High-content screening to distinguish between attachment and post-attachment steps of human cytomegalovirus entry into fibroblasts and epithelial cells

Human cytomegalovirus (HCMV) enters cells through a complex pathway involving the interaction of multiple viral glycoproteins and cellular receptors. While HCMV clinical isolates enter a wide range of cell types, entry has historically been studied using a laboratory strain of virus that can only infect fibroblasts. Herein, we have constructed a HCMV reporter strain that contains GFP fused to the abundant tegument protein pp65 to allow for the direct visualization of virus attachment and entry. Furthermore, the UL131 gene of this strain was restored to clinical isolate sequence to expand our studies of entry into physiologically relevant epithelial cell types. Using the HCMV-GFP reporter virus, we developed an image-based assay and screened a library containing 65,000 compounds for the inhibition of virus entry into fibroblasts. In addition to assessing the effect on virus entry, automated image analysis provided information on compound toxicity and whether the compounds acted as attachment or post-attachment inhibitors. To identify therapeutically viable inhibitors capable of blocking entry in multiple cell types, the inhibitors were screened further for their ability to inhibit virus entry into epithelial cells. Compounds were identified that were able to inhibit virus entry into both cell types at either attachment or post-attachment steps.

MicroRNAs in breast cancer pathogenesis

Micro RNAs (miRNAs) are small non-coding RNAs which regulate fundamental cellular and developmental processes at the transcriptional and translational level. In breast cancer, expression of miRNAs is frequently dysregulated. Both tumor suppressor activity and oncogenic properties have been assigned to specific miRNAs, which modulate virtually all relevant stages of breast cancer progression, including tumor cell proliferation, apoptosis resistance, cancer cell migration, invasiveness and metastasis, tumor angiogenesis and cancer stem cell self-renewal. miRNA expression has been studied by microarray profiling, bead-based technologies and quantitative real-time PCR in archived formalin-fixed paraffin-embedded tumor specimens as well as blood and serum samples, allowing to identify specific miRNAs as novel diagnostic, prognostic and predictive markers. Moreover, the investigation of single nucleotide polymorphisms both in putative miRNA binding sites in the 3'UTRs of target genes, as well as in miRNA-endocing genes have revealed their diagnostic potential. In vitro experiments employing established breast cancer cell lines and in vivo xenograft studies have demonstrated the efficacy of oligonucleotide-based overexpression and inhibitor approaches of miRNA-targeted experimental therapies. Numerous studies have identified specific targets of miRNA action in breast cancer, including the established markers Her2/neu and ERalpha, TP53, and markers of angiogenesis. The future application of locked-nucleic acid miRNA inhibitors, and synergistic approaches involving conventional breast cancer therapeutics opens up promising new perspectives in breast cancer therapy.

HCA-vision: Automated neurite outgrowth analysis

Automating the analysis of neurons in culture represents a key aspect of the search for neuroactive compounds. A number of commercial neurite analysis software packages tend to measure some basic features such as total neurite length and number of branching points. However, with only these measurements, some differences between neurite morphologies that are clear to a human observer cannot be identified. The authors have developed a suite of image analysis tools that will allow researchers to produce quality analyses at primary screening rates. The suite provides sensitive and information-rich measurements of neurons and neurites. It can discriminate subtle changes in complex neurite arborization even when neurons and neurites are dense. This allows users to selectively screen for compounds triggering different types of neurite outgrowth behavior. In mixed cell populations, neurons can be filtered and separated from other brain cell types so that neurite analysis can be performed only on neurons. It supports batch processing with a built-in database to store the batch-processing results, a batch result viewer, and an ad hoc query builder for users to retrieve features of interest. The suite of tools has been deployed into a software package called HCA-Vision. The free version of the software package is available at http://www.hca-vision.com.

miR-145-dependent targeting of junctional adhesion molecule A and modulation of fascin expression are associated with reduced breast cancer cell motility and invasiveness

