Daniel Boda

Chemically induced skin carcinogenesis: Updates in experimental models (Review)

Skin cancer is one of the most common malignancies affecting humans worldwide, and its incidence is rapidly increasing. The study of skin carcinogenesis is of major interest for both scientific research and clinical practice and the use of in vivo systems may facilitate the investigation of early alterations in the skin and of the mechanisms involved, and may also lead to the development of novel therapeutic strategies for skin cancer. This review outlines several aspects regarding the skin toxicity testing domain in mouse models of chemically induced skin carcinogenesis. There are important strain differences in view of the histological type, development and clinical evolution of the skin tumor, differences reported decades ago and confirmed by our hands-on experience. Using mouse models in preclinical testing is important due to the fact that, at the molecular level, common mechanisms with human cutaneous tumorigenesis are depicted. These animal models resemble human skin cancer development, in that genetic changes caused by carcinogens and pro-inflammatory cytokines, and simultaneous inflammation sustained by pro-inflammatory cytokines and chemokines favor tumor progression. Drugs and environmental conditions can be tested using these animal models. keeping in mind the differences between human and rodent skin physiology.

Variations in the expression of TIMP1, TIMP2 and TIMP3 in cutaneous melanoma with regression and their possible function as prognostic predictors

Regression in melanoma is a frequent biological event of uncertain prognostic value as the lesion exhibits heterogeneous phenotypical features, both at the morphological and immunohistochemical level. In the present study, we examined the expression of tissue inhibitors of metalloproteinases (TIMP1, TIMP2 and TIMP3) in melanoma with regression. We specifically examined the expression levels of these TIMPs in regressed components (RC) and non-regressed components (NRC) of the tumor and compared their expression levels with those in non-regressed melanomas. We found that TIMP1 was overexpressed in the NRC of melanomas with partial regression (PR) compared with the NRC in melanomas with segmental regression (SR) (P=0.011). TIMP2 was overexpressed in the NRC of melanomas with PR compared with the NRC in melanomas with SR (PR/SR, P=0.009); or compared with the NRC in melanomas with simultaneous SR-PR (P=0.002); or compared with melanomas without regression (absence of regression) (P=0.037). Moreover, TIMP3 was overexpressed in the NRC of all melanomas with SR as compared to the RC component (P=0.007). Our findings on the differential expression of TIMP1, TIMP2 and TIMP3 in melanomas with regression support the hypothesis that the morphological differences identified in the melanoma regression spectrum may have a correlation with prognosis. This may explain the controversial findings within the literature concerning the biological and prognostic role of regression in melanoma.

Inflammation markers in cutaneous melanoma - edgy biomarkers for prognosis

There is a fine balance between inflammation and tumorigenesis. While environmentally induced inflammatory condition can precede a malignant transformation, in other cases an oncogenic change of unknown origin can induce an inflammatory microenvironment that promotes the development of tumors. Regardless of its origin, maintaining the inflammation milieu has many tumor-promoting effects. As a result, inflammation can aid the proliferation and survival of malignant cells, can promote angiogenesis and metastasis, can down-regulate innate/adaptive immune responses, and can alter responses to hormones and chemotherapeutic agents. There is an abundance of studies unveiling molecular pathways of cancer-related inflammation; this wealth of information brings new insights into biomarkers domain in the diagnosis and treatment improvement pursue. In cutaneous tissue there is an established link between tissue damage, inflammation, and cancer development. Inflammation is a self-limiting process in normal healthy physiological conditions, while tumorigenesis is a complex mechanism of constitutive pathway activation. Once more, in cutaneous melanoma, there is an unmet need for inflammatory biomarkers that could improve prognostication. Targeting inflammation and coping with the phenotypic plasticity of melanoma cells represent rational strategies to specifically interfere with metastatic progression. We have shown that there is a prototype of intratumor inflammatory infiltrate depicting a good prognosis, infiltrate that is composed of numerous T cells CD3+, Langerhans cells, few/absent B cells CD20+ and few/absent plasma cells. Circulating immune cells characterized by phenotype particularities are delicately linked to the stage melanoma is diagnosed in. Hence circulatory immune sub-populations, with activated or suppressor phenotype would give the physician a more detailed immune status of the patient. A panel of tissue/circulatory immune markers can complete the immune status, can add value to the overall prognostic of the patient and, as a result direct/redirect the therapy choice. The future lies within establishing low-cost, affordable/available, easily reproducible assays that will complete the pre-clinical parameters of the patient.

