (ORs) and associated 95% CIs for the identification of factors associated with NMSC diagnosis. A model was created to predict NMSC diagnoses using known risk factors and, potentially, VDR SNPs.

Results

A total of 97 cases and 100 controls were included. Of the 97 cases, 68 (70%) were men and 29 (30%) were women, with a mean (SD) age of 70 (11) years. Of the 100 controls, 46 (46%) were men and 54 (54%) were women, with a mean (SD) age of 63 (9) years. All participants self-identified as non-Hispanic white. A model including age, sex, and skin color was created to most effectively predict the incidence of skin cancer. Risk factors that significantly increased the odds of an NMSC diagnosis were light skin color (OR, 5.79 [95% CI, 2.79-11.99]), greater number of severe sunburns (OR, 2.59 [95% CI, 1.31-5.10]), light eye color (OR, 2.47 [95% CI, 1.30-4.67]), and less of an ability to tan (OR, 2.35 [95% CI, 1.23-4.48]). The risk factors of family history of NMSC (OR, 1.66 [95% CI, 0.90-3.07]) and light hair color (OR, 1.17 [95% CI, 0.51-2.71]) did not reach statistical significance. Participants with the BsmI SNP were twice as likely to develop NMSC than participants with no mutation (OR, 2.04 [95% CI, 1.02-4.08]; P = .045).

Conclusions and Relevance

The results of this study are especially useful in the early treatment and prevention of NMSC with chemopreventive agents (for those with the BsmI SNP). A screening for the BsmI SNP may emphasize the importance of sun protection and facilitate skin cancer prevention and, therefore, decrease the skin cancer burden.

Basal cell carcinoma pathogenesis and therapy involving hedgehog signaling and beyond

Basal cell carcinoma (BCC) of the skin is driven by aberrant hedgehog signaling. Thus blocking this signaling pathway by small molecules such as vismodegib inhibits tumor growth. Primary cilium in the epidermal cells plays an integral role in the processing of hedgehog signaling-related proteins. Recent genomic studies point to the involvement of additional genetic mutations that might be associated with the development of BCCs, suggesting significance of other signaling pathways, such as WNT, NOTCH, mTOR, and Hippo, aside from hedgehog in the pathogenesis of this human neoplasm. Some of these pathways could be regulated by noncoding microRNA. Altered microRNA expression profile is recognized with the progression of these lesions. Stopping treatment with Smoothened (SMO) inhibitors often leads to tumor reoccurrence in the patients with basal cell nevus syndrome, who develop 10-100 of BCCs. In addition, the initial effectiveness of these SMO inhibitors is impaired due to the onset of mutations in the drug-binding domain of SMO. These data point to a need to develop strategies to overcome tumor recurrence and resistance and to enhance efficacy by developing novel single agent-based or multiple agents-based combinatorial approaches. Immunotherapy and photodynamic therapy could be additional successful approaches particularly if developed in combination with chemotherapy for inoperable and metastatic BCCs.

Loss of INK4a/Arf gene enhances ultraviolet radiation-induced cutaneous tumor development

The CDKN2A locus encodes for tumor suppressor genes p16^INK4a and p14^Arf which are frequently inactivated in human skin tumors. The purpose of this study was to determine the relationship between loss of INK4a/Arf activity and inflammation in the development of ultraviolet (UV) radiation-induced skin tumors. Panels of INK4a/Arf^-/- mice and wild-type (WT) mice were treated with a single dose of UVB (200 mJ/cm² ). For long-term studies, these mice were irradiated with UVB (200 mJ/cm² ) three times weekly for 30 weeks. At the end of the experiment, tissues were harvested from mice and assayed for inflammatory biomarkers and cytokines. A single dose of UVB resulted in a significant increase in reactive oxygen species (ROS) and 8-dihydroxyguanosine (8-oxo-dG) lesions in INK4a/Arf^-/- mice compared to WT mice. When subjected to chronic UVB, we found that 100% of INK4a/Arf^-/- mice had tumors, whereas there were no tumors in WT controls after 24 weeks of UVB exposure. The increase in tumor development correlated with a significant increase in nuclear factor (NF)-κB, cyclooxygenase-2 (COX-2), prostaglandin E₂ (PGE₂ ) and its receptors both in UVB-exposed skin and in the tumors. A significant increase was seen in inflammatory cytokines in skin samples of INK4a/Arf^-/- mice following treatment with chronic UVB radiation. Furthermore, significantly more CD11b⁺ Gr1⁺ myeloid cells were present in UVB-exposed INK4a/Arf^-/- mice compared to WT mice. Our data indicate that by targeting UVB-induced inflammation, it may be possible to prevent UVB-induced skin tumors in individuals that carry CDKN2A mutation.

