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.
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.
Department of Medical Oncology, P.O. Box 30.001, University Hospital Groningen, 9700RB, Groningen, The Netherlands. j.meijer@int.azg.nl
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Meijera
M J
MJ
van Luyn
E F
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Nienhuis
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N
Blom
N H
NH
Mulder
E G
EG
de Vries
D000906:Antibodies / Q000276:immunology; D000970:Antineoplastic Agents / Q000494:pharmacology; D018288:Carcinoma, Small Cell / Q000473:pathology / Q000648:ultrastructure*; D002945:Cisplatin / Q000494:pharmacology*; D018736:DNA Adducts / Q000276:immunology / Q000648:ultrastructure*; D004273:DNA, Neoplasm / Q000187:drug effects / Q000378:metabolism; D019008:Drug Resistance, Neoplasm / Q000502:physiology*; D006801:Humans; D007150:Immunohistochemistry; D008854:Microscopy, Electron; D014407:Tumor Cells, Cultured
D000906:Antibodies; D000970:Antineoplastic Agents; D018736:DNA Adducts; D004273:DNA, Neoplasm; D002945:Cisplatin