Polypeptide from Chlamys farreri inhibits UVB-induced HaCaT cells apoptosis via inhibition CD95 pathway and reactive oxygen species

Polypeptide from Chlamys farreri (PCF) is a novel marine active product isolated from gonochoric Chinese scallop Chlamys farreri which has recently been found to be an effective antioxidant. In this study, we assessed the effect of PCF on UVB-induced intracellular signalling of apoptosis in HaCaT cells. Pre-treatment with PCF significantly inhibited UVB-induced apoptosis in HaCaT cells. PCF strongly reduced the intracellular reactive oxygen species (ROS) level followed by inhibiting the release of cytochrome c. The expression of CD95 and Fas-associating protein with death domain (FADD) was eliminated in a dose-dependent manner by PCF pre-treatment in UVB-irradiated HaCaT cells, followed by inhibition of cleavage of procaspase-8, whose activation induced cell apoptosis. Furthermore, pre-treatment with the ROS scavenger N-acetylcysteine (NAC) and the caspase-8 inhibitor z-IETD-fmk was found to effectively prevent UVB-induced apoptosis, suggesting that UVB-induced HaCaT cell apoptosis was partially due to generation of ROS and activation of the caspase-8 pathway. Consequently, the protective effect of PCF against UVB irradiation in HaCaT cells is exerted by suppression of generation of ROS followed by inhibition of cytochrome c release and inactivation of Fas-FADD-caspase-8 pathway, resulting in blockage of UVB-induced apoptosis.     

Polypeptide from Chlamys farreri inhibits UVB-induced HaCaT cells apoptosis via inhibition CD95 pathway and reactive oxygen species

Polypeptide from Chlamys farreri (PCF) is a novel marine active product isolated from gonochoric Chinese scallop Chlamys farreri which has recently been found to be an effective antioxidant. In this study, we assessed the effect of PCF on UVB-induced intracellular signalling of apoptosis in HaCaT cells. Pre-treatment with PCF significantly inhibited UVB-induced apoptosis in HaCaT cells. PCF strongly reduced the intracellular reactive oxygen species (ROS) level followed by inhibiting the release of cytochrome c. The expression of CD95 and Fas-associating protein with death domain (FADD) was eliminated in a dose-dependent manner by PCF pre-treatment in UVB-irradiated HaCaT cells, followed by inhibition of cleavage of procaspase-8, whose activation induced cell apoptosis. Furthermore, pre-treatment with the ROS scavenger N-acetylcysteine (NAC) and the caspase-8 inhibitor z-IETD-fmk was found to effectively prevent UVB-induced apoptosis, suggesting that UVB-induced HaCaT cell apoptosis was partially due to generation of ROS and activation of the caspase-8 pathway. Consequently, the protective effect of PCF against UVB irradiation in HaCaT cells is exerted by suppression of generation of ROS followed by inhibition of cytochrome c release and inactivation of Fas-FADD–caspase-8 pathway, resulting in blockage of UVB-induced apoptosis.     

Fas Antigen Modulates Ultraviolet B-Induced Apoptosis of SVHK Cells: Sequential Activation of Caspases 8, 3, and 1 in the Apoptotic Process

