Ultrastructural morphology and localisation of cisplatin-induced platinum-DNA adducts in a cisplatin-sensitive and -resistant human small cell lung cancer cell line using electron microscopy

Biochem Pharmacol. 2001 Mar 1;61(5):573-8. doi: 10.1016/s0006-2952(00)00584-0.

Abstract

Ultrastructural morphology (transmission electron microscopy) and localisation of cisplatin-induced platinum (Pt)-DNA adducts (immunoelectron microscopy) were analysed in the human small cell lung cancer cell line GLC(4) and its 40-fold in vitro acquired cisplatin-resistant subline GLC(4)-CDDP, which is characterised by, among other things, a decreased DNA platination. Immunolabelling of Pt-DNA adducts was performed with the polyclonal antibody GPt, known to detect the main Pt-containing intrastrand and interstrand DNA adducts. Morphological analysis of GLC(4) and GLC(4)-CDDP at the ultrastructural level showed cells with a high nucleus/cytoplasm ratio with the majority of nuclei containing one or more nucleoli. GLC(4)-CDDP showed, in contrast to GLC(4), an extensive Golgi apparatus and an increased number of mitochondria. DNA platination was detectable in both GLC(4) and GLC(4)-CDDP. Immunoelectron microscopy showed Pt-DNA adducts primarily in the nucleus, preferentially at loci with high-density chromatin (e.g. heterochromatin, pars granulosa around nucleoli, condensed DNA in proliferating and apoptotic cells), and in mitochondria. The level of detectable Pt-DNA adducts was cell cycle status-dependent. In both cell lines, Pt-DNA adduct levels increased from non-dividing interphase cells to dividing cells and were highest in cells undergoing apoptosis. Overall localisation of Pt-DNA adducts was comparable in GLC(4) and GLC(4)-CDDP cells.

MeSH terms

  • Antibodies / immunology
  • Antineoplastic Agents / pharmacology
  • Carcinoma, Small Cell / pathology
  • Carcinoma, Small Cell / ultrastructure*
  • Cisplatin / pharmacology*
  • DNA Adducts / immunology
  • DNA Adducts / ultrastructure*
  • DNA, Neoplasm / drug effects
  • DNA, Neoplasm / metabolism
  • Drug Resistance, Neoplasm / physiology*
  • Humans
  • Immunohistochemistry
  • Microscopy, Electron
  • Tumor Cells, Cultured

Substances

  • Antibodies
  • Antineoplastic Agents
  • DNA Adducts
  • DNA, Neoplasm
  • Cisplatin