Zhenhui Peng

Downregulation of tazarotene induced gene-2 (TIG2) in skin squamous cell carcinoma

Tazarotene, an RARbeta/gamma-selective synthetic retinoid, was found to induce three genes, tazarotene-induced genes (TIG) 1, 2 and 3. TIG2 was abundantly expressed in non-lesional psoriatic skin, but at lower levels in psoriatic lesions. The protein precursor encoded by TIG2, called prochemerin, can be converted into bioactive chemerin. Chemerin can then bind to chemerin receptor, resulting in chemoattracting dendritic cells and macrophages, and serving as a bridge between innate and adaptive immunity. Our objective was to investigate the role of TIG2 in skin squamous cell carcinoma (SCC). The levels of TIG2-protein and transcript in normal skin tissues, uninvolved skin and SCC lesions were determined by immunohistochemistry and in situ hybridization. TIG2-protein and transcript were detected in all layers of normal epidermis and uninvolved skin adjacent to SCC lesions. In addition, TIG2 was also expressed in the corneum, granular layers and the upper and middle layers of stratum spinosum of the marginal part of SCC lesions. On the other hand, TIG2-protein and transcript were barely detectable around the keratin pearls of SCC 1-2, and were not detectable at all in SCC 3-4.

Apoptosis induced by synthetic retinoic acid CD437 on human melanoma A375 cells involves RIG-I pathway

Human malignant melanoma is notoriously resistant to currently available pharmacological modulation. Our aim was to evaluate the anti-tumor effect of a novel synthetic retinoid 6-[3-(1-adamantyl)-4-hydroxyphenyl]-2-naphthalene carbo-xylic acid (CD437) on melanoma cell line A375. Analysis of cell morphology showed that CD437 promoted marked apoptosis in A375 cells. To explore the mechanisms of CD437-induced apoptosis, an NF-κB-luciferase reporter assay was performed, demonstrating that apoptosis induction by CD437 required activation of transcription factor NF-κB. Importantly, based on the findings that RIG-I (retinoic acid inducible gene I) can be induced by retinotic acid and can activate NF-κB through a CARD-containing adaptor protein VISA, we proposed a hypothesis that RIG-I was involved in the signal pathway of NF-κB activation induced by CD437 through the adaptor protein VISA. By specially cleaving VISA with hepatitis C virus (HCV) non-structural (NS)3/4A, the RIG-I pathway was blocked, with subsequent simultaneous inhibition of CD437-induced NF-κB activation and cell apoptosis in A375 cells. These results support our hypothesis and suggest that RIG-I may be a useful intermediate biologic marker for retinoid chemoprevention and treatment studies.

Isolation and antitumor activities of acidic polysaccharide from Gynostemma pentaphyllum Makino

Two acidic polysaccharides (GP-B1 and GP-C1) were obtained from Gynostemma pentaphyllum. The molecular weights (Mw) of the two fractions were 79 kDa for GP-B1 and 126 kDa for GP-C1. GP-B1 was composed of Gal, Ara, Man, Rha, Xyl, Glc, GalA and GlcA in a molar ration of 3.5:3.2:0.6:0.9:0.3:0.5:0.6:0.4. GP-C1 consisted of Gal, Ara, Man, Rha, Glc, and GlcA in the proportions of 2.1:1.0:0.3:0.5:0.4:0.9. Among them, GP-B1 treatment had a significant inhibitory effect on the growth of melanoma B16 in vivo and in vitro. Meanwhile GP-B1 could increase the relative spleen weight and stimulate the splenocyte proliferation alone or combined with ConA. Moreover, GP-B1 treatment induced an evident increase in the level of serum TNF-α, IFN-γ, and IL-12 and a reduction for IL-10 production. These results indicate that the antitumor effects of GP-B1 are associated with immunostimulation.

Alteration and significance of heparin-binding epidermal-growth-factor-like growth factor in psoriatic epidermis.

Background: Heparin-binding epidermal-growth-factor-like growth factor (HB-EGF) has proved to be a mitogen of keratinocytes, which may be involved in the pathogenesis of inflammatory diseases, but its mechanism in psoriasis remains unknown. Objective: To investigate the alteration of HB-EGF in the epidermis of active psoriasis vulgaris. Methods: The expression of HB-EGF in normal skin tissues, uninvolved tissues and psoriatic lesions was detected by in situ hybridization and immunohistochemistry. Results: HB-EGF mRNA and protein were located in the basal layer of normal epidermis (10/10, 100.00%), with nearly no expression in the suprabasal layers (1/10, 10.00%); the expression of HB-EGF was located not only in the basal layer (21/21, 100.00%), but was also seen as focal overexpression in the suprabasal layers of uninvolved epidermis (20/21, 95.24%) and the marginal part of psoriatic lesions (18/21, 85.71%), while nearly no expression of HB-EGF was found in the central part of psoriatic lesions (1/21, 4.76%). Conclusion: HB-EGF may play an important role in the early pathogenesis of psoriasis.