Abstract LB-170: A novel, nontoxic RXR agonist, UAB30, targets Fanconi anemia DNA repair pathway to act as potent cancer chemopreventive agent

UAB30, a synthetic analog of 9-cis-RA is a potent retinoid X receptors (RXR) agonist. It was found to have significantly low retinoic acid receptor (RAR)-binding activity. This unique property of UAB30 is responsible for its low lipid toxicity. Thus, it does not cause elevation in serum triglycerides both in humans and in experimental animals. These properties with favorable pharmacokinetics make it a suitable candidate for chronic use as chemopreventive agent. Here, we show that UAB30 is highly effective in inhibiting UVB-induced pathogenesis of skin cancers in Ptch1+/-/SKH-1 hairless mice. Similar to humans, this unique genetically engineered murine model develops both basal cell carcinomas (BCCs) and squamous cell carcinomas (SCCs) of the skin following chronic UVB irradiation. Compared to controls, the UAB30-treated group showed a 48% reduction in tumor number and a 78% reduction in tumor volume. The number of papillomas, BCCs, and SCCs were reduced by 33%, 74%, and 76%, respectively. UAB30 also diminished UVB-induced skin inflammation, hyperplasia, and enhanced differentiation of suprabasal epidermal cells. The expression of cyclins A, D1, D2, and D3, and cdc25A were decreased in UAB30 treated SCCs, while pro-apoptotic proteins, Bax and cleaved caspase 3 were increased. UAB30 when topically applied 30 min after each UVB irradiation for 30 weeks, it showed significant reduction in cancer development. A 57% reduction in tumor number and 72% reduction in tumor volume were observed. BCCs and SCCs were reduced by 55% and 60%, respectively. We also demonstrate that UAB30 acts by a unique molecular mechanism. Induction of lethal DNA double strand breaks (DSBs) characterized by the presence of p-γH2AX was observed following UAB30 treatment. These effects were more prominent in cancer cells than normal keratinocytes. Induction of DSBs was associated with the activation of DNA damage response (DDR) signaling leading to increased phosphorylation of ATM, Rad50, and Chk2. These effects paralleled with the reduction in cell cycle proteins and cell cycle arrest in G2/M phase followed by apoptosis of arrested cells. UAB30-induced DSBs and DDR were not dependent on ROS as we did not observe significant induction of ROS in UAB30-treated cells and did not notice any protective effect of N-acetyl cysteine. These effects were similar to DDR and changes in proliferation/apoptosis response observed following treatment with cisplatin which is known inducer of DSBs. Moreover, other RXR agonists were significantly less potent in inducing DSBs and DDR responses. The underlying mechanism for the accumulation of DSBs was the diminished ability of cancer cells to repair these DNA lesions. Reduction in FANCD2 and FANCC, the Fanconi anemia core complex proteins which are known to be involved in DSBs repair appear to be the cause of extensive DNA damage associated tumor cell death.

Citation Format: Sandeep C. Chaudhary, Craig A. Elmets, Mohammad Athar. A novel, nontoxic RXR agonist, UAB30, targets Fanconi anemia DNA repair pathway to act as potent cancer chemopreventive agent [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr LB-170. doi:10.1158/1538-7445.AM2017-LB-170

Naproxen Inhibits UVB-induced Basal Cell and Squamous Cell Carcinoma Development in Ptch1+/- /SKH-1 Hairless Mice

Naproxen possesses anti-proliferative and pro-apoptotic effects besides its known anti-inflammatory functions. Here, we demonstrate the anticancer effects of naproxen against UVB-induced basal cell carcinoma (BCCs) and squamous cell carcinoma (SCCs) in a highly susceptible murine model of UVB carcinogenesis. Naproxen significantly inhibited UVB-induced BCCs and SCCs in this model. Tumor number and volume were significantly decreased (P < 0.005 and P < 0.05, respectively). Inhibition in UVB-induced SCCs and BCCs was 77% and 86%, respectively, which was associated with reduced PCNA and cyclin D1 and increased apoptosis. As expected, inflammation-related iNOS, COX-2 and nuclear NFκBp65 were also diminished by naproxen treatment. Residual tumors excised from naproxen-treated animal were less invasive and showed reduced expression of epithelial-mesenchymal transition (EMT) markers N-cadherin, Vimentin, Snail and Twist with increased expression of E-cadherin. In BCC and SCC cells, naproxen-induced apoptosis and activated unfolded protein response (UPR) signaling with increased expression of ATF4, p-eIF2α and CHOP. Employing iRNA-based approaches, we found that naproxen-induced apoptosis was regulated by CHOP as sensitivity of these cutaneous neoplastic cells for apoptosis was significantly diminished by ablating CHOP. In summary, these data show that naproxen is a potent inhibitor of UVB-induced skin carcinogenesis. ER stress pathway protein CHOP may play an important role in inducing apoptosis in cancer cells.

The impact of oral Polypodium leucotomos extract on ultraviolet B response: A human clinical study

BACKGROUND

There is a rationale for adding systemic photoprotective agents to the current photoprotection regimen.

OBJECTIVE

This study was designed to objectively evaluate the molecular and photobiologic effects of oral administration of Polypodium leucotomos extract (PLE).

METHODS

In all, 22 subjects with Fitzpatrick skin phototype I to III were enrolled. On day 1, subjects were irradiated with visible light, ultraviolet (UV) A1, and UVB (using 308-nm excimer laser). Evaluation was done immediately and 24 hours after irradiation. On days 3 and 4, irradiation and evaluation process was repeated after ingestion of PLE.

