Cystatin C and cysteine proteinases during the development and therapy of Lewis lung adenocarcinoma in mice.

We measured plasma cystatin C concentration and activity of cathepsins B and L in tumor tissue as possible markers for the efficiency of antitumor therapy and prognostic criteria for Lewis lung adenocarcinoma in mice. Plasma cystatin C concentration markedly decreased in mice with tumors. During successive therapy the increase in plasma cystatin C concentration correlated with the degree of inhibition of tumor growth. Activities of cathepsins B and L in the liver increased in animals with tumors. In mice receiving successive antitumor therapy activities of cathepsins B and L increased in tumor tissue, but decreased in the liver (compared to untreated animals).