Enhanced expression of protein kinase C gene caused by solar radiation

Korean red ginseng powder in the treatment of melasma: an uncontrolled observational study

Exposure to the sun, ultraviolet radiation, and oxidative stress are the chief etiologic factors responsible for melasma. The ingredients of Korean red ginseng powder, which include ginsenoside and phenolic compounds, have antioxidative effects and reduce ultraviolet B-induced pigmentation. This study was designed to evaluate the effectiveness and safety of Korean red ginseng powder in patients with melasma. In 25 female patients, 3 g of Korean red ginseng powder was orally administered for a 24 week period. The level of pigmentation and erythema were determined and clinical improvement was evaluated by the melasma area and severity index (MASI), melasma quality of life scale (MELASQoL), and patient- and investigator-rated global improvement scale. After 24 weeks, the MASI score decreased from 8.8 to 5.6, and MELASQoL showed improvement in 91% of patients (p<0.05). The mean level of pigmentation decreased from 184.3 to 159.7 and erythema levels decreased from 253.6 to 216.4 (p<0.05). Additionally, 74% of the patients showed some improvement in both patient- and investigator-rated global improvement scales at week 24. Korean red ginseng powder was well tolerated by most of the patients. In conclusion, Korean red ginseng powder showed good tolerability and beneficial effects in patients with melasma. The use of Korean red ginseng would be counted as a useful adjunctive therapy for patients with melasma.

Rac1 mediates dendrite formation in response to melanocyte stimulating hormone and ultraviolet light in a murine melanoma model

Melanocytes are pigment producing cells that reside in the basal layer of the epidermis, and form multiple long dendritic processes that transport melanosomes from the melanocyte cell body to the dendritic tips, and then to keratinocytes. Dendrite formation requires actin polymerization in the newly forming dendrite, and dendrite formation in melanocytes is stimulated by hormones and ultraviolet light. The rho-subfamily of monomeric guanosine triphosphate-binding proteins is implicated in remodeling the cellular actin cytoskeleton, resulting in the formation of filopodia, lamellipodia, and stress fibers, as well as in oncogenesis and activation of the Jun/p38 mitogen activated kinase cascade. In this paper we show that rac1 induces the formation of dendrite-like structures when activated mutants are transiently expressed in B16F1 murine melanoma cells and in four human melanoma cell lines. Activated mutants of cdc42 and rhoA induced the formation of filopodia and stress fibers, respectively, in B16F1 cells, but not dendrites. A dominant negative inhibitor of rac1 abrogated the ability of alpha-melanocyte stimulating hormone, a peptide hormone known to stimulate melanocyte dendrite formation, and ultraviolet light, to induce dendrite formation in B16F1 cells, and alpha-melanocyte stimulating hormone and ultraviolet light stimulated the localization of rac1 to dendrite cell membranes. These results suggest that rac1 is an important signaling intermediate in dendrite formation in B16F1 cells, and that rac1 mediates the well-known ability of alpha-melanocyte stimulating hormone and ultraviolet light to induce dendrite formation.

Mechanisms of radiation-induced gene responses

While identifying genes differentially expressed in cells exposed to ultraviolet radiation, we identified a transcript with a 25-nucleotide region that is highly conserved among a variety of species, including Bacillus circulans, pumpkin, yeast, Drosophila, mouse, and man. In the 5' untranslated region of a gene, the sequence is predominantly in a +/+ orientation with respect to the coding DNA strand; while in the coding region and the 3' untranslated region, the sequence is most frequently in a -/+ orientation. The element is found in many different genes that have diverse functions. Gel mobility shift assays demonstrated the presence of a protein in HeLa cell extracts that binds to the sense and antisense single-stranded consensus oligomers, as well as to double-stranded oligonucleotide. When double-stranded oligomer was used, the size shift demonstrated an additional protein-oligomer complex larger than the one bound to either sense or antisense single-stranded consensus oligomers alone. This element may bind to protein(s) that maintain DNA in a single-stranded orientation for transcription, or be important in the transcription-coupled DNA repair process.

