GPNMB is expressed in human epidermal keratinocytes but disappears in the vitiligo lesional skin

GPNMB is involved in multiple cellular functions including cell adhesion, stress protection and stem cell maintenance. In skin, melanocyte-GPNMB is suggested to mediate pigmentation through melanosome formation, but details of keratinocyte-GPNMB have yet to be well understood. We confirmed the expression of GPNMB in normal human epidermal keratinocytes (NHEKs) by reducing the expression using siRNA. A higher calcium concentration of over 1.25 mM decreased the GPNMB expression. Histological staining showed that GPNMB was expressed in the basal layer of normal skins but completely absent in vitiligo skins. The normal expression of GPNMB in nevus depigmentosus skin suggested that lack of GPNMB is characteristic of vitiligo lesional skins. IFN-γ and IL-17A, two cytokines with possible causal roles in vitiligo development, inhibited GPNMB expression in vitro. Approximately 4–8% of the total GPNMB expressed on NHEKs were released possibly by ADAM 10 as a soluble form, but the process of release was not affected by the cytokines. The suppressive effect of IFN-γ on GPNMB was partially via IFN-γ/JAK2/STAT1 signaling axis. Decreased GPNMB expression in keratinocytes may affect melanocyte maintenance or survival against oxidative stress although further studies are needed. These findings indicate a new target for vitiligo treatment, focusing on the novel role of IFN-γ and IL-17 in downregulating keratinocyte-GPNMB.

FTY720 and cisplatin synergistically induce the death of cisplatin-resistant melanoma cells through the downregulation of the PI3K pathway and the decrease in epidermal growth factor receptor expression

Sphingosine kinase (SK), a key enzyme in sphingosine-1-phosphate (S1P) synthesis, is known to be overexpressed in various types of cancer cells. The effects of anticancer agents on SK1/S1P signaling have not yet been fully assessed in melanoma cells. In the present study, we investigated the effects of the combination of FTY720, an S1P receptor antagonist, and cisplatin, a DNA-damaging agent, on the induction of the death of human melanoma cells, as well as the molecular mechanisms involved. The viability of various human melanoma cell lines was examined following treatment with anticancer drugs. The cisplatin-resistant SK-Mel-28 and cisplatin-sensitive A375 cell lines were selected for this analysis. Protein expression and apoptotic rates were evaluated by western blot analysis following treatment with cisplatin and/or FTY720. Following treatment with a combination of FTY720 and cisplatin, cell viability significantly decreased and the expression of apoptosis-associated cleaved poly(ADP-ribose) polymerase (PARP) was significantly higher in comparison to treatment with cisplatin alone in the SK-Mel-28 cells. In addition, the combination of FTY720 and cisplatin reduced the protein expression of SK1 and the phosphorylation levels of phosphoinositide 3-kinase (PI3K), Akt and mTOR in the SK-Mel-28 cells; the expression of epidermal growth factor receptor (EGFR) was also markedly reduced. These findings suggest that FTY720 and cisplatin synergistically induce cell death through the downregulation of the PI3K/Akt/mTOR pathway and the decrease in EGFR expression in SK-Mel-28 cells. Thus, the combination of FTY720 and cisplatin may have therapeutic potential for chemotherapy-resistant melanoma, and the effects are likely exerted through the downregulation of S1P signaling.

Depression, quality of life (QoL) and will to live of community-dwelling postmenopausal women in three Asian countries: Korea, China and Japan

The purpose of this study was to examine the prevalence of screening-detected depression and the association of depression with QoL in community-dwelling postmenopausal women living in three Asian countries. We examined self-reported questionnaires and conducted the study. A total of 698 community-dwelling postmenopausal women living in three Asian countries participated in this study. The mean age was 59.4±6.6 years (±SD) Depressive symptoms were assessed using a 15-item geriatric depression scale (GDS-15). Using the cut-off of 5/6 for the GDS-15, the percentages of subjects with depression were 39.0% of the Korean subjects, 29.2% of the Chinese subjects, and 33.9% of the Japanese subjects. For the assessment of QoL, we used the EQ-5D of the EuroQoL Group. The following five dimensions were assessed: mobility, self-care, usual activities, pain/discomfort and anxiety/depression. The proportions of subjects reporting problems for each dimension were examined. Subjects with depression had significantly lower levels of some dimensions of QoL than those without depression in all three countries. In all three countries, 29.2-39.0% of community-dwelling postmenopausal women had screening-detected depression, which was significantly associated with a lower level of some dimensions of QoL. These results suggest that clinicians should pay more attention to depression in community-dwelling postmenopausal women.

Possible usefulness of apocynin, an NADPH oxidase inhibitor, for nitrate tolerance: prevention of NO donor-induced endothelial cell abnormalities

The long-term benefits of nitroglycerin therapy are limited by tolerance development. Understanding the precise nature of mechanisms underlying nitroglycerin-induced endothelial cell dysfunction may provide new strategies to prevent tolerance development. In this line, we tested interventions to prevent endothelial dysfunction in the setting of nitrate tolerance. When bovine aortic endothelial cells (BAECs) were continuously treated with nitric oxide (NO) donors, including nitroglycerin, over 2-3 days, basal production of nitrite and nitrate (NO(x)) was diminished. The diminished basal NO(x) levels were mitigated by intermittent treatment allowing an 8-h daily nitrate-free interval during the 2- to 3-day treatment period. Addition of the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase inhibitor apocynin restored the basal levels of NO(x) that were decreased by continuous nitroglycerin treatment of BAECs. Apocynin caused significant improvement of increased mRNA and protein levels of endothelial nitric oxide synthase (eNOS) in BAECs given nitroglycerin continuously over the treatment period. Apocynin also reduced endothelial production of reactive oxygen species (ROS) after continuous nitroglycerin treatment. These results showed an essential similarity to the effects of a nitrate-free interval. Application of the NOS inhibitor N(omega)-nitro- l-arginine methyl ester caused a recovery effect on basal NO(x) and eNOS expression but was without effect on ROS levels in continuously NO donor-treated BAECs. In conclusion, the present study characterized abnormal features and functions of endothelial cells following continuous NO donor application. We suggest that inhibition of NADPH oxidase, by preventing NO donor-induced endothelial dysfunction, may represent a potential therapeutic strategy that confers protection from nitrate tolerance development.