Ultraviolet B wavelength dependence for the regulation of two major matrix-metalloproteinases and their inhibitor TIMP-1 in human dermal fibroblasts

The Human Epidermal Basement Membrane: A Shaped and Cell Instructive Platform That Aging Slowly Alters

One of the most important functions of skin is to act as a protective barrier. To fulfill this role, the structural integrity of the skin depends on the dermal-epidermal junction—a complex network of extracellular matrix macromolecules that connect the outer epidermal layer to the underlying dermis. This junction provides both a structural support to keratinocytes and a specific niche that mediates signals influencing their behavior. It displays a distinctive microarchitecture characterized by an undulating pattern, strengthening dermal-epidermal connectivity and crosstalk. The optimal stiffness arising from the overall molecular organization, together with characteristic anchoring complexes, keeps the dermis and epidermis layers extremely well connected and capable of proper epidermal renewal and regeneration. Due to intrinsic and extrinsic factors, a large number of structural and biological changes accompany skin aging. These changes progressively weaken the dermal–epidermal junction substructure and affect its functions, contributing to the gradual decline in overall skin physiology. Most changes involve reduced turnover or altered enzymatic or non-enzymatic post-translational modifications, compromising the mechanical properties of matrix components and cells. This review combines recent and older data on organization of the dermal-epidermal junction, its mechanical properties and role in mechanotransduction, its involvement in regeneration, and its fate during the aging process.

Fighting against Skin Aging: The Way from Bench to Bedside

As the most voluminous organ of the body that is exposed to the outer environment, the skin suffers from both intrinsic and extrinsic aging factors. Skin aging is characterized by features such as wrinkling, loss of elasticity, laxity, and rough-textured appearance. This aging process is accompanied with phenotypic changes in cutaneous cells as well as structural and functional changes in extracellular matrix components such as collagens and elastin. In this review, we summarize these changes in skin aging, research advances of the molecular mechanisms leading to these changes, and the treatment strategies aimed at preventing or reversing skin aging.

Coordinated activation of a cluster of MMP genes in response to UVB radiation

Ultraviolet (UV) B radiation is a dangerous environmental stressor, which can lead to photoaging, inflammation, immune suppression and tumour formation. A recent report has shown the transcriptional activation of several skin-specific genes including matrix metalloproteases (MMPs) in response to UV irradiation. Here, we use a novel human keratinocyte model, HKerE6SFM, to demonstrate that UVB activates the transcription of most members of the 11q22.3 MMP gene cluster including MMP13, MMP12, MMP3, MMP1 and MMP10. Curiously, the expression of the well-characterized UVB-inducible MMP9, which is located outside of the cluster, remains unchanged. In accordance with the increased expression of the MMP gene cluster upon UVB irradiation, RNA polymerase II showed increased occupancy at their promoters following UVB irradiation. The results also demonstrate increased acetylated histone H3K9 levels at the promoters of the MMP13, MMP12, MMP3, MMP1 and MMP10 genes. These findings suggest a coordinated transcriptional activation of genes in the MMP cluster at 11q22.3 and that acetylation of histone H3 at lysine 9 has an important role in the UVB-dependent enhancement of transcription of MMP genes in this region.

Upregulation of MMP12 and its activity by UVA1 in human skin: potential implications for photoaging

UVA1 constitutes around 75% of the terrestrial UV radiation, and most of the output of artificial tanning sources. However, the molecular effects of UVA1 in human skin in vivo are surprisingly poorly understood. We have examined time-dependent whole-genome expression, along with mRNA and protein changes in the skin after one minimal erythema dose of spectrally pure UVA1 (50 J cm(-2)) and 300 nm UVB (30 mJ cm(-2)). After 24 hours, the genes induced to the greatest extent were those involved in extracellular matrix remodeling with both UVA1 (P=5.5e-7) and UVB (P=2.9e-22). UVA1 and UVB caused different effects on matrix metalloproteinase (MMP) expression: UVB induced MMP1, MMP3, and MMP10 mRNA at 24 hours to a much greater extent than UVA1. MMP12 induction by UVA1 at 6 hours is marked and much greater than that by UVB. We have found that MMP12 mRNA induction by UVA1 resulted in expression of MMP12 protein, which is functional as an elastase. This induction of elastase activity did not occur with UVB. We hypothesize that the UVA1 induction of MMP12 mediates some of its photoaging effects, particularly by contributing to elastin degeneration in late solar elastosis. MMP12 is a good marker of UVA1 exposure.