Interferon-gamma (IFN-gamma) induces various apoptosis-related proteins, including Fas antigen (Fas) in keratinocytes. Ultraviolet B (UVB) irradiation produces "sunburn cells," a specific type of apoptosis. Previously, we reported that IFN-gamma augments Fas-dependent apoptosis of SV40-transformed human keratinocytes (SVHK cells). Caspases are a new class of cysteine proteinases that play an important role in apoptosis. We investigated the mechanism of UVB-induced apoptosis by examining activation of the caspase cascade. UVB irradiation of SVHK cells increased the activities of caspases 1, 3, and 8, which were detected at 3 h, and peak activities occurred at 6 h. Pretreatment of SVHK cells with IFN-gamma significantly increased the activity of caspases 1, 3, and 8. UVB-induced caspase 8 stimulation was significantly suppressed only by caspase 8 inhibitor, while inhibitors of caspases 1, 3, and 8 significantly suppressed UVB-induced caspase 1 stimulation. Caspase 3 and 8 inhibitors, but not caspase 1 inhibitor, significantly suppressed UVB-induced caspase 3 activity, suggesting sequential activation of caspases 8, 3, and 1 in UVB-irradiated SVHK cells. Cross-linking and immunoprecipitation analyses showed multimerization of Fas antigen following UVB irradiation of SVHK cells. Pretreatment of SVHK cells with IFN-gamma significantly augmented UVB-induced apoptosis that was accompanied by increased Fas expression. The susceptibility to UVB-induced apoptosis was also increased in Fas-transfected SVHK cells (F2 cells). Neutralizing anti-Fas antibody significantly suppressed caspase activation and Fas-dependent apoptosis of SVHK cells and F2 cells. In contrast, UVB-induced caspase activation and apoptosis were not inhibited by neutralizing anti-Fas antibody in both cell lines. Our results suggest that UVB directly activates Fas and subsequent caspase cascade resulting in apoptosis of SVHK cells. Furthermore, the expression level of Fas antigen in keratinocytes influenced their susceptibility to UVB-induced apoptosis.     

Potentiation of UVB-induced apoptosis by novel phytosphingosine derivative, tetraacetyl phytosphingosine in HaCaT cell and mouse skin

Inappropriate apoptosis results in the epidermal hyperplasia as in psoriasis and UVB irradiation has been successfully used to treat this kind of skin disorders. Previously, we reported that the novel phytosphingosine derivative, tetraacetyl phytosphingosine (TAPS) induced apoptosis in HaCaT cells. This study examined the effect of UVB irradiation and/or TAPS on the induction of apoptosis in HaCaT. 10 mJ/cm2 of UVB irradiation or 10 microM of TAPS alone exhibited weak cytotoxicity but co-treatment of UVB and TAPS synergistically enhanced the cytotoxicity and apoptosis in HaCaT. The cells treated with UVB and TAPS showed much higher levels of cleaved caspase-3, -8, -9 and Bax than with UVB or TAPS alone, whereas Bcl-2 level was decreased by co-administration of UVB and TAPS. In hairless mice, co-treatment of UVB and TAPS synergistically increased apoptosis, as shown in the HaCaT co-treated with UVB and TAPS. Furthermore, UVB irradiation caused an increase of apoptotic cells in the epidermis and the TAPS-treated mice showed an increase of apoptotic cells in the dermis as well as in the epidermis. These results suggest that the TAPS co-treatment synergistically increases the level of UVB-induced apoptosis via caspase activation by regulating the level of pro-apoptotic Bax and anti-apoptotic Bcl-2.     

Crude polysaccharide from an anti-UVB cell clone of <Emphasis Type="Italic">Bupleurum scorzonerifolium</Emphasis> protect HaCaT cells against UVB-induced oxidative stress

Bupleurum scorzonerifolium Willd has been found to have a wide range of immunopharmacologic functions. We isolated an anti-UVB B. scorzonerifolium cell clone and found elevated level of polysaccharides. In this study, we investigated the ability of crude polysaccharide (CP) from the anti-UVB B. scorzonerifolium cell clone to inhibit UVB-induced photodamage using a human skin keratinocyte cell line, HaCaT. Cells were UVB irradiated and then incubated in presence of different concentrations of CP. MTT assay showed that the CP did not induce cytotoxic effect under 10 mg/mL and after UVB irradiation, CP can inhibit UVB-induced HaCaT cell death. Decreased reactive oxygen species and lipid peroxidation and increased superoxide dismutase activity showed that CP can act as a free radical scavenger. Furthermore, CP had a strong protective ability against UVB-induced DNA damage. These effects were compared to the crude polysaccharide (CP′) from normal B. scorzonerifolium callus at concentration of 20 mg/mL. The portion of crude polysaccharide (CP) from the anti-UVB B. scorzonerifolium cell clone was more than 2.5-fold higher than crude polysaccharide (CP′) from normal B. scorzonerifolium callus. Taken together, the protective mechanisms of crude polysaccharide from the anti-UVB B. scorzonerifolium cell clone against UVB-induced photodamage occur by the inhibition of UVB-induced reactive oxygen species production, lipid peroxidation and DNA damage.     

