Sulfuric acid-induced skin neoplasms in immunocompetent mice.

This study investigates the carcinogenic potential of chronic dermal exposure (16 weeks) to sulfuric acid (SA) in immunocompetent mice. Clinical assessments, histopathological analyses, immunohistochemical analyses and biochemical assays were conducted to evaluate skin irritation, oxidative stress biomarkers and the potential carcinogenic effect of SA. Results indicated that prolonged exposure to SA leads to various alterations in skin structure, notably inflammation, preneoplastic and neoplastic proliferation in hair follicles, as well as hyperkeratosis and acanthosis, resulting in an increased epidermal thickness of 98.50 ± 21.6 µm. Immunohistochemistry analysis further corroborates these observations, showcasing elevated nuclear expression of p53 and Ki-67, with a significant mitotic index of (57.5% ± 2.5%). Moreover, biochemical analyses demonstrate that SA induces lipid peroxidation in the skin, evidenced by a high level of Malondialdehyde and a consequential reduction in catalase activity. These findings suggest that prolonged exposure to SA can induce skin neoplasms, highlighting the need for stringent safety measures in environments where SA is frequently used. This study underscores the potential occupational health risks associated with SA exposure.

Is diet related to skin condition? A Mendelian randomization study.

Observational studies have revealed associations between various dietary factors and skin conditions. However, the causal relationship between diet and skin condition is still unknown. Data on 17 dietary factors were obtained from the UK Biobank. Data on four skin conditions were derived from the UK Biobank and another large-scale GWAS study. Genetic predictions suggested that the intake of oily fish was associated with a lower risk of skin aging (OR: 0.962, P = 0.036) and skin pigmentation (OR: 0.973, P = 0.033); Tea intake was associated with a lower risk of skin pigmentation (OR: 0.972, P = 0.024); Salad/raw vegetables intake was associated with a lower risk of keratinocyte skin cancer (OR: 0.952, P = 0.007). Coffee intake was associated with increased risk of skin aging (OR: 1.040, P = 0.028); Pork intake was associated with increased risk of skin aging (OR: 1.134, P = 0.020); Beef intake was associated with increased risk of cutaneous melanoma (OR: 1.013, P = 0.016); Champagne plus white wine intake was associated with increased risk of cutaneous melanoma (OR: 1.033, P = 0.004); Bread intake was associated with increased risk of keratinocyte skin cancer (OR: 1.026, P = 0.013). Our study results indicate causal relationships between genetically predicted intake of oily fish, tea, salad/raw vegetables, coffee, pork, beef, champagne plus white wine, and bread and skin conditions.

14-3-3σ/Stratifin and p21 limit AKT-related malignant progression in skin carcinogenesis following MDM2-associated p53 loss.

To study mechanisms driving/inhibiting skin carcinogenesis, stage-specific expression of 14-3-3σ (Stratifin) was analyzed in skin carcinogenesis driven by activated rasHa/fos expression (HK1.ras/fos) and ablation of PTEN-mediated AKT regulation (K14.creP/Δ5PTENflx/flx). Consistent with 14-3-3σ roles in epidermal differentiation, HK1.ras hyperplasia and papillomas displayed elevated 14-3-3σ expression in supra-basal keratinocytes, paralleled by supra-basal p-MDM2166 activation and sporadic p-AKT473 expression. In bi-genic HK1.fos/Δ5PTENflx/flx hyperplasia, basal-layer 14-3-3σ expression appeared, and alongside p53/p21, was associated with keratinocyte differentiation and keratoacanthoma etiology. Tri-genic HK1.ras/fos-Δ5PTENflx/flx hyperplasia/papillomas initially displayed increased basal-layer 14-3-3σ, suggesting attempts to maintain supra-basal p-MDM2166 and protect basal-layer p53. However, HK1.ras/fos-Δ5PTENflx/flx papillomas exhibited increasing basal-layer p-MDM2166 activation that reduced p53, which coincided with malignant conversion. Despite p53 loss, 14-3-3σ expression persisted in well-differentiated squamous cell carcinomas (wdSCCs) and alongside elevated p21, limited malignant progression via inhibiting p-AKT1473 expression; until 14-3-3σ/p21 loss facilitated progression to aggressive SCC exhibiting uniform p-AKT1473. Analysis of TPA-promoted HK1.ras-Δ5PTENflx/flx mouse skin, demonstrated early loss of 14-3-3σ/p53/p21 in hyperplasia and papillomas, with increased p-MDM2166/p-AKT1473 that resulted in rapid malignant conversion and progression to poorly differentiated SCC. In 2D/3D cultures, membranous 14-3-3σ expression observed in normal HaCaT and SP1ras61 papilloma keratinocytes was unexpectedly detected in malignant T52ras61/v-fos SCC cells cultured in monolayers, but not invasive 3D-cells. Collectively, these data suggest 14-3-3σ/Stratifin exerts suppressive roles in papillomatogenesis via MDM2/p53-dependent mechanisms; while persistent p53-independent expression in early wdSCC may involve p21-mediated AKT1 inhibition to limit malignant progression.

