Caesalpinia sappan L., belonging to the family Leguminosae, is a medicinal plant that is distributed in Southeast Asia. The dried heartwood of this plant is used as a traditional ingredient of food, red dyes, and folk medicines in the treatment of diarrhea, dysentery, tuberculosis, skin infections, and inflammation. Brazilin is the major active compound, which has exhibited various pharmacological effects, including anti-platelet activity, anti-hepatotoxicity, induction of immunological tolerance, and anti-inflammatory and antioxidant activities. The present study aimed to evaluate the antioxidant activity and expression of antioxidant enzymes of C. sappan L. extract and its major compound, brazilin, in human epidermal keratinocytes exposed to UVA irradiation. Our results indicated that C. sappan L. extract reduced UVA-induced HO production via GPX7 activation. Moreover, brazilin exhibited antioxidant effects that were similar to those of C. sappan L. via glutathione peroxidase 7 (GPX7), suggesting that C. sappan L. extract and its natural compound represent potential treatments for oxidative stress-induced photoaging of skin.
Antioxidants ; pharmacology ; Benzopyrans ; pharmacology ; Caesalpinia ; chemistry ; Humans ; Hydrogen Peroxide ; toxicity ; Keratinocytes ; cytology ; drug effects ; enzymology ; radiation effects ; Oxidative Stress ; drug effects ; radiation effects ; Peroxidases ; genetics ; metabolism ; Plant Extracts ; pharmacology ; Protective Agents ; pharmacology ; Ultraviolet Rays

PURPOSE: Acute side effects of radiation such as oral mucositis are observed in most patients. Although several potential radioprotective agents have been proposed, no effective agent has yet been identified. In this study, we investigated the effectiveness of synthetic compound 3-amino-3-(4-fluoro-phenyl)-1H-quinoline-2,4-dione (KR22332) as a radioprotective agent. MATERIALS AND METHODS: Cell viability, apoptosis, the generation of reactive oxygen species (ROS), mitochondrial membrane potential changes, and changes in apoptosis-related signaling were examined in human keratinocyte (HaCaT). RESULTS: KR22332 inhibited irradiation-induced apoptosis and intracellular ROS generation, and it markedly attenuated the changes in mitochondrial membrane potential in primary human keratinocytes. Moreover, KR22332 significantly reduced the protein expression levels of ataxia telangiectasia mutated protein, p53, and tumor necrosis factor (TNF)-alpha compared to significant increases observed after radiation treatment. CONCLUSION: KR22332 significantly inhibited radiation-induced apoptosis in human keratinocytes in vitro, indicating that it might be a safe and effective treatment for the prevention of radiation-induced mucositis.
Apoptosis/drug effects/physiology ; Cell Line, Tumor ; Cell Survival/drug effects/physiology ; Humans ; Keratinocytes/metabolism ; Membrane Potential, Mitochondrial/drug effects/physiology ; Radiation-Protective Agents/chemistry/*pharmacology ; Reactive Oxygen Species/metabolism

PURPOSE: Acute side effects of radiation such as oral mucositis are observed in most patients. Although several potential radioprotective agents have been proposed, no effective agent has yet been identified. In this study, we investigated the effectiveness of synthetic compound 3-amino-3-(4-fluoro-phenyl)-1H-quinoline-2,4-dione (KR22332) as a radioprotective agent. MATERIALS AND METHODS: Cell viability, apoptosis, the generation of reactive oxygen species (ROS), mitochondrial membrane potential changes, and changes in apoptosis-related signaling were examined in human keratinocyte (HaCaT). RESULTS: KR22332 inhibited irradiation-induced apoptosis and intracellular ROS generation, and it markedly attenuated the changes in mitochondrial membrane potential in primary human keratinocytes. Moreover, KR22332 significantly reduced the protein expression levels of ataxia telangiectasia mutated protein, p53, and tumor necrosis factor (TNF)-alpha compared to significant increases observed after radiation treatment. CONCLUSION: KR22332 significantly inhibited radiation-induced apoptosis in human keratinocytes in vitro, indicating that it might be a safe and effective treatment for the prevention of radiation-induced mucositis.
Apoptosis/drug effects/physiology ; Cell Line, Tumor ; Cell Survival/drug effects/physiology ; Humans ; Keratinocytes/metabolism ; Membrane Potential, Mitochondrial/drug effects/physiology ; Radiation-Protective Agents/chemistry/*pharmacology ; Reactive Oxygen Species/metabolism