Polypeptide from Chlamys farreri inhibits murine thymocytes apoptosis and modulates UVB induced signaling pathway activation

Polypeptide from Chlamys farreri (PCF) has been identified as a potent antioxidant and photoprotective agent. In this study, we investigated whether PCF could inhibit apoptosis of murine thymocytes induced by ultraviolet B (UVB) and modulate UVB induced the mitogen-activated protein kinases (MAPKs) cascade in vitro. Our results show that PCF inhibit UVB-induced apoptotic cell death in murine thymocytes. We also found that PCF potently stimulated the phosphorylation of ERKs, which is involved in the cell survival-signaling cascade. Furthermore, the specific inhibition of the ERKs pathways by PD98059 reduced the cytoprotective effect of PCF. On the other hand, the JNKs and p38 inhibitor SP600125 and SB203580 additively enhanced the cytoprotective effect of PCF. We concluded that the activation of JNKs and p38 kinase played an important role in UVB-induced apoptosis, and PCF likely exerted its cytoprotective effect in thymocytes through ERKs activation. These suggested that part of the antiapoptotic effect of PCF might be mediated by its ability to modulate the MAPKs cascade.     

The Protecting Effect of Deoxyschisandrin and Schisandrin B on HaCaT Cells against UVB-Induced Damage

Schisandra chinensis is a traditional Chinese medicine that has multiple biological activities, including antioxidant, anticancer, tonic, and anti-aging effects. Deoxyschisandrin (SA) and schisandrin B (SB), the two major lignans isolated from S. chinensis, exert high antioxidant activities in vitro and in vivo by scavenging free radicals, such as reactive oxygen species (ROS). Ultraviolet B-ray (UVB) radiation induces the production of ROS and DNA damage, which eventually leads to cell death by apoptosis. However, it is unknown whether SA or SB protects cells against UVB-induced cellular DNA damage. Our study showed that both SA and SB effectively protected HaCaT cells from UVB-induced cell death by antagonizing UVB-mediated production of ROS and induction of DNA damage. Our results showed that both SA and SB significantly prevented UVB-induced loss of cell viability using 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assays. Dichloro-dihydro-fluorescein diacetate (DCFH-DA) assays showed that the production of ROS following UVB exposure was inhibited by treatment with SA and SB. Moreover, SA and SB decreased the UVB-induced DNA damage in HaCaT cells by comet assays. In addition, SA and SB also prevented UVB-induced cell apoptosis and the cleavage of caspase-3, caspase-8 and caspase-9. In a word, our results imply that the antioxidants SA and SB could protect cells from UVB-induced cell damage via scavenging ROS.     

Protective effect of inositol hexaphosphate against UVB damage in HaCaT cells and skin carcinogenesis in SKH1 hairless mice

UVB radiation damages keratinocytes, potentially inducing chronic skin damage, cutaneous malignancy, and suppression of the immune system. Naturally occurring agents have been considered for prevention and treatment of various kinds of cancer, including skin cancer. Inositol hexaphosphate (IP6), an antioxidant, is a naturally occurring polyphosphorylated carbohydrate that has shown a strong anticancer activity in several experimental models. We assessed the protective effects of IP6 against UVB irradiationinduced injury and photocarcinogenesis by using HaCaT cells (human immortalized keratinocytes) and SKH1 hairless mice. We found that IP6 counteracts the harmful effects of UVB irradiation and increases the viability and survival of UVB-exposed cells. Treatment with IP6 after UVB irradiation (30 mJ/cm(2)) arrested cells in the G(1) and G(2) M phases while decreasing the S phase of the cell cycle. Treatment with IP6 also decreased UVB-induced apoptosis and caspase 3 activation. Topical application of IP6 followed by exposure to UVB irradiation in SKH1 hairless mice decreased tumor incidence and multiplicity as compared with control mice. Our results suggest that IP6 protects HaCaT cells from UVB-induced apoptosis and mice from UVB-induced tumors.     

