INSULIN-LIKE GROWTH-FACTOR-I IS NOT MITOGENIC FOR THE WALKER-256 CARCINOSARCOMA

This study was designed to determine whether intravenous infusion of r ecombinant human insulin-like growth factor 1 (IGF-1) stimulates tumor growth. In order to determine the potential interaction between nutri tion and IGF-1 administration the study was conducted in fasting rats and during continuous feeding by total parenteral nutrition. Tumor cel l cycle kinetics including labeling index, DNA synthesis time, cell cy cle time in Go/G1, and G2/M in the total cell cycle, and potential dou bling time were determined by flow cytometry after in vivo pulse label ing the rats bearing the Walker-256 Carcinosarcoma with 5'-bromo-2'-de oxyuridine (BrdUrd). The results show that IGF-1 treatment has no sign ificant effects on the proliferative characteristics of the tumor mode l regardless of the feeding status of the animal. This study provides preliminary cell-cycle kinetics data on the short-term effect of IGF-1 on tumor growth. Failure to show a significant effect of IGF-1 on the proliferative characteristics of the tumor suggests that IGF-1 may be given to cancer patients in amounts sufficient to promote weight gain without deleterious stimulation of tumor proliferation.