Spontaneous chondroma formation in CD2-Cre-driven Erk-deficient mice.

Lineage-specific Cre Tg mice are widely used to delineate the functions of genes in a tissue-specific manner. Several T-cell-specific promoter cassettes have been developed; however, the activities of those promoters in non-T cells have not been investigated extensively. Here, we report that CD2-Cre-mediated deletion of Erk proteins by generating CD2-Cre × Erk1-/-Erk2flox/flox (Erk∆CD2-Cre) mice results in abnormal cartilage hyperplasia. Histological analysis revealed that this abnormality is caused by aberrant hyperplasia of chondrocytes. The presence of Erk-deficient T cells is not required for this chondroma formation, as it was similarly observed in the absence of T cells in a CD3ε-deficient background. In addition, adoptive transfer of bone marrow cells from Erk∆CD2-Cre mice to wild-type recipients did not cause chondroma formation, suggesting that Erk-deficient non-immune cells are responsible for this abnormality. By tracing Cre-expressed tissues using a ROSA26-STOP-RFP allele, we found that the chondroma emitted RFP fluorescence, indicating that functional Cre is expressed in hyperplastic chondrocytes in Erk∆CD2-Cre mice. Furthermore, RFP+ chondrocytes were also found in an Erk-sufficient background, albeit without aberrant growth. These results suggest that unexpected expression of CD2-driven Cre in chondrocytes generates Erk-deficient chondrocytes, resulting in hyperplastic cartilage formation. Recently, two independent reports showed that CD4-Cre-mediated Ras-Erk signaling ablation led to similar abnormal cartilage formation (Guittard, G., Gallardo, D. L., Li, W. et al. 2017. Unexpected cartilage phenotype in CD4-Cre-conditional SOS-deficient mice. Front. Immunol. 8:343; Wehenkel, M., Corr, M., Guy, C. S. et al. 2017. Extracellular signal-regulated kinase signaling in CD4-expressing cells inhibits osteochondromas. Front. Immunol. 8:482). Together with these reports, our study suggests that an unexpected link exists between T-like cell and chondrocyte lineages during ontogeny.

Therapeutic potential of CAMPATH-1H in skeletal tumours.

AIMS: CD 52 is a glycosylphosphatidylinositol (GPI)-anchored glycoprotein that is expressed abundantly on all lymphocytes, monocytes, macrophages, eosinophils and in the male genital tract. To date, the physiological role of CD52 on lymphocytes has not been elucidated. However, an antibody directed to CD52 called CAMPATH-1H has been shown to be capable of depleting lymphocytes. The aim of this study was to analyse tissue and cell lines of non-neoplastic bone, cartilage and skeletal tumours for CD52 expression. METHODS AND RESULTS: The expression of CD52 mRNA and protein both in vivo and in vitro was detected. Malignant tumours showed higher CD52 expression compared to benign tumours, suggesting a role in the development and progression of bone tumours. Interestingly, immunohistochemistry and flow cytometry revealed that CD52 was expressed not only on the surface of tumour cells, but also in the cytoplasm. The results obtained in osteosarcoma cells showed that CAMPATH-1H leads to a complement-independent reduction of viable cells. CONCLUSION: CD52 is expressed in a variety of bone tumours and the in vitro studies presented herein suggest that CAMPATH-1H treatment might have therapeutic potential for osteosarcoma patients.

A case of a CD56-expressing ectomesenchymal chondromyxoid tumor of the tongue: potential diagnostic usefulness of commonly available CD56 over CD57.

