Interspecies contamination of the KM3 cell line: implications for CD63 function in melanoma metastasis

Human, mouse or rat? Species authentication of glioma-derived cell cultures

Cell culture and the use of cell lines are often fundamental requirements in basic scientific research. It is of the utmost importance for researchers to ensure that the cell lines in use have a well defined origin and are routinely re-analysed to highlight possible areas of contamination. In this preliminary study species specific primers were designed to easily distinguish between human, mouse and rat DNA with standard agarose gel electrophoresis. Inter-species contamination is often the most common form of contamination experienced, with the most common of cell lines in use being of human, mouse and rat derivation. A PCR-based assay was therefore developed to ensure an accurate, quick and cost effective means of determining any cell line contamination which could be easily executed on a routine basis. Furthermore, this simple PCR is able to identify the species in the inter-species mixture of DNA and therefore provides a valuable tool for the authentication of human cell lines.

Targeting of tetraspanin proteins--potential benefits and strategies

The tetraspanin transmembrane proteins have emerged as key players in malignancy, the immune system, during fertilization and infectious disease processes. Tetraspanins engage in a wide range of specific molecular interactions, occurring through the formation of tetraspanin-enriched microdomains (TEMs). TEMs therefore serve as a starting point for understanding how tetraspanins affect cell signalling, adhesion, morphology, motility, fusion and virus infection. An abundance of recent evidence suggests that targeting tetraspanins, for example, by monoclonal antibodies, soluble large-loop proteins or RNAi technology, should be therapeutically beneficial.

Uroplakin Ib gene transcription in urothelial tumor cells is regulated by CpG methylation

Uroplakin Ib is a structural protein on the surface of urothelial cells. Levels of uroplakin Ib mRNA are dramatically reduced or absent in many transitional cell carcinomas, but the molecular mechanisms responsible remain undetermined. Previously, we showed that loss of uroplakin Ib expression correlated with CpG methylation of Sp1/NFkappaB-binding motifs within the proximal promoter. In this study, we show that reporter activity was completely blocked by the methylation of three CpG pairs in this promoter region. Gel shift analysis using purified proteins or nuclear extracts showed that Sp1 and NFkappaB bound to motifs encompassing two of the three CpG pairs. Interestingly, the methylation of these two CpG sites did not prevent the binding of proteins to the promoter in gel shift analyses. Additionally, mutation of these two CpGs did not affect reporter activity, but mutation of 6-bp fragment spanning each CpG partially inhibited reporter activity, suggesting that these sites were functional. A requirement for both Sp1 and NFkappaB in regulating reporter activity was confirmed in transfection experiments using plasmids expressing individual proteins. Our data suggest that the methylation of specific CpG sites can silence the uroplakin Ib promoter, at least in part, by blocking the binding of Sp1 and NFkappaB, although other factors may be involved.

Tetraspanin microdomains in immune cell signalling and malignant disease

A contemporary goal of researchers in leucocyte signalling has been to uncover how cells physically organize and compartmentalize signalling molecules into efficient, regulated signalling networks. This work has revealed important roles of membrane microdomains that are characterized by their distinctive protein and lipid compositions. Recent studies have demonstrated that besides typical cholesterol- and glycosphingolipid-enriched 'rafts', leucocyte membranes are equipped with a different type of microdomain, made up of tetraspanin proteins. Tetraspanin proteins are involved in the organization of tetraspanin-enriched microdomains by virtue of their capacity to specifically associate with key molecules, including integrins, leucocyte receptors and signalling proteins. The aspects of leucocyte function influenced by tetraspanin microdomains include adhesion, proliferation and antigen presentation. However, the mechanisms by which tetraspanin complexes link to intracellular signalling pathways, are still largely unknown. This review discusses how tetraspanin microdomains might function to regulate signalling in lymphoid and myeloid cells, and how they relate to lipid rafts. In addition, we discuss new insights into the role of tetraspanins in malignant disease.

Trials, tribulations, and trends in tumor modeling in mice

Selection of mouse models of cancer is often based simply on availability of a mouse strain and a known compatible tumor. Frequently this results in use of tumor models long on history but short on homology and quality control. Other factors including genetics, sex, immunological status, method and site of tumor implantation, technical competence, biological activity of the tumor, protocol sequence and timing, and selection of endpoints interact to produce outcomes in tumor models. Common reliance on survival and tumor burden data in a single mouse model often skews expectations towards high remission and cure rates; a finding seldom duplicated in clinical trials. Inherent limitations of tumor models coupled with the advent of new therapeutic targets reinforce need for careful attention to design, conduct, and stringent selection of in vivo and ex vivo endpoints. Preclinical efficacy testing for anti-tumor therapies should progress through a series of models of increasing sophistication that includes incorporation of genetically engineered animals, and orthotopic and combination therapy models. Pharmacology and safety testing in tumor-bearing animals may also help to improve predictive value of these models for clinical efficacy. Trends in bioinformatics, genetic refinements, and specialized imaging techniques are helping to maintain mice as the most scientifically and economically powerful model of malignant neoplasms.