UBC Theses and Dissertations
Characterizations of a tumor-associated antigen COX-1 Sheu, Fong-Shyong
By using modified hybridoma technology, monoclonal antibodies against an ovarian tumor cell line, OC-3-VGH, were generated in Dr. Lee's laboratory. Among these antibodies, RP 215 was shown to react specifically with a tumor-associated antigen, COX-1. On SDS gel, COX-1 has a molecular weight of 60 KD and exists as an aggregate in the natural- state. A highly purified COX-1 was obtained mainly by immunoaffirtity chromatography, with RP 215 as the affinity ligand, from the shed medium of cultured tumor cells. A solid phase enzyme immunoassay was established using RP 215 as the capturing and the detecting antibody with a sensitivity of 1 AU/ml. This immunoassay kit could be used to determine the levels of COX-1 in the culture medium and in the sera of cancer patients. COX-1 was characterized under a variety of experimental conditions. At temperatures higher than 50°C or in the presence of trypsin at 37°C, COX-1 immunoactivity was found to decrease with incubation time. However, COX-1 was not affected by incubation with carbohydrate-digestive enzymes including neuraminidase, Beta-galactosidase and fucosidase or carbohydrate modifying agents such as NaIO₄. Concanavalin A had no effect on the immunoactivity of COX-1 to RP 215. Furthermore, rabbit antisera against COX-1 were raised, and these polyclonal antisera were shown to exhibitsimilar immunoactivity to that of RP 215 monoclonal antibody. Using the established sandwich enzyme immunoassay, serum levels of COX-1 among patients with ovarian or cervical cancers were determined retrospectively through interlaboratory evaluations and collaborations. Compared to those of normal individuals and benign tumors, serum levels of COX-1 were significantly elevated and can be correlated to the progression of the disease among cancer patients. Preliminary data indicated the COX-1 can complement other established tumor markers such as CA 125 for the purpose of monitoring patients with ovarian or cervical cancers.
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