Anti-photoaging potential of Botulinum Toxin Type A in UVB-induced premature senescence of human dermal fibroblasts in vitro through decreasing senescence-related proteins

This study was aimed to evaluate the anti-photoaging effects of Botulinum Toxin Type A (BoNTA) in Ultraviolet B-induced premature senescence (UVB-SIPS) of human dermal fibroblasts (HDFs) in vitro and the underlying mechanism. We established a stress-induced premature senescence model by repeated subcytotoxic exposures to Ultraviolet B (UVB) irradiation. The aging condition was determined by cytochemical staining of senescence-associated β-galactosidase (SA-β-gal). The tumor suppressor and senescence-associated protein levels of p16(INK-4a), p21(WAF-1), and p53 were estimated by Western blotting. The G1 phase cell growth arrest was analyzed by flow cytometry. The mRNA expressions of p16, p21, p53, COL1a1, COL3a1, MMP1, and MMP3 were determined by real-time PCR. The level of Col-1, Col-3, MMP-1, and MMP-3 were determined by ELISA. Compared with the UVB-irradiated group, we found that the irradiated fibroblasts additionally treated with BoNTA demonstrated a decrease in the expression of SA-β-gal, a decrease in the level of tumor suppressor and senescence-associated proteins, a decrease in the G1 phase cell proportion, an increase in the production of Col-1 and Col-3, and a decrease in the secretion of MMP-1 and MMP-3, in a dose-dependent manner. Taken together, these results indicate that BoNTA significantly antagonizes premature senescence induced by UVB in HDFs in vitro, therefore potential of intradermal BoNTA injection as anti-photoaging treatment still remains a question.

Gardenia jasminoides Extract Attenuates the UVB-Induced Expressions of Cytokines in Keratinocytes and Indirectly Inhibits Matrix Metalloproteinase-1 Expression in Human Dermal Fibroblasts

Ultraviolet radiation (UV) is a major cause of photoaging, which also involves inflammatory cytokines and matrix metalloproteinases (MMP). The present study was undertaken to examine the UVB-protecting effects of yellow-colored plant extracts in cell-based assays. HaCaT keratinocytes were exposed to UVB in the absence or presence of plant extracts, and resulting changes in cell viability and inflammatory cytokine expression were measured. Of the plant extracts tested, Gardenia jasminoides extract showed the lowest cytotoxicity and dose-dependently enhanced the viabilities of UVB-exposed cells. Gardenia jasminoides extract also attenuated the mRNA expressions of interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) in HaCaT cells stimulated by UVB. Conditioned medium from UVB-exposed HaCaT cells was observed to stimulate MMP-1 protein expression in human dermal fibroblasts, and this effect was much smaller for the conditioned medium of HaCaT cells exposed to UVB in the presence of Gardenia jasminoides extract. Gardenia jasminoides extract also exhibited antioxidative and antiapoptotic effects in HaCaT cells exposed to UVB. These results indicated that UVB-induced injury and inflammatory responses of skin cells can be attenuated by yellow-colored plant extracts, such as Gardenia jasminoides extract.

Involvement of MIF in basement membrane damage in chronically UVB-exposed skin in mice

Solar ultraviolet (UV) B radiation is known to induce matrix metalloproteinases (MMPs) that degrade collagen in the basement membrane. Macrophage migration inhibitory factor (MIF) is a pluripotent cytokine that plays an essential role in the pathophysiology of skin inflammation induced by UV irradiation. This study examined the effects of MIF on basement membrane damage following chronic UVB irradiation in mice. The back skin of MIF transgenic (Tg) and wild-type (WT) mice was exposed to UVB three times a week for 10 weeks. There was a decrease in intact protein levels of type IV collagen and increased basement membrane damage in the exposed skin of the MIF Tg mice compared to that observed in the WT mice. Moreover, the skin of the MIF Tg mice exhibited higher MIF, MMP-2 and MMP-9 expression and protein levels than those observed in the WT mice. We also found that chronic UVB exposure in MIF Tg mice resulted in higher levels of neutrophil infiltration in the dermis compared with that observed in the WT mice. In vitro experiments revealed that MIF induced increases in the MMPs expression, including that of MMP-9 in keratinocytes and MMP-2 in fibroblasts. Cultured neutrophils also secreted MMP-9 stimulated by MIF. Therefore, MIF-mediated basement membrane damage occurs primarily through MMPs activation and neutrophil influx in murine skin following chronic UVB irradiation.

Skin anti-aging strategies

Skin aging is a complex biological process influenced by a combination of endogenous or intrinsic and exogenous or extrinsic factors. Because of the fact that skin health and beauty is considered one of the principal factors representing overall "well-being" and the perception of "health" in humans, several anti-aging strategies have been developed during the last years. It is the intention of this article to review the most important anti-aging strategies that dermatologists have nowadays in hand, including including preventive measurements, cosmetological strategies, topical and systemic therapeutic agents and invasive procedures.

