Changes in Proteasome Chymotrypsin-Like Activity during the Development of Human Mammary and Thyroid Carcinomas

Changes in the proteasome chymotrypsin-like activity in mammary and thyroid carcinomas in comparison with the adjacent tissue were studied at stages T1-4 N0-3 M0 and T2-3 N0-1 M0, respectively. The activities changed in a wave-like manner over the course of mammary carcinoma growth in cases with and without metastases. The minimum increment of the activity in the tumor was recorded during the T2N0 stage in the absence of local metastases. The increment of the activity reached the peak in N1 tumors of the same size with metastases. The activities in the tumor and adjacent tissues virtually did not differ during the T3-4 N1-3 stages. The time course of proteasome activity changes in thyroid tumors of the studied stages was similar to that in mammary carcinoma. The results can be used for development of methods for evaluating the aggressiveness of mammary and thyroid tumors.