[CANCER RESEARCH 35, 670-672, March 1975] SUMMARY Sialyltransferase activity was measured in plasma sam pies using desialated fetuin as the acceptor and cytidine 5'-phosphate-sialic acid as donor. The data show an in creased enzyme level in 56 of 65 cancer patients studied, as compared with normal control values. The enzyme was not significantly elevated during lactation or in liver cirrhosis, but it was elevated in rheumatoid arthritis. Of the patients with cancer, 35 showed plasma enzyme levels above any value encountered in rheumatoid arthritis plasmas. The determinants of enzyme level in cancer appear to be complex; monitoring of plasma sialyltransferase may be of value in measuring tumor progression, metastatic involve ment, or success of therapeutic programs. INTRODUCTION One of the distinguishing features of the cancer cell is a surface that differs in many respects from its normal counterpart (for a recent review of this topic, see Ref. I 2). It is not surprising, therefore, that several types of neoplastic transformation are accompanied by alterations in the composition ofcell glycoproteins which are (20, 21) a major structural component of the cell surface. One such altera tion is an elevation in the level of sialic acid on the cell surface (22, 23); levels of enzyme activity involved in transfer of sialic acid residues from CMP-sialic acid to suitable acceptors must be elevated in such transformed cells. The data are not clear-cut and results may depend on the assay system in use, choice of acceptors, growth rate of cells being examined, and, where relevant, host factors (3, I I, 13, 19, 23). Recently, Bosmann and Hall (6) reported an unambiguous increase in sialytransferase levels in breast and colon tumor tissue as compared with adjoining normal tissue. In this study we have compared plasma sialyltrans ferase levels in plasma of normal donors and patients with neoplastic and selected nonneoplastic disease. The data show a generalized increase in enzyme level in neoplastic disease, but the determinants of enzyme level are not yet elucidated. ‘ Supported in part by NIH Grants CA 16053 and CA 07177. 2 Professor of Pharmacology and Oncology, Wayne State University School of Medicine, Detroit, Mich. 3 Summer Research Fellow from the Royal Free Hospital School of Medicine, University of London, London, England. Received Sepatember 9, 1974: accepted November 13, 1974. MATERIALS AND METHODS Plasma samples were collected in citrate tubes, the red cells were removed by centrifugation, and the plasma was used directly or stored frozen for I to 3 days. Under such conditions, enzyme values were not affected. Enzyme activity was measured in a system containing I nmole of CMP-['4C]sialic acid (200 Ci/mole), 500 jzg of desialated fetuin (4), 15 MM MnCl2 , 10 @tMN-2-hydroxyethylpipera zine-N-2'-ethanesulfonic acid buffer at pH 6.5, and 0.02% Triton X-lOO in a total volume of I 15 zl. Each tube contained 25 @l of plasma (2 to 3 mg of protein) prepared as described above. Incubations were terminated after 30 mm by addition of I % phosphotungstic acid in 0. 1 N HCI. The precipitates were washed with 10% trichloroacetic acid twice and once with ethanol:ether (2: 1) and solubilized with NCS solubilizer (Amersham/Searle Corp., Arlington Heights, Ill.): and radioactivity was measured by liquid scintillation techniques. In some experiments Mn2@ was replaced with an equivalent amount of EDTA, the.pI-I of the buffer was changed, and other anticoagulants were used, as described below. All incubations were carried out at 37°. High-voltage paper electrophoresis of reaction mixtures was sometimes carried out (10). Endogenous levels of enzyme activity could be measured in the absence of added desialized fetuin. The measurements used here were carried out using a saturating level of the desialized fetuin acceptor to measure total capacity for sialyltransferase activity. RESULTS The procedure described above is based on methods in general use (I, 3, 4, 6, 9—1, 13, 23, 24). The choice of the anticoagulant was critical; heparinized or EDTA-treated blood was unsatisfactory (Table I). The optimal pH was 6.5 for all samplestested. Addition ofTriton X-lOO, a non-ionic detergent, did not alter activity but aided in eliminating appearance of insoluble material especially during storage. Use of native, nondesialized fetuin resulted in a substantial loss of acceptor activity. In other studies, we found negligi ble sialidase activity in these samples. Enzyme activity was proportional to the amount of added plasma and to time of incubation. Mixtures of.plasmas from normal subjects and cancer patients showed expected values; no evidence for activators or inhibitors could be demonstrated. The data compiled (Chart 1) show comparisons using plasma samples from normal donors, lactating women, and CANCER RESEARCH VOL. 35 670 Elevated Plasma Sialyltransferase in the Cancer Patient' David Kessel2 and Janet Allen3 Departments of Oncology and Pharmacology, Wayne State University School of Medicine, and the Michigan Cancer Foundation, Detroit, Michigan 48201 on August 4, 2015. © 1975 American Association for Cancer Research. cancerres.aacrjournals.org Downloaded from