HIV expression is induced in dying cells

Using HeLa cells stably transfected with an HIV-LTR-CAT construct, we demonstrated a peak in CAT induction that occurs in viable (but not necessarily cell-division-competent) cells 24 h following exposure to some cell-killing agents. gamma rays were the only cell-killing agent which did not induce HIV transcription; this can be attributed to the fact that gamma-ray-induced apoptotic death requires functional p53, which is not present in HeLa cells. For all other agents, HIV-LTR induction was dose-dependent and correlated with the amount of cell killing that occurred in the culture. Doses which caused over 99% cell killing induced HIV-LTR transcription maximally, demonstrating that cells that will go on to die by 14 days are the cells expressing HIV-LTR-CAT.

alpha-Tocopherol, an inhibitor of epidermal lipid peroxidation, prevents ultraviolet radiation from suppressing the skin immune system

We investigated the involvement of epidermal lipid peroxidation in the induction of ultraviolet radiation (UVR)-induced suppression of the skin immune system. The shaved dorsal skin of C3H/HeJ mice was irradiated with one of two subinflammatory solar-simulated UVR protocols 3 days per week for 4 weeks. Then half of 1 mg, 1, 2.5 or 5 mg alpha-tocopherol in a vehicle of acetone was topically applied to the shaved dorsal skin before UVR, A 5 mg dose of vitamin E gave complete protection against a UVR protocol that induced a 55% reduction in the contact hypersensitivity response to 2,4,6-trinitrochlorobenzene and a 23% reduction in epidermal Langerhans cell density. Lower doses were ineffective. alpha-Tocopherol was unable to protect against a higher UVR protocol. As 5 mg alpha-tocopherol did not prevent postirradiation inflammatory edema it is unlikely that the antioxidant acted as a sunscreen. However, 5 mg alpha-tocopherol inhibited UVR-induced epidermal lipid peroxidation, suggesting that this may be one mechanism by which alpha-tocopherol prevented UVR-induced local immunosuppression. Scavenging of UVR-generated lipid peroxides and reactive oxygen may have inhibited loss of cell membrane integrity preventing depletion of LC numbers, thus protecting from local immunosuppression.

Biphasic response of the metallothionein promoter to ultraviolet radiation in human melanoma cells

Because metallothionein (MT) is elevated and may be protective in UV-irradiated skin, we have studied the effects of UV and other agents on MT transcription using the sheep MT 1A promoter, linked to the beta-galactosidase gene and stably transfected into human cell lines. beta-galactosidase reporter activity was inducible by adding Zn2+ ions to the medium (100 microM for 2-4 h). Two differentiating agents, butyric acid and azelaic bishydroxamic acid (ABHA), significantly increased the response to Zn2+ in a melanoma cell line (MM96L-gal). UVB (280-315 nm) had two distinct, time-dependent effects. During the first 4 h after irradiation, high doses of UVB inhibited induction by Zn2+, an effect that was made more acute by simultaneous exposure to the differentiating agents. These changes in reporter activity were not due to alterations in Zn2+ transport into the cell. The UVB-depressed MT response subsequently recovered and by 24 h was double the control, yet remained sensitive to ABHA. Reporter activity in transfected HeLa cells differed from that in MM96L, being depressed 4 and 24 h after UVB and insensitive to ABHA at both times. Galactosidase reporter activity driven by non-MT promoters was not affected by these treatments. Dependence of MT transcriptional activity on UV-related DNA damage could be inferred because equitoxic UVC (254 nm) affected the response to Zn2+ in a similar fashion, whereas UVA, cisplatin and a methylating agent had no effect. The MT response was partly dependent on the PKC signal transduction pathway because it was inhibited by phorbol ester in HeLa, and by bisindolyl maleimide in HeLa and MM96L. The biphasic MT transcriptional response may model a signal transduction pathway that gives an early, depressed response to acute UV damage, with exacerbation by concurrent differentiation stimuli, but switches to a positive, cell-specific and potentially protective response at later times.