This study is to investigate the effect and mechanism of puerarin on DNA damage of HaCaT cells induced by UVB. Puerarin pre-treated cells were irradiated with UVB at 30 mJ x cm(-2). Twenty four hours after irradiation, DNA damage was detected by comet assay, ceramide was measured by thin layer chromatography and gas chromatography, intracellular free calcium ion was analyzed by flow cytometry, the phosphorylation level of p38 protein was examined by Western blotting method. Levels of DNA damage, ceramide, free calcium ion and p-p38 protein were elevated in UVB model cells. Contrary to the model group, all indicators above were reduced in all groups pre-treated by puerarin. Puerarin restrains the ceramide accumulation to block downstream p38 MAPK pathway and calcium ion rising, therefore reduces DNA damage in HaCaT cells induced by UVB.
Calcium ; metabolism ; Cell Line ; Ceramides ; metabolism ; DNA Damage ; drug effects ; radiation effects ; Down-Regulation ; Humans ; Isoflavones ; pharmacology ; Keratinocytes ; cytology ; metabolism ; Phosphorylation ; Signal Transduction ; drug effects ; Ultraviolet Rays ; adverse effects ; p38 Mitogen-Activated Protein Kinases ; metabolism

12(S)-Hydroxyheptadeca-5Z,8E,10E-trienoic acid (12-HHT) is an enzymatic product of prostaglandin H2 (PGH2) derived from cyclooxygenase (COX)-mediated arachidonic acid metabolism. Despite the high level of 12-HHT present in tissues and bodily fluids, its precise function remains largely unknown. In this study, we found that 12-HHT treatment in HaCaT cells remarkably down-regulated the ultraviolet B (UVB) irradiation-induced synthesis of interleukin-6 (IL-6), a pro-inflammatory cytokine associated with cutaneous inflammation. In an approach to identify the down-stream signaling mechanism by which 12-HHT down-regulates UVB-induced IL-6 synthesis in keratinocytes, we observed that 12-HHT inhibits the UVB-stimulated activation of p38 mitogen-activated protein kinase (MAPK) and nuclear factor kappa B (NF-kappaB). In addition, we found that 12-HHT markedly up-regulates MAPK phosphatase-1 (MKP-1), a critical negative regulator of p38 MAPK. When MKP-1 was suppressed by siRNA knock-down, the 12-HHT-mediated inhibitory effects on the UVB-stimulated activation of p38 MAPK and NF-kappaB, as well as the production of IL-6, were attenuated in HaCaT cells. Taken together, our results suggest that 12-HHT exerts anti-inflammatory effect via up-regulation of MKP-1, which negatively regulates p38 MAPK and NF-kappaB, thus attenuating IL-6 production in UVB-irradiated HaCaT cells. Considering the critical role of IL-6 in cutaneous inflammation, our findings provide the basis for the application of 12-HHT as a potential anti-inflammatory therapeutic agent in UV-induced skin diseases.
Anti-Inflammatory Agents, Non-Steroidal/pharmacology ; Cell Line ; Dual Specificity Phosphatase 1/biosynthesis/genetics ; Enzyme Activation ; Fatty Acids, Unsaturated/*pharmacology ; Humans ; Interleukin-6/*biosynthesis ; Keratinocytes/*metabolism/radiation effects ; NF-kappa B/metabolism ; RNA Interference ; RNA, Small Interfering ; Receptors, Leukotriene B4/genetics ; Signal Transduction/drug effects ; Skin Diseases/drug therapy ; *Ultraviolet Rays ; Up-Regulation ; p38 Mitogen-Activated Protein Kinases/metabolism

