Cysteine conjugate beta-lyase activity in human renal carcinomas.
Cysteine conjugate beta-lyase, an enzyme that converts cysteine S-conjugates to free thiols, pyruvate and ammonia, is normally expressed primarily in the liver and kidney. In theory, this selective distribution affords the opportunity to target thiol-containing drugs to these organs and, perhaps, to tumors derived from them. To assess the potential for delivery of such drugs to kidney-derived tissue, we have used a typical beta-lyase substrate, S-(2-benzothiazolyl)-L-cysteine, to measure the beta-lyase activity in normal and tumor tissue of kidneys removed from patients with renal carcinoma. Although considerable heterogeneity in enzyme activity levels was observed in normal and tumor-derived samples, a high proportion of tumor samples had enzyme activity that was at least 50% of that observed in adjacent normal tissue. Frequently, hypoxanthine-guanine phosphoribosyltransferase activity was observed to be greater in the tumor than in normal tissue. These results may aid in the development of therapy for renal carcinomas.
Nelson
J A
JA
Department of Experimental Pediatrics, University of Texas M. D. Anderson Cancer Center, Houston 77030, USA.
Pan
B F
BF
Swanson
D A
DA
Elfarra
A A
AA
D000328:Adult; D000368:Aged; D052160:Benzothiazoles; D013437:Carbon-Sulfur Lyases; D002292:Carcinoma, Renal Cell / Q000201:enzymology*; D003545:Cysteine / Q000031:analogs & derivatives; D005260:Female; D006801:Humans; D007041:Hypoxanthine Phosphoribosyltransferase / Q000378:metabolism; D007680:Kidney Neoplasms / Q000201:enzymology*; D008190:Lyases / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D013379:Substrate Specificity
D052160:Benzothiazoles; C034680:S-(2-benzothiazolyl)cysteine; D007041:Hypoxanthine Phosphoribosyltransferase; D008190:Lyases; D013437:Carbon-Sulfur Lyases; C019969:S-alkylcysteine lyase; D003545:Cysteine