The effects of the broadband UVA radiation on myeloid leukemia cells: the possible role of protein kinase C in mediation of UVA-induced effects

We examined the effects of broadband UVA radiation (320-400 nm) on a rat myeloid leukemia cell line-chloroma (ChL). A Phillips face tanner model HB 171/A was used as a light source. Chloroma were irradiated through a 5 mm thick glass filter that cut off all of the UVB contamination. The irradiances were measured, from 250 to 400 nm, with a well-characterized and calibrated double-grating spectroradiometer Optronic 742. The overall uncertainty of dose evaluation was estimated to be +/-15% (2 sigma). The cells were irradiated with UVA doses of 4 and 8 J/cm2 and cultured thereafter for 24 h. After this period of time, a marked decline up to 50% was observed in cell proliferation in UVA-irradiated ChL cultures. The cell proliferation decline was found to be caused by simultaneously occurring G2/M phase cell cycle arrest and apoptosis in part of the UVA-irradiated ChL population. Concomitantly, with the decline in cell proliferation, an increase was observed in the expression of the major histocompatibility (MHC) class I and II antigens. Because protein kinase C (PKC) is known to regulate cell proliferation, apoptosis and expression of MHC antigens, and because UVA was shown to regulate PKC activity/expression, we therefore examined whether UVA irradiation has any effect on the expression of isozymes of PKC. Western blots revealed that ChL express alpha, beta I, delta, epsilon, eta, and zeta/iota isozymes of PKC and that expression of all isozymes declined 24 h after UVA irradiation (8 J/cm2). Finally, PKC activation in ChL by exposure to phorbol ester caused cell cycle arrest in G1 phase but did not induce apoptosis. This suggests that the previously shown UVA-induced PKC activation in ChL might be responsible for the induction of MHC antigens but the simultaneously observed ChL apoptosis is likely to be mediated by PKC down-regulation. All together, our results suggest that UVA, at irradiance levels that resemble the outdoor exposure, may have profound effects on the immune-related properties of leukocytes. Thus, we speculate that in vivo the immune functions of leukocytes passing through dermal capillaries might be altered by exposure to solar UVA radiation.

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

The wavelength dependence for the regulation of two major matrix-metalloproteinases, interstitial collagenase (MMP-1) and stromelysin-1 (MMP-3), and their major inhibitor, tissue inhibitor of metalloproteinases (TIMP-1), was studied in human dermal fibroblasts in vitro. Monochromatic irradiation at 302, 307, 312 and 317 nm with intensities ranging from 20 to 300 J/m2 increased MMP-1 and MMP-3 mRNA steady-state levels and the secretion of the corresponding proteins up to 4.4-fold, whereas almost no increase was observed at wavelengths < 290 nm. In contrast, the synthesis of TIMP-1 increased only marginally. This imbalance may contribute to the severe connective tissue damage related to photoaging of the skin. The wavelengths responsible for MMP-1 and MMP-3 induction reported here are distinct from the absorption spectrum of DNA and are different from results previously reported in the literature. Importantly, they overlap with wavelengths whose intensity is predicted to increase on the earth's surface upon ozone depletion. Intensities and particular wavelengths used in our studies in vitro can be absorbed readily by fibroblasts within the skin in vivo and, thus, are relevant for risk assessment and development of protective agents.

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

The wavelength dependence for the regulation of two major matrix-metalloproteinases, interstitial collagenase (MMP-1) and stromelysin-1 (MMP-3), and their major inhibitor, tissue inhibitor of metalloproteinases (TIMP-1), was studied in human dermal fibroblasts in vitro. Monochromatic irradiation at 302, 307, 312 and 317 nm with intensities ranging from 20 to 300 J/m2 increased MMP-1 and MMP-3 mRNA steady-state levels and the secretion of the corresponding proteins up to 4.4-fold, whereas almost no increase was observed at wavelengths < 290 nm. In contrast, the synthesis of TIMP-1 increased only marginally. This imbalance may contribute to the severe connective tissue damage related to photoaging of the skin. The wavelengths responsible for MMP-1 and MMP-3 induction reported here are distinct from the absorption spectrum of DNA and are different from results previously reported in the literature. Importantly, they overlap with wavelengths whose intensity is predicted to increase on the earth's surface upon ozone depletion. Intensities and particular wavelengths used in our studies in vitro can be absorbed readily by fibroblasts within the skin in vivo and, thus, are relevant for risk assessment and development of protective agents.

