keratan-sulfate and Testicular-Neoplasms

Germ cell tumours, the most common solid cancers in young males, display pluripotentiality for embryonal and somatic differentiation. Specific surface antigens are useful in the study of cellular differentiation and for clinical diagnosis. A mouse monoclonal antibody (4C4-mAb) has been developed against a human embryonal carcinoma (EC) cell line (NCR-G3) isolated from a combined form of testicular germ cell tumour. On immunohistological and immuno-electron microscopic examination, the 4C4 antigen (4C4) was detected on the surface of NCR-G3 and gold particles were exclusively detected on the microvilli of the cells. In both formalin-fixed paraffin wax sections and touch-smear specimens, 4C4 was detected specifically in EC, while the antigen was not expressed in other types of germ cell tumour or in the other solid tumours tested. Tunicamycin diminished the antigenicity of NCR-G3 cells. In biochemical studies, 4C4 was found in a high molecular weight region ranging from 1 x 10(6) to 1 x 10(7) kD, which disappeared after periodate treatment. The density of 4C4 was 1.5 g/cm(3) after equilibrium centrifugation. These results imply that 4C4 is a proteoglycan. Furthermore, endo- and exo-glycosidase treatment revealed that 4C4 is a keratan sulphate proteoglycan that contains sialyl and fucosyl moieties. With EC-specific and formalin-resistant characteristics, 4C4 may be a specific marker for diagnosing EC among a variety of germ cell tumours.

Topics: Animals; Antibodies, Monoclonal; Antibody Specificity; Biomarkers, Tumor; Chondroitin Sulfate Proteoglycans; Germinoma; Humans; Immunoenzyme Techniques; Keratan Sulfate; Lumican; Male; Mice; Mice, Inbred BALB C; Neoplasm Proteins; Neoplasm Transplantation; Testicular Neoplasms; Tumor Cells, Cultured

We recently purified a 200 kD peanut agglutinin-binding glycoprotein from the embryonal carcinoma cell line HT-E (833K) that is expressed selectively in nonseminomatous germ cell tumors. We now further characterize gp200 using Western blot analysis to compare normal and malignant testicular germ cells for reactivity to peanut agglutinin, a plant lectin that recognizes terminal D-galactosyl residues, and GCTM-2, a monoclonal antibody that recognizes a 200 kD keratan-sulfate proteoglycan on human embryonal carcinoma. The results indicate that normal germ cells express gp200 as a membrane-bound 230 kD glycoform that expresses terminal galactose residues. This 230 kD glycoprotein is absent on spermatozoa but present on seminomatous germ cell tumors and somatic tissue and does not express terminal galactose on its carbohydrate side chains. In contrast, nonseminomatous germ cell tumors express a heavily sialylated glycoform of gp200 that does express terminal galactose residues. These results describe a glycoprotein that exists in several glycoforms in normal and malignant testicular germ cells. The differential expression of these glycoforms may help in understanding the ontogeny of germ cell tumors.

Topics: Blotting, Western; Carcinoma, Embryonal; Galactose; Germinoma; Glycoproteins; Humans; Keratan Sulfate; Male; Membrane Glycoproteins; Molecular Weight; Receptors, Mitogen; Seminoma; Sialoglycoproteins; Spermatozoa; Testicular Neoplasms; Testis; Tumor Cells, Cultured