Screening the critical protein subnetwork to delineate potential mechanisms and protective agents associated with arsenic-induced cutaneous squamous cell carcinoma: A toxicogenomic study.

Recent studies show that complex mechanisms are involved in arsenic-induced malignant transformation of cells. This study aimed to decipher molecular mechanisms associated with arsenic-induced cutaneous squamous cell carcinoma (cSCC) and suggest potential protective factors. RNA-seq-based differentially expressed genes between arsenic-exposed human keratinocytes (HaCaT) and controls were used to construct a protein-protein interaction (PPI) network and discover critical subnetwork-based mechanisms. Protective compounds against arsenic toxicity were determined and their target interactions in the core sub-network were identified by the comparative toxicogenomic database (CTD). The binding affinity between the effective factor and target was calculated by molecular docking. A total of 15 key proteins were screened out as critical arsenic-responsive subnetwork (FN1, IL-1A, CCN2, PECAM1, FGF5, EDN1, FGF1, PXDN, DNAJB9, XBP1, ERN1, PDIA4, DNAJB11, FOS, PDIA6) and 7 effective protective agents were identified (folic acid, quercetin, zinc, acetylcysteine, methionine, catechin, selenium). The GeneMANIA predicted detailed interactions of the subnetwork and revealed terms related to unfolded protein response as the main processes. FN1, IL1A and CCN2, as top significant genes, had good docking affinity with folic acid and quercetin, as selected key compounds. Integration of gene expression and protein-protein interaction related to arsenic exposure in cSCC explored the potential mechanisms and protective agents.

NRF3 suppresses squamous carcinogenesis, involving the unfolded protein response regulator HSPA5.

Epithelial skin cancers are extremely common, but the mechanisms underlying their malignant progression are still poorly defined. Here, we identify the NRF3 transcription factor as a tumor suppressor in the skin. NRF3 protein expression is strongly downregulated or even absent in invasively growing cancer cells of patients with basal and squamous cell carcinomas (BCC and SCC). NRF3 deficiency promoted malignant conversion of chemically induced skin tumors in immunocompetent mice, clonogenic growth and migration of human SCC cells, their invasiveness in 3D cultures, and xenograft tumor formation. Mechanistically, the tumor-suppressive effect of NRF3 involves HSPA5, a key regulator of the unfolded protein response, which we identified as a potential NRF3 interactor. HSPA5 levels increased in the absence of NRF3, thereby promoting cancer cell survival and migration. Pharmacological inhibition or knock-down of HSPA5 rescued the malignant features of NRF3-deficient SCC cells in vitro and in preclinical mouse models. Together with the strong expression of HSPA5 in NRF3-deficient cancer cells of SCC patients, these results suggest HSPA5 inhibition as a treatment strategy for these malignancies in stratified cancer patients.

C-type natriuretic peptide (CNP) inhibits 7,12-Dimethylbenz[a]anthracene (DMBA)/Croton oil-induced skin tumor growth by modulating inflammation in Swiss albino mice.