Ectomesenchymal chondromyxoid tumors (ECTs) are rare. Only approximately 55 cases have been reported in the English literature. Distinguishing ECTs from soft tissue myoepithelioma (STM) is often difficult owing to morphological and immunohistochemical similarities. Here, we present a case of an ECT arising from the anterior dorsum of the tongue in a 24-year-old woman. Grossly, the tumor was soft, had a myxoid appearance, and measured 8×7×7 mm. Microscopically, it was well-demarcated, lacked a fibrous capsule, and predominantly consisted of short, spindle to ovoid cells in a myxoid background. Vimentin, glial fibrillary acidic protein (GFAP), and S-100 protein were strongly positive on immunohistochemical analysis. While CD56 was moderately immunopositive, cytokeratin (AE1/AE3) and alpha-smooth muscle actin (αSMA) showed focal weak positivity. Thus, the immunohistochemical findings suggested a diverse immunophenotype, indicating mesenchymal (vimentin and αSMA positive), neurogenic (S100, GFAP, and CD56 positive), and epithelial differentiation (cytokeratin positive). This reflected the fact that ECTs probably arise from uncommitted ectomesenchymal cells that have the potential for multilineage differentiation. The immunohistochemical staining pattern observed for ECTs slightly differs from that of STMs. Strongly positive staining for GFAP and weakly positive staining for cytokeratin are observed in ECTs, whereas the opposite is typically observed for STMs. These findings indicated that the patterns of expression on immunohistochemistry differ between ECTs and STMs, although inevitably, there was some overlap. Thus, CD56 expression in the case presented here is noteworthy, and it could potentially become an adjunct diagnostic marker for ECT instead of previously used CD57.

Biological characterization of human bone tumors. VIII. Expression of HLA-DR antigens in bone tumors and tumor-like lesions.

A total of 45 cases of bone tumors and tumor-like lesions were studied in order to determine the expression of an HLA-DR antigen by the monoclonal antibody 910-D-7, and its possible correlation with histology, using the indirect immunoperoxidase method on frozen sections. The pattern of antigen expression was nearly constant for the individual cell types, though varying in intensity, and did not depend on the biological behavior of the respective lesions. No clear correlation could be established between antigen expression and cell maturation. Although the biological significance of antigen expression in these tumors is not yet understood, it is clear that here, too, the mere presence of an HLA-DR antigen cannot be interpreted as a sign of malignant transformation.

The identity of proliferating cells in bone tumors with cartilaginous components: evaluation by double-immunohistochemical staining using proliferating cell nuclear antigen and S-100 protein.

S-100 protein (S-100) appears to be a marker for bone tumors of cartilaginous origin. Any analyses of proliferative activity in S-100-positive tumor cells, however, has not yet been presented. This study assessed the proliferative activity of those cells by means of a double-immunohistochemical staining method using proliferating cell nuclear antigen (PCNA) and S-100. The most intense reactivity for S-100 was found in the well-differentiated chondrocytes of enchondromas, osteochondromas, and osteosarcomas. On the contrary, the more immature the tumor cells were, the more intensely positive they were for PCNA. In parosteal chondrosarcoma, exceptionally, PCNA-positive as well as S-100-positive cells were abundant, suggesting that these proliferating cells produced S-100. In periosteal osteosarcoma, however, the proliferating cells labeled by PCNA revealed little reactivity for S-100. This immunohistochemical method is potentially useful to know the identity and origin of proliferating cells and may sometimes be diagnostic for bone tumors containing cartilaginous elements.

[Immunological study in carcinogenesis. Distribution of tissue incompatibility antigens (system HL-A) in oncological patients]. / Immunologicheskie issledovaniia pri kantserogeneze. Raspredelenie antigenov tkanevoi nesovmestimosti (sistemy HL-A) u onkologicheskikh bol'nykh

