Effect of Pituitary Growth Hormone on Transplantable Mouse Tumors

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Abstract
In a recent study of the effect of growth hormone on a mammary adenocarcinoma transplantable in DBA/1 mice, Mirand and Hoffman reported that tumor volume was significantly increased when the host mouse was given hormone beginning at the time of inoculation. Reid''s review indicates that mouse tumor response to growth hormone was not a consistent finding. We examined this problem further with more quantitative experiments on 4 mouse tumors using purified growth hormone which we assayed for its effect on hypopituitary dwarf mice. From our studies the following data are presented: (1) Growth hormone was assayed for potency by its effect on body weights of adult hypopituitary dwarf mice. Their body weights increased by more than a factor of 2 during 4 weeks'' administration of the hormone. (2) Four different transplantable tumors responded to growth hormone given to the host mice. The latent period of the tumor is reduced and the mass of the tumor is much greater than that of the controls. (3) Tumor bearing host mice showed a significant body weight increase under action of growth hormone. Enhanced tumor growth due to the hormone did not reduce the host body weight. (4) Maximum average tumor mass attained by the 4 different tumors is independent of the host body weight. While growth hormone increases the tumor as well as the hosts weight, average mass of tumor grown is constant and characteristic of the tumor-host combination. (5) Data suggest that growth hormone plays a supportive role in mammary carcinoma.