The pathophysiological role of extracellular matrix proteoglycans in human thyroid diseases.

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I established a simple and sensitive method for detecting FGF-2-binding heparan sulfate and characterized them in papillary thyroid carcinomas and normal thyroids. The thyroid extracts were applied on to a Q-Sepharose anion exchange column. After the column was washed with 10 mM phosphate buffer, one μg of human recombinant FGF-2 was added onto the column. The column was eluted with a gradient of NaCl (0.3-1.5 M). Each fraction was blotted onto nitrocellulose membrane. Immunoreactivity of heparan sulfate and FGF-2 was revealed by the incubation of membranes with the specific antibodies, and quantitatively estimated by measuring the density of the color product. In normal thyroids, immunoreactivity of heparan sulfate was detected as two peaks at 0.7 and 0.9 M NaCl. Heparan sulfate containing fractions also showed FGF-2 immunoreactivity, indicating the complex formation of FGF-2 and heparan sulfate. In papillary thyroid carcinomas, immunoreactivity of heparan sulfate showed various elution profile on Q-Sepharose chromatography, including single peak at 0.7 M NaCl and the one similar to that of the normal thyroids. However, FGF-2 immunoreactivity wad detected only in the fractions eluting at 0.7 M NaCl. This loss of a subpopulation of FGF-2-binding heparan sulfate in human papillar thyroid carcinomas may lead to the increase of free FGF-2 bioavailable in extracellular matrix.