DEL-1, as an anti-neutrophil transepithelial migration molecule, inhibits airway neutrophilic inflammation in asthma.

BACKGROUND: Neutrophil migration into the airways is a key process in neutrophilic asthma. Developmental endothelial locus-1 (DEL-1), an extracellular matrix protein, is a neutrophil adhesion inhibitor that attenuates neutrophilic inflammation. METHODS: Levels of DEL-1 were measured in exhaled breath condensate (EBC) and serum in asthma patients by ELISA. DEL-1 modulation of neutrophil adhesion and transepithelial migration was examined in a co-culture model in vitro. The effects of DEL-1-adenoviral vector-mediated overexpression on ovalbumin/lipopolysaccharide (OVA/LPS)-induced neutrophilic asthma were studied in mice in vivo. RESULTS: DEL-1 was primarily expressed in human bronchial epithelial cells and was decreased in asthma patients. Serum DEL-1 concentrations were reduced in patients with severe asthma compared with normal subjects (567.1 ± 75.3 vs. 276.8 ± 29.36 pg/mL, p < .001) and were negatively correlated to blood neutrophils (r = -0.2881, p = .0384) and neutrophil-to-lymphocyte ratio (NLR) (r = -0.5469, p < .0001). DEL-1 concentrations in the EBC of severe asthmatic patients (113.2 ± 8.09 pg/mL) were also lower than normal subjects (193.0 ± 7.61 pg/mL, p < .001) and were positively correlated with the asthma control test (ACT) score (r = 0.3678, p = .0035) and negatively related to EBC IL-17 (r = -0.3756, p = .0131), myeloperoxidase (MPO) (r = -0.5967, p = .0055), and neutrophil elastase (NE) (r = -0.5488, p = .0009) expression in asthma patients. Neutrophil adhesion and transepithelial migration in asthma patients were associated with LFA-1 binding to ICAM-1 and inhibited by DEL-1. DEL-1 mRNA and protein expression in human bronchial epithelial cells were regulated by IL-17. Exogenous DEL-1 inhibited IL-17-enhanced neutrophil adhesion and migration. DEL-1 expression was decreased while neutrophil infiltration was increased in the airway of a murine model of neutrophilic asthma. This was prevented by DEL-1 overexpression. CONCLUSIONS: DEL-1 down-regulation leads to increased neutrophil migration across bronchial epithelial cells and is associated with neutrophilic airway inflammation in asthma.

Efficacy and safety of low-dose oral isotretinoin monotherapy versus combined therapy with picosecond laser for the treatment of acne scars in Asian population.

PURPOSE: Acne scars are common in patients with moderate to severe acne. Isotretinoin is the first-line treatment for those patients, but whether oral isotretinoin can improve acne scar is not clear. Picosecond lasers (FxPico) has been reported to improve acne scars. In the present study, we evaluated the clinical efficacy of low-dose isotretinoin with or without FxPico treatment for acne scars. MATERIALS AND METHODS: A total of 48 patients with acne scars were enrolled and were randomly assigned to receive low dose oral isotretinoin or not. For all the patients in both treatment groups, one side of face were randomly assigned to be treated with picosecond laser. Assessments, including photos, échelle d'évaluation clinique des cicatrices d'acné (ECCA) and Global Acne Grading System (GAGS) score, the number of lesions, melanin and erythema indexes, transepidermal water loss were assessed at 0, 1, 2, and 3 month. Side effects, Dermatology Life Quality Index (DLQI) and satisfaction were recorded before and after the study. RESULTS: A total of 44 patients completed the study (24 received oral low dose isotretinoin and 20 did not). Low dose oral isotretinoin treated group showed significant improvement on ECCA (from 112.5 [50-180] to 105 [50-160]), GAGS score (from 12.6 ± 3.3 to 10.1 ± 3.0), the count of papules (from 4.3 ± 3.7 to 1.0 ± 1.5) than the blank group, and higher improvement were noticed after isotretinoin combined with FxPico. All the side effects were temporary and tolerable, no adverse effects were observed. Higher DLQI and patients' satisfaction were achieved by oral isotretinoin alone and isotretinoin combined with FxPico. CONCLUSIONS: This is the first paper showing the improvement of scars by early low dose-isotretinoin intervention with or without the combination of picosecond laser. Early intervention with oral low-dose isotretinoin is effective for the treatment and prevention of acne scars, the combined therapy with FxPico can achieve better outcome.

Early acne scar intervention with 1064 nm picosecond laser in patients receiving oral isotretinoin: a randomized split-face controlled pilot study.