C-type natriuretic peptide (CNP) exhibits anti-inflammatory activity besides its natriuretic and diuretic functions. The present study aimed to determine the anticancer and synergistic therapeutic activity of CNP against a 7,12-Dimethylbenz[a]anthracene (DMBA)/Croton oil-induced skin tumor mouse model. CNP (2.5 µg/kg body weight) was injected either alone and/or in combination with Cisplatin (CDDP) (2 mg/kg body weight) for 4 weeks. The dorsal skin tumor incidences/growth and mortality rate were recorded during the experimental period of 16 weeks. The serum C-reactive protein (CRP), and lactate dehydrogenase (LDH) levels, infiltrating mast cells, and AgNORs proliferating cells count were analyzed in control and experimental mice. Further, the expression profile of marker genes of proliferation, inflammation, and progression molecules were analyzed using Reverse transcriptase-polymerase chain reaction (RT-PCR)/quantitative PCR (qPCR), western blot, and immunohistochemistry. The DMBA/Croton oil-induced mice exhibited 100% tumor incidence. Whereas, CNP alone, CDDP alone, and CNP+CDDP combination-treated mice exhibited 58%, 46%, and 24% tumor incidence, respectively. Also, a marked reduction in the levels of serum CRP and LDH, the number of infiltrating mast cells count and AgNORs proliferating cells count were noticed in the mice skin sections. Further, a significant reduction in both mRNA and protein expression levels of proliferation, inflammation, and progression markers were noticed in CNP (p < 0.01), CDDP (p < 0.01), and CNP+CDDP combination (p < 0.001) treated mice, respectively. The results of the present study suggest that CNP has anticancer activity. Further, the CNP+CDDP treatment has more promising anticancer activity as compared with CNP or CDDP alone treatment, probably due to the synergistic antiproliferative and anti-inflammatory activities of CNP and CDDP.

Orobol, 3'-hydroxy-genistein, suppresses the development and regrowth of cutaneous SCC.

Chronic solar ultraviolet exposure is a major risk factor for cutaneous squamous cell carcinoma (cSCC), which is the second most common type of skin cancer. Our previous data showed that total protein and phosphorylation levels of T-LAK cell-originated protein kinase (TOPK) were enhanced in solar-simulated light (SSL)-induced skin carcinogenesis and overexpressed in actinic keratosis (AK) and cSCC human skin tissues compared to those in matched normal skin. Thus, targeting TOPK activity could be a helpful approach for treating cSCC. Our data showed that orobol directly binds to TOPK in an ATP-independent manner and inhibits TOPK kinase activity. Furthermore, orobol inhibited anchorage-independent colony formation by SCC12 cells in a dose-dependent manner. After discontinuing the treatment, patients commonly return to tumor-bearing conditions; therefore, therapy or intermittent dosing of drugs must be continued indefinitely. Thus, to examine the efficacy of orobol against the development and regrowth of cSCC, we established mouse models including prevention, and therapeutic models on the chronic SSL-irradiated SKH-1 hairless mice. Early treatment with orobol attenuates chronic SSL-induced cSCC development. Furthermore, orobol showed therapeutic efficacy after the formation of chronic SSL irradiation-induced tumor. In the mouse model with intermittent dosing of orobol, our data showed that re-application of orobol is effective for reducing tumor regrowth after discontinuation of treatment. Moreover, oncogenic protein levels were significantly attenuated by orobol treatment in the SSL-stimulated human skin. Thus, we suggest that orobol, as a promising TOPK inhibitor, could have an effective clinical approach to prevent and treat the development and regrowth of cSCC.

DNA Methylome and Transcriptome Study of Triterpenoid CDDO in TPA-Mediated Skin Carcinogenesis Model.

