Heterogeneity of the chromatin fine structure in DNA-diploid breast cancer cells

The chromatin fine structure of Feulgen-stained DNA-diploid tumour cells was studied by means of image cytometry in fine-needle aspiration biopsies of 115 breast cancer patients. The investigation was focused on diploid, several subtypes of polyploid, and aneuploid tumours. Only the clearly separable diploid peaks of these tumours were measured cytometrically by an OPTIMAS-based image analysis system, which led to a set of 93 primary cytometric features in each diploid subpopulation. The results demonstrate that the diploid tumours are clearly different to the diploid compartments of various subtypes of polyploid and aneuploid tumours. Between those diploid subpopulations from polyploid tumours, chromatin structure differences also exist. A higher degree of similarity between polyploid and aneuploid tumours, compared to diploid, became evident. The actual structural differences between the diploid subpopulations indicate both increasing variances within the peak and increasingly coarse and contrasted, irregular chromatin structure with the occurrence of tetraploid, octoploid, and aneuploid DNA-histogram peaks. Therefore, the structural effects of an increasing genomic instability seems not to be restricted to the non-diploid cell populations.