Pin1 is required for ultraviolet A-stimulated cyclooxygenase-2 induction in mouse epidermal cells

Eriodictyol protects skin cells from UVA irradiation-induced photodamage by inhibition of the MAPK signaling pathway

Solar UVA irradiation-generated reactive oxygen species (ROS) induces the expression of matrix metalloproteinase 1 (MMP-1), leading to photoaging, however the molecular mechanism remains unclear. In the present study, we found that eriodictyol remarkably reduces UVA-mediated ROS generation and protects the skin cells from oxidative damage and the ensuing cell death. Moreover eriodictyol pretreatment significantly down-regulates the UVA-induced MMP-1 expression, and lowers the inflammatory responses within the skin cells. Pretreatment with eriodictyol upregulates the expression of tissue inhibitory metalloproteinase 1 (TIMP-1) and collagen-I (COL-1) at the transcriptional level in a dose-dependent manner. UVA-induced phosphorylation levels of c-Jun N-terminal kinase (JNK), extracellular signal-regulated kinase (ERK) and p38 leading to increased MMP-1 expression are significantly reduced in eriodictyol-treated skin cells. In addition, eriodictyol pretreatment significantly suppresses inflammatory cytokines and inhibits the activation of MAPK signaling cascades in skin cells. Taken together, our results demonstrate that eriodictyol has both potent anti-inflammatory and anti-photoaging effects.

Functional polymorphism of PIN1 rs2233679 is associated with the progression of CIN to early cervical cancer in Hunan Chinese

OBJECTIVE

Peptidyl-prolyl cis/trans isomerase NIMA-interacting 1 (PIN1) involves alteration of the structure, function, intracellular localization and/or stability of the phosphorylated protein on serine or threonine residues which relates to inflammation and tumorigenesis. Association between PIN1 promoter polymorphisms and cancer risk were reported in several cancers. We intend to study the relationship between the polymorphism of PIN1 promoter and cervical cancer initiation and development.

MATERIALS AND METHODS

We genotyped two common single nucleotide polymorphisms (SNPs) (rs2233678 and rs2233679) in the promoter of the PIN1 gene in healthy controls, patients with CIN or cervical cancer. We used polymerase chain reaction and DNA sequencing methods to analyze these two SNPs in 179 patients and 223 healthy controls. Luciferase activity assay was used to detect PIN1 expression driven by the rs2233679.

RESULTS

The results revealed that the carriers of rs2233679 genotypes CT/TT had a significantly increased risk of cervical cancer in patients with CIN compared with genotype CC (odds ration [OR] = 2.924, 95% confidence interval [CI] = 1.093-7.819, P = 0.033). Luciferase activity assay results revealed that PIN1 expression driven by the rs2233679 genotype TT was higher than the genotype CC (P < 0.05). On the other hand, no significant correlation between the healthy controls and patients was found for PIN1 rs2233678 which showed that rs2233678 genotypes CG/GG is 95% in healthy controls and 100% in patients.

CONCLUSION

PIN1 rs2233679 genotype CT/TT may be a risk factor of early cervical cancer compared with genotype CC in Hunan populations. Our findings suggest that PIN1 rs2233679 genotype CT/TT might involve in the progression of the precancerous stage developing to early cancer by enhancing PIN1 expression.

Nrf2- and Bach1 May Play a Role in the Modulation of Ultraviolet A-Induced Oxidative Stress by Acetyl-11-Keto-β-Boswellic Acid in Skin Keratinocytes

BACKGROUND

Exposure of human skin to solar ultraviolet A (UVA) irradiation causes severe oxidative stress with damage to various cellular components and concomitant inflammation and carcinogenesis.

OBJECTIVE

The aim of this study is to investigate the protective effect of acetyl-11-keto-β-boswellic acid (AKBA) against UVA radiation on human skin keratinocytes.

METHODS

HaCaT cells were pretreated with AKBA followed by UVA irradiation. Radiation effects on cell morphology, cell viability, intracellular reactive oxygen species (ROS) levels, and antioxidant enzymes were examined.

RESULTS

AKBA reduces UVA irradiation-induced cell viability loss, accompanied by a decreased production of UVA-induced ROS, decreased malondialdehyde, and increased superoxide dismutase expression. In addition, AKBA increased basal and UVA-induced levels of Nrf2 (NF-E2-related factor 2), the redox-sensitive factor, and its target genes NQO1 and heme oxygenase-1 (HO-1), whereas expression of the transcriptional repressor Bach1 (BTB and CNC homology 1) was reduced. Furthermore, the cytoprotective effects of AKBA against UVA-derived oxidative damage were accompanied by modulating expression of inflammatory mediators (i.e., cyclooxygenase-2 and nuclear factor-κB) and NOX1.

CONCLUSIONS

AKBA protects skin cells from UVA-induced damage by modulating inflammatory mediators and/or ROS production. Therefore, AKBA has potential in the development of skin care products.