Overexposure to ultraviolet radiation and environmental carcinogens drive skin cancer development through redox imbalance and gene mutation. Antioxidants such as triterpenoids have exhibited anti-oxidative and anti-inflammatory potentials to alleviate skin carcinogenesis. This study investigated the methylome and transcriptome altered by tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) or TPA with 2-cyano 2,3-dioxoolean-1,9-dien-28-oic acid (CDDO). The results show that CDDO blocks TPA-induced transformation dose dependently. Several differential expressed genes (DEGs) involved in skin cell transformation, while counteracted by CDDO, were revealed by differential expression analysis including Lyl1, Lad1, and Dennd2d. In CpG methylomic profiles, the differentially methylated regions (DMRs) in the promoter region altered by TPA while showing the opposite methylation status in the CDDO treatment group were identified. The correlation between DNA methylation and RNA expression has been established and DMRs showing inverse correlation were further studied as potential therapeutic targets. From the CpG methylome and transcriptome results, CDDO significantly restored gene expression of NAD(P)H:quinone oxidoreductase 1 (Nqo1) inhibited by TPA by decreasing their promoter CpG methylation. Ingenuity Pathways Analysis (IPA) shows that CDDO neutralized the effect of TPA through modulating cell cycles, cell migration, and inflammatory and immune response regulatory pathways. Notably, Tumor Necrosis Factor Receptor 2 (TNFR2) signaling was significantly downregulated by CDDO potentially contributing to prevention of TPA-induced cell transformation. Overall, incorporating the transcriptome, CpG methylome, and signaling pathway network, we reveal potential therapeutic targets and pathways by which CDDO could reverse TPA-induced carcinogenesis. The results could be useful for future human study and targets development for skin cancer.

Chemopreventive agents on a mouse skin carcinogenesis model: an integrative review / Agentes quimiopreventivos em um modelo de carcinogênese de pele em camundongos: uma revisão integrativa / Agentes quimiopreventivos en un modelo de carcinogénesis cutánea en ratón: una revisión integradora

Squamous cell carcinoma (SCC) is a non-melanoma skin cancer, with chronic sun exposure as the main risk factor. Excisional surgery is the most indicated treatment; however, patients can suffer functional, aesthetic, and psychological damage depending on the lesion site. Topical administration of 7,12-dimethylbenz[a]anthracene (DMBA) and 12-O-Tetradecanoylphorbol-13- acetate (TPA) induce to the appearance of benign skin tumors in mice, some of which develop into SCC. This protocol has been used to analyze the effects of many chemopreventive agents that may block or inhibit the mechanisms of action of chemical carcinogenesis. We compared the effects of chemopreventive agents in an induced skin carcinogenesis animal model. In the Scopus, PubMed, and EMBASE databases, we searched for manuscripts published between June 16, 2011, and June 16, 2021. We excluded studies conducted in vitro or on transgenic mice; in addition, studies without drug dosage, route of administration, or tumor incidence were excluded. We selected 26 studies and analyzed their main characteristics and the outcomes of tumorigenesis analysis. Most chemopreventive agents have shown excellent potential to inhibit the development of skin tumors. This review also discusses the standardization of studies in animal models to ensure better responses and future randomized clinical trials for cancer treatment and prevention.

O carcinoma espinocelular cutâneo (CEC) é um câncer de pele não melanoma, com a exposição solar crônica como o principal fator de risco. A cirurgia excisional é o tratamento mais indicado; entretanto, os pacientes podem sofrer danos funcionais, estéticos e psicológicos dependendo do local da lesão. A administração tópica de 7,12-dimetilbenz[a]antraceno (DMBA) e 12-O- Tetradecanoilforbol-13-acetato (TPA) induz ao aparecimento de tumores cutâneos benignos em camundongos, alguns dos quais evoluíram para CEC. Este protocolo tem sido utilizado para analisar os efeitos de muitos agentes quimiopreventivos que podem bloquear ou inibir os mecanismos de ação da carcinogênese química. Comparamos os efeitos de agentes quimiopreventivos em um modelo animal que foi induzido à carcinogênese de pele. Nas bases de dados Scopus, PubMed e EMBASE, buscamos manuscritos publicados entre 16 de junho de 2011 e 16 de junho de 2021. Excluímos estudos realizados in vitro ou em camundongos transgênicos; além disso, estudos sem dosagem de drogas, via de administração ou incidência de tumores foram excluídos. Selecionamos 26 estudos e analisamos suas principais características e os resultados da análise da tumorigênese. A maioria dos agentes quimiopreventivos tem demonstrado excelente potencial para inibir o desenvolvimento de tumores cutâneos. Esta revisão também discute a padronização de estudos em modelos animais para garantir melhores respostas e futuros ensaios clínicos randomizados para tratamento e prevenção do câncer.

