Gabriella Emri

Low concentrations of formaldehyde induce DNA damage and delay DNA repair after UV irradiation in human skin cells.

Abstract:  Long‐term occupational exposure to formaldehyde (FA) increases the risk for nasopharyngeal squamous cell carcinoma. As the skin is also in contact with FA by environmental exposure, we tested the genotoxic properties of appropriate low concentrations (<100 µM) of FA on cultured keratinocytes and fibroblasts of human skin. The initial DNA damage was assessed by comet assay. The induction of DNA protein crosslinks was measured by the ability of FA to reduce DNA migration induced by methyl‐methane‐sulfonate. Upon 4 h of exposure to FA, significant (P < 0.05) crosslink formations were observed in fibroblasts (50 µM FA) and in keratinocytes (25 µM FA). Upon 8 h of exposure to FA (25 µM FA), significant crosslink formations were observed in both the cell types. FA is known to inhibit different DNA repair pathways. Therefore, we studied the effect of FA on UV‐induced repair. Human keratinocytes and fibroblasts exposed to 10 µM FA prior to UV irradiation showed disturbed repair kinetics after UVC and UVB, but not after UVA irradiation. Single‐strand breaks (SSBs) derived from nucleotide excision repair disappeared 6 h after solely UVC (3 mJ/cm2) or 3 h solely UVB (30 mJ/cm2) exposure in both the cell types. In the presence of FA, SSBs were still present at these time points containing a reference to a delay in DNA resynthesis/ligation. FA at a concentration not inducing micronuclei (12.5 µM) caused significant increase of UVC‐induced (4 mJ/cm2) chromosomal damage. Proliferation of keratinocytes and fibroblasts was in parallel to observed DNA damages. In conclusion, our data suggest that environmental exposure to FA may contribute to UV‐induced skin carcinogenesis.

The role of CCND1 alterations during the progression of cutaneous malignant melanoma

It is well demonstrated that CCND1 amplification is a frequent event in the acral subtype of cutaneous malignant melanoma; however, its role in the other subtypes of the disease is still controversial. The objectives of this study were to evaluate genetic and expression alterations of CCND1 with a focus on primary cutaneous melanomas, to define BRAF and NRAS mutation status, and correlate the data with clinical–pathological parameters. CCND1 amplification was associated with ulceration and the localization of the metastasis. After correction for the mutation state of BRAF and NRAS genes, CCND1 amplification in samples without such mutations was associated with ulceration and sun exposure. The cyclin D1 (CCND1) mRNA level decreased in lesions with multiple metastases and was correlated with both the mRNA levels and mutation state of BRAF and NRAS genes. Primary melanomas with BRAFV600 or NRASQ61 mutations exhibited lower CCND1 mRNA level. CCND1 protein expression was associated with Breslow thickness, metastasis formation, and shorter survival time. These observations suggest that CCND1 alterations are linked to melanoma progression and are modified by BRAF and NRAS mutations. Our data show that CCND1 amplification could have a prognostic relevance in cutaneous melanoma and highlight that altered CCND1 gene expression may influence the metastatic progression, survival, and the localization of metastases.

Reference genes for quantitative real time PCR in UVB irradiated keratinocytes.

Real time quantitative reverse transcription-polymerase chain reaction (qRT-PCR) is a sensitive and highly reproducible method often used for determining mRNA levels. To enable proper comparison of gene expression genes expressed at stabile levels within the cells in the studied experimental system need to be identified and used as reference. Ultraviolet B (UVB) radiation is an exogenous carcinogenic stimulus in keratinocytes, and UVB elicited changes have extensively been studied by qRT-PCR, yet a comparison of commonly used reference genes in UVB treatment is lacking. To find the best genes for compensating slight inter-sample variations in keratinocytes in UVB experiments and to understand the potential effects of improper reference gene (RG) selection we have analyzed the mRNA expression of 10 housekeeping genes in neonatal human epidermal keratinocytes (NHEK) after UVB treatment. The biological effect of the used UVB light source was validated by trypane blue exclusion, MTT and comet assays. 20-40mJ/cm(2) dose was chosen for the experiments. The stability of the 10 RGs was assessed by the GeNorm and Normfinder software tools. Regardless of their slightly different algorithm the programs found succinate dehydrogenase complex subunit A (SDHA) to be the best individual RG and SDHA and phosphoglycerate kinase-1 (PGK1) as the most suitable combination. Analysis of the expression of tumor necrosis factor alpha (TNFalpha) and vascular endothelial growth factor (VEGF) found that while the perception of changes in TNF-alpha, a gene undergoing marked upregulation after UVB irradiation is independent of the used RG, changes seen in the more modestly upregulated VEGF are greatly effected by reference gene selection. These findings highlight the importance of reference gene selection in UVB irradiation experiments, and provide evidence that using SDHA or the combination of SDHA and PGK1 as standards could be a reliable method for normalizing qRT-PCR results in keratinocytes after UVB treatment.

Correlation among metallothionein expression, intratumoural macrophage infiltration and the risk of metastasis in human cutaneous malignant melanoma

Background  The formation of metastases and the efficacy of systemic therapies in cutaneous malignant melanoma (CMM) depend on the characteristics of the tumour cells and the host immune response. Aberrant expression of metallothionein (MT) has been observed in several types of cancers with poor prognoses.