Preventive Effects of β-Thujaplicin Against UVB-Induced MMP-1 and MMP-3 mRNA Expressions in Skin Fibroblasts

Solar UV radiation damages human skin by affecting skin tone and resiliency and leads to premature aging (photoaging). The skin damage is caused by the activation of the AP-1 transcription factor, which increases matrix metalloproteinase (MMP) expression and collagen degradation. An increase of interleukin (IL)-6 is also correlated with the activation of MMP-1 expression. β-thujaplicin has shown both acaricidal and antimicrobial activities. Also, β-thujaplicin has been shown to be protective against apoptosis due to the oxidative effects of UV irradiation. However, the effect of β-thujaplicin on UVB-induced MMPs had not been investigated. In this study, after UVB exposure, MMP-1 and IL-6 production in human skin fibroblasts was examined in the presence of β-thujaplicin, vitamin C, and vitamin E. The expression of MMP-1, MMP-3, tissue inhibitor of metalloproteinase (TIMP-1, TIMP-3) and procollagen mRNA was also investigated. Results showed that UVB-induced MMP-1 production was suppressed by the β-thujaplicin treatment in a dose-dependent manner, but not by vitamin C and vitamin E. β-thujaplicin also prevented the up-regulation of MMP-1 and MMP-3 mRNA. Moreover, the UVB-suppressed procollagen gene expression was restored to normal by β-thujaplicin. Neither UVB nor β-thujaplicin affected the mRNA expression of TIMP-1 and TIMP-3. The IL-6 production induced by UVB was lower in β-thujaplicin treated fibroblasts than in the controls. In conclusion, this study shows the capability of β-thujaplicin in preventing MMP-1 production due to UVB irradiation via inhibition of MMP gene expression. Importantly, the UVB-suppressed procollagen gene expression can be restored to normal by β-thujaplicin. These findings indicate that β-thujaplicin is a promising and potent agent to inhibit UVB-induced MMP-1 and MMP-3 gene expression in skin fibroblasts.

Sema4D, the ligand for Plexin B1, suppresses c-Met activation and migration and promotes melanocyte survival and growth

Semaphorins are secreted and membrane bound proteins involved in neural pathfinding, organogenesis, and tumor progression, through Plexin and neuropilins receptors. We recently reported that Plexin B1, the Semaphorin 4D receptor, is a tumor suppressor protein for melanoma, in part, through inhibition of the oncogenic c-Met tyrosine kinase receptor. In this report we show that Sema4D is a protective paracrine factor for normal human melanocyte survival in response to ultraviolet irradiation, that it stimulates proliferation, and regulates the activity of the c-Met receptor. c-Met receptor signaling stimulates melanocyte migration, in part through down-regulation of the cell adhesion molecule E-cadherin. Sema4D suppressed activation of c-Met in response to its ligand hepatocyte growth factor (HGF), and partially blocked the suppressive effects of HGF on E-cadherin expression in melanocytes and HGF-dependent migration. These data demonstrate a role for Plexin B1 in maintenance of melanocyte survival and proliferation in the skin, and suggest that Semaphorin 4D and Plexin B1 act cooperatively with HGF and c-Met to regulate c-Met dependent effects in human melanocytes. Because our data show that Plexin B1 is profoundly down-regulated by UVB in melanocytes, loss of Plexin B1 may accentuate HGF dependent effects on melanocytes, including melanocyte migration.

Risk factors associated with cataracts and lens luxations in captive pinnipeds in the United States and the Bahamas

OBJECTIVE

To determine risk factors for lens luxation and cataracts in captive pinnipeds in the United States and the Bahamas.

DESIGN

Cross-sectional study.

ANIMALS

111 pinnipeds (99 California sea lions [Zalophus californianus], 10 harbor seals [Phoca vitulina], and 2 walruses [Odobenus rosmarus]) from 9 facilities.

PROCEDURES

Eyes of each pinniped were examined by a veterinary ophthalmologist for the presence of cataracts or lens luxations and photographed. Information detailing husbandry practices, history, and facilities was collected with a questionnaire, and descriptive statistical analyses were performed for continuous and categorical variables. Odds ratios and associated 95% confidence intervals were estimated from the final model.

RESULTS

Risk factors for lens luxation, cataracts, or both included age >or= 15 years, history of fighting, history of ocular disease, and insufficient access to shade.

CONCLUSIONS AND CLINICAL RELEVANCE

Diseases of the lens commonly affect captive pinnipeds. Access to UV-protective shade, early identification and medical management of ocular diseases, and prevention of fighting can limit the frequency or severity of lens-related disease in this population. An extended life span may result from captivity, but this also allows development of pathological changes associated with aging, including cataracts.

Anti-photoaging and photoprotective compounds derived from marine organisms

Marine organisms form a prominent component of the oceanic population, which significantly contribute in the production of cosmeceutical and pharmaceutical molecules with biologically efficient moieties. In addition to the molecules of various biological activities like anti-bacterial, anti-cancerous, anti-inflammatory and anti-oxidative etc., these organisms also produce potential photoprotective or anti-photoaging agents, which are attracting present day researchers. Continuous exposure to UV irradiation (both UV-A and UV-B) leads to the skin cancer and other photoaging complications, which are typically mediated by the reactive oxygen species (ROS), generated in the oxidative pathways. Many of the anti-oxidative and anti-photoaging compounds have been identified previously, which work efficiently against photodamage of the skin. Recently, marine originated photoprotective or anti-photoaging behavior was observed in the methanol extracts of Corallina pilulifera (CPM). These extracts were found to exert potent antioxidant activity and protective effect on UV-A-induced oxidative stress in human dermal fibroblast (HDF) cells by protecting DNA and also by inhibiting matrix metalloproteinases (MMPs), a key component in photoaging of the skin due to exposure to UV-A. The present review depicts various other photoprotective compounds from algae and other marine sources for further elaborative research and their probable use in cosmeceutical and pharmaceutical industries.

