Michael D. Allen

Identification of ZNF313 / RNF114 as a novel psoriasis susceptibility gene

Psoriasis is an immune-mediated skin disorder that is inherited as a multifactorial trait. Linkage studies have clearly identified a primary disease susceptibility locus lying within the major histocompatibility complex (MHC), but have generated conflicting results for other genomic regions. To overcome this difficulty, we have carried out a genome-wide association scan, where we analyzed more than 408,000 SNPs in an initial sample of 318 cases and 288 controls. Outside of the MHC, we observed a single cluster of disease-associated markers, spanning 47 kb on chromosome 20q13. The analysis of two replication data sets confirmed this association, with SNP rs495337 yielding a combined P-value of 1.4 x 10(-8) in an overall sample of 2679 cases and 2215 controls. Rs495337 maps to the SPATA2 transcript and is in absolute linkage disequilibrium with five SNPs lying in the adjacent ZNF313 gene (also known as RNF114). Real-time PCR experiments showed that, unlike SPATA2, ZNF313 is abundantly expressed in skin, T-lymphocytes and dendritic cells. Furthermore, an analysis of the expression data available from the Genevar database indicated that rs495337 is associated with increased ZNF313 transcripts levels (P = 0.003), suggesting that the disease susceptibility allele may be a ZNF313 regulatory variant tagged by rs495337. Homology searches indicated that ZNF313 is a paralogue of TRAC-1, an ubiquitin ligase regulating T-cell activation. We performed cell-free assays and confirmed that like TRAC-1, ZNF313 binds ubiquitin via an ubiquitin-interaction motif (UIM). These findings collectively identify a novel psoriasis susceptibility gene, with a putative role in the regulation of immune responses.

Rigidity sensing and adaptation through regulation of integrin types.

Tissue rigidity regulates processes in development, cancer and wound healing. However, how cells detect rigidity, and thereby modulate their behaviour, remains unknown. Here, we show that sensing and adaptation to matrix rigidity in breast myoepithelial cells is determined by the bond dynamics of different integrin types. Cell binding to fibronectin through either α5β1 integrins (constitutively expressed) or αvβ6 integrins (selectively expressed in cancer and development) adapts force generation, actin flow, and integrin recruitment to rigidities associated with healthy or malignant tissue, respectively. In vitro experiments and theoretical modelling further demonstrate that this behaviour is explained by the different binding and unbinding rates of both integrin types to fibronectin. Moreover, rigidity sensing through differences in integrin bond dynamics applies both when integrins bind separately and when they compete for binding to fibronectin.

Tumour-associated tenascin-C isoforms promote breast cancer cell invasion and growth by matrix metalloproteinase-dependent and independent mechanisms

IntroductionThe stromal microenvironment has a profound influence on tumour cell behaviour. In tumours, the extracellular matrix (ECM) composition differs from normal tissue and allows novel interactions to influence tumour cell function. The ECM protein tenascin-C (TNC) is frequently up-regulated in breast cancer and we have previously identified two novel isoforms – one containing exon 16 (TNC-16) and one containing exons 14 plus 16 (TNC-14/16).MethodsThe present study has analysed the functional significance of this altered TNC isoform profile in breast cancer. TNC-16 and TNC-14/16 splice variants were generated using PCR-ligation and over-expressed in breast cancer cells (MCF-7, T47D, MDA-MD-231, MDA-MB-468, GI101) and human fibroblasts. The effects of these variants on tumour cell invasion and proliferation were measured and compared with the effects of the large (TNC-L) and fully spliced small (TNC-S) isoforms.ResultsTNC-16 and TNC-14/16 significantly enhanced tumour cell proliferation (P < 0.05) and invasion, both directly (P < 0.01) and as a response to transfected fibroblast expression (P < 0.05) with this effect being dependent on tumour cell interaction with TNC, because TNC-blocking antibodies abrogated these responses. An analysis of 19 matrix metalloproteinases (MMPs) and tissue inhibitor of matrix metalloproteinases 1 to 4 (TIMP 1 to 4) revealed that TNC up-regulated expression of MMP-13 and TIMP-3 two to four fold relative to vector, and invasion was reduced in the presence of MMP inhibitor GM6001. However, this effect was not isoform-specific but was elicited equally by all TNC isoforms.ConclusionsThese results demonstrate a dual requirement for TNC and MMP in enhancing breast cancer cell invasion, and identify a significant role for the tumour-associated TNC-16 and TNC-14/16 in promoting tumour invasion, although these isoform-specific effects appear to be mediated through MMP-independent mechanisms.

