Effects of cysteine upon tumor cells.
Cysteine had been reported to increase survival time in thymoma-bearing mice and the interpretation suggested was that this was due to inhibition of a collagenase activity associated with some tumor cells by a chelating action of cysteine. In the present work it was shown that cysteine was a particularly potent inhibitor of amino acid transport into S37 ascites tumor cells, raising another possible interpretation of the earlier data. Sarcomas have previously been reported to lack collagenase activity; a survival study using S37 cells was therefore undertaken in an attempt to distinguish between possible interpretations of the earlier data involving thymomas. A null result was obtained with either cysteine or EDTA, reinforcing the earlier interpretation that survival enhancement with thymoma-bearing mice was due to an effect on collagenase. Other sulfhydryl analogs were found to inhibit transport also, and the effect was more pronounced with system L than system A. The reason for cysteine's particularly potent action on amino acid transport may be associated either with chelation of a metal ion involved in transport, or the involvement of the gamma-glutamyl cycle in the support of amino acid transport.
D000596:Amino Acids / Q000378:metabolism; D000818:Animals; D003545:Cysteine / Q000494:pharmacology*; D004492:Edetic Acid / Q000494:pharmacology; D008297:Male; D051379:Mice; D003012:Microbial Collagenase / Q000037:antagonists & inhibitors; D012513:Sarcoma, Experimental / Q000188:drug therapy* / Q000378:metabolism; D013438:Sulfhydryl Compounds / Q000494:pharmacology; D005723:gamma-Glutamyltransferase / Q000378:metabolism
D000596:Amino Acids; D013438:Sulfhydryl Compounds; D004492:Edetic Acid; D005723:gamma-Glutamyltransferase; D003012:Microbial Collagenase; D003545:Cysteine