The role of serine and glutamine in the metabolism of malignant bone tumors and their significance in the diagnosis and prognosis of bone tumors.

Some malignant tumors of soft tissues that metastasize to bones are characterized by an insignificant increase in the levels of certain amino acids in the serum of the host. Primary malignant bone tumors, on the other hand, tend to increase significantly the concentration of amino acids in the host serum. We found that malignant transformation of bones, cartilage, and connective tissue induced changes in the metabolism of the patients which led to a significant elevation of several amino acids in their serum. Only alanine and cysteine showed a decreased level in the sera of patients with bone tumors. A significant increase in the concentration of amino acids in the sera of patients with bone tumors, as compared to control subjects, was found in serine, glutamine, leucine, isoleucine, lysine, arginine, and histidine (p less than 0.001). The elevated levels of serine and glutamine suggest their possible use in diagnostics, differential diagnostics, and in the study of therapeutic effects in these malignancies.