Early acne scar intervention is important. Oral isotretinoin is widely used in patients with moderate to severe acne. Picosecond laser has shown a promising effect on scar clearance. However, there is a lack of reports on the efficacy and safety of early acne scar management by using 1064-nm picosecond laser in patients receiving low-dose oral isotretinoin. Twenty-four patients with atrophic acne scars of Fitzpatrick skin type III to V were enrolled. All patients were receiving low-dose oral isotretinoin (0.12-0.22 mg/kg/day) during the treatment. The face of the participants was randomly assigned to receive 2 sessions of fractional picosecond 1064 nm Nd: YAG laser (FxPico) treatment and 2 follow-ups, with an interval of 1 month (month 0-3). Clinical efficacy and safety were assessed by photographs, ECCA grading scale, the number of scar lesions melanin and erythema indexes (MI and EI), TEWL, DLQI, and patient satisfaction and the adverse events were recorded on every visit. FxPico significantly decreased the ECCA score and showed higher improvement in the ECCA score. FxPico treated side achieved a significant reduction in all acne scar types, while only boxcar scars and rolling scars showed higher improvement. TEWL but not MI or EI were significantly improved. DLQI and patient satisfaction were higher with the FxPico-treated side than control side. No adverse effects were observed and all the side effects observed were temporary and tolerable. Early intervention by FxPico on patients receiving low-dose oral isotretinoin is a safe and effective modality to improve atrophic acne scars.

Efficacy and safety of low-level light therapy by delicate pulsed light combined with low-dose oral isotretinoin for the treatment of acne vulgaris: a randomized split-face study.

Acne vulgaris (AV) is a common dermatosis that causes psychological problems. Isotretinoin is the first-line treatment for moderate-to-severe AV, but its onset of effect is delayed. Although light-based therapy is widely used in the treatment of AV, there is a lack of reports on delicate pulsed light (DPL) which has a narrow therapeutic spectrum (500-600 nm). Low-level light therapy (LLLT) has shown an emerging role in anti-inflammatory effects and skin repair. This study investigates the efficacy and safety of low-dose oral isotretinoin combined with LLLT using DPL in patients with moderate-to-severe AV. Thirty-six patients with moderate-to-severe AV were enrolled and received low-dose oral isotretinoin (10-20 mg/day). The two sides of the face were randomly assigned to receive DPL (6-9 J/cm2) or not at an interval of 2 weeks for 4 treatment sessions (weeks 0, 2, 4, 6). Photos, GAGS score, counts of papules, pustules, comedones, TEWL, melanin and erythema index, side effects, efficacy, and satisfactory score were recorded at each visit and at 4 weeks after the final treatment (week 10). Thirty-three patients completed the study. DPL and oral isotretinoin combined therapy exhibited significantly improved GAGS score as well as the number of the lesions from week 2 and maintained until week 10. At the end of the observation, the improvement of GAGS was 70.88% on the DPL and isotretinoin combined side versus 62.12% on the side with isotretinoin monotherapy (p = 0.0009). The improvement for papule number was 61.58% on the DPL combined side versus 43.33% on the control side (p < 0.0001), for comedone was 63.15% versus 43.30% (p = 0.0008). TEWL and indexes of melanin and erythema also had better outcomes with DPL combined therapy at week 10. All the side effects were temporary and tolerable; no adverse effects were observed. Oral low-dose isotretinoin combined with LLLT by DPL offers a combination with reduced side effects and better outcomes within a limited treatment duration, which advances the onset of effect of isotretinoin monotherapy and improves lesion clearance.

Establishment and development of a CZE-UV method for rapid measurement of aprotinin potency.

A new method for the measurement of aprotinin potency by CZE-UV detector was established for the first time. The on-line mixing of substrate, trypsin and aprotinin using at-inlet technology was realized by the established method. Enzymatic reaction, separation, and detection of substrate and product can be performed simultaneously online. The aprotinin potency can be measured within 4 min. The response surface methodology was used to optimize the incubation conditions of trypsin and substrate, and the optimized conditions were obtained under 17.39 mM phosphate buffer at pH 7.6, 1.40 min of incubation time. The repeatability of proposed method was evaluated in three different systems of capillary zone electrophoresis: (i) only substrate; (ii) trypsin and substrate; (iii) aprotinin, trypsin and substrate, and the RSDs of migration times and peak areas of substrate were less than 2.7 and 3.1%, respectively. The RSDs of migration times and peak areas of product were less than 2.1 and 3.0%, respectively. A formula was also developed to calculate the aprotinin potency in this method. In a word, the established CZE-UV method was convenient, fast, and environmentally friendly for the measurement of aprotinin potency.

