microRNA-mediated keratinocyte hyperproliferation in psoriasis vulgaris

Background Psoriasis is a chronic inflammatory skin disease characterized by intense proliferation and abnormal differentiation of keratinocytes, although the pathogenesis is still not completely clarified. Objectives We investigated the mechanism of keratinocyte proliferation seen in psoriasis, focusing on microRNA (miRNA). Materials and methods miRNAs were extracted from tissues and sera of psoriasis, atopic dermatitis and healthy control. To determine pathogenic miRNAs, we performed miRNA polymerase chain reaction (PCR) array analysis. The results were confirmed with quantitative real‐time PCR, in situ hybridization, immunohistochemistry, transient transfection of siRNA and inhibitor in cultured keratinocytes and Western blotting. Results PCR array analysis using tissue miRNA demonstrated miR‐424 level was markedly decreased in psoriasis skin in vivo. Protein expression of mitogen‐activated protein kinase kinase 1 (MEK1) or cyclin E1, predicted target genes of miR‐424, was increased in psoriatic skin, although their mRNA levels were not. The transfection of specific inhibitor of miR‐424 in normal human keratinocytes led to upregulation of MEK1 or cyclin E1 protein, and resulted in increased cell proliferation. On the other hand, cell number was significantly decreased when cells were transfected with siRNA for MEK1 or cyclin E1. Furthermore, we first investigated serum miRNA levels in psoriasis. Although not significant, serum miR‐424 concentration tended to be decreased in patients with psoriasis compared with healthy controls. Conclusions Decreased miR‐424 expression and subsequently increased MEK1 or cyclin E1 may play a key role in the pathogenesis of psoriasis. Investigation of the regulatory mechanisms of keratinocyte proliferation by miRNA may lead to new treatments and a disease activity marker.     

miRNA miR‐17‐92 cluster is differentially regulated in the imiqumod‐treated skin but is not required for imiqumod‐induced psoriasis‐like dermatitis in mice

MicroRNAs (miRNAs) play very important roles in the control of immune cell and keratinocyte development and function and are implicated in skin inflammatory diseases, including psoriasis. miRNA miR‐17‐92 was reported to promote the differentiation of Th1 and Th1 cells and to regulate cell proliferation and apoptosis. Here we showed that imiquimod (IMQ) differentially regulates the expression of miR‐17‐92 cluster in the mouse skin, upregulating miR‐17 and miR‐19 families and downregulating miR‐92. To investigate whether miR‐17‐92 cluster is functionally involved in the psoriasis, we have generated three mutant mice with specific deletion or overexpression of miR‐17‐92 cluster in keratinocytes, or with deletion of miR‐17‐92 cluster in T cells. Interestingly, deletion or overexpression of miR‐17‐92 cluster in keratinocytes, or deletion of miR‐17‐92 in T cells did not significantly affect IMQ‐induced psoriasis‐like dermatitis development in the mutant mice compared with wild‐type littermates. Thus, miRNA miR‐17‐92 cluster may not be a key factor regulating imiqumod‐induced psoriasis‐like dermatitis.     

Laser capture microdissection followed by next‐generation sequencing identifies disease‐related microRNAs in psoriatic skin that reflect systemic microRNA changes in psoriasis

Psoriasis is a systemic disease with cutaneous manifestations. MicroRNAs (miRNAs) are small non‐coding RNA molecules that are differentially expressed in psoriatic skin; however, only few cell‐ and region‐specific miRNAs have been identified in psoriatic lesions. We used laser capture microdissection (LCM) and next‐generation sequencing (NGS) to study the specific miRNA expression profiles in the epidermis (Epi) and dermal inflammatory infiltrates (RD) of psoriatic skin (N = 6). We identified 24 deregulated miRNAs in the Epi and 37 deregulated miRNAs in the RD of psoriatic plaque compared with normal psoriatic skin (FCH > 2, FDR < 0.05). Interestingly, 9 of the 37 miRNAs in RD, including miR‐193b and miR‐223, were recently described as deregulated in circulating peripheral blood mononuclear cells (PBMCs) from patients with psoriasis. Using flow cytometry and qRT‐PCR, we found that miR‐193b and miR‐223 were expressed in Th17 cells. In conclusion, we demonstrate that LCM combined with NGS provides a robust approach to explore the global miRNA expression in the epidermal and dermal compartments of psoriatic skin. Furthermore, our results indicate that the altered local miRNA changes seen in the RD are reflected in the circulating immune cells, suggesting that miRNAs may contribute to the pathogenesis of psoriasis.     