Cordycepin inhibits UVB-induced matrix metalloproteinase expression by suppressing the NF-kappaB pathway in human dermal fibroblasts

Cordycepin (3-deoxyadenosine) has been shown to exhibit many pharmacological activities, including anti-cancer, anti-inflammatory, and anti-infection activities. However, the anti-skin photoaging effects of cordycepin have not yet been reported. In the present study, we investigated the inhibitory effects of cordycepin on matrix metalloproteinase-1 (MMP-1) and -3 expressions of the human dermal fibroblast cells. Western blot analysis and real-time PCR revealed cordycepin inhibited UVB-induced MMP-1 and -3 expressions in a dose-dependent manner. UVB strongly activated NF-kappaB activity, which was determined by IkappaBalpha degradation, nuclear localization of p50 and p65 subunit, and NF-kappaB binding activity. However, UVB-induced NF-kappaB activation and MMP expression were completely blocked by cordycepin pretreatment. These findings suggest that cordycepin could prevent UVB-induced MMPs expressions through inhibition of NF-kappaB activation. In conclusion, cordycepin might be used as a potential agent for the prevention and treatment of skin photoaging.

Expression profiling of senescent-associated genes in human dermis from young and old donors. Proof-of-concept study

It is often described that it is difficult to really discriminate the cause of intrinsic skin aging. The aim of this study was to compare the profiles of expression of senescence-associated genes in biopsies of dermis from young and old human donors. TGF-beta1 was up-regulated in the dermis of old donors as well as the TGF-beta1-regulated genes. The anti-oxidant enzymes Selenium-dependent Glutathione peroxidase and Glutatione S-Transferase Theta 1 were also up-regulated in old dermis as well as Tumor Necrosis Factor Receptor Superfamily 1A. None of these genes had altered expression level in skin fibroblasts embedded in a collagen matrix and exposed to sublethal doses of UVB, suggesting their involvement in intrinsic aging. This study represents a proof-of-concept of larger whole transcriptome studies where all avenues should be used to subtract changes in gene expression due to extrinsic aging from changes potentially due to intrinsic aging.

Interleukin-1beta and macrophage migration inhibitory factor (MIF) in dermal fibroblasts mediate UVA-induced matrix metalloproteinase-1 expression

BACKGROUND

Exposure to solar UV radiation is the main environmental factor that causes premature aging of the skin. Matrix metalloproteinases (MMP)-1 is a member of the MMP family and degrades types I and III collagens, which are the major structural components of the dermis.

OBJECTIVE

We evaluated the involvement IL-1beta and macrophage migration inhibitory factor (MIF) in MMP-1 expression under ultraviolet A (UVA) irradiation.

METHODS

IL-1beta and MIF in MMP-1 expression in cultured human dermal fibroblasts and the UVA effects on MMPs production using IL-1alpha/beta-deficient mice were analyzed. Furthermore, fibroblasts derived from MIF-deficient mice were used to analyze the effect of IL-1beta-induced MMPs production.

RESULTS

IL-1beta-enhanced MIF expression and induced MMP-1 in cultured human dermal fibroblasts. IL-1beta-induced MMP-1 expression is inhibited by neutralizing anti-MIF antibody. Dermal fibroblasts of IL-1alpha/beta-deficient mice produced significantly decreased levels of MMPs compared to wild-type mice after UVA irradiation. Furthermore, fibroblasts of MIF-deficient mice were much less sensitive to IL-1beta-induced MMPs production. On the contrary, IL-1beta produced significantly decreased levels of MMPs in MIF-deficient mice fibroblasts. The up-regulation of MMP-1 mRNA by IL-1beta stimulation was found to be inhibited by a p38 inhibitor and a JNK inhibitor. In contrast, the MEK inhibitor and inhibitor were found to have little effect on expression of MMP-1 mRNA.

CONCLUSIONS

IL-1beta is involved in the up-regulation of UVA-induced MMP-1 in dermal fibroblasts, and IL-1beta and MIF cytokine network induce MMP-1 and contribute to the loss of interstitial collagen in skin photoaging.