Skin exposure to low-dose ultraviolet B (UVB) light up-regulates the expression of matrix metalloproteinase-1 (MMP-1), thus contributing to premature skin aging (photo-aging). Although cyclooxygenase-2 (COX-2) and its product, prostaglandin E2 (PGE2), have been associated with UVB-induced signaling to MMP expression, very little are known about the roles of lipoxygenases and their products, especially leukotriene B4 (LTB4) and 12(S)-hydroxyeicosatetraenoic acid (12(S)-HETE), in MMP-1 expression in skin keratinocytes. In the present study, we demonstrate that BLT2, a cell surface receptor for LTB4 and 12(S)-HETE, plays a critical role in UVB-mediated MMP-1 upregulation in human HaCaT keratinocytes. Moreover, our results demonstrated that BLT2-mediated MMP-1 upregulation occurs through a signaling pathway dependent on reactive oxygen species (ROS) production and the subsequent stimulation of ERK. Blockage of BLT2 via siRNA knockdown or with the BLT2-antagonist LY255283 completely abolished the up-regulated expression of MMP-1 induced by low-dose UVB irradiation. Finally, when HaCaT cells were transiently transfected with a BLT2 expression plasmid, MMP-1 expression was significantly enhanced, along with ERK phosphorylation, suggesting that BLT2 overexpression alone is sufficient for MMP-1 up-regulation. Together, our results suggest that the BLT2-ROS-ERK-linked cascade is a novel signaling mechanism for MMP-1 upregulation in low-dose UVB-irradiated keratinocytes and thus potentially contributes to photo-aging.
12-Hydroxy-5,8,10,14-eicosatetraenoic Acid/biosynthesis ; Cell Line ; Extracellular Signal-Regulated MAP Kinases/metabolism ; Humans ; Keratinocytes/metabolism/*radiation effects ; Leukotriene B4/biosynthesis ; Matrix Metalloproteinase 1/*biosynthesis ; Phosphorylation ; Reactive Oxygen Species/metabolism ; Receptors, Leukotriene B4/*physiology ; Signal Transduction ; Ultraviolet Rays/*adverse effects

OBJECTIVETo investigate the mechanism involved in aging process of immortalized human keratinocyte (HaCaT) and primary human epidermis keratinocyte of adults (HEKa) irradiated by ultraviolet B(UVB).

METHODSHEKa and HaCaT were repeatedly exposed to UVB at a subcytotoxic level. SA-beta-Gal staining was performed to evaluate the senescence state; flow cytometry was applied to detect the changes of apoptosis, necrosis and cell cycle. Intracellular levels of superoxide dismutase (SOD) and malondialdehyde (MDA) were measured by ELISA method. Western blot was performed to detect the expression pattern of redox protein p66Shc and RT-PCR was performed to determine the mRNA level of human telomerase reverse transcriptase (hTERT).

RESULTStrong positive SA-beta-Gal staining was observed in both HEKa cell and HaCaT cells after UVB irradiation. Apoptosis rate increased from (1.81 +/-0.25)% to (4.43 +/-0.28)% and necrosis rate increased from (0.05 +/-0.01)% to (0.10 +/-0.03)% in HaCaT cell, but no marked arrest of cell cycle was observed during UVB irradiation. As a contrast, apoptosis rate of in HEKa cells significantly increased from (0.65 +/-0.05)% to (59.53 +/-2.35)%, and the necrosis rate in HEKa cells also reached (3.89 +/-0.24)%(P<0.05). Growth arrest in G0/G1 phase was also found in HEKa cells. In both cell lines, intracellular level of SOD decreased and MDA increased remarkably after UVB exposure, and an increased expression of p66Shc protein was also observed. High level of hTERT mRNA was detected in HaCaT cells and UVB exposure had little effect on its expression.

CONCLUSIONThe stress-induced premature senescence (SIPS) in HaCaT and HEKa cell lines by UVB irradiation might be closely associated with increased intracellular levels of oxidative stress, not related to the telomerase expression.

Apoptosis ; Cell Line ; Cells, Immobilized ; radiation effects ; Cellular Senescence ; physiology ; radiation effects ; Humans ; Keratinocytes ; cytology ; radiation effects ; Malondialdehyde ; metabolism ; Skin ; cytology ; Superoxide Dismutase ; metabolism ; Telomerase ; genetics ; metabolism ; radiation effects ; Ultraviolet Rays ; beta-Galactosidase ; pharmacology

OBJECTIVETo explore the involvement of p38 and ERK signal transduction pathways in UVB-induced cell apoptosis.

