Cutaneous squamous cell carcinoma (SCC) is an easily occurred cancer, which can worsen the quality of life considerably. It is known that external stimulus such as ultraviolet (UV) radiation induces cutaneous SCC via provoking oxidative stress. NAD(P)H dehydrogenase 1 (NQO1) is a ubiquitous flavoenzyme that functions as a guardian against oxidative stress. However, the effect of NQO1 on cutaneous SCC is not clearly elucidated. In this study, we investigated the effect of NQO1 on cutaneous SCC cells using the recombinant adenoviruses that can upregulate and/or downregulate NQO1 expression. Overexpression of NQO1 resulted in significant decrease of cell proliferation and colony forming activity of SCC lines (SCC12 and SCC13 cells). By contrast, knockdown of NQO1 increased the cell proliferation and colony forming activity. Accordingly, the levels of proliferation-related regulators, such as CDK4, CDK6, SOX2 and p63, were decreased by overexpression of NQO1, while those were increased by knockdown of NQO1. In addition, NQO1 affected the invasion and migration of SCC cells in a very similar way, with the regulation of epithelial-mesenchymal transition (EMT)-related molecules, including E-cadherin, N-cadherin, Vimentin, Snail and Slug. Finally, overexpression of NQO1 decreased the level of phosphorylated AKT, JNK and p38 MAPK, while knockdown of NQO1 increased the level of phosphorylated signaling molecules. Based on these data, NQO1 has tumor suppressive function in cutaneous SCC cells.

A reduced lipid content in the stratum corneum is a major cause of skin barrier function deterioration in various diseases. Accordingly, the promotion of lipid production is a potential strategy to improve skin barrier function. Recent studies support the beneficial effects of adiponectin on lipid metabolism and senescence in keratinocytes. We screened plant extracts that enhance the lipid synthesis of keratinocytes via sirt1-nuclear hormone receptor signaling in the adiponectin pathway. The levels of major lipid synthesis enzymes and transcription factors as well as sphingolipids, involved in adiponectin-associated keratinocyte lipid production, were evaluated in plant extracts or the adiponectin-treated human epidermal equivalent. The mRNA expression levels of fatty acid synthase, HMG-CoA reductase, and serine palmitoyl transferase were increased in the extracts of fruits of Lycium barbarum L., Prunus tomentosa, and Melia toosendan among 20 extracts from treated plants. The transcription factors SIRT1, LXRα, PPARs, and SREBP were also upregulated. The levels of ceramide and its downstream sphingolipid metabolites were significantly increased. Expression levels of keratinocyte differentiation markers were also increased. In particular, among the extracts with a detectable effect, Melia toosendan fructus showed the highest expression of lipid synthase. These results indicate that the Melia toosendan fructus extract is an appropriate material for improving skin barrier function.

The β-catenin signaling is essential for maintaining the cancer stem cell phenotype, because that ablation of the β-catenin gene results in the loss of cancer stem cells and complete tumor regression. However, the precise action mechanism and downstream effectors of β-catenin signaling remain to be elucidated. In this study, we attempted to find the β-catenin-regulated gene in squamous cell carcinoma (SCC) cells. To identify the β-catenin-regulated genes in SCC cells, we overexpressed β-catenin using recombinant adenovirus in SCC13 cells, then screened the putative downstream genes. We found that CREB (cAMP response element binding protein 1) is upregulated by β-catenin in human SCC13 cell line. When β-catenin was overexpressed, the expression levels for CREB was significantly increased. To investigate the potential effect of CREB on cancer cell behavior, we overexpressed CREB using recombinant adenovirus in SCC13 cells. As a result, overexpression of CREB led to the marked increase of clonogenic activity. These results suggest that CREB is a β-catenin--regulated transcription factor that promotes cancer characteristics in SCC cells, providing new insight into the molecular mechanism underlying the regulation of cancer stemness by β-catenin in SCC.

Brimonidine is a highly specific α2 adrenergic receptor agonist and acts on vascular smooth muscle to constrict blood vessels. Currently, it is used for the treatment of rosacea as a gel formulation under the brand name of Mirvaso. We experienced that Mirvaso treatment of patients with acne and rosacea resulted in alleviation of flushing as well as improvement of acne. Since it is well recognized that inflammatory reaction induced by Propionibacterium acnes (P. acnes) is critically important in the pathogenesis of acne, we speculate that brimonidine has anti-inflammatory activity in addition to its vaso-constrictive effect. In this study, we investigated the effects of brimonidine tartrate on P. acnes-induced inflammation in monocytes and keratinocytes that are importantly involved in acne pathogenesis. We examined the expression of α2 adrenergic receptor in both monocytes and keratinocytes. When applied to both cells, brimonidine tartrate suppressed the P. acnes-induced pro-inflammatory cytokine such as IL-1β, IL-6, and IL-8 in monocytes and keratinocytes. Also, brimonidine tartrate reduced pro-inflammatory cytokine secretion by P. acnes. These results demonstrate that brimonidine has additional anti-inflammatory property besides its vaso-constrictive potential, suggesting that brimonidine is beneficial in the treatment of patients with acne and rosacea via dual action mechanisms.