Micro RNAs are small non-coding RNAs, which regulate fundamental cellular and developmental processes at the transcriptional and translational level. In breast cancer, miR-145 expression is downregulated compared with healthy control tissue. As several predicted targets of miR-145 potentially regulate cell motility, we aimed at investigating a potential role for miR-145 in breast cancer cell motility and invasiveness. Assisted by Affymetrix array technology, we demonstrate that overexpression of miR-145 in MDA-MB-231, MCF-7, MDA-MB-468 and SK-BR-3 breast cancer cells and in Ishikawa endometrial carcinoma cells leads to a downregulation of the cell-cell adhesion protein JAM-A and of the actin bundling protein fascin. Moreover, podocalyxin and Serpin E1 mRNA levels were downregulated, and gamma-actin, transgelin and MYL9 were upregulated upon miR-145 overexpression. These miR-145-dependent expression changes drastically decreased cancer cell motility, as revealed by time-lapse video microscopy, scratch wound closure assays and matrigel invasion assays. Immunofluorescence microscopy demonstrated restructuring of the actin cytoskeleton and a change in cell morphology by miR-145 overexpression, resulting in a more cortical actin distribution, and reduced actin stress fiber and filopodia formation. Nuclear rotation was observed in 10% of the pre-miR-145 transfected MDA-MB-231 cells, accompanied by a reduction of perinuclear actin. Luciferase activation assays confirmed direct miR-145-dependent regulation of the 3'UTR of JAM-A, whereas siRNA-mediated knockdown of JAM-A expression resulted in decreased motility and invasiveness of MDA-MB-231 and MCF-7 breast cancer cells. Our data identify JAM-A and fascin as novel targets of miR-145, firmly establishing a role for miR-145 in modulating breast cancer cell motility. Our data provide a rationale for future miR-145-targeted approaches of antimetastatic cancer therapy.

An imaging assay to analyze primary neurons for cellular neurotoxicity

The development of high-content screening technologies including automated immunostaining, automated image acquisition and automated image analysis have enabled higher throughput of cellular imaging-based assays. Here we used high-content imaging to thoroughly characterize the cultures of primary rat cerebellar granule neurons (CGNs). We describe procedures to isolate and cultivate the CGNs in 96-well and 384-well format, as well as a procedure to freeze and thaw the CGNs. These methods allow the use of CGNs in 96-well format analyzing 2500 samples per experiment using freshly isolated cells. Down-scaling to 384-well format and freezing and thawing of the CGNs allow even higher throughput. A cellular assay with rat CGN cultures was established to study the neurotoxicity of compounds in order to filter out toxic compounds at an early phase of drug development. The imaging-based toxicity assay was able to reveal adverse effects of compounds on primary neurons which were not detected in neuroblastoma or other cell lines tested.

Increased expression of the adult stem cell marker Musashi-1 in endometriosis and endometrial carcinoma

Adult stem cells are thought to be responsible for the high regenerative capacity of the human endometrium, and have been implicated in the pathology of endometriosis and endometrial carcinoma. The RNA-binding protein Musashi-1 is associated with maintenance and asymmetric cell division of neural and epithelial progenitor cells. We investigated expression and localization of Musashi-1 in endometrial, endometriotic and endometrial carcinoma tissue specimens of 46 patients. qPCR revealed significantly increased Musashi-1 mRNA expression in the endometrium compared to the myometrium. Musashi-1 protein expression presented as nuclear or cytoplasmic immunohistochemical staining of single cells in endometrial glands, and of single cells and cell groups in the endometrial stroma. Immunofluorescence microscopy revealed colocalization of Musashi-1 with its molecular target Notch-1 and telomerase. In proliferative endometrium, the proportion of Musashi-1-positive cells in the basalis layer was significantly increased 1.5-fold in the stroma, and three-fold in endometrial glands compared to the functionalis. The number of Musashi-1 expressing cell groups was significantly increased (four-fold) in proliferative compared to secretory endometrium. Musashi-1 expressing stromal cell and cell group numbers were significantly increased (five-fold) in both endometriotic and endometrial carcinoma tissue compared to secretory endometrium. A weak to moderate, diffuse cytoplasmic glandular staining was observed in 50% of the endometriosis cases and in 75% of the endometrioid carcinomas compared to complete absence in normal endometrial samples. Our results emphasize the role of Musashi-1-expressing endometrial progenitor cells in proliferating endometrium, endometriosis and endometrioid uterine carcinoma, and support the concept of a stem cell origin of endometriosis and endometrial carcinoma.

