Growth hormone and prostate cancer growth and metastasis in tumor-bearing animals.

Abstract

Growth hormone has been shown to stimulate muscle protein synthesis, improve nitrogen balance and promote wound healing in a variety of catabolic states. Its role in the tumor-bearing host is controversial because of its potential to stimulate tumor growth. Twenty-seven Lobund/Wistar rats bearing a subcutaneous prostate tumor implant (PA-III), were randomized to receive growth hormone (1,000 mU/kg/day) or placebo (saline) in the protein-fed and protein-depleted states. Body weight, primary tumor growth and tumor metastasis were assessed to determine the effect of growth hormone and dietary protein intake on these parameters. Growth hormone significantly increased carcass weight in protein-fed animals and reduced carcass weight loss in protein-depleted animals. No stimulation of primary tumor growth occurred and tumor:body weight ratio was similar in all treatment groups. Inhibition of spontaneous pulmonary metastasis occurred following growth hormone therapy in protein-fed and protein-depleted animals. Thus, in this tumor model, growth hormone was found to support host growth selectively and inhibit pulmonary metastasis and may be used as an adjunct to treat cancer cachexia effectively in the future.