ELEVATION OF 4-BETA-GALACTOSYLTRANSFERASE ACTIVITY FOR PARAGLOBOSIDE SYNTHESIS IN SERA OF PATIENTS WITH CANCER

Galactosyltransferase activities in sera of cancer patients were deter mined by assaying the formation of paragloboside from UDP-galactose an d lactotriaosylceramide immobilized on microtiter plates by means of t he enzyme-linked immunosorbent assay using a monoclonal antibody, H-11 , directed to paragloboside. Enzyme properties were as follows. Optimu m pH was 6.8 in cacodylate buffer, and K(m) values were 2-mu-M for lac totriaosylceramide and 29-mu-M for UDP-galactose. The enzyme activity was inhibited by the addition of alpha-lactalbumin. Glucose (20 mM) in hibited the enzyme activity in the presence of alpha-lactalbumin (0.1 mg/ml) but not in its absence. These enzyme properties are similar to those of bovine milk galactosyltransferase, indicating that the enzyme in the sera might be lactose synthetase. The enzyme activities in ser a from patients with cancer, patients with benign disease, or a refere nce sample group were assayed. The activity was below the limit of det ection (5.5 pmol/25-mu-l serum/2 h) in the reference sample group. Rem arkable elevations of the enzyme activity were observed with high inci dence in patients with cancer, especially those with blood cancer (100 %). A high incidence was observed in the progressive stage, and the en zyme activity was detected at stage 1 in lung, esophagus, stomach, col orectal, and testis cancer. The enzyme activity in sera from patients with benign disease was elevated in 22% of the patients. After effecti ve therapies, the enzyme activity decreased to below the limit of dete ction. Release of the galactosyltransferase into culture medium of can cer cells could be demonstrated. These observations suggest that the g alactosyltransferase is released from cancer tissue into the circulati on. The present method for the assay of galactosyltransferase may be u seful for the detection of patients with cancer and for monitoring neo plastic recurrence after therapy.