DNA damage enhances melanogenesis

Although the ability of UV irradiation to induce pigmentation in vivo and in vitro is well documented, the intracellular signals that trigger this response are poorly understood. We have recently shown that increasing DNA repair after irradiation enhances UV-induced melanization. Moreover, addition of small DNA fragments, particularly thymine dinucleotides (pTpT), selected to mimic sequences excised during the repair of UV-induced DNA photoproducts, to unirradiated pigment cells in vitro or to guinea pig skin in vivo induces a pigment response indistinguishable from UV-induced tanning. Here we present further evidence that DNA damage and/or the repair of this damage increases melanization. (i) Treatment with the restriction enzyme Pvu II or the DNA-damaging chemical agents methyl methanesulfonate (MMS) or 4-nitroquinoline 1-oxide (4-NQO) produces a 4- to 10-fold increase in melanin content in Cloudman S91 murine melanoma cells and an up to 70% increase in normal human melanocytes, (ii) UV irradiation, MMS, and pTpT all upregulate the mRNA level for tyrosinase, the rate-limiting enzyme in melanin biosynthesis. (iii) Treatment with pTpT or MMS increases the response of S91 cells to melanocyte-stimulating hormone (MSH) and increases the binding of MSH to its cell surface receptor, as has been reported for UV irradiation. Together, these data suggest that UV-induced DNA damage and/or the repair of this damage is an important signal in the pigmentation response to UV irradiation. Because Pvu II acts exclusively on DNA and because MMS and 4-NQO, at the concentrations used, primarily interact with DNA, such a stimulus alone appears sufficient to induce melanogenesis. Of possible practical importance, the dinucleotide pTpT mimics most, if not all, of the effects of UV irradiation on pigmentation, tyrosinase mRNA regulation, and response to MSH without the requirement for antecedent DNA damage.

Prevention of photocarcinogenesis by topical administration of pure epigallocatechin gallate isolated from green tea

Topical application of purified (-)-epigallocatechin-3-gallate (EGCG), a polyphenolic antioxidant isolated from green tea, inhibited photocarcinogenesis in BALB/cAnNHsd mice with no visible toxicity. Mice were treated with 0, 10, or 50 mg of EGCG in 200 microliters of acetone three times weekly for three weeks before ultraviolet (UV) treatments began and throughout the experiment. UV radiation consisted of five 30-minute exposures per week to banks of six FS40 Westinghouse sunlamps for 25 weeks. In the photocarcinogenesis study, mice received a total dose of approximately 2.1 x 10(6) J/m2. Skin cancer incidence in UV-irradiated mice was 96% at 28 weeks after the first UV treatment; EGCG at 10 or 50 mg reduced this incidence to 62% and 29%, respectively. UV-induced immunosuppression, assessed by the inability of UVB-irradiated mice to reject a syngeneic antigenic tumor, was not influenced by topical EGCG. Oral administration of 0, 100, or 500 mg of pure EGCG per liter of drinking water (approximately 0, 0.56, or 2.8 mg/day, respectively) did not decrease UV-induced skin tumor incidence, rate of primary tumor growth, or inability to reject antigenic tumors. Thus induction of skin tumors by UV radiation was significantly reduced by topical, but not by oral, administration of purified EGCG through a mechanism distinct from inhibition of photoimmunosuppression.

UV-induced changes in cell cycle and gene expression within rabbit lens epithelial cells

Damage to lens epithelial cells is a probable initiation process in cataract formation mediated by UV radiation. In these experiments, we investigated the effects of exposure to 254 nm radiation on cell cycle progression and gene expression in the rabbit lens epithelial cell line N/N1003A. The RNA was harvested at various times following exposure to UV (254 nm) radiation and analyzed by dot-blot and northern blot hybridizations. These results revealed that during the first 6 h following exposure of the cells to UV, there was, associated with decreasing dose, a decrease in accumulation of transcripts specific for histones H3 and H4 and an increase in the mRNA encoding protein kinase C and beta- and gamma-actin. Using flow cytometry, we detected an accumulation of cells in G1/S phase of the cell cycle 1 h following exposure to 254 nm radiation. The observed changes in gene expression, especially the decreased accumulation of histone transcripts reported here, may play a role in UV-induced inhibition of cell cycle progression.

