Entropy of Feulgen-stained 17-β-estradiol-transformed human breast epithelial cells as assessed by restriction enzymes and image analysis

MCF-10F human breast epithelial cells when transformed with 17-β-estradiol (E2) give rise to highly invasive C5 cells that generate adenocarcinomas in SCID mice. From these tumors, cell lines such as C5-A6-T6 and C5-A8-T8 have been derived. Variable patterns of chromatin supraorganization have been demonstrated for these cells during the transformation/tumorigenesis progress, when assessing chromatin entropy by image analysis in Feulgen-stained preparations. Since epigenetic dysregulation might contribute to the chromatin textural repatterning in transformed MCF-10F cells, the association of the variable chromatin packing states with global DNA methylation was investigated in these cells after their treatment with restriction enzymes followed by Feulgen staining and chromatin entropy evaluation by image analysis. The results indicate that although -CmCGG- sequences may affect chromatin supraorganization in some of the analyzed cell types (perhaps due to localized hypermethylation), not all the chromatin condensation patterns in these cells with transformation and/or tumorigenesis are associated with DNA methylation (e.g. E2 cells). Chromatin supraorganization remodeling in C5-A6-T6 and C5-A8-T8 cells may be attained by different mechanisms, with C5-A6-T6 chromatin packing states perhaps being associated with local DNA hypermethylation or other epigenetic factors, and C5-A8-T8 likely being associated with global DNA hypomethylation, as reported in the literature for other cell types. Thus, we assume that a variable epigenetic modulation affecting the higher-order packing states of chromatin in the estrogen-transformed MCF-10F cell model could be evident with the chromatin entropy study by image analysis.