Cell and Tissue Research

, Volume 322, Issue 2, pp 257–267

Nuclear patterns of human breast cancer cells during apoptosis: characterisation by fractal dimension and co-occurrence matrix statistics

Regular Article

DOI: 10.1007/s00441-005-0030-2

Cite this article as:
Losa, G.A. & Castelli, C. Cell Tissue Res (2005) 322: 257. doi:10.1007/s00441-005-0030-2

Abstract

An analytical strategy combining fractal geometry and grey-level co-occurrence matrix (GLCM) statistics was devised to investigate ultrastructural changes in oestrogen-insensitive SK-BR3 human breast cancer cells undergoing apoptosis in vitro. Apoptosis was induced by 1 μM calcimycin (A23187 Ca2+ ionophore) and assessed by measuring conventional cellular parameters during the culture period. SK-BR3 cells entered the early stage of apoptosis within 24 h of treatment with calcimycin, which induced detectable changes in nuclear components, as documented by increased values of most GLCM parameters and by the general reduction of the fractal dimensions. In these affected cells, morphonuclear traits were accompanied by the reduction of distinct gangliosides and loss of unidentifiable glycolipid molecules at the cell surface. All these changes were shown to be involved in apoptosis before the detection of conventional markers, which were only measurable during the active phases of apoptotic cell death. In overtly apoptotic cells treated with 1 μM calcimycin for 72 h, most nuclear components underwent dramatic ultrastructural changes, including marginalisation and condensation of chromatin, as reflected in a significant reduction of their fractal dimensions. Hence, both fractal and GLCM analyses confirm that the morphological reorganisation of nuclei, attributable to a loss of structural complexity, occurs early in apoptosis.

Keywords

Early/late apoptosisNuclear eu-/hetero-chromatinFractal dimensionGrey-level co-occurrence matrix (GLCM) analysisSurface gangliosidesHuman breast cancer cells

Abbreviations

FD

fractal dimension

GLCM

grey-level co-occurrence matrix

FITC

fluorescein isothiocyanate

PI

propidium iodide

TLE

total lipid extract

NM

perinuclear membrane

NMBHC

nuclear membrane-bound heterochromatin space and outline

SHC

scattered heterochromatin space and outline

HC

total heterochromatin space and outline

IC

inter(eu)chromatin space and outline

TdT

Terminal deoxynucleotidyl Transferase

Copyright information

© Springer-Verlag 2005

Authors and Affiliations

  1. 1.Institute for Scientific Interdisciplinary StudiesLocarnoSwitzerland
  2. 2.Faculty of Biology and MedicineUniversity of LausanneLausanneSwitzerland
  3. 3.OCL HospitalLuganoSwitzerland