The roles of Akt and NOSs in regulation of VLA-4-mediated melanoma cell adhesion to endothelial VCAM-1 after UVB-irradiation

UVB-reduced avidity between M624 melanoma and HUVEC cells is dependent on the interaction of VLA-4 with its endothelial ligand VCAM-1. Our previous studies suggested that a spatial organization of α4 integrin, one of the two subunits of VLA-4, on the melanoma cell surface contributed to the changes in avidity for VCAM-1 upon UVB-irradiation. In this study, we demonstrate that Akt plays an important role in regulation of the expression and surface level of α4 integrin on melanoma cells upon UVB-irradiation. While the cell surface level of α4 integrin is not significantly affected by UVB-irradiation or Akt inhibitor alone, it is dynamically altered after UVB-irradiation when Akt is inhibited. Inhibition of Akt also reverses the reduction of avidity of cells after the irradiation. Our data also shows that UVB reduces the level of Akt. The inhibition of Akt activity correlates with a reduced amount of coupled cNOS and reduced amount of iNOS after UVB-irradiation. However, the effect of NOSs on melanoma cell adhesion appears due to their roles in regulation of apoptosis after UVB-irradiation. Base on these results, we propose that the UVB-induced reduction of avidity of melanoma cells is coordinatively regulated by NOSs and Akt through two differential mechanisms.     

Resveratrol Couples Apoptosis with Autophagy in UVB-Irradiated HaCaT Cells

UVB radiation causes about 90% of non-melanoma skin cancers by damaging DNA either directly or indirectly by increasing levels of reactive oxygen species (ROS). Skin, chronically exposed to both endogenous and environmental pro-oxidant agents, contains a well-organised system of chemical and enzymatic antioxidants. However, increased or prolonged free radical action can overwhelm ROS defence mechanisms, contributing to the development of cutaneous diseases. Thus, new strategies for skin protection comprise the use of food antioxidants to counteract oxidative stress. Resveratrol, a phytoalexin from grape, has gained a great interest for its ability to influence several biological mechanisms like redox balance, cell proliferation, signal transduction pathways, immune and inflammatory response. Therefore, the potential of resveratrol to modify skin cell response to UVB exposure could turn out to be a useful option to protect skin from sunlight-induced degenerative diseases. To investigate into this matter, HaCaT cells, a largely used model for human skin keratinocytes, were treated with 25 or 100 µM resveratrol for 2 and 24 hours prior to UVB irradiation (10 to 100 mJ/cm²). Cell viability and molecular markers of proliferation, oxidative stress, apoptosis, and autophagy were analyzed. In HaCaT cells resveratrol pretreatment: reduces UVB-induced ROS formation, enhances the detrimental effect of UVB on HaCaT cell vitality, increases UVB-induced caspase 8, PARP cleavage, and induces autophagy. These findings suggest that resveratrol could exert photochemopreventive effects by enhancing UVB-induced apoptosis and by inducing autophagy, thus reducing the odds that damaged cells could escape programmed cell death and initiate malignant transformation.     