Ultraviolet B-induced matrix metalloproteinase-1 and -3 secretions are mediated via PTEN/Akt pathway in human dermal fibroblasts

Matrix Metalloproteinases (MMPs) are crucial enzymes for ultraviolet irradiation-induced photoaging in human skin. Ultraviolet B (UVB) stimulates dermal fibroblasts to increase MMP-1 and -3 expression and extracellular matrix (ECM) degradation in photoaging. We investigated whether phosphatase and tensin homolog (PTEN)/Akt pathway is involved in secretions of MMP-1 and -3 in human dermal fibroblasts. The increase in MMP-1 and -3 expression and secretion occurred along with the increase in PTEN and Akt phosphorylation by UVB irradiation in a dose- and time-dependent manner. However, treatment with a casein kinase 2 inhibitor, 5,6-dichloro-1-beta-D-ribofuranosyl-benzimidazole, inhibited their phosphorylations and MMP-1 and -3 secretions. Transfection of wild-type PTEN (Wt-PTEN) decreased basal and UVB-induced MMP-1 and -3 secretions, as well as activator protein-1 (AP-1) activity, while transfection of small interference RNA of PTEN (siRNA-PTEN), phosphatase-inactive PTEN (C124S-PTEN), or lipid phosphatase-inactive PTEN (G129E-PTEN) increased basal or UVB-induced MMP-1 and -3 secretions and AP-1 activity. Transfection of constitutively active Akt (Myr-Akt) also increased basal or UVB-induced MMP-1 and -3 secretions, as well as AP-1 activity. However, transfection of kinase-inactive Akt (K179M-Akt) decreased their secretions, but showed no significant change of AP-1 activity without UVB irradiation, and a significant increase of AP-1 activity with UVB irradiation. Treatment with the phosphatidylinositol 3-kinase inhibitors, LY294002 or wortmannin, downregulated basal and UVB-induced MMP-1 and -3 secretions. In conclusion, UVB irradiation increases PTEN and Akt phosphorylation in human dermal fibroblasts, and these inhibition of PTEN and activation of Akt by phosphorylation are involved in UVB-induced MMP-1 and -3 secretions partly through upregulation of AP-1 activity.

Role of macrophage migration inhibitory factor (MIF) in the skin

Macrophage migration inhibitory factor (MIF) functions as a pleiotropic protein, participating in both inflammation and immune responses. MIF was originally discovered as a lymphokine involved in delayed type hypersensitivity and various macrophage functions, including phagocytosis, and tumor surveillance. Recently, MIF has been re-evaluated as a pro-inflammatory cytokine and identified as a pituitary-derived hormone, potentiating endotoxemia. MIF is ubiquitously expressed in various tissues, including the skin. Clinical evidence of increased MIF expression in inflammatory diseases supports this potential role of MIF in inflammation. In addition to its role in inflammation, MIF has been shown to exhibit growth-promoting activity, with anti-MIF antibodies effectively suppressing tumor growth and tumor-associated angiogenesis. This review presents the latest findings on the roles of MIF in the skin with regard to inflammation, the immune response, skin disease, tumorigenesis and cutaneous wound healing, and discusses its potential functions in various pathophysiological states.

Immunohistochemical expression of matrix metalloproteinases 1, 2, 9, and 14 in dermatofibrosarcoma protuberans and common fibrous histiocytoma (dermatofibroma)

CONTEXT

Common fibrous histiocytoma (cFH) or dermatofibroma and dermatofibrosarcoma protuberans (DFSP) are 2 spindle cell mesenchymal tumors that are distinguished in part by their microscopic growth patterns and clinically by the greater propensity for DFSP to recur. Matrix metalloproteinases (MMPs) potentially play a role in modulating the growth patterns of cFH and DFSP by remodeling the extracellular matrix.

OBJECTIVE

To evaluate the immunohistochemical (IHC) expression of MMP-1, MMP-2, MMP-9, and MMP-14 in DFSP and cFH, because (1) MMP-1, MMP-2, MMP-9, and MMP-14 are synthesized by dermal fibroblasts, the major constituent of DFSP and cFH; and (2) platelet-derived growth factor B, which is overexpressed in most examples of DFSP because of t(17;22), activates ets-1, a transcription factor that regulates molecules associated with tumor invasion and metastasis, including MMP-1, MMP-3, and MMP-9.

DESIGN

Immunohistochemical studies were performed on archived, formalin-fixed, paraffin-embedded tissue of DFSP (n = 48) and cFH (n = 47).Results.-Significant IHC expression (>10% of tumor cells) in cFH included MMP-14 (27 [59%] of 46 tumors positive), MMP-2 (21 [47%] of 45 tumors positive), MMP-9 (9 [20%] of 45 tumors positive), and MMP-1 (6 [13%] of 46 tumors positive). No DFSPs showed significant IHC expression of any of the MMPs evaluated. However, anti- MMP-2 highlighted a rich microvascular element within deep tumor tissue present in 81% of DFSPs with a prominent subcutaneous component.

CONCLUSION

Our IHC results indicate that MMP-1 and MMP-9 are not up-regulated in DFSP. Convincing expression of MMP-14 in cFH suggests that this MMP may affect the growth pattern of the lesion, perhaps by activating MMP-2 expression in tumor cells. In DFSP, MMP-2 may play a role in tumor angiogenesis.

