In addition to their physiologic effects in inflammation and angiogenesis, chemokines are involved in cancer pathology. The aim of this study was to determine whether the chemokine stromal cell -derived factor 1 (SDF-1) induces the growth, migration, and invasion of human hepatoma cells. We show that SDF-1 G protein -coupled receptor, chemokine

Because cells are sensitive to mechanical forces, weightlessness might act on stress-dependent cell changes. We hypothesized that the integration of environmental factors might induce specific cytoskeletal architecture patterns, characterized by quantitative image analysis. Human breast cancer cells MCF-7, flown in space in a photon capsule, were fixed after 1.5, 22, and 48 h in orbit. Cells subjected to weightlessness were compared with 1g in-flight and ground controls. Postflight, fluorescent labelings were performed to visualize cell proliferation (Ki-67), signal transduction (phosphotyrosine), three cytoskeleton components (microtubules, microfilaments, and intermediate filaments), and chromatin structure. Confocal microscopy and image analysis were used to quantify cycling cells and mitosis, modifications of the cytokeratin network, and chromatin structure. In weightlessness, phosphotyrosine signal transduction was lower, more cells were cycling, and mitosis was prolonged. Finally, cell proliferation was reduced as a consequence of a cell-cycle blockade. Microtubules were altered in many cells. The perinuclear cytokeratin network was more loosely 'woven', and chromatin structure was modified. The prolongaion of mitosis can be explained by an alteration of microtubule self-organization in weightlessness, involving reaction-diffusion processes. The loosening of the perinuclear cytokeratin network and modification of chromatin distribution are in agreement with basic predictions of cellular tensegrity.

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A method for the quantification of nuclear DNA in thick tissue blocks by confocal scanning laser microscopy is presented. Tissues were stained en bloc for DNA by chromomycin A3. Three-dimensional images, 60 Fm deep, were obtained by stacking up confocal fluorescent images obtained with an MRC-BOO (Bio-Rad, Richmond, CA). The effects due to bleaching and attenuation by depth of fluorescence emission were corrected mathematically. The DNA contents were estimated by summing up the detected emission intensities (discretized into pixel gray levels) from each segmented nucleus. Applications to an adult rat liver and to a human in situ carcinoma of theesophagus are shown to demonstrate, respectively, the precision of the method and its potential usefulness in histopathology. Comparisons are made with DNA histograms obtained on the same materials by image cytometry on smears and by flow cytometry. Ploidy peaks obtained with the confocal method, although wider than with other methods, are well separated. Confocal image cytometry offers the invaluable advantage of preserving the tissue architecture and therefore allowing, for instance, the selection of histological regions and the evaluation of the degree of heterogeneity of a tumor.Key terms: DNA cytometry, confocal laser microscopy, histology, 3-D There is a considerable interest in DNA cytometry, notably because of the importance of searching for correlations of nuclear DNA content with cancer prognosis in individual patients (e.g., 22, 40, 62).The two methods commonly used a t present for nuclear DNA content analysis, image cytometry (ICM) and flow cytometry (FCM), are not devoid of limitations. Observing the tissue architecture may be important in identifying regions for cytometry and, therefore, the main shortcoming of ICM on smears or imprints and of FCM is obviously that they do not allow the study of DNA contents in situ. Even ICM on histological sections does not allow this, as the tissue structure is observed in projection and the resulting nuclear profiles are usually either incomplete if the section is thin or overlapping if the section is thick enough to include a sufficient proportion of complete nuclei. Finally, preparation procedures for ICM and FCM may produce a selection bias of a given cell type (9) and/or nuclear debris (27).'This paper is an expanded version of a work presented at the