The role of H2O2 as a mediator of UVB-induced apoptosis in keratinocytes

Apoptosis is an active form of cell death that is initiated by a variety of stimuli, including reactive oxygen species (ROS) and ultraviolet (UV) radiation. Previously, it has been reported that UVB-irradiation of keratinocytes leads to intracellular generation of hydrogen peroxide (H₂O₂) and that antioxidants can inhibit ROS-induced apoptosis. Although both UVB-irradiation and H₂O₂-incubation led to increased intracellular H₂O₂ levels, the antioxidants catalase and glutathione monoester (GME), inhibited apoptosis only when induced by H₂O₂, not by UVB. Furthermore, extracellular signal-regulated kinase (ERK), a prominent member of the mitogen-activated protein kinase (MAPK) family, was found to be activated by treatment with both UVB and H₂O₂. Inhibition of ERK phosphorylation by pre-treatment with PD98059 resulted in enhanced apoptosis after H₂O₂-exposure. However, no significant difference of apoptosis was observed between cells with and without inhibitor pre-treatment upon UVB-irradiation. DNA damage in the form of cyclobutane pyrimidine dimers was observed after exposure to UVB, but no photoproducts were found in H₂O₂-treated cells. These results suggest a ROS-independent pathway of UVB-induced apoptosis. Although UVB-irradiation causes moderate increase in H₂O₂, the generation of H₂O₂ does not contribute to the induction of apoptosis. Moreover, activation of ERK only blocks H₂O₂-dependent apoptosis but has no impact on UVB-induced apoptosis.     

Protective effect of green tea polyphenols against ultraviolet B-induced damage to HaCaT cells

Many deleterious effects on the skin have been associated with the ultraviolet B (UVB) portion of the solar spectrum. The role of green tea polyphenols (GTP) in protecting HaCaT cells against the UVB-induced damages was examined. The promotion effect of low level GTP on cell viability was revealed in a dose-dependent manner. High level GTP had a cytotoxic effect. UVB induced destruction of HaCaT cells, including shedding of cell membrane microvilli, degeneration of nucleus and nucleols and changes of mitochondrial size and internal cristae. GTP alleviated the UVB-induced destructive morphological changes in HaCat cells. It is considered that GTP affords protection against the UVB-induced stress via both interacting with UVB-induced reactive oxygen species and attenuating mitochondrion-mediated apoptosis.     

Decreased ceramide transport protein (CERT) function alters sphingomyelin production following UVB irradiation

Increased cellular ceramide accounts in part for UVB irradiation-induced apoptosis in cultured human keratinocytes with concurrent increased glucosylceramide but not sphingomyelin generation in these cells. Given that conversion of ceramide to non-apoptotic metabolites such as sphingomyelin and glucosylceramide protects cells from ceramide-induced apoptosis, we hypothesized that failed up-regulation of sphingomyelin generation contributes to ceramide accumulation following UVB irradiation. Because both sphingomyelin synthase and glucosylceramide synthase activities were significantly decreased in UVB-irradiated keratinocytes, we investigated whether alteration(s) in the function of ceramide transport protein (or CERT) required for sphingomyelin synthesis occur(s) in UVB-irradiated cells. Fluorescently labeled N-(4,4-difluoro-5,7-dimethyl-4-bora-3a,4a-diaza-s-indacene-3-pentanoyl)-d-erythro-sphingosine (C(5)-DMB-ceramide) relocation to the Golgi was diminished after irradiation, consistent with decreased CERT function, whereas the CERT inhibitor N-(3-hydroxy-1-hydroxymethyl-3-phenylpropyl)dodecanamide (1R,3R isomer) (HPA-12) produced an equivalent effect. UVB irradiation also induced the rapid formation of a stable CERT homotrimer complex in keratinocytes as determined by Western immunoblot and mass spectrometry analyses, a finding replicated in HeLa, HEK293T, and HaCaT cells and in murine epidermis. Ceramide binding activity was decreased in recombinant CERT proteins containing the UVB-induced homotrimer. The middle region domain of the CERT protein was required for the homotrimer formation, whereas neither the pleckstrin homology (Golgi-binding) nor the START (ceramide-binding) domains were involved. Finally like UVB-treated keratinocytes, HPA-12 blockade of CERT function increased keratinocyte apoptosis, decreased sphingomyelin synthesis, and led to accumulation of ceramide. Thus, UVB-induced CERT homotrimer formation accounts, at least in part, for apoptosis and failed up-regulation of sphingomyelin synthesis following UVB irradiation, revealing that inactive CERT can attenuate a key metabolic protective mechanism against ceramide-induced apoptosis in keratinocytes.     

