[Features of immune proteasome expression in the development of rat central nervous system]

Formation of the central nervous system in ontogeny and function in adult mammals are controlled by universal ubiquitin-proteasome proteolytic system. The aim of this work was to study the dynamics of expression of immune proteasomes in comparison with the dynamics of ChLA and CLA proteasome and expression of the transcription factor Zif268 in the structures of the brain (cortex, hippocampus, and brainstem) in embryonic (E19, E21 days of embryonic development) and early postnatal (P1, P3, P4, P5, P7, P15 days of post-natal development) development in rats. ChLA and CLA in clarified homogenates of rat brain structures were determined by hydrolysis of fluorogenic commercial oligopeptides Suc-LLVY-AMC and Z-LLG-AMC, respectively. In the cortex and hippocampus of the brain was observed upregulation of immune subunits LMP7 during the active formation of biochemical mediatory structure and efferent neuronal projections at the period P7-P15. In the cerebral cortex during this period ChLA and CLA also are increased. In all structures of the brain the LMP2 immune subunits content was significantly increased at the period P7-P15. Contents of proteolytic constitutive subunit β1 in all structures decreased by P4 compare to P1 levels and was increased on P15 relative to the P1 levels. However, the level of expression of proteolytic constitutive subunit β5 increased in cortex, hippocampus and brainstem from E21 and reached maximum values on P3, P5 and P1, respectively with a sharp decrease to P7 in all studied structures. In all structures expression of LM P2 immune subunits and β1 constitutive subunits increased simultaneously with LMP7 immune subunits and sharply on P15. Also shown a positive correlation of increased expression regulator PA28 and constitutive β5 subunits in the hippocampus during the period P3-P5 and in the brainstem at the period P1-P5. The peculiarity of the studied brain regions during P7-P15 of rat early development is a correlation of expression of immune subunits LMP2 and LMP7 proteasome and ChLA with the expression of the transcription factor Zif268. Probably immune proteasome plays an important role in the regulation of key biochemical processes in the early ontogenesis of the central nervous system and are necessary for the emergence and realization of synaptic plasticity in the brain structures studied in rats.

Proteasome functioning in breast cancer: connection with clinical-pathological factors

Breast cancer is one of four oncology diseases that are most widespread in the world. Moreover, breast cancer is one of leading causes of cancer-related deaths in female population within economically developed regions of the world. So far, detection of new mechanisms of breast cancer development is very important for discovery of novel areas in which therapy approaches may be elaborated. The objective of the present study is to investigate involvement of proteasomes, which cleave up to 90% of cellular proteins and regulate numerous cellular processes, in mechanisms of breast cancer development. Proteasome characteristics in 106 patient breast carcinomas and adjacent tissues, as well as relationships of detected proteasome parameters with clinical-pathological factors, were investigated. Proteasome chymotrypsin-like activity was evaluated by hydrolysis of fluorogenic peptide Suc-LLVY-AMC. The expression of proteasome subunits was studied by Western-blotting and immunohistochemistry. The wide range of chymotrypsin-like activity in tumors was detected. Activity in tumors was higher if compared to adjacent tissues in 76 from 106 patients. Multiple analysis of generalized linear models discovered that in estrogen α-receptor absence, tumor growth was connected with the enhanced expression of proteasome immune subunit LMP2 and proteasome activator PA700 in tumor (at 95% confidence interval). Besides, by this analysis we detected some phenomena in adjacent tissue, which are important for tumor growth and progression of lymph node metastasis in estrogen α-receptor absence. These phenomena are related to the enhanced expression of activator PA700 and immune subunit LMP7. Thus, breast cancer development is connected with functioning of immune proteasome forms and activator PA700 in patients without estrogen α-receptors in tumor cells. These results could indicate a field for search of new therapy approaches for this category of patients, which has the worst prognosis of health recovery.

[Proteasome activity in tumors of female reproductive system]

Proteasomes (multiproteinase protein complexes) are known to play an important role in cancer pathogenesis, however, few information about their activity in human tumor tissues is available so far. We studied chymotrypsin-like activity of proteasomes in tissues of breast cancer (BC) and endometrial cancer (EC). The chymotrypsin-like total proteasome activity and the 20S and 26S proteasome activity in malignant tissues were shown to be significantly higher in malignant tumors than in normal tissues. No increase in proteasome activity was registered with larger tumor size in both BC and EC, whereas proteasome activity was changed with respect to the extent of tumor involvement. In breast cancer tissues, significant reductions in the total and the 26S proteaome activities were observed in tumors with regional lymph node metastases as compared to tumors without metastases. In endometrial cancer tissues, the total proteasome activity and the 20S and 26S proteasome activities were increased as the depth of myometrial invasion. The data obtained indicate that the proteasome acyivity is significantly changed in the process of cancerogenesis and further study is needed to develop new additional prognostic criteria and effective anti-tumor agents in molecular-directed therapy.