The Carbohydrate on Human Chorionic Gonadotropin Produced by Cancer Cells
Standard hCG and its subunits in pregnancy urine and serum contain N-linked biantennary oligosaccharides (1), through which they bind the lectin Con A (2). However, as recently shown, that produced by nontrophoblastic malignancies and in vitro by choriocarcinoma cells only partially binds this lectin (Table 1). On this basis, it has been suggested that cancer cell hCG subunits have an alternative oligosaccharide structure (3, 4), or a reduced carbohydrate content or are sugar-free (4). The DoT and CaSki cell lines were established from the tumors of two patients with epidermoid carcinoma of the cervix. Immunoreactive hCG/hCGß was detected in the serum of both patients and in the spent medium from the corresponding cell lines (5, 6). The hCG from DoT and CaSki cell lines only partially binds Con A. To study this phenomenon, the hCG produced by DoT cells was compared with standard hCG in terms of its oligosaccharide structure. Methods are described whereby the oligosaccharides on trace amounts of ectopic glycoprotein can be compared to those of glycoprotein with known oligosaccharide structure. Methods, developed with mg quantities of standard hCGß, were applied to trace amounts of ectopic hCGß from DoT culture fluids.
KeywordsHuman Chorionic Gonadotropin Neuraminic Acid Liquid Scintillation Spectrometry Reductive Methylation Mannose Content
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