Arsenite pre-conditioning reduces UVB-induced apoptosis in corneal epithelial cells through the anti-apoptotic activity of 27 kDa heat shock protein (HSP27)

Exposure to ultraviolet (UV) light poses a health risk for eye disease, and solar ultraviolet in the B range (UVB, 280-320 nm) is known to be related to various corneal disorders. In this study, we investigated whether pre-conditioning of cells with arsenite (AsO2(-1)) can reduce UVB-induced apoptosis in human corneal epithelial cells, and whether the anti-apoptotic activity of 27 kDa heat shock protein (HSP27), a small heat shock protein, plays a role in this protection. UVB at levels comparable to physiologic solar exposure induces apoptosis of corneal epithelial cells in culture, demonstrated by activation of caspase 9 and caspase 3, and DNA fragmentation. When cells were pre-conditioned with arsenite prior to UVB exposure, the UVB-induced cell death was reduced, and UVB-induced activation of caspases and DNA fragmentation was inhibited. When cells were pre-treated with SB 203580, which inhibits HSP27 phosphorylation through inhibition of p38 MAP kinase activation, the arsenite-induced reduction of UVB-induced apoptosis was partially reversed. Arsenite pre-conditioning inhibited UVB-induced apoptosis in a two-phase pattern, which was temporally correlated with arsenite-induced HSP27 expression and phosphorylation. Neutralization of intracellular HSP27 with its antibody reduced arsenite's inhibition of UVB-induced caspase3 activation. Our results suggest that forms of stress that upregulate HSP27 and its phosphorylation may be useful as novel approaches to prevent adverse ocular effects arising from UV exposure in humans.     

Sustained release of Smac/DIABLO from mitochondria commits to undergo UVB-induced apoptosis

Apoptotic response of keratinocytes to UVB irradiation has physiological significance on photocarcinogenesis. Here, we show that the sustained release of Smac/DIABLO from mitochondria is an important event for the onset of apoptosis in keratinocytes exposed to UVB irradiation. In human keratinocyte HaCaT cells, UVB irradiation at 500 J/m², but not at 150 J/m², induces apoptosis. Significant activations of caspases-9 and -3, and slight activation of caspase-7 were observed only in 500 J/m² UVB irradiated HaCaT cells. Correspondingly, the cleavage of PARP, a substrate of caspases-3 and -7, was detected in cells irradiated at 500 J/m² UVB, but not at 150 J/m². However, with both 150 and 500 J/m² UVB irradiation, cytochrome c, an activator of caspase-9 via the formation of apoptosome, was released from mitochondria to the cytosol at the same extent. In contrast, significant amounts of Smac/DIABLO are released from mitochondria to the cytosol only with 500 J/m² UVB irradiation, and that the level of XIAP is decreased. These results suggest that the extent of Smac/DIABLO efflux from mitochondria is a determinant whether a cell will undergo apoptosis or survival.     

NADPH oxidase and cyclooxygenase mediate the ultraviolet B-induced generation of reactive oxygen species and activation of nuclear factor-kappaB in HaCaT human keratinocytes

The detrimental effects of ultraviolet B (UVB) irradiation have been connected with the enhanced generation of reactive oxygen species (ROS) by UVB. However, the exact source of ROS produced by UVB has not been clearly revealed yet. In this study, we determined the source of ROS production and its role in the UVB-induced activation of nuclear factor (NF)-kappaB in HaCaT human keratinocytes. UVB irradiation generated ROS in a dose-dependent manner, and this was significantly inhibited by diphenylene iodonium (DPI), apocynin (Apo) and neopterine (Neo), inhibitors of the NADPH oxidase, and indomethacin (Indo), a cyclooxygenase (COX) inhibitor, but not by the mitochondrial electron transport inhibitors and other cytosolic enzyme inhibitors. In addition, these inhibitors of the NADPH oxidase and COX significantly blocked the UVB irradiation-induced nuclear translocation of NF-kappaB. These results suggest that the NADPH oxidase and COX may be major sources for the UVB-induced ROS generation, and play an essential role in the activation of NF-kappaB which is involved in the expression of a variety of genes induced by UVB in HaCaT cells. These results further suggest that these enzymes may be good targets for the preventive strategy of UVB-induced skin injury.     

