THE EFFECT OF THYROXINE ANALOGUES ON A TRANSPLANTABLE MOUSE PITUITARY TUMOR1

Publisher Website
Google Scholar
Abstract
Twenty-seven compounds structurally related to thyroxine were tested for their effect in depressing the growth of a TSH secreting pituitary tumor. After the transplanted tumor had grown to approximately 1.5 cubic centimeters in radiothyroidectomized hosts, compounds were injected daily for various periods of time. Measurements of tumor size were made weekly. Quantitative data were obtained relating amounts of the compounds required to suppress tumor growth. Activity of the analogues was calculated in terms of relative potency compared to L-thyroxine. Triiodothyronine was the only compound as effective as L-thyroxine. No compounds were found more effective. Most analogues compare well when compared on the basis of preventing a thiouracil induced goiter and effectiveness in inhibiting tumor growth. No compound which failed to show thyroxine-like activity, by previously reported methods, was found capable of preventing tumor growth. No compound even in high doses caused the completed disappearance of established tumors.