By means of a micromethod of lymphocytotoxic test the content of eleven HL-A antigens (1, 2, 3, 5, 7, 8, 9, 10, 11, 12 and 13) was studied in 200 healthy human subjects, 100 patients with rheumatoid polyarthritis and 82 patients with bone tumors. The latter included 50 patients with benign tumors (osteoblastoclastomas, chondroblastomas, chondromas, non-osteogenic fibromas) and 32 patients with malignant tumors (chondro- and osteosarcomas, Ewing sarcoma, malignant osteoblastoclastomas). It was found that in patients with different bone tumors antigen HL-7 was encountered reliably more frequently than in control groups, in patients with malignant tumor also antigen HL-A10 was more often detected. The most frequently observed haplotyes in oncological patients were HL-A3/7 and HL-A2/7. In patients with rheumatoid polyarthritis antigen HL-A3 was found more rarely and antigen HL-A10 more frequently than in healthy subjects. The most frequent haplotypes in this group were as follows: HL-A2/7, HL-A2/8 and HL-A11/12. The possible mechanisms of the relationship between HL-A antigens and the development of pathology are discussed. Some considerations are offered concerning the possibility to utilize HL-A typing for an accessory differential diagnosis.

[Comparative analysis of immunoreactive indices in malignant and benign bone tumors]. / Sravnitel'nyi analiz pokazatelei immunologicheskoi reaktivnosti pri zlokachestvennykh i dobrokachestvennykh opukholiakh kostei.

The paper discusses the results of a study of immunologic surveillance in patients with bone tumors. T-lymphocyte deficiency was found in 21-32% of cases only, while all patients showed changes in the level of some T-cell subpopulations and their ratio. Patients with malignant tumors (mostly osteosarcoma) revealed a lowered response to PHA and a high frequency of sensitization to tumor antigens. In those cases, serum, blood--circulating T-cells and tumor--infiltrating lymphocytes showed a suppressor activity. A moderately decreased response to PHA, a low frequency of sensitization to tumor antigens and a stimulating activity in serum, blood--circulating T-cells and lymphocytes were registered in cases of benign tumors (mainly giant cell tumors). Suppressor activity of blood T-lymphocytes was matched by a high level of TG cells, while stimulating effect--by a low one.

Immunhistochemical demonstration of different collagen types in the normal epiphyseal plate and in benign and malignant tumors of bone and cartilage.

Several benign and malignant tumors of bone and cartilage were examined by means of type-specific collagen antibodies in connection with indirect immunofluorescence technique in order to determine wether there is a positive correlation between cell morphology and gene expression as refered to the synthesis of tissue- or cell-specific collagen. In general benign bone and cartilage tumors show the collagen type corresponding to the original maternal tissue. In malignant osteogenic tumors a strong positive correlation was found between morphologic differentiation of osteosarcoma cells and tissue specific collagen synthesarcomas. Unrelated to the grade of differentiation and the type of malignant tumor, collagen type III could be demonstrated in all tumors investigated, occurring rather from vascular stroma than from the tumor cell itself.

Monoclonal antibody to human cartilage cells and its reactivities to chondrocytic tumors.

A murine monoclonal antibody (E10) was made against cultured cartilage cells. The E10 antibody binding is localized to the surface of cultured cartilage cells in suspension and is present in the cytoplasm in paraffin embedded sections. There is no reactivity with cartilage matrix, or with the matrix of cartilaginous tumors. Reactivity is removed by treatment with trypsin and hyaluronidase, but not by treatment with heparinase, neuraminidase, and chondroitinase. Regeneration of E10 antigen after trypsinization takes 48 hours in chondrocytes in tissue culture. SDS-polyacrylamide gel electrophoresis of an E10 immune precipitate of cultured chondrocytes results in two peaks: one at a very high molecular weight and a small fragment at approximately 250 kd. Specificity has been demonstrated by cytofluorometry, immunofluorescence, and immunohistochemistry, in both frozen and paraffin-embedded tissues. Positive reactivity was seen in cultured cartilage cells, chondrocytes in fetal and adult cartilage, chondrosarcomas, and chordomas. Minimal reactivity was found in a chondromyxoid liposarcoma. Acinar cells of salivary and sweat glands and mast cells in various tissues and tumors were also positive. There was no reactivity with other tissues and tumors, including myxoid and mucinous tumors and epithelial tissues.