Proteasome activity in tumors of the female reproductive system

Although proteasomes (multiproteinase protein complexes) are known to play an important role in cancer pathogenesis, there is little information about their activity in human tumor tissues. The chymotrypsin-like activity of proteasomes in breast cancer (BC) and endometrial cancer (EC) tissues was studied. It was shown that the chymotrypsin-like total proteasome activity and the 20S and 26S proteasome pool activities were significantly higher in malignant than in normal tissues. An increase in the size of either BC or EC tumors did not affect the proteasome activity, whereas the propagation of a malignant process did. If compared with BC non-metastatic tumors, a reliable decrease in the total activity and the 26S proteasome activity was observed in BC tumors with regional lymph node metastases. In EC tissues, the total proteasome activity and the 20S and 26S proteasome pool activities increased when the depth of tumor myometrial invasion grew. These data demonstrated that the proteasome activity significantly varied in the process of carcinogenesis. Further proteasome studies could serve as the basis for the development of new criteria for prognosis of female reproductive system cancer and the search for effective antitumor agents in targeted therapy.