Pattern of MHC class I and immune proteasome expression in Walker 256 tumor during growth and regression in Brattleboro rats with the hereditary defect of arginine-vasopressin synthesis.

Dynamics of the expression of MHC class I, immune proteasomes and proteasome regulators 19S, PA28, total proteasome pool and proteasome chymotrypsin-like activity in Walker 256 tumor after implantation into Brattleboro rats with the hereditary defect of arginine-vasopressin synthesis was studied. The tumor growth and regression in Brattleboro rats were accompanied by changes in the proteasome subunit level unlike the tumor growth in WAG rats with normal expression of arginine-vasopressin gene. In the tumor implanted into Brattleboro rats the immune proteasome level was maximal between days 14 and 17, when the tumor underwent regression. Conversely, the expression of proteasome regulators tended to decrease during this period. Immune proteasomes are known to produce antigen epitopes for MHC class I to be presented to CD8+ T lymphocytes. Enhanced expression of immune proteasomes coincided with the recovery of MHC class I expression, suggesting the efficient presentation of tumor antigens in Brattleboro rats.

Proteasomes in Patient Rectal Cancer and Different Intestine Locations: Where Does Proteasome Pool Change?

A special problem in the surgery of rectal cancer is connected with a need for appropriate removal of intestine parts, along with the tumor, including the fragment close to the sphincter. To determine the length of fragments to remove, it is necessary to reveal areas without changes in molecule functioning, specific for tumor. The purpose of the present study was to investigate functioning the proteasomes, the main actors in protein hydrolysis, in patient rectal adenocarcinoma and different intestine locations. Chymotrypsin-like and caspase-like activities, open to complex influence of different factors, were analyzed in 43-54 samples by Suc-LLVY-AMC- and Z-LLE-AMC-hydrolysis correspondingly. Both activities may be arranged by the decrease in the location row: cancer→adjacent tissue→proximal (8-20 cm from tumor) and distal (2 and 4 cm from tumor) sides. These activities did not differ noticeably in proximal and distal locations. Similar patterns were detected for the activities and expression of immune subunits LMP2 and LMP7 and expression of 19S and PA28αß activators. The largest changes in tumor were related to proteasome subtype containing LMP2 and PA28αß that was demonstrated by native electrophoresis. Thus, the results indicate a significance of subtype LMP2-PA28αß for tumor and absence of changes in proteasome pool in distal fragments of 2-4 cm from tumor.

New approach to study of T cellular immunity development: parallel investigation of lymphoid organ formation and changes in immune proteasome amount in rat early ontogenesis.

The expression pattern and distribution of proteasome immune subunits LMP7 and LMP2 in the developing rat spleen and liver as well as the periarterial lymphoid sheath formation were investigated. LMP7 and LMP2 were detected by immunoblotting in the spleen on the 21st embryonic day and during the first postnatal days in equal amounts. Their levels increased by the 8th and 18th postnatal days. Double immunofluorescent labeling the spleen cells revealed LMP7 and LMP2 in T and B lymphocytes localized in the red pulp in embryogenesis. Few T lymphocytes were discovered in periarterial zones on the 8th postnatal day. T lymphocytes filled these zones and formed lymphoid sheaths by the 18-19th day. In the liver, LMP7 and LMP2 were revealed by the 17-19th postnatal day. Immunofluorescent analysis showed their presence in hepatocytes at this period. The data suggest that T cell-mediated immune response in relation to hepatocytes is possible beginning from 18th to 19th postnatal day.