EFFECT OF GROWTH-HORMONE ON TUMOR AND HOST IN AN ANIMAL-MODEL

Background: The relative effects of growth hormone on tumor versus hos t growth and protein metabolism are not known. This study examines the influence of recombinant rat growth hormone (r-rGH) on host and tumor growth, host body composition, and protein synthesis of tumor and hos t in tumor-bearing rats. Methods: After left flank implantation of met hylcholanthrene-induced sarcoma, 28 Fischer rats with palpable tumor w ere treated with s.c. saline or 1 mg/kg/day r-rGH for 11 days. At deat h, fractional protein synthetic rates (FSRs) of tumor, liver, and gast rocnemius muscle were determined. In a separate experiment, 27 tumor-b earing rats received saline or 1 mg/kg/day r-rGH for 2 weeks. Tumor an d host growth and host body composition were analyzed. Results: Animal s treated with r-rGH had significantly higher liver FSR than did contr ols (233 +/- 27%/day vs. 110 +/- 4%/day, respectively). No significant differences were associated with growth hormone administration with r espect to tumor growth, host composition, or FSR of tumor or muscle. C onclusions: Growth hormone stimulates liver protein synthesis, without changing tumor growth, protein synthesis, or host composition in this rat sarcoma model. Further investigation of growth hormone as an anti cachectic agent is warranted.