Imiquimod is known to exert its effects through Toll-like receptor 7 (TLR7) and/or TLR8, resulting in expression of proinflammatory cytokines and chemokines. Keratinocytes have not been reported to constitutively express TLR7 and TLR8, and the action of imiquimod is thought to be mediated by the adenine receptor, not TLR7 or TLR8. In this study, we revealed the expression of TLR7 in keratinocytes after calcium-induced differentiation. After addition of calcium to cultured keratinocytes, the immunological responses induced by imiquimod, such as activation of NF-κB and induction of TNF-α and IL-8, were more rapid and stronger. In addition, imiquimod induced the expression TLR7, and acted synergistically with calcium to induce proinflammatory cytokines. We confirmed that the responses induced by imiquimod were significantly inhibited by microRNAs suppressing TLR7 expression. These results suggest that TLR7 expressed in keratinocytes play key roles in the activation of NF-κB signaling by imiquimod, and that their modulation in keratinocytes could provide therapeutic potential for many inflammatory skin diseases.

Propionibacterium acne and sebaceous glands are considered to have an important role in the development of acne. Although information regarding the activation of innate immunity by P. acnes in the sebaceous gland is limited, different P. acnes phylotypes and a higher prevalence of follicular P. acnes macrocolonies/biofilms in sebaceous follicles of skin biopsies from acne compared with control skin and occasionally single P. acnes clusters in single sebaceous glands have been detected. In this study, we investigated whether P. acnes activates the inflammasome in human sebaceous glands in vivo and in vitro. We found that IL-1β expression was upregulated in sebaceous glands of acne lesions. After stimulation of human sebocytes with P. acnes, the activation of caspase-1 and secretion of IL-1β were enhanced significantly. Moreover, knocking down the expression of NLRP3 abolished P. acnes-induced IL-1β production in sebocytes. The activation of the NLRP3 inflammasome by P. acnes was dependent on protease activity and reactive oxygen species generation. Finally, we found that NALP3-deficient mice display an impaired inflammatory response to P. acnes. These results suggest that human sebocytes are important immunocompetent cells that induce the NLRP3 inflammasome, and that P. acnes-induced IL-1β activation in sebaceous glands may have a role in combating skin infections and in acne pathogenesis.

BACKGROUND:Melanocyte dendrites serve as the principal conduit for melanosome transfer. The dendrite formation requires actin polymerization mediated by Rho family GTPases including RhoA, Rac1 and Cdc42.OBJECTIVE:The aim of this study is to investigate and explore the involvement of p38 MAPK in melanocyte dendrite formation.METHODS:We transduced melanoma cells with adenovirus harboring the expression cassette for constitutive active form of MKK6, an upstream MAPKK for p38 MAPK.RESULTS:We investigated the effect of melanogenic inducers on melanocyte dendricity, using SK-mel-24 melanoma cells because that this cell line is refractory to several melanogenic inducers in terms of melanogenesis. TPA-induced the phosphorylation of p38 MAPK and the elongation of dendrite length, suggesting that MKK6 may be involved in this process. Overexpression of the constitutive active form of MKK6 resulted in significant elongation of dendrites in the melanoma cell line SK-mel-24. Moreover, overexpression of MKK6 ultimately led to the upregulation of Cdc42 and Rac1, suggesting that MKK6 acts as a crucial upstream signaling molecule for Rho family GTPases. When overexpressed in normal human epidermal melanocytes, MKK6 led also the increase of dendrite length.CONCLUSION:These results suggest that MKK6 is an authentic regulator for melanocytes dendricity, through the modulation of Rho family GTPases.

BACKGROUND:A callus is a local thickening of skin, characterized by accelerated keratinization and a reduced rate of desquamation. However, the mechanism of callus formation is not fully understood.OBJECTIVES:To evaluate the expression patterns, in callused skin, of genes that are implicated in keratinization and adhesion/desquamation.METHODS:Samples of skin from the dorsum of the foot (DF), centre of the plantar arch (CP) and anterior aspect of the heel (AH) were obtained from fresh cadavers, and protein and gene expression were determined by immunohistochemistry and reverse transcription-polymerase chain reaction, respectively.RESULTS:The stratum corneum in the DF showed a splitting phenotype by conventional haematoxylin and eosin staining, while the stratum corneum was normal in the AH. Cells of the stratum corneum in the AH were nonsquamous. Expression of cornification-related molecules including involucrin, filaggrin, caspase 14 and calcium-sensing receptor was higher in the AH. Similarly, expression of adhesive proteins such as corneodesmosin, desmoglein 1 and desmocollin 1 was increased in the AH. However, protease-activated receptor 2 expression was reduced in the stratum granulosum in the AH. The number of proliferating cells in the stratum basale was significantly increased in the AH, compared with the DF and CP.CONCLUSIONS:Our data suggest that calluses form as a result of hyperproliferation and incomplete differentiation of epidermal keratinocytes, and increased expression of adhesion molecules.