Genetic support for the role of the NLRP3 inflammasome in psoriasis susceptibility.

NACHT leucine-rich repeat- and PYD-containing (NLRP)3 protein controls the inflammasome by regulating caspase-1 activity and interleukin (IL)-1ß processing. The contribution of IL-1ß in the pathogenesis of psoriasis is well recognized. Polymorphisms in NLRP3 and caspase recruitment domain-containing protein (CARD)8, a negative regulator of caspase-1 activity, have been associated with susceptibility to common inflammatory diseases, such as Crohn's disease and rheumatoid arthritis. To investigate the role for genetic variants in the NLRP3 inflammasome in psoriasis susceptibility. In a patient sample comprising 1988 individuals from 491 families and 1002 healthy controls, genotypes for four selected single-nucleotide polymorphisms (SNPs) in NLRP3 (three SNPs) and CARD8 (one SNP) were determined by TaqMan(®) Allelic Discrimination. Using the transmission disequilibrium test (TDT), a significant increase in the transmission of the NLRP3 rs10733113G genotype to a subgroup of patients with more widespread psoriasis was demonstrated (P = 0.015). Using logistic regression analysis in 741 patients with psoriasis and 1002 controls, the CARD8 rs2043211 genotype was significantly different in cases and controls in overall terms [OR 1.3 (1.1-1.5), P = 0.004] and for both genders. Our data support the hypothesis that the inflammasome plays a role in psoriasis susceptibility.

The expression of Psoriasin (S100A7) and CD24 is linked and related to the differentiation of mammary epithelial cells.

Psoriasin (S100A7), a member of the S100 family of calcium-binding proteins, is highly expressed in high-grade ductal carcinoma in situ (DCIS) and in the benign hyperproliferative skin disorder psoriasis. The gene that encodes psoriasin and many other S100 genes are located within a gene cluster on chromosome region 1q21, known as the epidermal differentiation complex. This cluster contains genes for several differentiation markers that play important roles in the terminal differentiation of the epidermis. The purpose of the present study was to evaluate the role of psoriasin in the differentiation process of mammary epithelial cells. Normal mammary epithelial cells (MCF10A) cultured in confluence and suspension, conditions known to induce psoriasin expression, demonstrated a shift towards a more differentiated phenotype indicated by an increase in the expression of the luminal differentiation markers CD24 and MUC1 and the reduced expression of the breast stem cell marker CD44. The expression of psoriasin and MUC1 was most pronounced in the CD24(+)-enriched fraction of confluent MCF10A cells. The shift towards a more differentiated phenotype was abolished upon the downregulation of psoriasin using short hairpin RNA (shRNA) and small interfering RNA (siRNA). Using specific inhibitors, we showed that psoriasin and CD24 expression was regulated by reactive oxygen species (ROS) and the nuclear factor (NF)-κB signaling pathways. While immunohistochemical analyses of DCIS showed heterogeneity, the expression of psoriasin and CD24 showed a similar staining pattern. Our findings suggest that the expression of psoriasin is linked to the luminal differentiation marker CD24 in mammary epithelial cells. Psoriasin demonstrated an essential role in the shift towards a more differentiated CD24(+) phenotype, supporting the hypothesis that psoriasin plays a role in the differentiation of luminal mammary epithelial cells.

Psoriasin (S100A7) increases the expression of ROS and VEGF and acts through RAGE to promote endothelial cell proliferation.

Psoriasin (S100A7), originally identified in psoriasis, is a calcium-binding protein belonging to the multigenic S100 family. In high-grade ductal carcinoma in situ, psoriasin was identified as one of the most abundant transcripts. We have previously shown that psoriasin was induced by reactive oxygen species (ROS). Moreover, the downregulation of psoriasin by short hairpin RNA (shRNA) led to the reduced expression of vascular endothelial growth factor (VEGF) and inhibited tumor growth in vivo. The aim of the present study was to investigate whether psoriasin could have direct effects on endothelial cells. In this study we demonstrated that psoriasin increased VEGF expression in mammary epithelial cells. The treatment of endothelial cells with recombinant psoriasin increased proliferation comparable to that of recombinant VEGF protein. No change in proliferation was seen when endothelial cells were infected with psoriasin-expressing adenoviruses, suggesting that the proliferative effect of psoriasin was mediated by a specific receptor. Treatment with sRAGE, targeting the receptor for advanced glycation end products (RAGE), thus inhibited endothelial cell proliferation and tube formation enhanced by recombinant psoriasin. We showed that VEGF expression was not induced by hydrogen peroxide, when psoriasin was silenced by shRNA, which led to the hypothesis that psoriasin induces ROS. Indeed, psoriasin was shown to induce ROS in both endothelial and epithelial cells. Moreover, sRAGE inhibited the psoriasin-dependent generation of ROS in endothelial cells. Finally, treatment with antioxidant Bcl-2 protein abolished the effect of psoriasin on endothelial cell proliferation. Our data suggest that psoriasin expression in mammary epithelial cells leads to increased endothelial cell proliferation in a paracrine manner through RAGE. Psoriasin may therefore play a role in breast cancer progression by promoting oxidative stress response and angiogenesis.

Expression patterns of S100 proteins in melanocytes and melanocytic lesions.