Characterization of 9p21 copy number alterations in human melanoma by fluorescence in situ hybridization

Alteration of the CDKN2A (alias p16) tumor suppressor gene, located on 9p21, occurs frequently in familial and sporadic melanomas. Beside CDKN2A, other genes (e.g., CDKN2B, and ARF/p14(ARF), long considered distinct from CDKN2A) on this locus are often deleted or mutated in a large number of tumors including glioma, bladder cancer, and lung cancer. The aim of this study was to evaluate the deletion pattern of the 9p21 locus on a cell-by-cell basis in a large number of melanoma samples using fluorescence in situ hybridization (FISH). In an analysis of 81 primary lesions targeting the 9p21 region and chromosome 9 centromere, high frequency of 9p21 loss (84%) was found. Deletion of 9p21 was present in both early- and late-stage melanomas with similar frequencies. Extra 9p21 copies were rarely seen; they were always associated with polysomy 9 and were observed only in advanced stage melanomas (6 tumors). This FISH study strengthens the hypothesis that the loss of 9p21 occurs frequently in primary melanoma, that the deletion is present in early and late stages of the disease with similar frequency, and that it affects a large extent of the locus.

Photosensitivity skin disorders in childhood

Photosensitivity in childhood is caused by a diverse group of diseases. It usually indicates idiopathic photodermatoses, first of all polymorphic light eruption. It may be an early symptom of genetic disorders such as porphyria or very rare genophotodermatoses. Photosensitivity secondary to topical or systemic external agents as well as photoexacerbated dermatoses is not so frequent in childhood. Here we present our experience with childhood photosensitivity skin diseases collected over a 40‐year period.

Microarray analysis of metallothioneins in human diseases—A review

Metallothioneins (MTs), low molecular mass cysteine-rich proteins, which are able to bind up to 20 monovalent and up to 7 divalent heavy metal ions are widely studied due to their functions in detoxification of metals, scavenging free radicals and cells protection against the oxidative stress. It was found that the loss of the protective effects of MT leads to an escalation of pathogenic processes and carcinogenesis. The most extensive area is MTs expression for oncological applications, where the information about gene patterns is helpful for the identification biological function, resistance to drugs and creating the correct chemotherapy. In other medical applications the effect of oxidative stress to cell lines exposed to heavy metals and hydrogen peroxide is studied as well as influence of drugs and cytokines on MTs expression and MTs expression in the adipose tissue. The precise detection of low metallothionein concentrations and its isoforms is necessary to understand the connection between quantity and isoforms of MTs to size, localization and type of cancer. This information is necessary for well-timed therapy and increase the chance to survival. Microarray chips appear as good possibility for finding all information about expression of MTs genes and isoforms not only in cancer, but also in other diseases, especially diabetes, obesity, cardiovascular diseases, ageing, osteoporosis, psychiatric disorders and as the effects of toxic drugs and pollutants, which is discussed in this review.

Highly abundant defense proteins in human sweat as revealed by targeted proteomics and label-free quantification mass spectrometry.

The healthy human skin with its effective antimicrobial defense system forms an efficient barrier against invading pathogens. There is evidence suggesting that the composition of this chemical barrier varies between diseases, making the easily collected sweat an ideal candidate for biomarker discoveries.

Marked genetic differences between braf and nras mutated primary melanomas as revealed by array comparative genomic hybridization

Somatic mutations of BRAF and NRAS oncogenes are thought to be among the first steps in melanoma initiation, but these mutations alone are insufficient to cause tumor progression. Our group studied the distinct genomic imbalances of primary melanomas harboring different BRAF or NRAS genotypes. We also aimed to highlight regions of change commonly seen together in different melanoma subgroups. Array comparative genomic hybridization was performed to assess copy number changes in 47 primary melanomas. BRAF and NRAS were screened for mutations by melting curve analysis. Reverse transcription PCR and fluorescence in-situ hybridization were performed to confirm the array comparative genomic hybridization results. Pairwise comparisons revealed distinct genomic profiles between melanomas harboring different mutations. Primary melanomas with the BRAF mutation exhibited more frequent losses on 10q23–q26 and gains on chromosome 7 and 1q23–q25 compared with melanomas with the NRAS mutation. Loss on the 11q23–q25 sequence was found mainly in conjunction with the NRAS mutation. Primary melanomas without the BRAF or the NRAS mutation showed frequent alterations in chromosomes 17 and 4. Correlation analysis revealed chromosomal alterations that coexist more often in these tumor subgroups. To find classifiers for BRAF mutation, random forest analysis was used. Fifteen candidates emerged with 87% prediction accuracy. Signaling interactions between the EGF/MAPK–JAK pathways were observed to be extensively altered in melanomas with the BRAF mutation. We found marked differences in the genetic pattern of the BRAF and NRAS mutated melanoma subgroups that might suggest that these mutations contribute to malignant melanoma in conjunction with distinct cooperating oncogenic events.

Hemochromatosis (HFE) gene mutations and hepatitis C virus infection as risk factors for porphyria cutanea tarda in Hungarian patients

Aim: It is not clear whether the mutations in hemochromatosis (HFE) gene and hepatitis C virus (HCV) infection act independently in the pathogenesis of porphyria cutanea tarda (PCT). The prevalence of both risk factors varies greatly in different parts of the world. PCT patients from Hungary were evaluated to assess both factors.