Differential expression analysis of miRNA in peripheral blood mononuclear cells of patients with non‐segmental vitiligo

Vitiligo is a common depigmentary skin disease that may follow a pattern of multifactorial inheritance. The essential factors of its immunopathogenesis is thought to be the selective destruction of melanocytes. As a new class of microregulators of gene expression, miRNA have been reported to play vital roles in autoimmune diseases, metabolic diseases and cancer. This study sought to characterize the different miRNA expression pattern in the peripheral blood mononuclear cells (PBMC) of patients with non‐segmental vitiligo (NSV) and healthy individuals and to examine their direct responses to thymosin α1 (Tα1) treatment. The miRNA expression profile in the PBMC of patients with NSV was analyzed using Exiqon's miRCURY LNA microRNA Array. The differentially expressed miRNA were validated by real‐time quantitative polymerase chain reaction. We found that the expression levels of miR‐224‐3p and miR‐4712‐3p were upregulated, and miR‐3940‐5p was downregulated in the PBMC. The common clinical immune modulator Tα1 changed the miRNA expression profile. Our analysis showed that differentially expressed miRNA were associated with the mechanism of immune imbalance of vitiligo and that Tα1 could play an important role in changing the expression of these miRNA in the PBMC of patients with NSV. This study provided further evidence that miRNA may serve as novel drug targets for vitiligo therapeutic evaluation.     

Serum miRNA expression profiles change in autoimmune vitiligo in mice

It is widely believed that non‐segmental vitiligo results from the autoimmune destruction of melanocytes. MicroRNAs (miRNAs), a class of small non‐coding RNAs that negatively regulate gene expression, are involved in the immune cell development and function and regulate the development of autoimmune diseases. Recent studies demonstrate that functional miRNAs can be detected in the serum and serve as biomarkers of various diseases. In the present study, we used a mouse autoimmune vitiligo model, in which melanocyte autoreactive CD4⁺ T cells were adoptively transferred into Rag1^?/? host mice. Serum miRNA expression was profiled in vitiligo developed mice and control mice using TaqMan RT‐PCR arrays. We have found that the expressions of 20 serum miRNAs were changed in vitiligo mice compared to control mice. Three increased miRNAs, miR‐146a, miR‐191, and miR‐342‐3p, were further confirmed by a single TaqMan RT‐PCR. Our findings suggest that miRNAs may be involved in vitiligo development and serum miRNAs could serve as serum biomarkers for vitiligo in mice.     

Hair shaft miRNA‐221 levels as a new tumor marker of malignant melanoma

miRNA‐221 (miR‐221) is known to be abnormally expressed in many human cancers. The serum levels of miR‐221 have been reported as a tumor marker for malignant melanoma (MM). We hypothesized that the hair shaft miR‐221 levels may be increased in patients with MM. We therefore assessed the possibility that hair shaft miR‐221 levels could be a marker for MM. The hair shaft miR‐221 levels were significantly higher in patients with MM than controls. The rates of increased hair shaft miR‐221 levels above the cut‐off value were comparable to those of serum 5‐S‐CD, which is a tumor marker commonly used for MM. Measurements of the hair shaft miR‐221 levels could have potential clinical value in the detection of MM. This is the first report investigating the hair shaft levels of an miRNA in patients with MM. Our investigations offer new insight into the relationship between miR‐221 and MM, and may provide a new, non‐invasive way to screen for melanoma.     