The Epstein-Barr Virus-Encoded LMP2A and LMP2B Proteins Promote Epithelial Cell Spreading and Motility

ABSTRACT The frequent expression of latent membrane proteins LMP2A and LMP2B in Epstein Barr virus (EBV)-associated tumors suggests that these proteins play a role in EBV-induced epithelial cell growth transformation. Expression of LMP2A and LMP2B had no effect on the morphology of squamous epithelial cells in monolayer culture, but their expression was associated with an increased capacity to spread and migrate on extracellular matrix. Although the mechanisms by which LMP2A and LMP2B promote cell spreading and motility are unclear, the use of selective pharmacological inhibitors has established a role for tyrosine kinases in this phenotype but ruled out contributions of phosphatidylinositol 3-kinase, extracellular signal-regulated kinase/mitogen-activated protein kinase, and protein kinase C. The ability of LMP2B to induce a phenotype that is virtually indistinguishable from that of LMP2A suggests that regions of the LMP2 protein in addition to the cytosolic amino terminus are capable of inducing phenotypic effects in epithelial cells. Thus, rather than serving to modulate the activity of LMP2A, LMP2B may directly engage signaling pathways to influence epithelial cell behavior such as cell adhesion and motility.

Prognostic and Therapeutic Impact of Argininosuccinate Synthetase 1 Control in Bladder Cancer as Monitored Longitudinally by PET Imaging

Targeted therapies have yet to have significant impact on the survival of patients with bladder cancer. In this study, we focused on the urea cycle enzyme argininosuccinate synthetase 1 (ASS1) as a therapeutic target in bladder cancer, based on our discovery of the prognostic and functional import of ASS1 in this setting. ASS1 expression status in bladder tumors from 183 Caucasian and 295 Asian patients was analyzed, along with its hypothesized prognostic impact and association with clinicopathologic features, including tumor size and invasion. Furthermore, the genetics, biology, and therapeutic implications of ASS1 loss were investigated in urothelial cancer cells. We detected ASS1 negativity in 40% of bladder cancers, in which multivariate analysis indicated worse disease-specific and metastasis-free survival. ASS1 loss secondary to epigenetic silencing was accompanied by increased tumor cell proliferation and invasion, consistent with a tumor-suppressor role for ASS1. In developing a treatment approach, we identified a novel targeted antimetabolite strategy to exploit arginine deprivation with pegylated arginine deiminase (ADI-PEG20) as a therapeutic. ADI-PEG20 was synthetically lethal in ASS1-methylated bladder cells and its exposure was associated with a marked reduction in intracellular levels of thymidine, due to suppression of both uptake and de novo synthesis. We found that thymidine uptake correlated with thymidine kinase-1 protein levels and that thymidine levels were imageable with [(18)F]-fluoro-L-thymidine (FLT)-positron emission tomography (PET). In contrast, inhibition of de novo synthesis was linked to decreased expression of thymidylate synthase and dihydrofolate reductase. Notably, inhibition of de novo synthesis was associated with potentiation of ADI-PEG20 activity by the antifolate drug pemetrexed. Taken together, our findings argue that arginine deprivation combined with antifolates warrants clinical investigation in ASS1-negative urothelial and related cancers, using FLT-PET as an early surrogate marker of response.

