Nuclear DNA Content and Chromatin Pattern of Rat Rhabdomyosarcoma Cell Sublines with Different Metastatic Potentials

Abstract

There is a constant need of features able to characterize potentially metastatic cells among the heterogeneous cell subpopulations which constitute a tumor. Image cytometry of metastatic tumor cells give rise to variable results, partly because of a heterogeneous origin of cells, or potential drug effects. The aim of this work was to characterize nuclear changes observed in metastatic cell clones issued in vitro from the same parental cell population The nuclear phenotypes of 6 cell sublines isolated from a rat rhabdomyosarcoma cell line and differing in their metastatic ability were evaluated by image cytometry on Feulgen‐stained preparations. Densitometric [5], geometric [3] and textural [9] features were computed from each nuclear image. For each cell subline, a metastatic score, ranging from 0 to 10, was calculated on the basis of in vitro invasivity data, by measuring the number of pulmonary metastases observed after s.c. graft of tumor cells in rats. Data obtained were compared to karyotype, growth characteristics, and oncogene expressions of cell lines. The nuclear DNA content, the chromosome numbers, the cell sublines doubling times, and the distribution of cells within the cell cycle appear unrelated with this score. On the contrary, increase in metastatic ability is accompanied by changes in chromatin pattern as assessed by textural features. Progressive increase in chromatin condensation can be observed in cell sublines with increasing metastatic score. These results were confirmed by an unsupervised multivariate partitioning of rhabdomyosarcoma cells which identified two separate subsets whose distributions within the analyzed cell lines correlate with their metastatic ability. These data suggest that, in rat rhabdomyosarcoma cell sublines, metastatic ability could be associated with nuclear morphological changes at the level of chromatin texture.

Inheritance of gene density–related higher order chromatin arrangements in normal and tumor cell nuclei

“…In conclusion, this report presents evidence for a radial higher order chromatin arrangement in a variety of different normal and malignant cell types, but suggests a decline in the gene density–correlated radial nuclear order of CTs in several tumor cell lines compared with their normal progenitor cells. The mechanisms leading to such a decline and to changes in heterochromatin patterns, such as increased amounts of facultative heterochromatin in the nuclear periphery ( Dufer et al, 2000 ), are not known. It is still an open question to which extent these changes are a consequence of or a cause for an altered gene expression pattern associated with changes of chromatin methylation and histone acetylation.…”

Ultrastructural Complexity of Nuclear Components During Early Apoptotic Phases in Breast Cancer Cells

“…They could be evaluated using unconventional methods of morphometry, based on fractal geometry [7]. This implies that the mostly irregular cell and nuclear components need not to undergo reductive representations and/or unrealistic approximations in order to be analyzed, as is usual in conventional morphometry when a single arbitrary scale is used to measure a large number of morphological features [8]. The irregularity and roughness of cell membranes and nuclear components (morphoultrastructural complexity) can be quantified by a single descriptive parameter, the fractal dimension (FD), while the true length contour and the actual surface area of biological bodies are obtained at the most suitable resolution scale [9][10][11][12].…”

Thalidomide alters nuclear architecture without ABCB1 gene modulation in drug-resistant myeloma cells

“…In 8226-Dox40 cells, significant variations were observed in E, and ENT, two features related to the spatial organization and distribution of the chromatin (15), and whose values are correlated neither to nuclear area nor to global chromatin condensation. Significant changes in chromatin higher-order organisation, evaluated through nuclear texture, have already been reported as markers of tumour cell aggressiveness or metastatic potential, either in experimental or clinical samples (22)(23)(24)(25). For instance, LM displays significant increases in invasive bladder tumours as compared to superficial tumours (25) and appears linked (together with E and GLD) to tumour size in breast carcinomas (unpublished data).…”