El carcinoma de células escamosas (CCE) es un cáncer de piel no melanoma, cuyo principal factor de riesgo es la exposición crónica al sol. La cirugía de escisión es el tratamiento más indicado; sin embargo, los pacientes pueden sufrir daños funcionales, estéticos y psicológicos dependiendo de la localización de la lesión. La administración tópica de 7,12-dimetilbenz[a]antraceno (DMBA) y 12-O-Tetradecanoilforbol-13-acetato (TPA) inducen a la aparición de tumores cutáneos benignos en ratones, algunos de los cuales se convierten en CCE. Este protocolo se ha utilizado para analizar los efectos de muchos agentes quimiopreventivos que pueden bloquear o inhibir los mecanismos de acción de la carcinogénesis química. Comparamos los efectos de los agentes quimiopreventivos en un modelo animal de carcinogénesis cutánea inducida. En las bases de datos Scopus, PubMed y EMBASE, se buscaron los manuscritos publicados entre el 16 de junio de 2011 y el 16 de junio de 2021. Se excluyeron los estudios realizados in vitro o en ratones transgénicos; además, se excluyeron los estudios sin dosis de fármacos, vía de administración o incidencia tumoral. Se seleccionaron 26 estudios y se analizaron sus características principales y los resultados del análisis de la tumorigénesis. La mayoría de los agentes quimiopreventivos han mostrado un excelente potencial para inhibir el desarrollo de tumores cutáneos. Esta revisión también analiza la estandarización de los estudios en modelos animales para garantizar mejores respuestas y futuros ensayos clínicos aleatorios para el tratamiento y la prevención del cáncer.

Isolation of cancer stem cells from skin squamous cell carcinoma.

Skin squamous cell carcinoma (skin SCC) is the most frequently occurring cancer. Skin is the first line of defense that provides protection from the external environment. Skin consists of epidermis, dermis, and hypodermis. The epidermis comprises of inter-follicular epidermis, hair follicles, sebaceous glands, and sweat glands. Stem cells within these epidermal compartments play crucial role in epidermal regeneration and repair. Various factors such as higher exposure to ultraviolet light (UV) of sun, genetic predisposition, exposure to carcinogens, etc. that give rise to skin cancer. Within the skin SCC, there exists a pool of cancer stem cells (CSCs) that are highly quiescent with self-renewal capacity. Further, isolation and molecular characterization of CSCs would enable to unravel mechanism involved in tumor progression, metastasis, relapse, and resistance to chemotherapeutic agents. To understand the sequential events of carcinogenesis, the two-stage skin carcinogenesis murine model is proposed, which employs the topical application of a chemical carcinogen, DMBA that causes several activating mutations occurring in the genes responsible for cell proliferation and growth. Further, initiation is followed by tumor promotion, which is induced by repeated application of tumor-promoting agent, TPA, which fixes the activating mutations resulting in the formation of a benign papilloma. Subsequently, papilloma further progresses to highly malignant SCC. Here, using the two-stage skin carcinogenesis murine model, we provide a detailed protocol for the isolation of CSCs from murine skin SCC. FACS sorting of CSCs is followed by assays such as invitro-spheroid assay, in vivo-tumorigenesis-limiting dilution and in vivo-tumorigenesis-serial transplantation assay and expression profiling.

The landscape of genetic alterations of UVB-induced skin tumors in DNA repair-deficient mice.

Non-melanoma skin cancer (NMSC) is mainly caused by ultraviolet (UV)-induced somatic mutations and is characterized by UV signature modifications. Xeroderma pigmentosum group A (Xpa) knockout mice exhibit extreme UV-induced photo-skin carcinogenesis, along with a photosensitive phenotype. We performed whole-exome sequencing (WES) of squamous cell carcinoma (SCC) samples after repetitive ultraviolet B (UVB) exposure to investigate the differences in the landscape of somatic mutations between Xpa knockout and wild-type mice. Although the tumors that developed in mice harboured UV signature mutations in a similar set of cancer-related genes, the pattern of transcriptional strand asymmetry was largely different; UV signature mutations in Xpa knockout and wild-type mice preferentially occurred in transcribed and non-transcribed strands, respectively, reflecting a deficiency in transcription-coupled nucleotide excision repair in Xpa knockout mice. Serial time point analyses of WES for a tumor induced by only a single UVB exposure showed pathogenic mutations in Kras, Fat1, and Kmt2c, which may be driver genes for the initiation and promotion of SCC in Xpa knockout mice. Furthermore, the inhibitory effects on tumor production in Xpa knockout mice by the anti-inflammatory CXCL1 monoclonal antibody affected the pattern of somatic mutations, wherein the transcriptional strand asymmetry was attenuated and the activated signal transduction was shifted from the RAS/RAF/MAPK to the PIK3CA pathway.