Establishing a sensitive capillary electrophoresis-UV method for direct determination of amino acids to evaluate vinegar quality.

In this study, the capillary electrophoresis method with ultraviolet detection was established to directly determine amino acids in vinegar, according to the coordination interaction between amino acids (AAs) and copper ions. The online sweeping technique was combined to improve the detection sensitivity. The quality of vinegar was evaluated with AAs as parameters by United Nations Food Agriculture Organization/Word Health Organization AAs model and principal component analysis. Optimum conditions were obtained under 50 mM CuSO4 and adjusted pH 4.40 with 8 mM acetate, 70 s injection time, 22.5 kV separation voltage, and 254 nm detected wavelength. Method validation, indicating good linearity (R2  > 0.9989), precision with an RSD less than 8.0% (n = 5), LOD (0.13-0.25 µg/mL), LOQ (0.43-0.83 µg/mL) and recovery (80.5-112.6%). Under the optimal conditions, AAs in vinegar can be directly separated which is propitious for the quality evaluation of vinegar.

Dual-plasmonic Au/graphene/Au-enhanced ultrafast, broadband, self-driven silicon Schottky photodetector.

High-performance photodetectors are desirable for various applications, including multi-wavelength image sensing, communication, and safety monitoring. In this study, we report the construction of a dual-surface plasmon-enhanced silicon Schottky photodetector using Au nanoparticles (NPs)/graphene/Au NPs hybrid structure as the electrode. It was found that the as-assembled device exhibited broad sensitivity, ranging from ultraviolet to near-infrared light (360-1330 nm) at room temperature, with a high response speed of 360 ns and a 3 dB bandwidth of 780 kHz at zero bias. Further theoretical simulation based on the finite-element method revealed that good device performance is associated with the contribution of the Au NPs/graphene/Au NPs electrode: intense dual-plasmonic resonance coupling is induced in a hybrid structure of two layers of metallic NPs separated by a uniform monolayer graphene. It not only can enhance light trapping and the localized electric field at the resonant and off-resonant wavelength regions, but is also beneficial for the tunneling of hot electrons. This work demonstrated the great potential of dual-plasmonic resonance coupling in optoelectronic devices and will lead to the development of advanced plasmonic devices.

Effects of indole-3-acetic acid on arsenic uptake and antioxidative enzymes in Pteris cretica var. nervosa and Pteris ensiformis.

A hydroponic experiment was conducted to investigate the effects of indole-3-acetic acid (IAA) on arsenic (As) uptake and antioxidative enzymes in fronds of Pteris cretica var. nervosa (As hyperaccumulator) and Pteris ensiformis (non-hyperaccumulator). Plants were exposed to 2 mg L-1 As(III), As(V) or dimethylarsinic acid (DMA) and IAA concentrations for 14 d. The biomass and total As in the plants significantly increased at 30 mg L-1 IAA. Superoxide dismutase (SOD) activities significantly increased with IAA addition. Catalase (CAT) activities showed a significant increase in P. ensiformis exposed to three As species at 30 or 50 mg L-1 IAA but varied in P. cretica var. nervosa. Peroxidase (POD) activities were unchanged in P. ensiformis except for a significant decrease at 50 mg L-1 IAA under As(III) treatment. However, a significant increase was observed in P. cretica var. nervosa at 10 mg L-1 IAA under As(III) or DMA treatment and at 50 mg L-1 IAA under As(V) treatment. Under DMA stress, malondialdehyde contents in fronds of P. cretica var. nervosa showed a significant decrease at 10 mg L-1 IAA but remained unchanged in P. ensiformis. Therefore, IAA enhanced As uptake and frond POD activity in P. cretica var. nervosa under As stress.

Plasmonic silver nanosphere enhanced ZnSe nanoribbon/Si heterojunction optoelectronic devices.

In this study, we report a localized surface plasmon resonance (LSPR) enhanced optoelectronic device based on a ZnSe:Sb nanoribbon (NR)/Si nano-heterojunction. We experimentally demonstrated that the LSPR peaks of plasmonic Ag nanoparticles (Ag NPs) can be readily tuned by changing their size distribution. Optical analysis reveals that the absorption of ZnSe:Sb NRs was increased after the decoration of the Ag NPs with strong LSPR. Further analysis of the optoelectronic device confirmed the device performance can be promoted: for example, the short-circuit photocurrent density of the ZnSe/Si heterojunction solar cell was improved by 57.6% from 11.75 to 18.52 mA cm(-2) compared to that without Ag NPs. Meanwhile, the responsivity and detectivity of the ZnSe:Sb NRs/Si heterojunction device increased from 117.2 to 184.8 mA W(-1), and from 5.86 × 10(11) to 9.20 × 10(11) cm Hz(1/2) W(-1), respectively.