Evaluation through in vivo reflectance confocal microscopy of the cutaneous neurogenic inflammatory reaction induced by capsaicin in human subjects

We perform an in vivo analysis of the effects of capsaicin on cutaneous microvascularization. A total of 29 healthy subjects are administered a solution of capsaicin (CAP group) or a vehicle solution (nonCAP group) on the dorsal side of the nondominant hand. The evaluation is performed using in vivo reflectance confocal microscopy (RCM). Ten minutes after administration, the area of the section, the perimeter, and the Ferets diameter of the capillaries in the dermal papillae become significantly larger in the CAP group as against the nonCAP group, and this difference is maintained until the conclusion of the experiment. In vivo RCM allows the investigation of cutaneous vascular reactions induced by capsaicin. As such, this method may constitute an useful technique both for research and clinical practice.

Stress-induced mast cell activation in glabrous and hairy skin.

Mast cells play a key role in modulation of stress-induced cutaneous inflammation. In this study we investigate the impact of repeated exposure to stress on mast cell degranulation, in both hairy and glabrous skin. Adult male Wistar rats were randomly divided into four groups: Stress 1 day (n = 8), Stress 10 days (n = 7), Stress 21 days (n = 6), and Control (n = 8). Rats in the stress groups were subjected to 2 h/day restraint stress. Subsequently, glabrous and hairy skin samples from animals of all groups were collected to assess mast cell degranulation by histochemistry and transmission electron microscopy. The impact of stress on mast cell degranulation was different depending on the type of skin and duration of stress exposure. Short-term stress exposure induced an amplification of mast cell degranulation in hairy skin that was maintained after prolonged exposure to stress. In glabrous skin, even though acute stress exposure had a profound stimulating effect on mast cell degranulation, it diminished progressively with long-term exposure to stress. The results of our study reinforce the view that mast cells are active players in modulating skin responses to stress and contribute to further understanding of pathophysiological mechanisms involved in stress-induced initiation or exacerbation of cutaneous inflammatory processes.

Neuroendocrine factors: The missing link in non‑melanoma skin cancer (Review)

Non-melanoma skin cancer (NMSC) is the most common form of cancer worldwide, comprising 95% of all cutaneous malignancies and approximately 40% of all cancers. In spite of intensive efforts aimed towards awareness campaigns and sun-protective measures, epidemiological data indicate an increase in the incidence of NMSC. This category of skin cancers has many common environmental triggers. Arising primarily on sun-exposed skin, it has been shown that ultraviolet radiation is, in the majority of cases, the main trigger involved in the pathogenesis of NMSC. Aside from the well-known etiopathogenic factors, studies have indicated that several neuroactive factors are involved in the carcinogenesis of two of the most common types of NMSC, namely basal cell carcinoma (BCC) and squamous cell carcinoma (SCC), with the exception of penile SCC, for which a paucity of specific data on their pathogenic role exists. The complex interaction between the peripheral nervous system and target cells in the skin appears to be mediated by locally released neuroendocrine factors, such as catecholamines, substance P, calcitonin gene-related peptide and somatostatin, as well as neurohormones, such as proopiomelanocortin and its derived peptides, α-melanocyte-stimulating hormone and adrenocorticotropin. All these factors have been, at least at some point, a subject of debate regarding their precise role in the pathogenesis of NMSC. There is also a significant body of evidence indicating that psychological stress is a crucial impact factor influencing the course of skin cancers, including SCC and BCC. Numerous studies have suggested that neuroendocrine factor dysregulation, as observed in stress reactions, may be involved in tumorigenesis, accelerating the development and progression, and suppressing the regression of NMSC. Further studies are required in order to elucidate the exact mechanisms through which neuroactive molecules promote or inhibit cutaneous carcinogenesis, as this could lead to the development of more sophisticated and tailored treatment protocols, as well as open new perspectives in skin cancer research.

