The transmembrane heparan sulfate proteoglycan syndecan-1 was identified from a human placenta cDNA library by the expression cloning method as a gene product that interacts with membrane type matrix metalloproteinase-1 (MT1- Syndecans are transmembrane heparan sulfate proteoglycans expressed on all adherent cells (1, 2) and have been proposed to play an important role in tissue morphogenesis by virtue of their ability to bind, via their covalently attached glycosaminoglycan chains, to a variety of extracellular adhesive molecules including fibronectin, thrombospondin, various collagens, and heparin-binding growth-associated molecules and growth factors such as basic fibroblast growth factor (3-8).MMPSince the expression of syndecans appears to be controlled during both development and the progression of tumor cells to the metastatic phenotype, it has been proposed that syndecans are important regulators of the migratory and invasive behaviors of both normal and transformed cells (9, 10). The syndecan family is composed of four closely related proteins (syndecan-1, -2, -3, and -4) encoded by four different genes. Syndecan-1 is abundant in normal epithelial cells and tissues, localizing to both basal and suprabasal cell layers (1). Disruption of syndecan-1 expression in cultured cells leads to an epithelial mesenchymal transformation, with associated changes in cell polarity and cell-cell adhesion and altered epithelium-specific gene expression (7, 11).The intact ectodomain of each syndecan is constitutively shed from cultured cells (12, 13) as part of normal cell surface heparan sulfate proteoglycan turnover (14). Ectodomain shedding appears to contribute to diverse pathophysiological events such as host defense, wound healing, arthritis, and Alzheimer's disease, but how shedding is regulated remains largely unknown (15-17).Matrix metalloproteinases (MMPs) 1 are a family of Zn 2ϩ -dependent enzymes that are known to cleave extracellular matrix proteins in normal and pathological conditions (18 -20). To date, more than 20 mammalian MMPs have been identified by cDNA cloning, and they can be subgrouped into soluble type and membrane type MMPs (MT-MMPs) (20,21). MMPs are overexpressed in various human malignancies and have been thought to contribute to tumor invasion and metastasis by degrading extracellular matrix components (18,22). Thus, the level of MMP expression correlates with the invasiveness or malignancy of tumors (23,24). Particularly, MT1-MMP, MMP-2, MMP-7, and MMP-9 have been reported to be most closely associated with tumor invasion and metastasis. Whereas degradation of extracellular matrix is an important aspect of MMP biology, growing evidence has demonstrated specific processing/activation or degradation of cell surface receptors and ligands. Fas ligand (25), tumor necrosis factor-␣ (26), the ectodomain of the fibroblast growth factor receptor-1 (27), the heparin-binding epidermal growth factor (28), and interleukin-8 (29) were reported to be released or activated by MMPs. MMPs also cleave and inac...

Metastasis is a feature of malignant neoplasms. Although rare, metastasizing pathologically benign mixed tumour has been reported. This report describes a 33-year-old woman with multiple lung metastases from mixed tumour. A small preauricular mass had been removed 23 years earlier. Six years later, the patient had the same symptom; the recurrent mass was resected. She was not aware of the exact pathological diagnosis of the previous tumours. One of the most common features of metastasizing mixed tumour is recurrence at the primary site. Inadequate resection of the primary tumour is often associated with metastasis. Thus, it is important for the head and neck surgeon to be aware of the concept of pathologically benign metastasizing mixed tumour and the importance of adequate surgical procedure.

pRB expression level can be used as a reliable predictor for recurrence of PTC.

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