[Transforming growth factor ß in prostate cancer: cellular effects and basic molecular mechanisms]. / "Transforming growth factor ß" im Prostatakarzinom : Zelluläre Wirkungen und molekulare Grundlagen.

The multifunctional cytokine transforming growth factor ß (TGFß) plays a dual role in prostate cancer (PCa), cell growth and tumorigenesis, reflected by its opposing properties of anti-oncogenic (e.g. growth inhibition and apoptosis) and pro-oncogenic effects (e.g. proliferation, cell motility and remodelling of the microenvironment). In the later stages of PCa, TGFß loses anti-proliferative and thereby tumor-suppressive functions and shifts to a tumorigenic phenotype, mainly initiated by cross-talk between TGFß signalling and other proliferation signal transduction pathways, such as mitogen-activated protein kinase (MAPK) and androgen receptor (AR) signalling. Although TGFß plays an important role in tumor progression little is known about the underlying effects of TGFß in the molecular pathology of PCa.

Active and inactive genes localize preferentially in the periphery of chromosome territories.

The intranuclear position of a set of genes was analyzed with respect to the territories occupied by the whole chromosomes in which these genes are localized. Genes and their respective chromosome territories were simultaneously visualized in three-dimensionally preserved nuclei applying dual color fluorescence in situ hybridization. Three coding (DMD, MYH7, and HBB) and two noncoding sequences (D1Z2 and an anonymous sequence) were analyzed in four different cell types, including cells where DMD and MYH7 are actively transcribed. Spatial analysis by confocal laser scanning microscopy revealed that the genes are preferentially located in the periphery of chromosome territories. This positioning was independent from the activity of the genes. In contrast, the non-expressed anonymous fragment was found randomly distributed or localized preferentially in the interior of the corresponding chromosome territory. Furthermore, the distribution of the analyzed genes within the territorial peripheries was found to be highly characteristic for each gene, and, again, independent from its expression. The impact of these findings with regard to the three-dimensional arrangement of the linear DNA string within chromosome territories, as well as with respect to a putative nuclear subcompartment confining gene expression, are discussed.

A tilting device for three-dimensional microscopy: application to in situ imaging of interphase cell nuclei.

The resolution of an optical microscope is considerably less in the direction of the optical axis (z) than in the focal plane (x-y plane). This is true of conventional as well as confocal microscopes. For quantitative microscopy, for instance studies of the three-dimensional (3-D) organization of chromosomes in human interphase cell nuclei, the 3-D image must be reconstructed by a point spread function or an optical transfer function with careful consideration of the properties of the imaging system. To alleviate the reconstruction problem, a tilting device was developed so that several data sets of the same cell nucleus under different views could be registered. The 3-D information was obtained from a series of optical sections with a Zeiss transmission light microscope Axiomat using a stage with a computer-controlled stepping motor for movement in the z-axis. The tilting device on the Axiomat stage could turn a cell nucleus through any desired angle and also provide movement in the x-y direction. The technique was applied to 3-D imaging of human lymphocyte cell nuclei, which were labelled by in situ hybridization with the DNA probe pUC 1.77 (mainly specific for chromosome 1). For each nucleus, 3-D data sets were registered at viewing angles of 0 degrees, 90 degrees and 180 degrees; the volumes and positions of the labelled regions (spots) were calculated. The results also confirm that, in principle, any angle of a 2 pi geometry can be fixed for data acquisition with a high reproducibility. This indicates the feasibility of axiotomographical microscopy of cell nuclei.