Decreased expression of E-cadherin and β-catenin in the lesional skin of patients with active psoriasis

Correspondence Decreased expression of E-cadherin and β -catenin in the lesional skin of patients with active psoriasis Keratinocyte proliferation outside the basal layer suggests an alteration in cell–cell interactions in active psoriasis. The molecular alterations in epidermal barrier function and the mechanisms underlying the perturbed state of proliferation and differentiation in psoriatic epidermis remain poorly understood. Keratinocytes interact with each other through intercellular junctions to regulate cellular shape, proliferation, and the passage of ions and molecules through the paracellular pathway. 1,2 Adherens junctions (AJs) are required for the establishment and maintenance of epithelial layers, mediating intercellular adhesion, sensing the presence of neighboring cells, and anchoring the actin cytoskeleton to protein complexes and the membrane in this region of the cell. 3

Two novel mutations of the ATP2C1 gene in Chinese patients with Hailey–Hailey disease

Hailey–Hailey disease (HHD; OMIM 169600) is an autosomal dominant blistering disease. Pathogenic mutations in ATP2C1 encoding the human secretory pathway Ca2+/Mn2+-ATPase protein 1 (hSPCA1) have been identified since 2000. The aim of this study was to report a Chinese pedigree and a sporadic case of HHD and to explore the genetic mutations. The Chinese pedigree and the sporadic case of typical HHD were subjected to mutation detection of ATP2C1. The 27 coding exons and their flanking sequences were amplified and sequenced. The heterozygous C to T transition at nucleotide 2753 in exon 26 and G to T transition at nucleotide 2090 in exon 21 of the ATP2C1 gene were identified in a pedigree and a sporadic case of HHD, respectively. The C2753T transition resulted in a novel nonsense mutation of glutamine codon (CAG) to a stop codon (TAG) at amino acid residue 865 (Q865X) and the G2090T transition resulted in a novel missense mutation of glycine condon (GGA) to Valine (GUA) at amino acid residue 645 (G645V) in hSPCA1. This study should be useful for genetic counseling and prenatal diagnosis for affected families and in expanding the repertoire of ATP2C1 mutations underlying HHD.

Wnt/β-Catenin and Wnt5a/Ca Pathways Regulate Proliferation and Apoptosis of Keratinocytes in Psoriasis Lesions.

Background/Aims: Wnt5a is overexpressed in psoriasis lesions, however the mechanism by which Wnt5a is involved in the pathogenesis of psoriasis is not clear. To address this, the expression of Wnt5a in psoriatic lesions and its effect on keratinocyte cell proliferation and apoptosis was examined in vitro. Methods: The expression levels of WNT5A, and genes encoding its receptors frizzled2 (FZD2) and frizzled5 (FZD5) were examined in samples obtained from individuals with psoriasis and healthy controls. Knockdown of Wnt5a with short interfering (si)RNAs was performed in cultured HaCaT keratinocytes and normal human keratinocytes (NHK), and the expression of Wnt5a, protein kinase C (PKC), and β-catenin were determined, and cell cycle activity, proliferation and apoptosis were assessed. Results: The expression of WNT5A, FZD2 and FZD5 mRNA and protein were increased in psoriatic lesions. Wnt5a knockdown suppressed proliferation and induced apoptosis in HaCaT and NHK cells. Additionally, expression of PCNA, MKI67, CCND1, BCL2, CTNNB1, and genes encoding PKC and survivin were downregulated, whereas CASP3 was upregulated. The mRNA levels of the Wnt pathway inhibitors DKK1 and SFRP1 were upregulated, Western blotting analyses demonstrated reduction in β-catenin and PKC protein levels. Conclusion: Knockdown of Wnt5a suppresses the proliferation of keratinocytes and induces apoptosis by inhibiting the Wnt/β-catenin or Wnt5a/Ca2+ pathways.

Effects of narrow-band ultraviolet B and tazarotene therapy on keratinocyte proliferation and TIG3 expression

Tazarotene plus narrow‐band ultraviolet B (NB‐UVB) therapy has been shown to enhance the efficacy in treating patients with psoriasis, while the mechanism is not clear. The present study aims to investigate the alteration of cell proliferation and TIG3 in cultured normal human keratinocytes after NB‐UVB and/or tazarotene treatment. Keratinocytes were exposed to NB‐UVB, then incubated with or without tazarotene, and then cell proliferation was detected by methyl thiazoleterazolium colorimetric assay and TIG3 mRNA expression and protein production was examined by real‐time reverse transcription polymerase chain reaction and immunocytochemistry, respectively. The results show that keratinocyte proliferation was inhibited and TIG3 mRNA expression and protein production were elevated by tazarotene at a dose higher than 0.1 µmol/L. In NB‐UVB single irradiating groups, only 200 mJ/cm2 NB‐UVB inhibited keratinocyte proliferation, and none of the irradiated groups had an effect on TIG3 expression. Moreover, tazarotene plus NB‐UVB have stronger effects than those separately. These results indicate NB‐UVB plus tazarotene may have synergistic effects on inhibiting keratinocyte proliferation and elevating TIG3 expression, which may have some implications for the understanding of how to treat psoriasis patients with tazarotene plus NB‐UVB.

A new mutation of the double-stranded RNA-specific adenosine deaminase gene in a family with dyschromatosis symmetrica hereditaria.

Background: Dyschromatosis symmetrica hereditaria (DSH) is a pigmentary genodermatosis characterized by a mixture of hyperpigmented and hypopigmented macules localized on the back of the extremities and caused by mutations in the double-stranded RNA-specific adenosine deaminase (DSRAD) gene. Objective: To identify gene mutations of DSRAD in patients with DSH. Methods: A Chinese pedigree of typical DSH was subjected to mutation detection in DSRAD. Direct sequencing of all PCR products of the whole coding regions of DSRAD was performed to identify the mutation. Results: A missense mutation 2747G→T in the DSRAD gene was found in the affected members but not in the healthy individuals in this family and in 50 unrelated controls. Conclusion: Our study found a novel missense mutation in exon 9 of the DSRAD gene. We add new variants to the knowledge of DSRAD mutations in DSH.

Two novel frameshift mutations of the DSRAD gene in Chinese pedigrees with dyschromatosis symmetrica hereditaria

Background  Dyschromatosis symmetrica hereditaria (DSH) is an autosomal dominant disorder characterized by a mixture of hyperpigmented and hypopigmented macules localized on the back of the extremities and caused by the mutations in the DSRAD gene.