Induction of MMP-10 and MMP-1 in a squamous cell carcinoma cell line by ultraviolet radiation

Ultraviolet radiation may cause non-melanoma skin cancer by genetic and epigenetic events. In this study, we investigated in a squamous cell carcinoma cell line, SCL-1, whether UV irradiation modulates the expression of matrix metalloproteinases, known to be involved in tumor progression and metastasis by degradation of extracellular matrix components. UVA or UVB irradiation of SCL-1 resulted in a rapid transcriptional up-regulation and increased secretion of two members of the matrix metalloproteinase family, MMP-10 (stromelysin-2) and MMP-1 (interstitial collagenase). The increase in MMP-10 steady-state mRNA levels was detected 1 hour after UVA and 4 h after UVB irradiation, whereas MMP-1 was upregulated 4 h after UVA and 16 h after UVB irradiation of tumor cells. UV-induced phosphorylation of extracellular regulated kinases (ERK-1/2) and p38 stress kinase and increased binding of AP-1 transcription factor preceded the rapid stimulation of MMPs in SCL-1 cells. Incubation of cells with the MEK1/2 inhibitor U0126 or the p38 inhibitor SB202190 abolished the UVA and UVB mediated induction of MMP-1 and MMP-10. In conclusion, this study shows that UV irradiation of squamous cell carcinoma results in a rapid up-regulation of MMPs. Our results suggest that the time course of induction of target genes, like MMPs, differs between cell types depending on the stimulus.

Ultraviolet A-induced Production of Matrix Metalloproteinase-1 Is Mediated by Macrophage Migration Inhibitory Factor (MIF) in Human Dermal Fibroblasts

Matrix metalloproteinases (MMPs) are thought to be responsible for dermal photoaging in human skin. In the present study, we evaluated the involvement of macrophage migration inhibitory factor (MIF) in MMP-1 expression under ultraviolet A (UVA) irradiation in cultured human dermal fibroblasts. UVA (20 J/cm(2)) up-regulates MIF production, and UVA-induced MMP-1 mRNA production is inhibited by an anti-MIF antibody. MIF (100 ng/ml) was shown to induce MMP-1 in cultured human dermal fibroblasts. We found that MIF (100 ng/ml) enhanced MMP-1 activity in cultured fibroblasts assessed by zymography. Moreover, we observed that fibroblasts obtained from MIF-deficient mice were much less sensitive to UVA regarding MMP-13 expression than those from wild-type BALB/c mice. Furthermore, after UVA irradiation (10 J/cm(2)), dermal fibroblasts of MIF-deficient mice produced significantly decreased levels of MMP-13 compared with fibroblasts of wild-type mice. Next we investigated the signal transduction pathway of MIF. The up-regulation of MMP-1 mRNA by MIF stimulation was found to be inhibited by a PKC inhibitor (GF109203X), a Src-family tyrosine kinase inhibitor (herbimycin A), a tyrosine kinase inhibitor (genistein), a PKA inhibitor (H89), a MEK inhibitor (PD98089), and a JNK inhibitor (SP600125). In contrast, the p38 inhibitor (SB203580) was found to have little effect on expression of MMP-1 mRNA. We found that PKC-pan, PKC alpha/beta II, PKC delta (Thr505), PKC delta (Ser(643)), Raf, and MAPK were phosphorylated by MIF. Moreover, we demonstrated that phosphorylation of PKC alpha/beta II and MAPK in response to MIF was suppressed by genistein, and herbimycin A as well as by transfection of the plasmid of C-terminal Src kinase. The DNA binding activity of AP-1 was significantly up-regulated 2 h after MIF stimulation. Taken together, these results suggest that MIF is involved in the up-regulation of UVA-induced MMP-1 in dermal fibroblasts through PKC-, PKA-, Src family tyrosine kinase-, MAPK-, c-Jun-, and AP-1-dependent pathways.

Ultraviolet-B irradiation and matrix metalloproteinases: from induction via signaling to initial events

Effects of sunlight have fascinated researchers for decades because nearly every living thing on earth is likely to be exposed to sunlight and the ultraviolet (UV) fraction of it. In addition to detrimental long-term effects such as immunosuppression and skin cancer, premature aging of the skin (photoaging) is a well-documented consequence of exposure to UVA and UVB. Photoaged skin is biochemically characterized by an overgrowth of abnormal elastic fibers in the dermis and by a dramatic decrease of distinct collagen types. Ultraviolet irradiation induces delayed UV-responsive genes, among them matrix metalloproteinases, which degrade macromolecules of the extracellular matrix, a hallmark in carcinogenesis and aging. We are interested in UVB-triggered initial events and in subsequent signaling resulting in enhanced expression of two major members of the matrix metalloproteinase family, the interstitial collagenase (MMP-1) and stromelysin-1 (MMP-3), in human dermal fibroblasts. Especially, these skin cells play a central role in connective tissue breakdown in photoaging and as stromal cells in tumor invasion and metastasis by means of their capability to produce matrix metalloproteinases. In this review, we will focus on UVB-triggered induction of matrix metalloproteinases, the so far identified components of the UVB-modulated signal transduction pathway(s), and the UVB irradiation-associated generation of reactive oxygen species (ROS). Finally, a potentially novel aspect in UVB irradiation-mediated expression of interstitial collagenase and stromelysin-1-namely, the involvement of reactive nitrogen species (RNS)-is discussed.

