Different Oxidative Stress Response in Keratinocytes and Fibroblasts of Reconstructed Skin Exposed to Non Extreme Daily-Ultraviolet Radiation

Experiments characterizing the biological effects of sun exposure have usually involved solar simulators. However, they addressed the worst case scenario i.e. zenithal sun, rarely found in common outdoor activities. A non-extreme ultraviolet radiation (UV) spectrum referred as “daily UV radiation” (DUVR) with a higher UVA (320–400 nm) to UVB (280–320 nm) irradiance ratio has therefore been defined. In this study, the biological impact of an acute exposure to low physiological doses of DUVR (corresponding to 10 and 20% of the dose received per day in Paris mid-April) on a 3 dimensional reconstructed skin model, was analysed. In such conditions, epidermal and dermal morphological alterations could only be detected after the highest dose of DUVR. We then focused on oxidative stress response induced by DUVR, by analyzing the modulation of mRNA level of 24 markers in parallel in fibroblasts and keratinocytes. DUVR significantly modulated mRNA levels of these markers in both cell types. A cell type differential response was noticed: it was faster in fibroblasts, with a majority of inductions and high levels of modulation in contrast to keratinocyte response. Our results thus revealed a higher sensitivity in response to oxidative stress of dermal fibroblasts although located deeper in the skin, giving new insights into the skin biological events occurring in everyday UV exposure

Skin color-specific and spectrally-selective naked-eye dosimetry of UVA, B and C radiations

Spectrally–selective monitoring of ultraviolet radiations (UVR) is of paramount importance across diverse fields, including effective monitoring of excessive solar exposure. Current UV sensors cannot differentiate between UVA, B, and C, each of which has a remarkably different impact on human health. Here we show spectrally selective colorimetric monitoring of UVR by developing a photoelectrochromic ink that consists of a multi-redox polyoxometalate and an e− donor. We combine this ink with simple components such as filter paper and transparency sheets to fabricate low-cost sensors that provide naked-eye monitoring of UVR, even at low doses typically encountered during solar exposure. Importantly, the diverse UV tolerance of different skin colors demands personalized sensors. In this spirit, we demonstrate the customized design of robust real-time solar UV dosimeters to meet the specific need of different skin phototypes. These spectrally–selective UV sensors offer remarkable potential in managing the impact of UVR in our day-to-day life

PTCH1+/− Dermal Fibroblasts Isolated from Healthy Skin of Gorlin Syndrome Patients Exhibit Features of Carcinoma Associated Fibroblasts

Gorlin's or nevoid basal cell carcinoma syndrome (NBCCS) causes predisposition to basal cell carcinoma (BCC), the commonest cancer in adult human. Mutations in the tumor suppressor gene PTCH1 are responsible for this autosomal dominant syndrome. In NBCCS patients, as in the general population, ultraviolet exposure is a major risk factor for BCC development. However these patients also develop BCCs in sun-protected areas of the skin, suggesting the existence of other mechanisms for BCC predisposition in NBCCS patients. As increasing evidence supports the idea that the stroma influences carcinoma development, we hypothesized that NBCCS fibroblasts could facilitate BCC occurence of the patients. WT (n = 3) and NBCCS fibroblasts bearing either nonsense (n = 3) or missense (n = 3) PTCH1 mutations were cultured in dermal equivalents made of a collagen matrix and their transcriptomes were compared by whole genome microarray analyses. Strikingly, NBCCS fibroblasts over-expressed mRNAs encoding pro-tumoral factors such as Matrix Metalloproteinases 1 and 3 and tenascin C. They also over-expressed mRNA of pro-proliferative diffusible factors such as fibroblast growth factor 7 and the stromal cell-derived factor 1 alpha, known for its expression in carcinoma associated fibroblasts. These data indicate that the PTCH1+/− genotype of healthy NBCCS fibroblasts results in phenotypic traits highly reminiscent of those of BCC associated fibroblasts, a clue to the yet mysterious proneness to non photo-exposed BCCs in NBCCS patients

In Vivo Methods for the Assessment of Topical Drug Bioavailability

This paper reviews some current methods for the in vivo assessment of local cutaneous bioavailability in humans after topical drug application. After an introduction discussing the importance of local drug bioavailability assessment and the limitations of model-based predictions, the focus turns to the relevance of experimental studies. The available techniques are then reviewed in detail, with particular emphasis on the tape stripping and microdialysis methodologies. Other less developed techniques, including the skin biopsy, suction blister, follicle removal and confocal Raman spectroscopy techniques are also described

Aging Alters Functionally Human Dermal Papillary Fibroblasts but Not Reticular Fibroblasts: A New View of Skin Morphogenesis and Aging

