gms | German Medical Science

On the molecular level, adhesion, motility and the capacity of tumor cells to invade surrounding tissue is determined by diverse groups of cell surface glycoproteins that influence a wide variety of biological processes by linking cell-cell and cell-matrix interactions to signaling pathways. Among those, tetraspanins play a special role as transmembrane adaptor proteins in functional complexes with adhesion molecules and other proteins that are implicated in various cell types in the regulation of cell differentiation, proliferation, motility, and invasion. For several malignant diseases, e.g. breast, colon, lung, and ovarian cancer, the levels of expression of the best-studied tetraspanin CD9 and other members of the protein family were found to correlate with the stage of tumor progression or appearance of metastases. Tspan-1 is a yet weakly characterized tetraspanin which, on basis of expression profiling with cDNA microarrays or differential display techniques, was suggested to contribute substantially to the malignant phenotypes in several human malignancies including pancreatic, cervical and ovarian cancer. By immunization of rabbits with synthetic peptides representing parts of the Tspan-1 extracellular domains, we generated a set of novel anti-Tspan1 antibodies suitable for Western blot analyses and immunohistochemistry. We describe the cellular localization of Tspan-1 in various types of ovarian carcinomas which, in most cases, strongly expressed this tetraspanin. In addition, we measured Tspan-1 expression of a panel of ovarian carcinoma-derived cell lines by real-time RT-PCR. Our results indicate that Tspan-1 is a relevant characteristic of ovarian cancer cells and suggest further analyses to identify molecular partners in membrane protein complexes that modulate their proliferation and invasiveness.