RESULTS

Clinical assessments and colorimetry data showed a decrease in UVB-induced changes in 17 of 22 subjects post-PLE administration; histology findings demonstrated such a decrease in all 22 subjects.

LIMITATIONS

Only 2 doses of PLE were given. Furthermore, subjects with skin phototypes I to III only were studied.

CONCLUSION

The results suggest that PLE can potentially be used as an adjunctive agent to lessen the negative photobiologic effects of UVB.

Shh and p50/Bcl3 signaling crosstalk drives pathogenesis of BCCs in Gorlin syndrome

Nevoid basal cell carcinoma syndrome (NBCCS) is a rare autosomal dominant disorder that is due, in large measure, to aberrant Shh signaling driven by mutations in the tumor suppressor gene Ptch1. Here, we describe the development of Ptch1^+/−/SKH-1 mice as a novel model of this disease. These animals manifest many features of NBCCS, including developmental anomalies and are remarkably sensitive to both ultraviolet (UVB) and ionizing radiation that drive the development of multiple BCCs. Just as in patients with NBCCS, Ptch1^+/−/SKH-1 also spontaneously develops BCCs and other neoplasms such as rhabdomyomas/rhabdomyosarcomas. Administration of smoothened inhibitors (vismodegib/itraconazole/cyclopamine) or non-steroidal anti-inflammatory drug (sulindac/sulfasalazine) each result in partial resolution of BCCs in these animals. However, combined administration of these agents inhibits the growth of UVB-induced BCCs by >90%. Employing small molecule- and decoy-peptide-based approaches we further affirm that complete remission of BCCs could only be achieved by combined inhibition of p50-NFκB/Bcl3 and Shh signaling. We posit that Ptch1^+/−/SKH-1 mice are a novel and relevant animal model for NBCCS. Understanding mechanisms that govern genetic predisposition to BCCs should facilitate our ability to identify and treat NBCCS gene carriers, including those at risk for sporadic BCCs while accelerating development of novel therapeutic modalities for these patients.

IL-23 Inhibits Melanoma Development by Augmenting DNA Repair and Modulating T Cell Subpopulations

In animal models, IL-12 and IL-23 participate in the development of malignant neoplasms of keratinocytes. However, the role of these cytokines in pigmented lesion development and their progression to melanoma has received little attention. IL-12p35, IL-23p19, and IL-12/IL-23p40 knockout mice on a C3H/HeN background, subjected to a melanomagenesis protocol, demonstrated profound differences in susceptibility to nevus initiation, transformation, tumorigenicity, and metastatic potential. IL-23 was found to be essential for melanocyte homeostasis, whereas IL-12 supported nevus development. A direct action of IL-23 on primary melanocytes, shown to be IL-23R⁺, demonstrated that DNA repair of damaged melanocytes requires IL-23. Furthermore, IL-23 modulated the cutaneous microenvironment by limiting regulatory T cells and IFN-γ and inhibiting IL-10 production. Neutralizing Ab to IFN-γ, but not IL-17, inhibited nevus development (p < 0.01).

Activating transcription factor 4 underlies the pathogenesis of arsenic trioxide-mediated impairment of macrophage innate immune functions

Chronic arsenic exposure to humans is considered immunosuppressive with augmented susceptibility to several infectious diseases. The exact molecular mechanisms, however, remain unknown. Earlier, we showed the involvement of unfolded protein response (UPR) signaling in arsenic-mediated impairment of macrophage functions. Here, we show that activating transcription factor 4 (ATF4), a UPR transcription factor, regulates arsenic trioxide (ATO)-mediated dysregulation of macrophage functions. In ATO-treated ATF4(+/+) wild-type mice, a significant down-regulation of CD11b expression was associated with the reduced phagocytic functions of peritoneal and lung macrophages. This severe immuno-toxicity phenotype was not observed in ATO-treated ATF4(+/-) heterozygous mice. To confirm these observations, we demonstrated in Raw 264.7 cells that ATF4 knock-down rescues ATO-mediated impairment of macrophage functions including cytokine production, bacterial engulfment and clearance of engulfed bacteria. Sustained activation of ATF4 by ATO in macrophages induces apoptosis, while diminution of ATF4 expression protects against ATO-induced apoptotic cell death. Raw 264.7 cells treated with ATO also manifest dysregulated Ca(++) homeostasis. ATO induces Ca(++)-dependent calpain-1 and caspase-12 expression which together regulated macrophage apoptosis. Additionally, apoptosis was also induced by mitochondria-regulated pathway. Restoring ATO-impaired Ca(++) homeostasis in ER/mitochondria by treatments with the inhibitors of inositol 1,4,5-trisphosphate receptor (IP3R) and voltage-dependent anion channel (VDAC) attenuate innate immune functions of macrophages. These studies identify a novel role for ATF4 in underlying pathogenesis of macrophage dysregulation and immuno-toxicity of arsenic.