5-Fluorouracil induces autophagic degeneration in rat oral keratinocytes

von Bültzingslöwen, I; Jontell, M; Hurst, P; Nannmark, U; Kardos, T

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Volume 37, Issue 6 , Pages 537-544, September 2001

5-Fluorouracil induces autophagic degeneration in rat oral keratinocytes

I von Bültzingslöwen
- Department of Endodontology and Oral Diagnosis, Faculty of Odontology, University of Göteborg, Box 450, S-405 30 Göteborg, Sweden
- Corresponding author. Tel.: +46-31-7733251; fax: +46-31-825416
M Jontell
- Department of Endodontology and Oral Diagnosis, Faculty of Odontology, University of Göteborg, Box 450, S-405 30 Göteborg, Sweden
P Hurst
- Department of Anatomy and Structural Biology, University of Otago School of Medicine, Great King Street, Dunedin, New Zealand
U Nannmark
- Institute of Anatomy and Cell Biology, Faculty of Medicine, University of Göteborg, Box 420, S-405 30 Göteborg, Sweden
T Kardos
- Department of Oral Sciences and Orthodontics, University of Otago School of Dentistry, Great King Street, Dunedin, New Zealand

Received 8 October 2000; accepted 4 November 2000.

Abstract

In this study, we investigated the effect of 5-fluorouracil (5-FU) on the keratinocytes of oral epithelium. Female Lewis rats were given 5-FU i.v. and were killed 12, 24 or 36 h after injection. The buccal mucosa was dissected. The number of nuclei with DNA strand breaks and the total number of nuclei per volume of the epithelial basal cell layer was estimated using terminal deoxynucleotidyl transferase (TdT)-mediated deoxyuridine triphosphate (dUTP)-biotin nick end labeling. Epithelial cells were analysed by flow cytometry, transmission electron microscopy and a dye exclusion test. The number of cells with DNA strand breaks increased in 5-FU treated rats. Flow cytometry showed a decrease in cell size and an increase in granularity with increasing doses of 5-FU. Dye exclusion gave no indication of degenerate cell membranes. By transmission electron microscopy, the cells showed evidence of degeneration, shrinkage and loss of cell-to-cell contact. Vacuolation was extensive and, in contrast to apoptotic cells, nuclear chromatin condensation seemed to occur centrally in the nuclei. The results show that 5-FU treatment in vivo induces alterations in rat oral keratinocytes that are consistent with autophagic degeneration.

Keywords: Apoptosis, Flow cytometry, Fluorouracil, In situ nick-end labeling, Necrosis, Microscopy, Electron, Mouth mucosa, Rat