Recent progress in studies of miRNA and skin diseases

miRNA is a family of small non‐coding RNA that consists of 22 nucleotides on average. miRNA are implicated in various cellular activities such as cell proliferation or migration via the modulation of gene expression, and also are linked to the pathogenesis of human diseases. This paper reviews recent research progress about the contribution of miRNA to the pathogenesis of various skin diseases, and possible application of miRNA as the disease markers in each disease. For example, downregulated miR‐424‐5p in psoriatic skin causes the overexpression of MEK1 and cyclin E1 in psoriatic keratinocytes, resulting in the keratinocyte overgrowth and hyperproliferation seen in the disease. Although there was no significant difference in the serum miR‐424‐5p levels between psoriasis patients and healthy controls, serum miR‐1266‐5p levels were significantly upregulated in psoriasis patients, and showed weak and inverse correlation with disease activity. Furthermore, combination of serum levels of miR‐146a‐5p and ‐203a‐3p was more reliable to distinguish psoriasis patients and normal subjects, than each miRNA alone. Hair shaft miR‐424‐5p levels were significantly higher in psoriasis patients than normal subjects, while hair root miR‐19a‐3p levels in psoriasis patients were inversely correlated with the duration between symptom onset and the first visit to the hospital. Future researches of miRNA will enable the advances of their clinical applications including the clarification of pathogenesis, disease markers and novel treatments.     

MicroRNA expression differs in cutaneous squamous cell carcinomas and healthy skin of immunocompetent individuals

Cutaneous squamous cell carcinoma (cSCC) is one of the most common skin cancers, but the influence of microRNA (miRNA) expression has only been sporadically analysed. We hypothesized that miRNAs are differentially expressed in cSCC and hence influence its development. We therefore isolated total miRNA from well‐differentiated cSCCs and from controls without SCC. Expression analyses of 12 miRNAs showed three significantly differentially expressed miRNAs. We identified a significant upregulation of the miR‐21 and the miR‐31, a proto‐oncogene like miR‐21. While the upregulated expression of miR‐21 has been known for some time, the increased expression of miR‐31 was never shown so clearly. Furthermore, we showed the upregulation of miRNA‐205, which has never been described before. The miR‐205 induces specific keratinocyte migration and could be a characteristic marker for cSCC. It has to be determined in following studies whether these upregulated expressions are specific for cSCC and if so, for which cSCC stages.     

Overexpression of miR‐200b inhibits the cell proliferation and promotes apoptosis of human hypertrophic scar fibroblasts in vitro

Hypertrophic scarring leads to a deformed appearance and contracted neogenetic tissue, resulting in physiological and psychological problems for patients. Millions of people suffer these discomforts each year. Emerging evidence has reported that miRNA contributed to hypertrophic scarring or keloid formation. In this study, nine hypertrophic scar samples and the matched normal skin tissues were used to perform a miRNA microarray. The results of miRNA array showed that miR‐200b was downregulated by more than 2‐fold, validated by qPCR in hypertrophic scar tissues and human hypertrophic scar fibroblasts, suggesting that there was an important correlation between miR‐200b and hypertrophic scarring. We also found that miR‐200b affected hypertrophic scarring through regulating the cell proliferation and apoptosis of human hypertrophic scar fibroblasts by affecting the collagen I and III synthesis, fibronectin expression and TGF‐β1/α‐SMA signaling. Thus, our study provides evidence to support that miR‐200b may be a useful target for hypertrophic scarring management.     

