[Indices of proteolysis in evaluation of resorption in bone tumors]. / Pokazateli proteoliza v otsenke rezorbtsii pri opukholiakh kosti.

Activities of acid and alkaline phosphatases, collagenase, cathepsin D, trypsin-like proteinases, alpha(1)-proteinase inhibitor (alpha(1)-PI), alpha(2)-macroglobulin (alpha(2)-MG) were measured in blood plasma and tumor tissue of patients with giant-cell tumor of the bone (GCTB) and bone chondrosarcoma. These tumors differed by enzymatic activities. GCTB is characterized by increased activity of alkaline phosphatase, while in chondrosarcoma tissue the activities of collagenase and cathepsin D were the highest. Activities of acid phosphatase, collagenase, trypsin-like proteinases were increased in the plasma of patients with both tumors; alpha(1)-PI/alpha(2)-MG ratio was increased. Bone resorption parameters correlated with proteolysis inhibitors. Activities of collagenase and acid phosphatase were increased in tumor tissue and plasma in the presence of low activities of alpha(2)-MG and increased alpha(1)-PI/alpha(2)-MG index, which seems to require special attention during the postoperative period.

The ubiquitous VA68 isoform of subunit A of the vacuolar H(+)-ATPase is highly expressed in human osteoclasts.

The 67-kDa subunit A of the vacuolar-type H(+)-ATPase carries the high affinity ATP binding site and together with the 57-kDa subunit B forms the catalytic domain. Two isoforms of subunit A, VA68 and HO68, were cloned from an osteoclastoma cDNA library. We have analyzed their respective expression patterns in different tissues by RNAase A protection and in situ hybridization. The HO68 isoform was found to be present only in the tumor originally used to construct the cDNA library, whereas the ubiquitous VA68 RNA isoform was detected in large osteoclastic cells, as well as in brian and kidney, by RNAse protection assay. Furthermore, we localized the strong signal observed in osteoclastoma RNA to the large osteoclastic cell by in situ hybridisation. These findings suggest that the subunit A highly expressed in human osteoclasts is the ubiquitous isoform, VA68.