Altered Microenvironment Promotes Progression of Preinvasive Breast Cancer: Myoepithelial Expression of αvβ6 Integrin in DCIS Identifies High-risk Patients and Predicts Recurrence

Purpose: This study investigated the functional and clinical significance of integrin αvβ6 upregulation in myoepithelial cells of ductal carcinoma in situ (DCIS). Experimental Design: Archival samples of DCIS and DCIS with associated invasion (n = 532) were analyzed for expression of αvβ6 by immunohistochemistry and ability to predict recurrence and progression assessed in an independent, unique cohort of DCIS cases with long-term follow-up. Primary myoepithelial cells and myoepithelial cell lines, with and without αvβ6 expression, were used to measure the effect of αvβ6 on growth and invasion of tumor cell lines in vitro and in a xenograft mouse model. Involvement of TGFβ signaling was established using mink lung epithelial cell (MLEC) assay and antibody inhibition, and expression and activation of matrix metalloproteinase (MMP)-9 established by Real Time-PCR and zymography. Results: Expression of αvβ6 is significantly associated with progression to invasive cancer (P < 0.006) and with recurrence over a median follow-up of 114 months in a series of matched DCIS cases treated with local excision. We show that expression of αvβ6 drives myoepithelial cells to promote tumor cell invasion in vitro and enhances mammary tumor growth in vivo. The tumor-promoting effect of αvβ6-positive myoepithelial cells is dependent on TGFβ-driven upregulation of MMP9 and can be abrogated by inhibiting this pathway. Conclusion: These findings indicate that altered myoepithelial cells in DCIS predict disease progression and recurrence and show that upregulation of αvβ6 on myoepithelial cells generates a tumor promoter function through TGFβ upregulation of MMP-9. These data suggest that expression of αvβ6 may be used to stratify patients with DCIS. Clin Cancer Res; 20(2); 344–57. ©2013 AACR.

Clinical and functional significance of α9β1 integrin expression in breast cancer: a novel cell-surface marker of the basal phenotype that promotes tumour cell invasion.

Integrin α9β1 is a receptor for ECM proteins, including Tenascin‐C and the EDA domain of fibronectin, and has been shown to transduce TGFβ signalling. This study has examined the expression pattern of α9β1 in 141 frozen breast carcinoma samples and related expression to prognostic indices, molecular subtype and patient outcome. Effects of α9β1 on tumour cell migration and invasion were assessed using blocking antibody and gene transduction approaches. Integrin α9β1 localized to myoepithelial cells in normal ducts and acini, a pattern maintained in DCIS. A subset (17%) of invasive carcinomas exhibited tumour cell expression of α9β1, which related significantly to the basal‐like phenotype, as defined by either CK5/6 or CK14 expression. Tumour expression of α9β1 showed a significant association with reduced overall patient survival (p < 0.0001; HR 5.94, 95%CI 3.26–10.82) and with reduced distant‐metastasis‐free survival (p < 0.0001; HR 6.37, CI 3.51–11.58). A series of breast cancer cell lines was screened for α9β1 with the highly invasive basal‐like GI‐101 cell line expressing significant levels. Both migration and invasion of this line were reduced significantly in the presence of α9‐blocking antibody and following α9‐knockdown with siRNA. Conversely, migratory and invasive behaviour of α9‐negative MCF7 cells and α9‐low MDA MB468 cells was enhanced significantly by over‐expression of α9. Thus, α9β1 acts as a novel marker of the basal‐like breast cancer subtype and expression is associated with reduced survival, while its ability to promote breast cancer cell migration and invasion suggests that it contributes to the aggressive clinical behaviour of this tumour subtype. Copyright

Genome-wide association study identifies three novel susceptibility loci for severe Acne vulgaris

Acne vulgaris (acne) is a common inflammatory disorder of the cutaneous pilo-sebaceous unit. Here we perform a genome-wide association analysis in the United Kingdom, comparing severe cases of acne (n=1,893) with controls (n=5,132). In a second stage, we genotype putative-associated loci in a further 2,063 acne cases and 1,970 controls. We identify three genome-wide significant associations: 11q13.1 (rs478304, Pcombined=3.23 × 10(-11), odds ratio (OR) = 1.20), 5q11.2 (rs38055, P(combined) = 4.58 × 10(-9), OR = 1.17) and 1q41 (rs1159268, P(combined) = 4.08 × 10(-8), OR = 1.17). All three loci contain genes linked to the TGFβ cell signalling pathway, namely OVOL1, FST and TGFB2. Transcripts of OVOL1 and TFGB2 have decreased expression in affected compared with normal skin. Collectively, these data support a key role for dysregulation of TGFβ-mediated signalling in susceptibility to acne.

Effect of dietary copper supplementation on cell composition and apoptosis in atherosclerotic lesions of cholesterol-fed rabbits.

