Thymosinα1 is chemopreventive for lung adenoma formation in A/J mice

The effects of thymosin (THN) alpha1 were investigated using the urethane injection carcinogenesis A/J mouse model. Lung adenomas were observed 2.5, 3, and 4 months after urethane injection (400 mg/kg i.p.) into female A/J mice. Daily administration of THN alpha1 (0.4 mg/kg, s.c.) reduced lung adenoma multiplicity significantly, by approximately 45, 40, and 17%, respectively, 2.5, 3, and 4 months after urethane injection. Animals treated with THN alpha1 had a significantly greater white cell density than control A/J mice. Endogenous THN alpha1-like peptides were detected in the mouse lung. By radioimmunoassay and by Western blot, prothymosin alpha, was detected in the mouse lung. By immunocytochemistry, THN alpha1-like peptides were detected in all lung compartments including the bronchus, adenoma, bronchioles, and alveoli. These results indicate that exogenous THN alpha1 prevents lung carcinogenesis in A/J mice. (C) 2000 Published by Elsevier Science Ireland Ltd.