Real-world data of pyrotinib-based therapy for patients with brain metastases of HER2-positive advanced breast cancer: a single-center retrospective analysis and molecular portraits.

Introduction: Pyrotinib is a novel irreversible pan-HER tyrosine kinase inhibitor (TKI). However, real-world data of pyrotinib-containing therapy in human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer (MBC) and developing brain metastases (BMs) are limited, and the genomic profile of this subpopulation is almost undefined. Methods and materials: Patients with BM of HER2-positive MBC (n = 35) treated with pyrotinib-containing therapy were enrolled in this analysis. Progression-free survival (PFS), overall survival (OS), objective response rate (ORR), disease control rate (DCR), and toxicity profiles were evaluated. Hazard ratios (HRs) and 95% confidence intervals (CIs) for disease progression were estimated using the Cox proportional hazards models. Targeted next-generation sequencing of 618 cancer-relevant genes was performed on plasma and primary breast tumors from patients with BM and without BM. Results: The median PFS time was 8.00 (95% CI, 5.98-10.017) months, and the median OS time was 23 (95% CI, 10.412-35.588) months. The ORR was 45.7%, and the DCR was 74.3%. In the Cox multivariate analysis, prior exposure to brain radiotherapy (HR = 3.268), received pyrotinib as third- or higher-line treatment (HR = 4.949), subtentorial brain metastasis (HR = 6.222), and both supratentorial and subtentorial brain metastases (HR = 5.863) were independently associated with increased risk of progression. The frequent grade 3-4 adverse event was increased direct bilirubin (14.3%), and two patients suffered from grade 3-4 diarrhea. In the exploratory genomic analysis, altered frequencies of FGFR3, CD276, CDC73, and EPHX1 were higher in the BM group. The consistency of mutated profiles of plasma and primary lesion in the BM group was significantly lower (30.4% vs. 65.5%; p = 0.0038). Conclusions: Pyrotinib-containing therapy shows favorable effectiveness and tolerable safety in patients with BM of HER2-positive MBC, particularly in a population that is brain radiotherapy-naïve, received pyrotinib as first- or second-line treatment, and developed supratentorial brain metastasis. In the exploratory genomic analysis, patients with BM showed distinct genomic features from patients without BM.

A prospective, randomized, split-face study of concomitant administration of low-dose oral isotretinoin with 30% salicylic acid chemical peeling for the treatment of acne vulgaris in Asian population.

BACKGROUND: Acne vulgaris (AV) is a common dermatosis. For moderate to severe AV, isotretinoin is the first-line treatment. Chemical peeling with supramolecular salicylic acid (SSA) was developed with water solubility and advanced skin penetration properties. In the present study, we investigated the efficacy and safety of oral low-dose isotretinoin combined with 30% SSA chemical peeling. METHODS: Thirty-three moderate-to-severe acne patients were enrolled and received oral low-dose (0.2-0.4 mg/kg/d) isotretinoin and were then randomly assigned to receive 30% SSA or not on each side of the face with 2-week intervals for four sessions. Photos, the number of lesions, GAGS score, skin indices (melanin, erythema, pore, and texture), hydration, and transepidermal water loss (TEWL) were assessed at 0, 2, 4, 6, and 10 weeks. Side effects, efficacy, and satisfactory rates were recorded. RESULTS: A total of 29 patients completed the study. Oral isotretinoin combined with SSA decreased response time compared to isotretinoin monotherapy, with significantly improved GAGS score, count of lesions, and efficacy (%) at 4-6 weeks. Skin indices of melanin, erythema, pore, and texture evaluated at week 10 were improved as well. Oral isotretinoin with or without SSA was effective by the lesion clearance; only SSA significantly improved the TEWL. All the side effects were temporary and tolerable, and no adverse effects were observed. CONCLUSION: Oral low-dose isotretinoin combined with 30% SSA is safe and effective, which advanced the onset of action and improves lesion clearance.

Glucagonoma syndrome with atypical necrolytic migratory erythema.

