Expression of the carcinoma-associated le(a)-le(x) oligosaccharide in vertebrate endoderm and its fetal derivatives.

The extended Le(a)-Le(x) oligosaccharide, expressed as a cell surface antigen by human squamous lung carcinomas marks cancer cells of tumors having poor prognosis. In order to see if the extended Le(a)-Le(x) also has a precisely controlled pattern of expression during embryogenesis, a survey of representative vertebrate embryos and fetuses in various stages was undertaken. Embryonic and fetal cells which express the epitope are derived from embryonic endoderm. No. epitope expression was demonstrated in tissues of ectodermal or mesodermal origin. Vertebrate conservation of this endodermal cell surface carbohydrate suggests function necessary for normal growth and development with inappropriate re-expression during carcinogenesis.