Protective effects of andrographolide sodium bisulfate on UV-induced skin carcinogenesis in mice model.

Although the mortality of skin cancer patients is relatively low, there are still a large number of patients died of these tumors at high incidence rate. Chronic exposure to solar UV irradiation is the most common cause of nonmelanoma skin tumors. Our research aimed to explore the effects of andrographolide sodium bisulfate (ASB) on UV-induced skin cancer and to reveal the underlying molecular mechanism. In the present study, histopathology changes, immunohistochemical analysis, ELISA analysis and western blot analysis were mainly used in vivo. The results indicated that ASB significantly inhibited increase of skin epidermal thickness, inflammatory cells infiltration and fibers damage in dermis, oxidative stress injury and skin carcinogenesis. Moreover, the western blot analysis showed that protein expressions of NF-κB, Nrf2, p62, LC3 II/I and p-p62 (Ser 349) in mouse skin induced by UV were dramatically suppressed in the ASB-pretreated groups. Overall, these results suggested that ASB exerted a strong preventive effect and potential therapeutic value against UV-induced skin carcinogenesis in mice through inhibiting NF-κB and Nrf2 signaling pathways and restoring autophagy.

Interleukin-38 promotes skin tumorigenesis in an IL-1Rrp2-dependent manner.

Interleukin-38 (IL-38) is strongly associated with chronic inflammatory diseases; however, its role in tumorigenesis is poorly understood. We demonstrated that expression of IL-38, which exhibits high expression in the skin, is downregulated in human cutaneous squamous cell carcinoma and 7,12-dimethylbenzanthracene/12-O-tetradecanoyl phorbol-13-acetate-induced mouse skin tumorigenesis. IL-38 keratinocyte-specific knockout mice displayed suppressed skin tumor formation and malignant progression. Keratinocyte-specific deletion of IL-38 was associated with reduced expression of inflammatory cytokines, leading to reduced myeloid cell infiltration into the local tumor microenvironment. IL-38 is dispensable for epidermal mutagenesis, but IL-38 keratinocyte-specific deletion reduces proliferative gene expression along with epidermal cell proliferation and hyperplasia. Mechanistically, we first demonstrated that IL-38 activates the c-Jun N-terminal kinase (JNK)/activator protein 1 signal transduction pathway to promote the expression of cancer-related inflammatory cytokines and proliferation and migration of tumor cells in an IL-1 receptor-related protein 2 (IL-1Rrp2)-dependent manner. Our findings highlight the role of IL-38 in the regulation of epidermal cell hyperplasia and pro-tumorigenic microenvironment through IL-1Rrp2/JNK and suggest IL-38/IL-1Rrp2 as a preventive and potential therapeutic target in skin cancer.

Chemopreventive Role of Black Tea Extract in Swiss Albino Mice Exposed to Inorganic Arsenic.

OBJECTIVE: Chronic exposure to inorganic arsenic (iAs) may cause a number of health problems including skin cancer. Present study is aimed to look into the potential of black tea extract (BTE) to prevent the development of skin carcinoma in Swiss albino mice. METHODS: The study was done on Swiss albino mice, chronically exposed to inorganic arsenic. 150 mice were housed in different cages, 5 in each cage. The control mice did not receive any treatment. Mice were sacrificed at 30, 90, 180, 270 and 330 days. Development of carcinogenesis was assessed by histological studies. Generation of Reactive Oxygen Species (ROS) and Reactive Oxygen Species (RNS) were estimated using 2',7'-dichlorodihydrofluorescein diacetate (DCFH-DA) and Greiss reagent respectively, and their consequences on DNA (by Micronuclei and Comet assay), protein (by protein carbonyl assay kit) and lipid (by lipid peroxidation) were estimated. Activity of antioxidant enzymes, along with total antioxidant capacity were measured by respective kits. Repair percentage was obtained by Comet assay. Western blotting was employed to study the expression of repair enzymes and expression of cytokines. Sandwich Enzyme-linked Immunosorbent Assay (ELISA) technique was employed to study the activity of various cytokines. RESULTS: At 330 days, invasive squamous cell carcinoma of the skin developed. With increasing time generation of ROS and RNS increased, causing damage to DNA, protein and lipid. Antioxidant defence system gets repressed with time. Capacity to repair the DNA damage is inhibited by iAs, due to alteration in repair enzymes - XRCC I, DNA Ligase I, PARP I, ERCC1, ERCC2, XPA, DNA Ligase IV, DNA PKc and Ku-70. Another consequence of iAs exposure is chronic inflammation due to disrupted cytokine level. Intervention with BTE reverses these deleterious effects, preventing development of skin carcinogenesis.