Long-wave ultraviolet radiation causes increase of membrane-bound fraction of protein kinase C in rat myeloid leukemia cells

We examined the effect of long-wave ultraviolet radiation (UVA) on protein kinase C (PKC) and on the proliferation of rat myeloid leukemia cell line (ChL). Exposure of cells to a single dose of UVA (8 J/cm2 at 372 +/- 10 nm) caused a rapid increase in the quantity of the membrane-bound PKC, as assessed by 3H-phorbol ester (3H-PMA) binding assay (performed at 4 degrees C). Within 2 h of UVA irradiation, three peaks of increased 3H-PMA binding to the ChL cells (by 70-100%) were observed at ca. 20, 60 and 95 min post-irradiation. The exposure of ChL to UVA caused also a rapid, but transient, decline in the cell proliferation rate (by 18% within 24 h). However, the statistically significant decrease in cell numbers was observed only 3 days later (down by 22%). The inhibition of ChL proliferation was not due to alteration of cell viability as determined by trypan blue exclusion assay, and neither was it caused by cell cycle arrest or apoptosis, as determined by flow cytometry analysis of propidium iodide-labelled cells and cell morphology in May-Grünvald-Giemsa-stained cell smears. Phorbol-ester-induced activation of PKC (performed at 37 degrees C) caused inhibition of ChL proliferation similar to that caused by UVA. This suggests that a UVA-induced increase of the membrane-bound fraction of PKC may be responsible for the UVA-induced inhibition of ChL proliferation.

Reassessment of the differential effects of ultraviolet and ionizing radiation on HIV promoter: the use of cell survival as the basis for comparisons

Effects of different radiation treatments on the human immunodeficiency virus-1 (HIV) promoter were reassessed for exposures comparable to those encountered in clinical or cosmetic practice, using survival of the host cell as a basis for comparisons. The exposures were performed with two ultraviolet radiation sources commonly used as medical or cosmetic devices (UVASUN 2000 and FS20 lamps), a germicidal (G15T8) lamp and an X-ray machine. The UVC component of the FS20 lamp was filtered out. The emission spectra of the lamps were determined. The characteristics of these sources allowed us to discriminate among effects of UVA1 (340-400 nm), UVB + UVA2 (280-340 nm) and UVC (254 nm) radiations. Effects of irradiation were ascertained using cultures of HeLa cells stably transfected with the HIV promoter linked to a reporter-chloramphenicol acetyl transferase-gene. The exposures used caused at least two logs of cell killing. In this cytotoxicity range, UVA1 or X radiations had no effect on the HIV promoter, whereas UVB + UVA2 or UVC radiations activated the HIV promoter in a fluence-dependent manner. Survivals following exposure to UVB + UVA2 or UVC radiation were (1) at the lowest measurable HIV promoter activation, 30 and 20%, respectively, (2) at one-half maximal activation, 6 and 3%, respectively and (3) at the maximal activation, 0.5 and 0.2%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Ultraviolet A decreases epidermal growth factor (EGF) processing in cultured human fibroblasts and keratinocytes: inhibition of EGF-induced diacylglycerol formation

