Cobalamin and folate binding proteins in human tumour tissue.

Abstract

The serum of an 84 yr old man with disseminated carcinoma contained extremely high concentrations of cobalamin and of a cobalamin-binding protein with transcobalamin I characteristics. Tumor tissue samples obtained at necropsy contained considerably higher concentrations of cobalamin-binding protein (R-binder) than normal tissues. Tumor tissues also contained increased concentrations of specific folate-binding protein. In all tissues studied a close correlation existed between unsaturated cobalamin and unsaturated folate binding and between total cobalamin and total folate binding. Related mechanisms for the synthesis of cobalamin-binding proteins of the R-binder class and folate-binding proteins by tumor tissue are suggested.