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Amino Acids in Epidermal Carcinogenesis in Mice^{* ,}

(From the Division of Cancer Research, Department of Anatomy, Washington University School of Medicine, St. Louis 10, Missouri, and The Lilly Research Laboratories, Indianapolis, Indiana)

1. The contents of lysine, isoleucine, leucine, methionine, valine, phenylalanine, threonine, histidine, glutamic acid, cystine, arginine, and tryptophan were determined by microbiological methods in hydrolysates of dried ground samples of whole normal mouse epidermis, of epidermis of mice receiving varying numbers of standardized applications of methylcholanthrene (MC) in benzene or of benzene alone, and of transplantable squamous cell carcinomata originally derived from a carcinoma produced on the back of a mouse by the application of the carcinogen.

2. The sum of the 12 amino acids showed highly significant increases over normal as a result of the treatment with MC and in the tumors when the results were expressed either in terms of mg. of amino acids per 100 mg. of dry weight of tissue or mg. of amino acid nitrogen per 100 mg. of tissue nitrogen. Benzene treatment produced a smaller relative increase in amino acid nitrogen and no significant change on the dry weight basis.

3. From a consideration of the individual values for the amino acids in the tissues studied it was concluded that benzene alone produced significant changes in amino acid distribution in the epidermis and that more extensive and different alterations were produced when MC in benzene was applied. The distribution of amino acids in the carcinomata was similar in most respects to that found in the precancerous hyperplastic epidermis.

^* Aided by grants from the U.S. Public Health Service and The Charles F. Kettering Foundation.

Presented in part before the Fourth International Cancer Research Congress held in St. Louis, Mo., Sept. 2–7, 1947.