INVOLVEMENT OF METHIONINE IN THE SYNTHESIS OF CERTAIN MEMBRANE-ASSOCIATED NUCLEOTIDE SUGARS BY HUMAN AMNION (WISH) CELLS

A plasma membrane preparation from human amnion (WISH) cells contained uridine diphosphate sugars and methyl-uridine diphosphate (mUDP) suga rs. The synthesis of mUDP-glucose, mUDP-mannose, and mUDP-fucose by th e membrane preparation occurred when supplemented with uridine-5'-diph osphate-glucose and S-adenosyl-L-methionine. It is suggested that this newly recognized route for fucose biosynthesis might be employed by c ertain transformed cells, and may partly account for the methionine de pendence of certain human tumors. Additionally, it is suggested that, in colon cancer, a deficiency of folic acid and methionine might affec t mUDP-sugar biosynthesis rather than the methylation of DNA.