METHODSHaCat cells were exposed to UVB irradiation for 1, 3, 5, 10, and 15 min, respectively, after which the cell survival was assessed using MTT assay, and the cell apoptosis observed under fluorescent microscope with Hoechst staining. Western blotting was used to examine the possible signal transduction pathway involved in the cell apoptosis following the exposures.

RESULTSFor the same incubation time following the exposure, the cell survival rate decreased gradually with the increase of UVB irradiation dose. At a fixed UVB irradiation dose, prolonged cell incubation following the exposure resulted in decreased cell survival rate, which, however, began to increase after the minimum rate was reached. At different UVB doses, cell exposure for 5 min caused the highest cell apoptosis rate, which peaked at 12 h during the post-irradiation incubation. The expressions of p38 and p53 were significantly decreased while p44/42 expression remained unchanged in the exposed cells.

CONCLUSIONUVB irradiation can induce growth inhibition and apoptosis of HaCat cells in a dose- and time-dependent manner, and p38 pathway other than ERK pathway is probably involved in UVB-induced cell apoptosis.

Apoptosis ; radiation effects ; Cells, Cultured ; Extracellular Signal-Regulated MAP Kinases ; metabolism ; Humans ; Keratinocytes ; cytology ; metabolism ; radiation effects ; Signal Transduction ; radiation effects ; Ultraviolet Rays ; p38 Mitogen-Activated Protein Kinases ; metabolism

OBJECTIVETo explore the effect of millimeter wave exposure at low power density on gene expression in human keratinocytes (HaCaT).

METHODSHaCaT keratinocytes were exposed to 30.16 GHz millimeter wave with power densities of 1.0 or 3.5 mW/cm2 for 30 min per day. Gene expression profiles were obtained using the Affymetrix human genome U95A GeneChip. Reverse-transcription polymerase chain reaction (RT-PCR) was performed to confirm the differential expression of genes obtained from Genechip analysis.

RESULTPAR-2 and ERGIC-53 genes in HaCaT cells were up-regulated by 3.5 mW/cm2 millimeter wave exposure for 4 times. ERGIC-53 gene was also up-regulated by 1.0 mW/cm2 millimeter wave exposure for 4 times. However, no significant change for PAR-2 expression was found after the same exposure.

CONCLUSIONMillimeter wave exposure could affect gene expression in human keratinocytes, which might be related to the intensity and the times of exposure.

Cells, Cultured ; Dose-Response Relationship, Radiation ; Electromagnetic Fields ; Gene Expression ; radiation effects ; Humans ; Keratinocytes ; metabolism ; radiation effects ; Mannose-Binding Lectins ; genetics ; metabolism ; Membrane Proteins ; genetics ; metabolism ; Microwaves ; Radiation ; Receptor, PAR-2 ; genetics ; metabolism ; Reverse Transcriptase Polymerase Chain Reaction ; Skin ; cytology

OBJECTIVETo investigate the changes in cell proliferation and retinoic acid receptor gamma (RARgamma) mRNA expression in normal human keratinocytes after acitretin treatment and/or narrow-band ultraviolet-B irradiation.

METHODSNormal human keratinocytes were exposed to irradiation with 100 mJ/cm square NB-UVB and/or subsequent 12-hour incubation with 1x10(-6) mol/L acitretin, and the expression of RARgamma mRNA in the cells was examined using RT-PCR and real-time quantitative RT-PCR.

RESULTSA 0.9- and a 2.3-fold increase in RARgamma mRNA expression was induced in the cells by exposure to 100 mJ/cm square NB-UVB and 10(-6) mol/L acitretin, respectively, and the expression was synergistically enhanced by 2.8-fold after their combined treatment.

CONCLUSIONUpregulated expression of RARgamma mRNA can be associated with keratinocyte growth inhibition after treatment with acitretin and NB-UVB irradiation.

Acitretin ; pharmacology ; Cells, Cultured ; Humans ; Keratinocytes ; drug effects ; radiation effects ; RNA, Messenger ; metabolism ; Receptors, Retinoic Acid ; metabolism ; Ultraviolet Rays