Necrolytic migratory erythema is most commonly associated with glucagonoma syndrome. We report a rare case of glucagonoma syndrome with necrolytic migratory erythema presenting as pruritic papules and follicular pustules in a 57-year-old woman; showing eosinophilic infiltration on histology. However, the final diagnosis was confirmed by demonstrating neuroendocrine tumour on histopathological examination of the liver metastases. Nutrition therapy was administered as a palliative treatment. This case also highlights the atypical clinical features and nonspecific histology of necrolytic migratory erythema which makes the diagnosis difficult.

Sensitive Analysis of Metoprolol Tartrate and Diltiazem Hydrochloride in Human Serum by Capillary Zone Electrophoresis Combining on Column Field-Amplified Sample Injection.

A sensitive capillary zone electrophoresis (CZE) combined with field-amplified sample injection (FASI) method was investigated to simultaneously determine diltiazem (DI) hydrochloride and metoprolol (ME) tartrate in human serum. This method was validated by linearity, limits of detection (LOD), stability, precision and accuracy, and the related parameters are linearity (r2 > 0.9980), intra- and inter-day precisions (intra-day relative standard deviation (RSD) is 2.3-3.4%, and inter-day RSD is 3.8-7.5%) and the LOD (0.02 ng/mL for ME tartrate and 0.01 ng/mL for DI hydrochloride). So the proposed method is rapid, sensitive and accurate for determination of these two anti-anginal drugs in human serum. As for enrichment conditions, it was helpful to add phosphoric acid and isopropanol into samples for enrichment efficiency. A model was established to illustrate the possible enrichment mechanism of analytes, and a theory of half-width was also applied in CZE combined with FASI method to evaluate the peak performance.

A Green HPLC Method for Determination of Nine Sulfonamides in Milk and Beef, and Its Greenness Assessment with Analytical Eco-Scale and Greenness Profile.

BACKGROUND: Sulfonamides have been widely used in the prevention and clinical treatment of bacterial diseases in livestock and poultry. The use of sulfonamides increases the risk of veterinary drug residues in animal derived foods. The traditional reversed phase liquid chromatography methods for sulfonamides residues detection in animal derived foods have the problem of high consumption of organic solvents. OBJECTIVE: The aim of this study was to establish a green high-performance liquid chromatography method for the detection of sulfonamides residues in different animal-origin foods. METHOD: The sample extraction solutions were purified by the Agela Cleanert PEP-2 cartridge and analyzed by the high-performance liquid chromatography method using ethanol as the green alternative solvent. RESULTS: The proposed method was validated in terms of linear range (20-1000 µg/kg), limit of detection (3.0-12.3 µg/kg), limit of quantitation (10-43 µg/kg), accuracy (80.7-101.3%), and repeatability and reproducibility (RSD <5.9% and RSD <8.5% respectively). CONCLUSIONS: The proposed method is an environmentally friendly, sensitive and reliable high-performance liquid chromatography method for simultaneous determination of sulfonamide residues in animal-origin foods. HIGHLIGHTS: In this work, we firstly developed a green high-performance liquid chromatography method for simultaneous determination of the residues of nine sulfonamides in milk and beef with ethanol as the green alternative solvent.

Basic Fibroblast Growth Factor Protects Astrocytes Against Ischemia/Reperfusion Injury by Upregulating the Caveolin-1/VEGF Signaling Pathway.

A previous in vivo study demonstrated that intracerebroventricular injection of basic fibroblast growth factor (bFGF) in middle cerebral artery occlusion rats increased the expression of caveolin-1 (cav-1) and vascular endothelial growth factor (VEGF) in cerebral ischemia penumbra. Because astrocytes are the largest population in the brain, the aim of this in vitro study was to investigate the influence of bFGF on cav-1 and VEGF expression in rat astrocytes following oxygen glucose deprivation/reoxygenation (OGD/R). For this, an ischemic model in vitro of oxygen glucose deprivation lasting for 6 h, followed by 24 h of reoxygenation was used. Primary astrocytes from newborn rats were pre-treated with siRNA targeting bFGF before OGD/R. Cell viability was measured by a CCK-8 assay. The protein and mRNA expressions of bFGF, cav-1, and VEGF were evaluated by western blotting, immunofluorescence staining, and reverse transcription-quantitative polymerase chain reaction. The results showed that OGD/R reduced cell viability, which was decreased further following bFGF knockdown; however, restoring bFGF improved cell survival. A cav-1 inhibitor abrogated the effect of bFGF on cell viability. The expression levels of bFGF mRNA, bFGF protein, cav-1 mRNA, cav-1 protein, and VEGF protein were higher in OGD/R astrocytes. bFGF knockdown markedly decreased the expression levels of cav-1 mRNA, cav-1 protein, and VEGF protein, which were effectively reversed by exogenous bFGF treatment. Moreover, exogenous bFGF treatment significantly increased the expression levels of cav-1 mRNA, cav-1 protein, and VEGF protein in OGD/R astrocytes; however, a cav-1 inhibitor abolished the effect of bFGF on VEGF protein expression. These results suggested that bFGF may protect astrocytes against ischemia/reperfusion injury by upregulating caveolin-1/VEGF signaling pathway.

