Protein transfer in tumor-bearing rats.

Abstract

Summary The following evidence was presented in support of the view that protein is transferred from the body tissues of Walker-carcinoma rats to the growing tumor without prior complete hydrolysis to free amino acids: ( a ) The level of conjugated amino acids in protein-free tissue extracts of tumor-bearing rats was higher than that in control animals. ( b ) Plasma protein labeled with leucine-C 14 was utilized by the tumors without extensive release of the labeled leucine in free form. The observation that actively growing labeled tumors released isotopic carbon to the metabolic pool argues against the contention that nitrogen metabolism in cancer tissue is strictly a one-way passage.