S100 proteins are differentially expressed in tumours of epithelial origin. Little is known about their expression in melanocyte-derived tumours of neuroectodermal origin. We have analysed the expression of some S100 proteins in this line of lesions using SAGE Genie informatics, cell culture and human tumour tissue. The pattern of expression of six S100 proteins was investigated at both the mRNA and protein levels, using quantitative real-time PCR, western blotting and immunohistochemical analysis. No differential expression was observed with respect to S100A4, S100A7, S100A8, S100A9 and S100A11. In contrast, S100A10 was downregulated in three melanoma cell lines compared with normal melanocytes. Using SAGE informatics, two-dimensional displays of microarray expression data from the NCI60_Novartis cell lines displayed a positive correlation between the expression of S100A10 and the expression of the proliferation marker, Ki67. Our data suggest that S100A10, like its binding partners S100A7 and annexin A2, is an oxidant-sensitive protein. In addition, higher expression of S100A10 was detected in melanocyte cell lines with long projections compared with melanoma cell lines with small ripples. In a panel of 47 melanocyte-derived lesions comprising melanocytic naevi and melanomas, S100A10 was expressed to varying degrees in the melanocytic lesions. The antigen was primarily expressed in regions with a strong proliferating or differentiating capacity, especially in regions in or near the epidermis. We suggest that S100A10 may play a role in the regulation of the proliferation or early maturation sequence of melanocytic lesions, and that it merits further study as a potential biomarker of activity.

S100A7 (Psoriasin), highly expressed in ductal carcinoma in situ (DCIS), is regulated by IFN-gamma in mammary epithelial cells.

BACKGROUND: The aim of the present work was to explore signal transduction pathways used in the regulation of S100A7 (psoriasin). Members of the S100 gene family participate in many important cellular functions. Psoriasin, S100A8 (calgranulin A) and S100A9 (calgranulin B) are expressed in ductal carcinoma in situ (DCIS), as well as in the hyperproliferative skin disease, psoriasis. In the latter condition, a disturbance in the STAT pathway has recently been reported. This pathway is implicated in the regulation of IFN-gamma, widely recognized as a key cytokine in psoriasis. IFN-gamma also exerts anti-tumor action in a number of tumor cell types, including breast cancer. We therefore examined the effect of IFN-gamma and STAT-signaling on the psoriasin expression. METHODS: We established a TAC2 mouse mammary epithelial cell line with tetracycline-inducible psoriasin expression (Tet-Off). Viability in cell culture was estimated using MTS assay. Protein and gene expression were evaluated by Western blotting and quantitative real-time PCR. Statistical analyses were assessed using a one-tailed, paired t-test. RESULTS: We report the downregulation of psoriasin by IFN-gamma in the MDA-MB-468 breast cancer cell line, as well as the downregulation of psoriasin induced by anoikis in cell lines derived from different epithelial tissues. In contrast, IFN-gamma had no suppressive effect on calgranulin A or calgranulin B. IFN-gamma is an important activator of the STAT1 pathway and we confirmed an active signaling pathway in the cell lines that responded to IFN-gamma treatment. In contrast, in the SUM190 breast carcinoma cell line, IFN-gamma did not suppress the expression of endogenous psoriasin. Moreover, a reduced phosphorylation of the STAT1 protein was observed. We showed that IFN-gamma treatment and the inhibition of the transcription factor NFkappaB had a synergistic effect on psoriasin levels. Finally, in TAC2 cells with tetracycline-induced psoriasin expression, we observed the increased viability of psoriasin-expressing cells after IFN-gamma treatment. CONCLUSION: Our data support the possibility that psoriasin expression is transcriptionally suppressed by IFN-gamma and that this effect is likely to be mediated by the activation of the STAT1 signaling pathway. The increased viability of psoriasin-expressing cells after IFN-gamma exposure suggests that psoriasin expression leads to the development of an apoptosis-resistant phenotype.

Psoriasin (S100A7) and calgranulin-B (S100A9) induction is dependent on reactive oxygen species and is downregulated by Bcl-2 and antioxidants.

S-100 proteins are calcium-binding proteins with important growth regulatory functions. Of these proteins, psoriasin and calgranulin-B have been shown to be highly upregulated in ductal carcinoma in situ (DCIS) of the breast and in psoriasis. The purpose of this study was to further elucidate the functional relevance of the overexpression of these two S-100 proteins in psoriasis and DCIS. We report the induction of both proteins by reactive oxygen species, phorbol ester TPA, and the induction of psoriasin in response to the PI3K inhibitor wortmannin. We also demonstrate that Bcl-2 overexpression represses the induction of psoriasin and calgranulin-B under these different conditions. The same effect was obtained with the antioxidant NAC, which indicates that the suppression of psoriasin and calgranulin-B induction is mediated by the antioxidant function of Bcl-2. Furthermore, we demonstrate that overexpression of a dominant negative IKKbeta also inhibits the induction of psoriasin suggesting that the NFkappaB pathway is involved in the induction of this protein. Also, we found NFkappaB responsive DNA elements in the upstream promoter region of psoriasin. MCF10A cells with a stable retroviral overexpression of psoriasin were significantly more resistant to H2O2-induced cell death than control cells further supporting the hypothesis that these S-100 proteins may play a role in oxidative stress response.