Activation of protein kinase CK2 is an early step in the ultraviolet B-mediated increase in interstitial collagenase (matrix metalloproteinase-1; MMP-1) and stromelysin-1 (MMP-3) protein levels in human dermal fibroblasts

Enhanced expression of matrix metalloproteinase (MMP)-1/interstitial collagenase and MMP-3/stromelysin-1 in skin fibroblasts and subsequent damage of dermal connective tissue in the context of sun-induced premature aging and skin tumour progression is causally linked to UVB irradiation. Here, we were interested in identifying components of the complex signal-transduction pathway underlying UVB-mediated up-regulation of these delayed UV-responsive genes and focused on components maximally activated early after irradiation. A 2.3-fold increase in protein kinase CK2 activity was measured at 20-40 min after low-dose UVB irradiation (at 10 mJ/cm2) of dermal fibroblasts. This UVB-mediated increase in CK2 activity was abrogated by pharmacological approaches using non-toxic concentrations of the CK2 inhibitor 5,6-dichloro-1-beta-d-ribofuranosylbenzimidazole (DRB). Preincubation of fibroblasts with DRB prior to UVB irradiation lowered MMP-1 by 49-69% and MMP-3 protein levels by 55-63% compared with UVB-irradiated controls. By contrast, the CK2 inhibitor did not affect the UVB-triggered transcription of MMPs. Furthermore, UVB irradiation of fibroblasts overexpressing a kinase-inactive mutant of CK2 (CK2alpha-K68A-HA) resulted in lowering of the protein levels of MMP-1 by 25% and MMP-3 by 22% compared with irradiated fibroblasts transfected with the vector control. This reduction in MMP protein levels correlated with the transfection efficiency. Taken together, we describe a novel aspect of protein kinase CK2, namely its inducible activity by UVB irradiation, and provide evidence that CK2 is an early mediator of the UVB-dependent up-regulation of MMP-1 and MMP-3 translation, whereas their major tissue inhibitor of matrix metalloproteinase-1 is not affected by CK2.

The effects of the melatonin on ultraviolet-B irradiated cultured dermal fibroblasts

It has been reported that reactive oxygen species (ROS) and oxygen-derived free radicals are generated by ultraviolet (UV) radiation and various chemicals and their important roles in cellular damage and apoptosis are being increasingly recognized. Melatonin is a hormone with multiple functions in humans, produced by the pineal gland and stimulated by beta-adrenergic receptors. Melatonin has been shown to have photo protection properties, but there has been little progress toward identifying the specific mechanisms of its action. To clarify the role of melatonin as a free radical scavenger, in response to ultraviolet-B (UVB) irradiation, we investigated the effects of UVB and melatonin on cytotoxicity, lipid peroxidation, terminal deoxynucleotidyl transferase-mediated digoxigenin-dUTP nick end-labeling (TUNEL) assay and alteration of cell cycle in cultured skin fibroblast. Cell survival curves after UVB irradiation showed dose dependent decrement pattern by trypan blue exclusion assay. Only 56% of dermal fibroblasts were survived at 140 mJ/cm2 UVB irradiation. The damage was associated with cell membrane lipid peroxidation, as shown by accumulation malondialdehyde (MDA). By pre-cultivation with melatonin (10(-9) M), a significant preventive effect was noted on the increase in the absolute number of surviving cells (up to 92.5% of cells were survived) and the levels of MDA were markedly decreased. These finding suggest significant correlation between an increase of lipid peroxide and cell viability. Morphological changes associated with apoptotic cell death were easily distinguished by TUNEL stain. Quantitative analysis of DNA content of skin fibroblasts was evaluated by flow cytometric analysis performed after vital staining with propidium iodide. UVB suppresses the G1 progression induced pre-G1 arrest leading to apoptotic changes of dermal fibroblast and those are blocked by melatonin pre-treatment. The results show the photodynamic effects of UVB that supposes the production of ROS and arrest the cell cycle. Melatonin, which have newly accepted as a potential UV protection properties, is effective membrane peroxidation inhibitor and prevent the pre-G1 arrest when present in relevant concentration during UVB irradiation.

