A new targeting approach for breast cancer gene therapy using the heparanase promoter

Gene therapy with adenoviral (Ad) vectors is a promising new approach in the treatment of cancer. Strategies to restrict adenoviral-mediated transgene expression are important to avoid gene transfer into normal cells. Heparanase (HPR) is overexpressed in breast cancer but downregulated in differentiated normal tissue. Expression of the HPR gene was evaluated in breast cancer cells. Biodistribution and liver tropism was evaluated in a mouse model. HPR is highly expressed in breast cancer tissue. The HPR promoter retained its fidelity in an adenovirus context and was activated in breast cancer cells but showed low activity in normal breast cells and the murine liver. We conclude that the HPR pathway is a promising target for the development of breast cancer directed gene therapy strategies.     

Multicolor chromosome painting in diagnostic and research applications

For many years whole chromosome painting probes have been the work-horses in a large variety of clinical and research molecular cytogenetic applications. In recent years painting probes have been complemented by an increasing number of further region-specific probes, which allow the specific staining of centromeres, subtelomeres or other regions within the genome. This development of new probe sets was greatly facilitated by the Human Genome Project from which well-characterized probes for any region within the genome have emerged. Furthermore, the evolution of different multicolor fluorescence in situ hybridization (FISH) technologies now allows the cohybridization of multiple DNA-probes of different colors. These developments have paved the way for FISH-based automated karyotyping or the simultaneous analysis of multiple defined regions within the genome. Using appropriate instrumentation and image processing, the analysis can be performed two-dimensionally on metaphase spreads or three-dimensionally in intact interphase nuclei. Here we summarize some of the most recent developments and discuss the application of painting probes in different scenarios.     

Multicolor FISH in two and three dimensions for clastogenic analyses

Chemicals may induce both numerical and structural aberrations. In addition to these chromosomal mutations, chemicals may render cells genetically unstable, which may result in chromosomal instability. For a detailed analysis, sophisticated approaches at single cell resolution are needed. Such approaches have become feasible by recent developments in molecular cytogenetics. In particular, new multicolor fluorescence in situ hybridization (FISH) technologies allow us now to study the effects of chemicals on chromosomes with unprecedented resolution. FISH provides opportunities to analyze the genome in two dimensions, i.e. on metaphase spreads, or in three dimensions, i.e. in interphase nuclei. An arsenal of diverse multicolor FISH approaches has been developed, which allows the analysis of the entire genome with one hybridization on metaphase spreads or the detailed visualization of selected chromosomal regions within intact interphase nuclei. These developments have been complemented by new resources for DNA probes, which have evolved from the human genome project. Here we will review the latest developments and provide some examples in which multicolor FISH technologies were applied to elucidate the effect of chemicals on chromosomes.     

Zebrafish model for allogeneic hematopoietic cell transplantation not requiring preconditioning

Recent work on vertebrate hematopoiesis has uncovered the presence of deeply rooted similarities between fish and mammals at molecular and cellular levels. Although small animal models such as zebrafish are ideally suited for genetic and chemical screens, the study of cellular aspects of hematopoietic development in lower vertebrates is severely hampered by the complex nature of their histocompatibility-determining genes. Hence, even when hosts are sublethally irradiated before hematopoietic cell transplantation, stable and long-term reconstitution by allogeneic stem cells often fails. Here, we describe the unexpected observation that transplantation and maintenance of allogeneic hematopoietic stem cells in zebrafish homozygous for the c-myb^t25127 allele, carrying a missense mutation (Ile181Asn) in the DNA binding domain can be achieved without prior conditioning. Using this model, we examined several critical parameters of zebrafish hematopoiesis in a near-physiological setting. Limiting dilution analysis suggests that the kidney marrow of adult zebrafish harbors about 10 transplantable hematopoietic stem cells; this tissue also contains thymus-settling precursors that colonize the thymic rudiment within days after transplantation and initiate robust T-cell development. We also demonstrate that c-myb mutants can be stably reconstituted with hematopoietic cells carrying specific genetic defects in lymphocyte development, exemplifying one of the many potential uses of this model in experimental hematology.     

Emergence of Lyme Disease on Treeless Islands,Scotland, United Kingdom

Lyme disease is usually associated with forested habitats but has recently emerged on treeless islands in the Western Isles of Scotland. The environmental and human components of Lyme disease risk in open habitats remain unknown. We quantified the environmental hazard and risk factors for human tick bite exposure among treeless islands with low and high Lyme disease incidence in the Western Isles. We found a higher prevalence of Borrelia burgdorferi sensu lato–infected ticks on high-incidence than on low-incidence islands (6.4% vs. 0.7%); we also found that residents of high-incidence islands reported increased tick bite exposure. Most tick bites (72.7%) occurred <1 km from the home, including many in home gardens. Residents of high Lyme disease incidence islands reported increasing problems with ticks; many suggested changing deer distribution as a potential driver. We highlight the benefits of an integrated approach in understanding the factors that contribute to Lyme disease emergence.