Nuclear methylation levels in normal and cancerous thyroid cells.
BACKGROUND
Most cancers show abnormal DNA methylation and a positive correlation between hypomethylation and tumour progression.


METHODS
In our laboratory the extent of DNA methylation in individual nuclei in normal, cancer and non-cancer thyroid tissue samples was quantified according to a previously described method of computer-assisted semi-quantitative analysis. Cancer and non-cancer samples were obtained from nine patients with different thyroid pathologies (one multinodular goitre and eight carcinomas). Quantitative analysis was performed in two sets of samples, i.e. individual nuclei from touch preparations and from tissue sections.


RESULTS
In all cancer specimens a statistically significant decrease of heterochromatin methylation was consistently observed. In both sets of samples a direct correlation was consistently observed between the extent of chromatin demethylation and the degree of malignancy.


CONCLUSIONS
Our preliminary results suggest that our method of cell-by-cell detection of intranuclear methylation abnormalities may be a useful tool in early identification of thyroid cancer lesions.
Department of Genetics and Molecular Biology, University of Rome La Sapienza, Rome, Italy.
Adriana
A
de Capoa
Claudio
C
Grappelli
Patrizia
P
Volpino
Marco
M
Bononi
Angelina
A
Musolino
Antonio
A
Ciardi
Antonino
A
Cavallaro
Vincenzo
V
Cangemi
D000328:Adult; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism; D019175:DNA Methylation; D005260:Female; D006570:Heterochromatin / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged; D013964:Thyroid Neoplasms / Q000235:genetics* / Q000378:metabolism
D006570:Heterochromatin