Activity and subunit composition of proteasomes in head and cervical squamous cell carcinomas.

The development of malignant neoplasm of the head and neck is related to the state of intracellular proteasome system. Elevation of total activity of proteasomes and specific activity of 20S proteasomal pool are accompanied by changes in proteasomal composition. Tumor size correlated with the content of regulatory proteasomal complex PA28. In the presence of regional metastases, 26S proteasome activity decreases and the content of proteasome immune subunit LMP7 in the tumor increases.