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Biphasic Changes of Tryptophan Peroxidase Level in Tumor-bearing Mice and in Mice Subjected to Growth Hormone and Stress^{* ,}

( Cancer Research Institute, New England Deaconess Hospital, and the Department of Biological Chemistry, Harvard Medical School, Boston, Mass.)

Quantitative assays were made of the liver tryptophan peroxidase activity in 38 controls, and 46 C57BL/6 mice bearing subcutaneous implants of the Lewis sarcoma 241.

A depression of the enzymatic activity to one-half the control level was found in mice bearing tumors less than 4.5 ml. in volume, and during the initial 18-day period of tumor growth.

Mice with tumors of a size larger than 4.5 ml. or after the first 18 days of tumor growth showed significant increases in the enzyme activity over the controls.

Changes analogous to this biphasic depression and elevation of the enzyme level in tumor-bearing animals could be produced in control mice by growth hormone and by adrenal-stimulating stress, respectively.

^* This investigation was supported by Grant A567 from the National Institute of Arthritis and Metabolic Diseases, United States Public Health Service, and by United States Atomic Energy Commission Contract No. AT (30-1)-901 with the New England Deaconess Hospital.

A preliminary report of this work was presented at the Meeting of the American Association for Cancer Research, Atlantic City, April, 1954 (28).

Received 7/16/56.