Endogenous trans-zeatin content in plants with different metal-accumulating ability: a field survey.

A field survey was conducted to evaluate soil metal pollution and endogenous trans-zeatin content in the leaves of plants growing at six sites in a metal-polluted area located in Gejiu, Yunnan, China. Five plant species were collected, and the physicochemical properties and concentrations of five metals in the soil were analyzed. The trans-zeatin content in plant leaves was measured by high-performance liquid chromatography. Based on the Nemerow pollution index, the six sites were classified into four levels of pollution (i.e., low, medium, high, and severely high). The degree of soil metal pollution was cadmium (Cd) > arsenic (As) > lead (Pb) > zinc (Zn) > copper (Cu). The leaf trans-zeatin content in Pteris vittata (an arsenic hyperaccumulator) increased significantly by 98.6 % in soil with a severely high level of pollution compared with soil at a low level of pollution. However, in non-hyperaccumulators Bidens pilosa var. radiata and Ageratina adenophora, a significant decrease in leaf trans-zeatin content of 35.6 and 87.6 %, respectively, was observed. The leaf trans-zeatin content in Artemisia argyi also decreased significantly by 73.6 % in high metal-polluted soil compared with that in medium metal-polluted soil. Furthermore, significant correlations were observed between leaf trans-zeatin content in Pteris vittata and As, Pb, and Cd concentrations in the soil; however, either no correlation or a negative one was observed in the other plant species. Therefore, a high content of trans-zeatin in the leaves of Pteris vittata may play an important role in its normal growth and tolerance to metals.

Vitamin C protects against UV irradiation-induced apoptosis through reactivating silenced tumor suppressor genes p21 and p16 in a Tet-dependent DNA demethylation manner in human skin cancer cells.

AIM: DNA methylation plays important roles in various kinds of carcinogenesis. Vitamin C could induce Tet-dependent DNA demethylation in embryonic stem cells. Therefore, the antagonizing activity of vitamin C on ultraviolet (UV)-induced apoptosis was investigated in this study. METHODS: Apoptosis of human epidermoid carcinoma A431 cells and p16-knockout (KO) or p21-KO fibroblasts was assessed by a fluorescence-activated cell sorter. Real-time PCR and western blot were used to determine the relative expression levels of p12, p21, and Tet1/2/3 genes. The global DNA methylation levels were determined using MethylFlash Methylated DNA Quantification Kit in A431 cells with or without vitamin C treatment. To examine the DNA demethylation activity of vitamin C, DNA immunoprecipitation (DIP)-qPCR was performed to determine the relative levels of 5-methylcytosine (5mC) or 5-hydroxymethylcytosine (5hmC) in p16 and p21 promoter regions containing cytosine-phosphorothiolated guanine (CpG) islands. RESULTS: The increasing apoptosis of A431 cells under prolonged UV irradiation was remarkably decreased by the combination of vitamin C treatment, suggesting that vitamin C protects against UV-induced apoptosis. Concurrently, vitamin C induced a significant reduction of global DNA methylation in a time- and dose-dependent manner in A431 cells. Vitamin C also reactivated the expression of p16 and p21 at mRNA and protein levels. Mechanistically, about 27% 5hmC-positive cells were observed in vitamin C-treated A431 cells, and the 5hmC enrichment at p16 and p21 promoter regions was also largely increased by vitamin C. Moreover, the expression of p16 and p21 was decreased in Tet1/2 double-knockdown cells, in which the inhibitory effect of vitamin C on UV-induced apoptosis was dismissed. Furthermore, the inhibition of UV-induced apoptosis on vitamin C treatment nearly disappeared in p16- or p21-knockout primary cultured fibroblasts. CONCLUSION: These results demonstrate that vitamin C effectively antagonizes UV-induced apoptosis through regulation of Tet activity, DNA demethylation, and subsequent tumor suppressor gene activation in skin cancer cells.