Amino acid requirements of a rat sarcoma as determined by a stem cell assay.

Knowledge of the amino acid requirements of a neoplasm is valuable in determining optimal nutritional support and antineoplastic therapy for the tumor-bearing host. The standard human tumor stem cell assay (HTSCA) was modified by reducing an individual amino acid below the normal plasma concentration of the Fischer 344 rat. All other amino acids were maintained at levels sufficient for normal HTSCA tumor colony growth. Twenty-two amino acids were tested at a mean concentration of 12% (range 3% to 35%) of their normal plasma level. Results indicated that all amino acids except L-glutamine and L-asparagine were present in sufficient quantity for normal tumor growth. Dose-response curves have shown more than 70% inhibition of tumor growth with a glutamine concentration of 50% and an asparagine concentration of 25%. Glutamine and asparagine levels of 4% and 1%, respectively, resulted in 100% inhibition. The data indicate that rat sarcoma stem cells are sensitive to decreased glutamine and asparagine concentrations.