HPV strain distribution in patients with genital warts in a female population sample

The incidence of human papillomavirus (HPV) in the human cancer domain is still a subject of intensive study. In this study, we examined cervical swab samples from 713 females with genital warts, and tested the samples for high- and low-risk genital HPV. HPV genotyping was assessed using a Genotyping test that detects HPV by the amplification of target DNA using polymerase chain reaction and nucleic acid hybridization. In total, we detected 37 anogenital HPV DNA genotypes [6, 11, 16, 18, 26, 31, 33, 35, 39, 40, 42, 45, 51, 52, 53, 54, 55, 56, 58, 59, 61, 62, 64, 66, 67, 68, 69, 70, 71, 72, 73 (MM9), 81, 82 (MM4), 83 (MM7), 84 (MM8), IS39 and CP6108] and investigated the incidence of these genotypes in the patients with genital warts. We found differences in the distribution of high-/low-risk strains and the incidence of high-risk strains was found to occur mainly in females under 35 years of age. The data from our study suggest that a detailed oral, rectal and genital identification of high-risk strains should be performed to visualize the entire pattern of possible triggers of carcinogenesis.

Reflectance confocal microscopy and dermoscopy for in vivo, non-invasive skin imaging of superficial basal cell carcinoma.

Superficial basal cell carcinoma (sBCC) is the second most frequent histological type of basal cell carcinoma (BCC), usually requiring a skin biopsy to confirm the diagnosis. It usually appears on the upper trunk and shoulders as erythematous and squamous lesions. Although it has a slow growth and seldom metastasizes, early diagnosis and management are of crucial importance in preventing local invasion and subsequent disfigurement. Dermoscopy is nowadays an indispensable tool for the dermatologist when evaluating skin tumors. Reflectance confocal microscopy (RCM) is a novel imaging technique that allows the non-invasive, in vivo quasi-microscopic morphological and dynamic assessment of superficial skin tumors. Moreover, it offers the advantage of performing infinite repeatable determinations to monitor disease progression and non-surgical treatment for sBCC. Herein, we present three lesions of sBCC evaluated using in vivo and non-invasive imaging techniques, emphasizing the usefulness of combining RCM with dermoscopy for increasing the diagnostic accuracy of sBCC.

Human papilloma virus: Apprehending the link with carcinogenesis and unveiling new research avenues (Review)

Human papilloma viruses (HPV) are a small group of non-enveloped viruses belonging to the Papillomaviridae family with strong similarities to polyoma viruses. The viral particles consist of a genome in the form of a circular double-stranded DNA, encompassing eight open reading frames, as well as a non-enveloped icosahedral capsid. HPV infection is considered the most common sexually transmitted disease in both sexes and is strongly implicated in the pathogenesis of different types of cancer. ‘High-risk’ mucosal HPV types, predominantly types 16, 18, 31, 33 and 35, are associated with most cervical, penile, vulvar, vaginal, anal, oropharyngeal cancers and pre-cancers. Screening for HPV is necessary for the prognosis and for determining treatment strategies for cancer. Novel HPV markers, including proteomic and genomic markers, as well as anti-papillomavirus vaccines are currently available. The aim of this comprehensive review was to thoroughly present the updated information on virus development, cancer occurrence, treatment and prevention strategies, in an attempt to shed further light into the field, including novel research avenues.

Proteomic Approaches to Biomarker Discovery in Cutaneous T-Cell Lymphoma

Cutaneous T-cell lymphoma (CTCL) is the most frequently encountered type of skin lymphoma in humans. CTCL encompasses multiple variants, but the most common types are mycosis fungoides (MF) and Sezary syndrome (SS). While most cases of MF run a mild course over a period of many years, other subtypes of CTCL are very aggressive. The rapidly expanding fields of proteomics and genomics have not only helped increase knowledge concerning the carcinogenesis and tumor biology of CTCL but also led to the discovery of novel markers for targeted therapy. Although multiple biomarkers linked to CTCL have been known for a relatively long time (e.g., CD25, CD45, CD45RA, and CD45R0), compared to other cancers (lymphoma, melanoma, colon carcinoma, head and neck cancer, renal cancer, and cutaneous B-cell lymphoma), information about the antigenicity of CTCL remains relatively limited and no dependable protein marker for CTCL has been discovered. Considering the aggressive nature of some types of CTCL, it is necessary to identify circulating molecules that can help in the early diagnosis, differentiation from inflammatory skin diseases (psoriasis, nummular eczema), and aid in predicting the prognosis and evolution of this pathology. This review aims to bring together some of the information concerning protein markers linked to CTCL, in an effort to further the understanding of the convolute processes involved in this complex pathology.