Protective effects of resveratrol against UVA-induced damage in ARPE19 cells

Ultraviolet radiation, especially UVA, can penetrate the lens, reach the retina, and induce oxidative stress to retinal pigment epithelial (RPE) cells. Even though it is weakly absorbed by protein and DNA, it may trigger the production of reactive oxygen species (ROS) and generate oxidative injury; oxidative injury to the retinal pigment epithelium has been implicated to play a contributory role in age-related macular degeneration (AMD). Studies showed that resveratrol, an abundant and active component of red grapes, can protect several cell types from oxidative stress. In this study, adult RPE cells being treated with different concentrations of resveratrol were used to evaluate the protective effect of resveratrol on RPE cells against UVA-induced damage. Cell viability assay showed that resveratrol reduced the UVA-induced decrease in RPE cell viability. Through flow cytometry analysis, we found that the generation of intracellular H₂O₂ induced by UVA irradiation in RPE cells could be suppressed by resveratrol in a concentration-dependent manner. Results of Western blot analysis demonstrated that resveratrol lowered the activation of UVA-induced extracellular signal-regulated kinase, c-jun-NH₂ terminal kinase and p38 kinase in RPE cells. In addition, there was also a reduction in UVA-induced cyclooxygenase-2 (COX-2) expression in RPE cells pretreated with resveratrol. Our observations suggest that resveratrol is effective in preventing RPE cells from being damaged by UVA radiation, and is worth considering for further development as a chemoprotective agent for the prevention of early AMD.

PIN1 inhibition suppresses osteoclast differentiation and inflammatory responses

Inflammatory responses and osteoclast differentiation play pivotal roles in the pathogenesis of osteolytic bone diseases such as periodontitis. Although overexpression or inhibition of peptidyl-prolyl cis/trans isomerase NIMA-interacting 1 (PIN1) offers a possible therapeutic strategy for chronic inflammatory diseases, the role of PIN1 in periodontal disease is unclear. The aim of the present study was to evaluate PIN1 expression in periodontitis patients as well as the effects of PIN1 inhibition by juglone or PIN1 small-interfering RNA (siRNA) and of PIN1 overexpression using a recombinant adenovirus encoding PIN1 (Ad-PIN1) on the inflammatory response and osteoclastic differentiation in lipopolysaccharide (LPS)- and nicotine-stimulated human periodontal ligament cells (PDLCs). PIN1 was up-regulated in chronically inflamed PDLCs from periodontitis patients and in LPS- and nicotine-exposed PDLCs. Inhibition of PIN1 by juglone or knockdown of PIN1 gene expression by siRNA markedly attenuated LPS- and nicotine-stimulated prostaglandin E2 (PGE2) and nitric oxide (NO) production, as well as cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) expression, whereas PIN1 overexpression by Ad-PIN1 increased it. LPS- and nicotine-induced nuclear factor (NF)-κB activation was blocked by juglone and PIN1 siRNA but increased by Ad-PIN1. Conditioned medium prepared from LPS- and nicotine-treated PDLCs increased the number of tartrate-resistant acid phosphatase-stained osteoclasts and osteoclast-specific gene expression. These responses were blocked by PIN1 inhibition and silencing but stimulated by Ad-PIN1. Furthermore, juglone and PIN1 siRNA inhibited LPS- and nicotine-induced osteoclastogenic cytokine expression in PDLCs. This study is the first to demonstrate that PIN1 inhibition exhibits anti-inflammatory effects and blocks osteoclastic differentiation in LPS- and nicotine-treated PDLCs. PIN1 inhibition may be a therapeutic strategy for inflammatory osteolysis in periodontal disease.

Enhanced eryptosis following juglone exposure

Juglone, a quinone isolated from Juglans mandshurica Maxim, has previously been shown to be effective against malignancy. The effect is at least partially due to stimulation of suicidal death or apoptosis of tumour cells. On the other hand, juglone has been shown to counteract apoptosis, for example, of neurons. In analogy to apoptosis of nucleated cells, erythrocytes may enter eryptosis, a suicidal death characterized by cell shrinkage and breakdown of phosphatidylserine asymmetry of the cell membrane with phosphatidylserine exposure at the erythrocyte surface. Stimulators of eryptosis include increase in cytosolic Ca(2+) activity [(Ca(2+) )i]. This study explored whether juglone stimulates eryptosis. To this end, erythrocyte volume was estimated from forward scatter, phosphatidylserine exposure at the erythrocyte surface from FITC annexin V binding, ceramide abundance from binding of fluorescent antibodies in flow cytometry and cytosolic ATP with a luciferin-luciferase-based assay. As a result, a 24-hr exposure of human erythrocytes to juglone (5 μM) significantly decreased erythrocyte forward scatter. Juglone (1-5 μM) significantly increased the percentage of annexin V binding cells. Juglone (5 μM) significantly increased ceramide abundance at the erythrocyte surface and decreased erythrocyte ATP concentration. The effect of juglone (10 μM) on annexin V binding was slightly but significantly blunted by removal of extracellular Ca(2+) and by addition of protein kinase C (PKC) inhibitor staurosporine (1 μM). In conclusion, juglone stimulates suicidal erythrocyte death or eryptosis at least in part by upregulation of ceramide abundance, energy depletion and activation of PKC.

UVA irradiation induced heme oxygenase-1: a novel phototherapy for morphea

Long wave UVA radiation (340-400 nm) causes detrimental as well as beneficial effects on human skin. Studies of human skin fibroblasts irradiated with UVA demonstrate increased expression of both antifibrotic heme oxygenase-1 (HO-1) and matrix metalloproteinase 1 (MMP-1). The use of UVA-induced MMP-1 is well-studied in treating skin fibrotic conditions such as localized scleroderma, now called morphea. However, the role that UVA-induced HO-1 plays in phototherapy of morphea has not been characterized. In the present manuscript, we have illustrated and reviewed the biological function of HO-1 and the use of UVA1 wavebands (340-400 nm) for phototherapy; the potential use of HO-1 induction in UVA therapy of morphea is also discussed.