Syndecan-1 deficiency aggravates anti-glomerular basement membrane nephritis

During the heterologous phase of experimental anti-glomerular basement membrane (anti-GBM) nephritis, leukocyte influx peaks within hours, whereas albuminuria occurs within 1 day. In the subsequent autologous phase, endogenous anti-GBM IgG develops and albuminuria persists. Heparan sulfate (HS) proteoglycans like syndecan-1 play multiple roles during inflammation and we evaluate its role in experimental anti-GBM disease using syndecan-1 knockout (sdc-1-/-) mice. During the heterologous phase, glomerular leukocyte/macrophage influx was significantly higher in the sdc-1-/- mice and this was associated with higher glomerular endothelial expression of specific HS domains. In the autologous phase, glomerular influx of CD4+/CD8+ T cells was higher in the sdc-1-/- mice and these mice had persistently higher albuminuria and serum creatinine levels than wild-type mice. This resulted in a more sever glomerular injury and increased expression of extracellular matrix proteins. The sdc-1-/- mice developed higher plasma levels and glomerular deposits of total mouse Ig and IgG1 anti-rabbit IgG, whereas the levels of mouse IgG2a anti-rabbit IgG were lower. Furthermore, decreased Th1 and higher Th2 renal cytokine/chemokine expression were found in the sdc-1-/- mice. Our studies show that syndecan-1 deficiency exacerbates anti-GBM nephritis shifting the Th1/Th2 balance towards a Th2 response.

Selective ETAR antagonist atrasentan inhibits hypoxia-induced breast cancer cell invasion

Tumour hypoxia, being widespread in solid tumours, is related to an increased risk of invasion and metastasis as well as to resistance to chemotherapy and radiotherapy. Hypoxia-inducible factor-1alpha (HIF-1alpha) has emerged as the key regulator of the cellular response to hypoxia. In primary breast cancers, HIF-1alpha is overexpressed, and high levels of HIF-1alpha predict for early relapse and increased metastasis. The endothelin (ET) axis, comprising the peptides ET-1, -2, -3 and their receptors A (ETAR) and B (ETBR), is another regulatory system of major relevance in human breast cancer. However, little is known about the interaction of HIF-1alpha and the ET axis in breast carcinomas. Therefore, we analysed expression of HIF-1alpha and the ET axis in 600 breast cancer tissue samples by immunohistochemistry, observing a significant correlation between expression of HIF-1alpha and ET-1 (P<0.001). In vitro, hypoxia was found to double ET-1 secretion of MCF-7 breast cancer cells (203.5% of controls; P<0.001), thereby promoting an invasive phenotype. Of note, real-time PCR analysis revealed that the increase of ET-1 was not due to enhanced transcription of the ET-1 gene. In invasion assays, breast cancer cell invasiveness was strongly increased by hypoxia (150.0% of controls; P=0.007). Most important, this increase was completely inhibited by the selective ETAR antagonist atrasentan. In conclusion, we provide evidence for a relevant interaction between hypoxia and the ET axis in breast cancer cells. Our data suggest that tumour hypoxia induces breast carcinoma invasiveness by releasing intracellularly stored ET-1. However, induction of invasiveness may be inhibited by selective ETAR antagonism, thus emphasising the promising status of the ET axis as a therapeutic target in breast cancer.