Role of IL‐10 and TGF‐β in melanoma

IL‐10 and TGF‐β are immunosuppressive cytokines expressed in tumors including melanoma and, therefore, deemed major cause for failing antitumor immune responses. Re‐evaluating their role, we compared their expression by quantitative RT‐PCR in melanoma and skin of healthy individuals, tested their induction in dendritic cells and T cells co‐cultured with tumor cells, and their effects on the immune cells. Both cytokines as well as their receptors were expressed in melanoma at significantly lower levels than in healthy skin. Consequently, the expressions of IL‐10‐responsive SOCS‐3 and TGF‐β‐responsive Smad‐7 were low in tumors but high in healthy skin. T cells co‐cultured with tumor cells developed an anergic state without increased IL‐10 or TGF‐β expression. In vitro tumor‐induced immature dendritic cells produced high IL‐10 levels and less efficiently induced T‐cell proliferation. Nonetheless, they could be induced to mature, and blocking IL‐10 did not alter the capacity of the resulting mature dendritic cells to stimulate T cells. Mature dendritic cells co‐cultured with tumor cells produced increased IL‐10 but decreased TGF‐β and more efficiently induced T‐cell proliferation. The lack of correlation of IL‐10 and TGF‐β with immune deficits in situ and in vitro suggests re‐evaluating their roles in cancer.     

Oncogenic BRAF signalling increases Mcl‐1 expression in cutaneous metastatic melanoma

The Bcl‐2 family member Mcl‐1 is essential for melanoma survival; however, the influence of oncogenic BRAF signalling remains elusive. In this study, Mcl‐1 splice variant expression was determined in a panel of melanoma cell lines in relation to BRAF mutational status. Mcl‐1L mRNA expression was increased in melanoma cells compared with primary melanocytes with significantly increased mRNA and protein expression observed in BRAF^V600E mutant melanoma cells. Although no change in Mcl‐1S mRNA was observed, Mcl‐1S protein expression also increased in BRAF mutant melanoma cells. Additionally, while over‐expression of mutant BRAF^V600E increased both Mcl‐1L and Mcl‐1S expression, inhibition of hyperactive BRAF signalling resulted in decreased Mcl‐1L expression. These studies suggest that the regulation of Mcl‐1 expression by BRAF signalling is increased by oncogenic activation of BRAF, revealing a mechanism of apoptotic resistance which may be overcome by the use of more specifically targeted Mcl‐1 inhibitors.     

miRNA-193b-5p抑制转录调节因子CITED2表达对黑素合成的影响

目的初步探讨miRNA(miR)-193b-5p对黑素合成的影响及可能机制。方法从健康男性包皮环切术后废弃的正常包皮组织中分离培养人原代黑素细胞。分别转染miR-NC模拟物(miR-NC mimics组)和miR-193b-5p模拟物(miR-193b-5p mimics组)至人原代黑素细胞及人黑素瘤MNT1细胞, 转染48 h时实时定量PCR(RT-qPCR)检测miR-193b-5p的过表达效率, 转染72 h时Western印迹检测黑素合成相关蛋白酪氨酸酶和小眼畸形相关转录因子的表达, 转染1周时采用氢氧化钠法测定细胞中黑素含量。通过TargetScan网站预测miR-193b-5p的靶基因并采用双荧光素酶报告实验验证, RT-qPCR及Western印迹检测miR-193b-5p过表达后该靶基因mRNA和蛋白表达水平的变化。两组间比较采用两独立样本t检验。结果人原代黑素细胞及人黑素瘤MNT1细胞中, miR-193b-5p mimics组miR-193b-5p的表达水平均显著高于miR-NC mimics组, t值分别为65.57、22.49, 均P < 0.001, 且...     

Aldo‐keto reductase 1C3 is overexpressed in skin squamous cell carcinoma (SCC) and affects SCC growth via prostaglandin metabolism