Urokinase activity in corneal fibroblasts may be modulated by DNA damage and secreted proteins

Proteases like urokinase-type plasminogen activator (uPA) play an important role in tumor invasion. Cells derived from ultraviolet radiation (UVR)-induced corneal sarcomas of Monodelphis domestica produce relatively high levels of uPA compared to the untransformed keratocytes suggesting a mechanism for their invasiveness. Because UVR is known to stimulate uPA production in many cell types, UVR exposure may further increase uPA expression in corneal tumor cells, thus enhancing their ability to infiltrate. We investigated control of basal uPA levels and the induction of uPA by UVR in transformed and untransformed corneal keratocytes from Monodelphis. These studies took advantage of the fact that Monodelphis possesses an active photolyase that can be stimulated to remove UVR-induced pyrimidine dimers by exposure to long-wavelength visible photoreactivating light (PRL). Our studies showed that significant induction of uPA occurred in response to 200 J/m2 UVR. This induction was partially blocked by treatment with PRL, indicating that DNA damage, the pyrimidine dimer in particular, played a role in uPA induction. In untransformed cultured corneal fibroblasts, the heparin-binding protein inhibitor, suramin, reduced basal uPA levels, UVR-induced uPA production and cell proliferation. Basic fibroblast growth factor, a heparin-binding growth factor known to be UVR-inducible in mesenchymal cells, stimulated uPA production and cell proliferation; however, anti-bFGF antibodies did not significantly decrease proliferation or basal uPA production. These findings suggested that basal levels of uPA secretion were modulated in response to heparin-binding growth factors and that these growth factors may also have mediated the effect of UVR on uPA levels.

The first peak of the UVB irradiation-dependent biphasic induction of vascular endothelial growth factor (VEGF) is due to phosphorylation of the epidermal growth factor receptor and independent of autocrine transforming growth factor alpha

Ultraviolet B (UVB) irradiation, the major damaging component of sunlight, has earlier been reported to enhance cutaneous angiogenesis in chronically sun-exposed skin. We herein provide first evidence for a biphasic induction of the vascular endothelial growth factor (VEGF) following UVB irradiation of the human epidermal cell line HaCaT. The first VEGF peak occurred on mRNA level at 1 h and on protein level at 4 h postirradiation and is fully mediated by the UVB-dependent phosphorylation of the epidermal growth factor receptor, which subsequent to its phosphorylation also initiates at least in part the synthesis of transforming growth factor alpha that confers as shown previously the second late VEGF peak at 8 h on mRNA and at 24 h on protein level.

Histological increase in inflammatory infiltrate in sun-exposed skin of female subjects: the possible involvement of matrix metalloproteinase-1 produced by inflammatory infiltrate on collagen degradation

To investigate morphological changes occurring during cutaneous photoageing, a correlation between the number of infiltrating cells in the dermis and the degree of collagen damage was examined using sections from clinically normal chronically sun-exposed and sun-protected skin of Japanese female subjects. Haematoxylin and eosin-stained sections from 134 sun-exposed (subjects aged 3-82 years) and 73 sun-protected (subjects aged 1-86 years) areas demonstrated a predominant lymphoid cell and to a lesser extent histiocyte infiltration. The mean +/- SD number of lymphoid cells and histiocytes in the sun-exposed skin sections (427.0+/-192.2 and 147.8+/-83.3 cells/mm2, respectively) was significantly higher than in the sun-protected skin sections (292.6+/-98.3 and 125.9+/-59.0 cells/mm2, respectively) (P < 0.001 and P < 0.05, respectively), and the number of lymphoid cells in the sun-exposed skin sections increased significantly with age up to 50 years (r = 0.400, P < 0.001). Sun-exposed skin sections with severe collagen degeneration had a significantly higher number of lymphoid cells than those with slightly degenerated collagen (mean 626.3 vs. 482.4 cells/mm2, P < 0.01). The mean count of mast cells in sun-exposed skin was 202.0 cells/mm2; this did not vary with the age of the subjects or the level of collagen damage. Immunohistochemical studies using 24 frozen sections identified most of the lymphoid cells infiltrating sun-exposed skin as memory T lymphocytes (CD3+, CD4+ and CD45RO+). The number of cells which displayed immunoreactivity to matrix metalloproteinase (MMP)-1 in the sun-exposed skin sections was significantly higher than in the sun-protected skin sections (mean 170.2 vs. 113.6 cells/mm2, P < 0.05). Among these cells were observed CD3 and MMP-1 double-stained T lymphocytes, and T lymphocytes contacting MMP-1-positive cells. These morphological observations suggest that T lymphocytes infiltrating photodamaged skin may play a part in the degeneration and reduction of collagen through MMP-1 activity.

Nuclear and non-nuclear targets of genotoxic agents in the induction of gene expression. Shared principles in yeast, rodents, man and plants

The interplay between environmental cues and the genetic response is decisive for the development, health and well-being of an organism. For some environmental factors a narrow margin separates beneficial and toxic impacts. With the increasing exposure to UV-B this dichotomy has reached public attention. This review will be concerned with the mechanisms that mediate a cellular genetic response to noxious agents. The toxic stimuli find access to the regulatory network inside cells by interacting at several points with cellular molecules - a process that converts the 'outside information' into 'cellular language'. As a consequence of such interactions, many adverse agents cause massive signal transduction and changes of gene expression. There is an interesting conservation of the mechanisms from yeast to man. An understanding of the genetic programs and of their phenotypic consequences is lagging behind.