We have previously shown that dietary copper supplementation modulates the formation of atherosclerotic lesions in the cholesterol-fed rabbit. In the present study, we have investigated the effects of copper supplementation on the cellular composition and characteristics of atherosclerotic lesions in cholesterol-fed NZW rabbits. Rabbits received a 1% cholesterol diet with or without 0.02% copper acetate (containing 12 and 0.3 mg copper per 100 g diet, respectively) for 12 weeks. The tunica intima was significantly smaller in the animals receiving copper supplements (0.016+/-0.005 vs. 0.068+/-0.019 mm(2), P<0.05) and this was accompanied by a significant increase in aortic copper content (4.0+/-0.8 vs. 1.8+/-0.2 microg/g tissue, P<0.05). The percentage area staining for smooth muscle cells (HHF-35 positive) was significantly lower in the intima of animals receiving copper supplements (7.13+/-1.02 vs. 9.72+/-0.82%, P<0.05). However, there were no significant differences in area staining for macrophages (RAM-11 positive) between groups (22.6+/-7.9 vs. 23.3+/-4.9%). There were also significantly fewer apoptotic cells (0.96+/-0.33 vs. 2.54+/-0.56%, P<0.005) in the aortic intima from animals supplemented with copper, but no difference in the number of proliferating cells. However, there was a reduction in intimal collagen staining (Sirius red positivity) in the animals receiving a copper supplement. Taken together, these data show that dietary copper can significantly affect the composition and progression of atherosclerotic lesions.

Loss of MMP-8 in ductal carcinoma in situ (DCIS)-associated myoepithelial cells contributes to tumour promotion through altered adhesive and proteolytic function

BackgroundNormal myoepithelial cells (MECs) play an important tumour-suppressor role in the breast but display an altered phenotype in ductal carcinoma in situ (DCIS), gaining tumour-promoter functions. Matrix metalloproteinase-8 (MMP-8) is expressed by normal MECs but is lost in DCIS. This study investigated the function of MMP-8 in MECs and the impact of its loss in DCIS.MethodsPrimary normal and DCIS-associated MECs, and normal (N-1089) and DCIS-modified myoepithelial (β6-1089) cell lines, were used to assess MMP-8 expression and function. β6-1089 lacking MMP-8 were transfected with MMP-8 WT and catalytically inactive MMP-8 EA, and MMP-8 in N-1089 MEC was knocked down with siRNA. The effect on adhesion and migration to extracellular matrix (ECM), localisation of α6β4 integrin to hemidesmosomes (HD), TGF-β signalling and gelatinase activity was measured. The effect of altering MEC MMP-8 expression on tumour cell invasion was investigated in 2D and 3D organotypic models.ResultsAssessment of primary cells and MEC lines confirmed expression of MMP-8 in normal MEC and its loss in DCIS-MEC. Over-expression of MMP-8 WT but not MMP-8 EA in β6-1089 cells increased adhesion to ECM proteins and reduced migration. Conversely, knock-down of MMP-8 in N-1089 reduced adhesion and increased migration. Expression of MMP-8 WT in β6-1089 led to greater localisation of α6β4 to HD and reduced retraction fibre formation, this being reversed by MMP-8 knock-down in N-1089. Over-expression of MMP-8 WT reduced TGF-β signalling and gelatinolytic activity. MMP-8 knock-down enhanced TGF-β signalling and gelatinolytic activity, which was reversed by blocking MMP-9 by knock-down or an inhibitor. MMP-8 WT but not MMP-8 EA over-expression in β6-1089 reduced breast cancer cell invasion in 2D and 3D invasion assays, while MMP-8 knock-down in N-1089 enhanced cancer cell invasion. Staining of breast cancer cases for MMP-8 revealed a statistically significant loss of MMP-8 expression in DCIS with invasion versus pure DCIS (p = 0.001).ConclusionsThese data indicate MMP-8 is a vital component of the myoepithelial tumour-suppressor function. It restores MEC interaction with the matrix, opposes TGF-β signalling and MMP-9 proteolysis, which contributes to inhibition of tumour cell invasion. Assessment of MMP-8 expression may help to determine risk of DCIS progression.