How to prevent skin damage from air pollution part 2: Current treatment options.

In the first part of this review, we have summarized the methods used to examine skin exposure to air pollution and the fundamental concept of skin-exposome interactions. Part 2 of this review focuses on dermatoses, whose aggravation or initiation by air pollution has been confirmed in evidence based medicine manner. Based on the model of photodermatology and photodermatoses, we propose a new concept of "polludermatoses." A key feature of this concept is identifying patients at risk, which will reveal the noxious effects of air pollutants on skin health. Identifying clinical signs of pollution-damaged skin could be beneficial in categorizing conditions caused or exacerbated by exposure to air pollution. Finally, we discuss the current treatment options and the pathogenetic processes targeted by these therapeutics or the development of novel treatment modalities.

Dynamic alteration in miRNA and mRNA expression profiles at different stages of chronic arsenic exposure-induced carcinogenesis in a human cell culture model of skin cancer.

Chronic arsenic exposure causes skin cancer, although the underlying molecular mechanisms are not well defined. Altered microRNA and mRNA expression likely play a pivotal role in carcinogenesis. Changes in genome-wide differential expression of miRNA and mRNA at 3 strategic time points upon chronic sodium arsenite (As3+) exposure were investigated in a well-validated HaCaT cell line model of arsenic-induced cutaneous squamous cell carcinoma (cSCC). Quadruplicate independent HaCaT cell cultures were exposed to 0 or 100 nM As3+ for up to 28-weeks (wk). Cell growth was monitored throughout the course of exposure and epithelial-mesenchymal transition (EMT) was examined employing immunoblot. Differentially expressed miRNA and mRNA profiles were generated at 7, 19, and 28-wk by RNA-seq, followed by identification of differentially expressed mRNA targets of differentially expressed miRNAs through expression pairing at each time point. Pathway analyses were performed for total differentially expressed mRNAs and for the miRNA targeted mRNAs at each time point. RNA-seq predictions were validated by immunoblot of selected target proteins. While the As3+-exposed cells grew slower initially, growth was equal to that of unexposed cells by 19-wk (transformation initiation), and exposed cells subsequently grew faster than passage-matched unexposed cells. As3+-exposed cells had undergone EMT at 28-wk. Pathway analyses demonstrate dysregulation of carcinogenesis-related pathways and networks in a complex coordinated manner at each time point. Immunoblot data largely corroborate RNA-seq predictions in the endoplasmic reticulum stress (ER stress) pathway. This study provides a detailed molecular picture of changes occurring during the arsenic-induced transformation of human keratinocytes.

Generation of a tissue-specific transgenic model for K8 phosphomutants: A tool to investigate the role of K8 phosphorylation during skin carcinogenesis in vivo.