Involvement of ROS/ASMase/JNK signalling pathway in inhibiting UVA-induced apoptosis of HaCaT cells by polypeptide from Chlamys farreri

Polypeptide from Chlamys farreri (PCF), a novel marine active material isolated from gonochoric Chinese scallop C. farreri, has potential antioxidant activity and protective effect against ultraviolet (UV) irradiation. The aim was to investigate whether PCF protects HaCaT cells from apoptosis induced by UVA and explore related molecular mechanisms. The results showed that PCF significantly prevented UVA-induced apoptosis of HaCaT cells. PCF not only strongly reduced the intracellular reactive oxygen species (ROS) production, but also diminished expression of acid sphingomyelinase (ASMase) and phosphorylated JNK in HaCaT cells radiated by UVA in a dose-dependent manner. Pre-treatment with ROS scavenger NAC, ASMase inhibitor Desipramine or JNK inhibitor SP600125 was found to effectively prohibit UVA-induced apoptosis and Desipramine markedly blocked phosphorylation of JNK. So it is concluded that PCF obviously protects HaCaT cells from apoptosis induced by UVA and protective effects may attribute to decreasing intracellular ROS level and blocking ASMase/JNK apoptotic signalling pathway.     

Involvement of ROS/ASMase/JNK signalling pathway in inhibiting UVA-induced apoptosis of HaCaT cells by polypeptide from Chlamys farreri

Polypeptide from Chlamys farreri (PCF), a novel marine active material isolated from gonochoric Chinese scallop C. farreri, has potential antioxidant activity and protective effect against ultraviolet (UV) irradiation. The aim was to investigate whether PCF protects HaCaT cells from apoptosis induced by UVA and explore related molecular mechanisms. The results showed that PCF significantly prevented UVA-induced apoptosis of HaCaT cells. PCF not only strongly reduced the intracellular reactive oxygen species (ROS) production, but also diminished expression of acid sphingomyelinase (ASMase) and phosphorylated JNK in HaCaT cells radiated by UVA in a dose-dependent manner. Pre-treatment with ROS scavenger NAC, ASMase inhibitor Desipramine or JNK inhibitor SP600125 was found to effectively prohibit UVA-induced apoptosis and Desipramine markedly blocked phosphorylation of JNK. So it is concluded that PCF obviously protects HaCaT cells from apoptosis induced by UVA and protective effects may attribute to decreasing intracellular ROS level and blocking ASMase/JNK apoptotic signalling pathway.     

6]-Gingerol prevents UVB-induced ROS production and COX-2 expression in vitro and in vivo

[6]-Gingerol, a naturally occurring plant phenol, is one of the major components of fresh ginger (Zingiber officinale Roscoe, Zingiberaceae) and has diverse pharmacologic effects. Here, we describe its novel anti-oxidant, anti-apoptotic, and anti-inflammatory activities in vitro and in vivo. In vitro, pre-treatment with [6]-gingerol reduced UVB-induced intracellular reactive oxygen species levels, activation of caspase-3, -8, -9, and Fas expression. It also reduced UVB-induced expression and transactivation of COX-2. Translocation of NF-kappaB from cytosol to nucleus in HaCaT cells was inhibited by [6]-gingerol via suppression of IkappaBalpha phosphorylation (ser-32). Examination by EMSAs and immunohistochemistry showed that topical application of [6]-gingerol (30 microM) prior to UVB irradiation (5 kJ/m(2)) of hairless mice, also inhibited the induction of COX-2 mRNA and protein, as well as NF-kappaB translocation. These results suggest that [6]-gingerol could be an effective therapeutic agent providing protection against UVB-induced skin disorders.