Aldo‐keto reductase 1C3 (AKR1C3) is an enzyme involved in metabolizing prostaglandins (PGs) and sex hormones. It metabolizes PGD₂ to 9α11β‐PGF₂, diverting the spontaneous conversion of PGD₂ to the PPARγ agonist, 15‐Deoxy‐Delta‐12, 14‐prostaglandin J2 (15d‐PGJ₂). AKR1C3 is overexpressed in various malignancies, suggesting a tumor promoting function. This work investigates AKR1C3 expression in human non‐melanoma skin cancers, revealing overexpression in squamous cell carcinoma (SCC). Effects of AKR1C3 overexpression were then evaluated using three SCC cell lines. AKR1C3 was detected in all SCC cell lines and its expression was upregulated in response to its substrate, PGD₂. Although attenuating AKR1C3 expression in SCC cells by siRNA did not affect growth, treatment with PGD₂ and its dehydration metabolite, 15d‐PGJ₂, decreased SCC proliferation in a PPARγ‐dependent manner. In addition, treatment with the PPARγ agonist pioglitazone profoundly inhibited SCC proliferation. Finally, we generated an SCC cell line that stably overexpressed AKR1C3 (SCC‐AKR1C3). SCC‐AKR1C3 metabolized PGD₂ to 9α11β‐PGF₂ 12‐fold faster than the parent cell line and was protected from the antiproliferative effect mediated by PGD₂. This work suggests that PGD₂ and its metabolite 15d‐PGJ₂ attenuate SCC proliferation in a PPARγ‐dependent manner, therefore activation of PPARγ by agonists such as pioglitazone may benefit those at high risk of SCC.     

Blocking glutamate‐mediated signalling inhibits human melanoma growth and migration

Glutamate is an excitatory neurotransmitter that has been shown to regulate the proliferation, migration and survival of neuronal progenitors in the central nervous system through its action on metabotropic and ionotropic glutamate receptors (GluRs). Antagonists of ionotropic GluRs have been shown to cause a rapid and reversible change in melanocyte dendritic morphology, which is associated with the disorganization of actin and tubulin microfilaments in the cytoskeleton. Intracellular expression of microtubule‐associated protein (MAP) 2a affects the assembly, stabilization and bundling of microtubules in melanoma cells; stimulates the development of dendrites; and suppresses melanoma cell migration and invasion. In this study, we investigated the relationship between glutamate‐mediated signalling and microtubules, cell dendritic morphology and melanoma cell motility. We found that metabotropic GluR1 and N‐methyl‐d ‐aspartate receptor antagonists increased dendritic branching and inhibited the motility, migration and proliferation of melanoma cells. We also demonstrated that the invasion and motility of melanoma cells are significantly inhibited by the combination of increased expression of MAP2a and either metabotropic GluR1 or N‐methyl‐d ‐aspartate receptor antagonists. Moreover, the blockade of glutamate receptors inhibited melanoma growth in vivo. Collectively, these results demonstrate the importance of glutamate signalling in human melanoma and suggest that the blockade of glutamate receptors is a promising novel therapy for treating melanoma.     

Correlation among metallothionein expression,intratumoural macrophage infiltration and the risk of metastasis in human cutaneous malignant melanoma

Background The formation of metastases and the efficacy of systemic therapies in cutaneous malignant melanoma (CMM) depend on the characteristics of the tumour cells and the host immune response. Aberrant expression of metallothionein (MT) has been observed in several types of cancers with poor prognoses. Objective To perform an immunohistochemical study on primary CMM comparing the MT expression of tumours without metastases (n = 23) to that of samples with haematogenous metastases (n = 23) and to examine the correlation between MT staining and immunological markers relevant in CMM progression. Methods The immunohistochemical labelling of different tumour sections was analysed using tissue microarrays for the evaluation of the suitability of this method in future studies. Results Our results suggest that MT overexpression is significantly more frequent in primary CMM with haematogenous metastases (P = 0.018) and that the overexpression is independent of the Breslow tumour thickness (R = 0.102, P = 0.501). Interestingly, MT overexpression of the tumour cells was correlated with the presence of tumour‐infiltrating CD68⁺ macrophages (P = 0.003), a known predictive factor for melanoma progression, thereby suggesting a role for MT in the development of a defective host immune response. Furthermore, the presence of CD163⁺ macrophages infiltrating the tumours correlated with metastasis formation (P < 0.001), whereas the presence CD1a⁺ dendritic cells surrounding the tumours was associated with a lower risk of haematogenous spread (P = 0.003). Conclusion Our results demonstrate that MT may represent a suitable prognostic factor that can characterize the metastasising ability of CMM and the tumour‐promoting host immune response.