Keratin 8/18, the predominant keratin pair of simple epithelia, is known to be aberrantly expressed in several squamous cell carcinomas (SCCs), where its expression is often correlated with increased invasion, neoplastic progression, and poor prognosis. The majority of keratin 8/18 structural and regulatory functions are governed by posttranslational modifications, particularly phosphorylation. Apart from filament reorganization, cellular processes including cell cycle, cell growth, cellular stress, and apoptosis are known to be orchestrated by K8 phosphorylation at specific residues in the head and tail domains. Even though deregulation of K8 phosphorylation at two significant sites (Serine73 /Serine431 ) has been implicated in neoplastic progression of SCCs by various in vitro studies, including ours, it is reported to be highly context-dependent. Therefore, to delineate the precise role of Kereatin 8 phosphorylation in cancer initiation and progression, we have developed the tissue-specific transgenic mouse model expressing Keratin 8 wild type and phosphodead mutants under Keratin 14 promoter. Subjecting these mice to 7,12-dimethylbenz(a)anthracene/12-O-tetradecanoylphorbol-13-acetate-mediated skin carcinogenesis revealed that Keratin 8 phosphorylation may lead to an early onset of tumors compared to Keratin 8 wild-type expressing mice. Conclusively, the transgenic mouse model developed in the present study ascertained a positive impact of Keratin 8 phosphorylation on the neoplastic transformation of skin-squamous cells.

Ultraviolet Radiation and Chronic Inflammation-Molecules and Mechanisms Involved in Skin Carcinogenesis: A Narrative Review.

The process of skin carcinogenesis is still not fully understood. Both experimental and epidemiological evidence indicate that chronic inflammation is one of the hallmarks of microenvironmental-agent-mediated skin cancers and contributes to its development. Maintaining an inflammatory microenvironment is a condition leading to tumor formation. Multiple studies focus on the molecular pathways activating tumorigenesis by inflammation and indicate several biomarkers and factors that can improve diagnostic and prognostic processes in oncology and dermatology. Reactive oxygen species produced by ultraviolet radiation, oxidizers, or metabolic processes can damage cells and initiate pro-inflammatory cascades. Considering the potential role of inflammation in cancer development and metastasis, the identification of early mechanisms involved in carcinogenesis is crucial for clinical practice and scientific research. Moreover, it could lead to the progress of advanced skin cancer therapies. We focus on a comprehensive analysis of available evidence and on understanding how chronic inflammation and ultraviolet radiation can result in skin carcinogenesis. We present the inflammatory environment as complex molecular networks triggering tumorigenesis and constituting therapeutic targets.

The transmembrane protein LRIG1 triggers melanocytic tumor development following chemically induced skin carcinogenesis.

The incidence of melanoma and nonmelanoma skin cancer has increased tremendously in recent years. Although novel treatment options have significantly improved patient outcomes, the prognosis for most patients with an advanced disease remains dismal. It is, thus, imperative to understand the molecular mechanisms involved in skin carcinogenesis in order to develop new targeted treatment strategies. Receptor tyrosine kinases (RTK) like the ERBB receptor family, including EGFR/ERBB1, ERBB2/NEU, ERBB3, and ERBB4, are important regulators of skin homeostasis and their dysregulation often results in cancer, which makes them attractive therapeutic targets. Members of the leucine-rich repeats and immunoglobulin-like domains protein family (LRIG1-3) are ERBB regulators and thus potential therapeutic targets to manipulate ERBB receptors. Here, we analyzed the function of LRIG1 during chemically induced skin carcinogenesis in transgenic mice expressing LRIG1 in the skin under the control of the keratin 5 promoter (LRIG1-TG mice). We observed a significant induction of melanocytic tumor formation in LRIG1-TG mice and no difference in papilloma incidence between LRIG1-TG and control mice. Our findings also revealed that LRIG1 affects ERBB signaling via decreased phosphorylation of EGFR and increased activation of the oncoprotein ERBB2 during skin carcinogenesis. The epidermal proliferation rate was significantly decreased during epidermal tumorigenesis under LRIG1 overexpression, and the apoptosis marker cleaved caspase 3 was significantly activated in the epidermis of transgenic LRIG1 mice. Additionally, we detected LRIG1 expression in human cutaneous squamous cell carcinoma and melanoma samples. Therefore, we depleted LRIG1 in human melanoma cells (A375) by CRISPR/Cas9 technology and found that this caused EGFR and ERBB3 downregulation in A375 LRIG1 knockout cells 6 h following stimulation with EGF. In conclusion, our study demonstrated that LRIG1-TG mice develop melanocytic skin tumors during chemical skin carcinogenesis and a deletion of LRIG1 in human melanoma cells reduces EGFR and ERBB3 expression after EGF stimulation.