Detection of amino acids as possible promoters of bladder cancer in rats by measuring their enhancement of agglutination of bladder cells by concanavalin A.

The effects of amino acids on the enhanced agglutinability of bladder cells with concanavalin A induced by subcarcinogenic treatment with N-butyl-N-(4-hydroxybutyl)nitrosamine were examined. The amino acids examined were L-alanine, L-arginine, L-asparagine, L-aspartic acid, L-cysteine, L-glutamic acid, L-glutamine, L-glycine, DL- and L-histidine, L-hydroxyproline, L-isoleucine, D- and L-leucine, L-lysine, L-methionine, DL- and L-phenylalanine, L-proline, L-serine, L-threonine, DL-, D- and L-tryptophan, L-tyrosine and D- and L-valine. They were added to powdered diet at a concentration of 2.0%. L-Leucine, L-isoleucine, L-valine, DL- and D-tryptophan prolonged the period during which the bladder cells showed enhanced agglutinability with concanavalin A. Leupeptin, a protease inhibitor, and L-leucyl-L-leucine were also examined at a concentration of 0.1% because of their similar chemical structures, and were found to have the same effect. The tumor-promoting effects of DL-tryptophan and leupeptin have already been established by in vivo carcinogenesis experiments. The effects of L-leucine, L-isoleucine, L-valine, D-tryptophan and L-leucyl-L-leucine, detected by this short term assay, suggest that these compounds may also be promoters of bladder cancer in rats.