Divergent and co-localization of the two small proteoglycans decorin and proteoglycan-100 in human skeletal tissues and tumors.

The core protein of a recently described small proteoglycan, proteoglycan-100, was localized in fetal human tissues by indirect immunocytochemistry and compared with the localization of known members of the small proteoglycan family. Co-localization of decorin and proteoglycan-100 was seen in bone tissue but decorin and proteoglycan-100 exhibited a substantially divergent distribution in fetal skin, cartilage and in the mineralization zone of the growth plate. Proteoglycan-100 was also found in striated muscle, nerve fibers, and synovial tissue. Immunostaining of a chondroblastic osteosarcoma demonstrated chondroid cells selectively expressing either proteoglycan-100 or decorin. Co-expression of both small proteoglycans was observed in sections from a chordoma. In fetal bone and in the two tumors, colocalization of proteoglycan-100 and of biglycan was also found. These results provide evidence of the wide and characteristic distribution of proteoglycan-100.