Understanding the contribution of the dermis in skin aging is a key question, since this tissue is particularly important for skin integrity, and because its properties can affect the epidermis. Characteristics of matched pairs of dermal papillary and reticular fibroblasts (Fp and Fr) were investigated throughout aging, comparing morphology, secretion of cytokines, MMPs/TIMPs, growth potential, and interaction with epidermal keratinocytes. We observed that Fp populations were characterized by a higher proportion of small cells with low granularity and a higher growth potential than Fr populations. However, these differences became less marked with increasing age of donors. Aging was also associated with changes in the secretion activity of both Fp and Fr. Using a reconstructed skin model, we evidenced that Fp and Fr cells do not possess equivalent capacities to sustain keratinopoiesis. Comparing Fp and Fr from young donors, we noticed that dermal equivalents containing Fp were more potent to promote epidermal morphogenesis than those containing Fr. These data emphasize the complexity of dermal fibroblast biology and document the specific functional properties of Fp and Fr. Our results suggest a new model of skin aging in which marked alterations of Fp may affect the histological characteristics of skin

Rac and Rho GTPases in cancer cell motility control

Rho GTPases represent a family of small GTP-binding proteins involved in cell cytoskeleton organization, migration, transcription, and proliferation. A common theme of these processes is a dynamic reorganization of actin cytoskeleton which has now emerged as a major switch control mainly carried out by Rho and Rac GTPase subfamilies, playing an acknowledged role in adaptation of cell motility to the microenvironment. Cells exhibit three distinct modes of migration when invading the 3 D environment. Collective motility leads to movement of cohorts of cells which maintain the adherens junctions and move by photolytic degradation of matrix barriers. Single cell mesenchymal-type movement is characterized by an elongated cellular shape and again requires extracellular proteolysis and integrin engagement. In addition it depends on Rac1-mediated cell polarization and lamellipodia formation. Conversely, in amoeboid movement cells have a rounded morphology, the movement is independent from proteases but requires high Rho GTPase to drive elevated levels of actomyosin contractility. These two modes of cell movement are interconvertible and several moving cells, including tumor cells, show an high degree of plasticity in motility styles shifting ad hoc between mesenchymal or amoeboid movements. This review will focus on the role of Rac and Rho small GTPases in cell motility and in the complex relationship driving the reciprocal control between Rac and Rho granting for the opportunistic motile behaviour of aggressive cancer cells. In addition we analyse the role of these GTPases in cancer progression and metastatic dissemination

Overexpression of caveolin-1 and -2 in cell lines and in human samples of inflammatory breast cancer

Inflammatory breast cancer (IBC) is the most aggressive form of locally advanced breast cancer (LABC). The IBC phenotype is characterized by an infiltrative growth pattern, increased (lymph)angiogenesis and the propensity to invade dermal lymphatics. In pancreatic cancer, interactions between caveolin-1 and RhoC GTPase, a key molecule in causing the IBC phenotype, regulate tumour cell motility and invasion. In this study we sought to investigate the role of caveolin-1 and -2 in IBC cell lines and in human IBC samples.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44235/1/10549_2005_Article_9002.pd

P16(INK4A) is implicated in both the immediate and adaptative response of human keratinocytes to UVB irradiation

The P16(INK4A-ARF) locus plays a crucial role in the control of cellular proliferation via both the Rb and P53 pathways. We previously demonstrated that this locus is altered in human skin carcinomas. In the present study we have studied the expression of the p16(INK4A-ARF) locus following UVB irradiation of normal human keratinocytes both at the mRNA (RT-PCR) and at the protein (Western blotting) levels. Our data confirmed that P16(INK4A) protein is induced by UVB at low (30 mJ cm(2)) and high (100 mJ cm(2)) doses and is observed after a single or repeated exposure implying that this response is involved in both the immediate and adaptative response to UVB. The apparent absence of induction p16(INK4A) mRNA suggested that P16(INK4A) protein is upregulated at the post-transcriptional level. Analysis by flow cytometry and BrdU staining indicated that the highest protein level of P16(INK4A) in the cells was associated with a G(2) cell cycle arrest. Comparative analysis of P16(INK4A) and P53 showed that they were differentially modulated in keratinocytes according to the UVB dose and regimen. Low, acute or repeated UVB exposures led to accumulation of both P16(INK4A) and p53, whereas at high UVB doses, P53 and P53-dependent genes were not induced or even downregulated and only a slight but reproducible stabilization of P16(INK4A) protein was observed. In our conditions, P14(ARF) did not seem to participate in the UV response in these cells as P14(ARF) protein did not vary. These results infer that P16(INK4A) plays a role in cell cycle regulation of keratinocytes submitted to UVB irradiation. They also reinforce our previous demonstration of the importance of inactivation of this gene in UV-induced skin carcinogenesis