The binding, uptake, and degradation of epidermal growth factor (EGF) has been studied in MRC5 human fibroblasts and NCTC 2544 human keratinocytes following ultraviolet A (UVA) irradiation at doses up to 18.9 J/cm2, which are not lethal to cells under our experimental conditions. A dose-dependent reduction in EGF binding was observed, with an approximately 75% decrease at the maximal studied UVA dose. At lower doses (6 to 12 J/cm2), EGF binding was more affected by ultraviolet A in fibroblasts than in keratinocytes. In both cell types, this effect of UVA appeared to be related to a reduction of the affinity of the EGF receptor for EGF. Kinetic studies by pulse-chase experiments indicated that EGF is more rapidly internalized by keratinocytes than by fibroblasts, and that UVA exposure resulted in a slower decay of EGF intracellular content. A 24-h pretreatment of cells with 5 x 10(-5) M vitamin E strongly reduced the appearance of light-induced lipid peroxidation products, measured via assay of thiobarbituric acid reactive substances formation, but only partially prevented the UVA-induced alterations of EGF processing by cells. Finally, UVA exposure almost completely abolished the EGF-induced increase in diacylglycerol production from 14C-arachidonic acid-labeled lipids in both cell types. These results demonstrate that UVA radiation induces important changes in EGF processing and could participate in the light-induced degenerative processes of the skin.

Evidence for the photoprotective effects of vitamin E

The antioxidant vitamin E (alpha-tocopherol) may protect both animal and plant cell membranes from light-induced damage. The various biochemical and biophysical modes of protection are considered. An examination is made of the evidence that vitamin E plays an important prophylactic role against a number of serious light-induced diseases and conditions of the eye (cataractogenesis and retinal photodeterioration) and skin (erythrocyte photohemolysis, photoerythema, photoaging and photocarcinogenesis) that are mediated by photooxidative damage to cell membranes.

Regulation of the Skin Immune System by Retinoids During Carcinogenesis

One of the immunosuppressive effects of both ultraviolet (UV) light and chemical carcinogens is to deplete Langerhans cells (LC) from the epidermis, suggesting that these cells play an important role in inducing immune responses to developing tumors during the early phases of carcinogenesis. Retinoids such as all-trans-retinoic acid (RA) are natural or synthetic derivatives of vitamin A; RA binds to nuclear receptors in the skin, effecting transcription of a wide range of genes. Topical application of RA prevents the tumor promotor 12-O-tetradecanoylphorbol-13-acetate (TPA) from depleting the density of LC in murine epidermis. In contrast, topical RA did not itself alter the normal LC density. RA also inhibited the development of TPA-induced immunosuppression to a locally applied contact sensitizer. Topical RA also prevented UV light from reducing the density of both LC and Thy-1+ dendritic epidermal cells (Thy-1+ dEC). However, the RA treatment did not prevent local immunosuppression to the contact sensitizer from developing in response to UV irradiation. The reasons for this are unclear, however, it is possible that RA does not inhibit some other immunosuppressive effect of UV light. Temarotene, a recently developed synthetic retinoid also inhibited UV light from reducing the LC and Thy-1+ dEC density from murine epidermis. Thus part of the anti-carcinogenic activity of retinoids may be due to their ability to protect LC during the early stages of carcinogenesis.

Interaction of TPA and ultraviolet B radiation in regulation of ODC gene expression in rat keratinocytes

Ultraviolet B radiation (UVB) and phorbol esters are known to promote tumor formation in skin; however, the interaction between UVB and phorbol esters in the regulation of gene expression remains incompletely understood. To define the interaction of UVB and phorbol esters in the control of keratinocyte gene expression, we have studied the effects of the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) and UVB on the regulation of ornithine decarboxylase (ODC) gene expression in a rat keratinocyte cell line. Both UVB and TPA alone increased ODC activity and induced the expression of the ODC gene. The combination of UVB and TPA produced a further increment in ODC gene expression at 12 h, but UVB markedly attenuated the TPA induction of ODC mRNA transcripts at 3 h. Protein synthesis inhibition with cycloheximide also induced ODC mRNA transcripts, but did not eliminate the further induction of ODC gene expression by UVB or TPA. No changes in actin gene expression following exposure to TPA/UVB were detected in the same experiments. UVB and TPA alone or in combination had no effect on the transcriptional activity of an ODC-chloramphenicol acetyltransferase fusion gene in transfected rat keratinocytes. The results of these studies suggest a complex posttranscriptional interaction of phorbol esters and UVB in the control of keratinocyte gene expression.