Salt and
detergent extracts of xenografted human embryonic
carcinoma and a human yolk sac
carcinoma were fractionated on different sets of
Sepharose columns covalently derivatized with
lactose,
asialofetuin,
melibiose,
mannan and
fucose. Successive elution by chelating
reagent and specific
sugar resulted in isolation of endogenous Ca2+-dependent and Ca2+-independent
carbohydrate-
binding proteins, as analyzed by gel electrophoresis. The
salt extracts of the embryonic
carcinoma contained a Ca2+-dependent
carbohydrate-binding protein at Mr66,000, that was undetectable in
yolk sac tumor extracts. Also, a Ca2+-independent
fucose-binding protein at Mr62,000 could be purified. In general, the pattern of
carbohydrate-
binding proteins showed quantitative and qualitative differences as compared to normal tissue. The
carbohydrate-
binding proteins were assayable as
agglutinin and showed no enzymatic activity. They can thus be defined as
lectins. Their presence within certain stages of differentiation and developmental regulation may contribute to improvement of the classification, diagnosis and
therapy of this
tumor class. These new
lectins may also be functionally related to the
stage-specific embryonic antigens like
SSEA-1.